Every biomedical imaging technique exploitsdifferent physical principles and can provide peculiarinformation, which is often unachievable with differenttechniques and can be further enhanced by the employment ofsuitable contrast agents (CAs). However, each imaging techniquetypically requires its own specific CAs, with correspondingincrements of procedure duration, costs and invasiveness for thepatients, who should undergo two injections. In the last years,great effort has been addressed toward the development ofmultimodal CAs that can be real-time detected by differenttechniques. In this context, we developed a new type of bimodalnanoparticles (NPs), consisting of silica nanospheres (NSs)covered by an outer shell of smaller superparamagnetic NPs, tobe used as dual-mode imaging CAs for ultrasound and magneticresonance imaging techniques. Aim of the present study was toevaluate the echographic detectability of these bimodal NPsthrough a recently developed algorithm that was originallyimplemented to detect pure silica NSs. In particular, weperformed a series of "in vitro" experiments on custom-designedtissue-mimicking phantoms, focused on a specific objective ofdirect clinical interest: the detection of multimodal NPs with adiameter of about 330 nm at a low and biocompatible volumeconcentration (0.2%). The obtained results demonstrated thepossibility of deleting the US echoes coming from structuresother than NPs with high effectiveness, therefore enhancing thebrightness of nanosized contrast agents in the final diagnosticimages. The effectiveness of the proposed method shows verypromising perspectives for future clinical applications.

The aim of this paper was to propose a novel approach to the ultrasound (US) characterizationof human bones through an improved measurement of the apparent integratedbackscatter (AIB). Four intact human femoral heads were studied ex vivo in their physiologicmorphological configuration, including cartilaginous, cortical and trabecular regions.Each sample underwent an US acquisition performed with a clinically-available echographicdevice and a micro-computed tomography (micro-CT) scan, whose spatial resolutionwas preliminarily optimized for this specific purpose. A dedicated US signalcompensation was employed in the AIB computation, to take into account the variabilityof sample-probe distance and cortical bone thickness. Obtained results showed an appreciableglobal correlation between AIB and the trabecular bone volume fraction as quantifiedby the micro-CT parameter BV/TV (r = 0.69). The proposed approach has interestingperspectives for a clinical translation as an innovative method for in vivo US measurementof proximal femur bone density.

Developing and testing novel ultrasound (US)investigation methods can be made difficult by commercialUS echographs. Typically, most devices can export only theechographic images, providing either beamformed RF ordemodulated echo-signal for acquisition by an external PC.Powerful but portable high-level commercial integratedcircuits would be required in order to obtain access to theraw RF signal. First examples of such systems forultrasound research are available (i.e. FEMMINA, ULAOP), although they are still far from size minimization. Inthis work we present a compact platform, consisting of adedicated electronic board to be coupled with the USbeamformer through an integrated analog front-end. Ourplatform was designed in order to simultaneously managethe RF flow data and to satisfy the following requirements:1) ensuring that the full dynamic range of analog to digitalconverter (ADC) is completely exploited in order tomaintain the ADC resolution capabilities through anappropriate amplifier, 2) denoising the RF signal input by aspecific designed filter, 3) limited size, 4) low cost and 5)plug-and-play connection to the PC via a further USB port.Also, a suitable custom-developed graphical user interfacewas developed, enabling signal visualization andmanagement of signal processing algorithms through anexternal PC. The output of an equivalent system, composedby commercially available stand-alone amplifier and ADCcomponents, was assumed as the standard for comparingand grading the performances of our board. Analyzing theoutput of both systems in the frequency domain, weobtained matching spectra with a difference up to 0.21 dB.The so realized close synergy between hardware andsoftware allows the acquisition and real-time processing ofthe echographic RF signals with fast data representation,allowing for the complete analysis of particular phenomenaupon the study of the interaction between US signals and theinvestigated target for specific clinical diagnosis (i.e.osteoporosis in the bone tissue, tissue typing applications).

To improve vessel contrast in high-resolution susceptibility-based brain venography, an automatic phase contrast enhancing procedure is proposed, based on a new phase mask filter suitable for maximizing contrast of venous MR signals. The effectiveness of the new approach was assessed both on digital phantoms and on acquired MR human brain images, and then compared with venographic results of phase masking methods in recent literature. The digital phantom consisted of a simulated MR dataset with given signal-to-noise ratios (SNRs), while real human data were collected by scanning healthy volunteers with a 3.0-T MR system and a 3D gradient echo pulse sequence. The new phase mask (NM) was more effective than the conventional mask (CM) both on the digital phantoms and on the acquired MR images. A quantitative comparison based on phantom venograms indicates how this phase enhancement can lead to a significant increase in the contrast-to-noise ratio (CNR) for all considered phase values as well as for all vessel sizes of clinical interest. Likewise, the in vivo brain venograms reveal a better depiction of the smallest venous vessels and the enhancement of many details undetectable in conventional venograms.

Aim of this work was to carry out a first clinical validation of a new ultrasound (US)-based approach to bone densitometry of lumbar spine. A total of 290 female patients were enrolled for this study (45-75 years of age, body mass index (BMI)<40 kg/m(2)) and all of them underwent two different diagnostic investigations: a lumbar DXA (dual-energy X-ray absorptiometry) and an US scan of the same vertebras, performed with an echographic device configured for the acquisition of both echographic images and unfiltered radiofrequency signals. US data analysis was carried out through an innovative algorithm, whose main features include: a) measurements are always performed on a specific region of interest of the vertebra, identified on the basis of both morphologic and spectral characteristics; b) analysis takes into account patient BMI; c) the algorithm is integrated with a reference database containing model acquisitions for different combinations of patient age, sex and BMI. Accuracy of final algorithm output, represented by the same diagnostic parameters of a DXA investigation, was evaluated through a direct comparison with DXA results. For 84.5% of the patients US diagnosis (osteoporotic, osteopenic, healthy) coincided with the corresponding DXA one and this accuracy level was not appreciably influenced by patient age nor by BMI. The proposed approach represents the first US method for osteoporosis diagnosis which is directly applicable on spine and has the potential to be effectively used for population mass screenings.

Aim of this work was to evaluate the effectiveness of a recently introduced ultrasound (US) method for osteoporosis diagnosis, when extensively used in a clinical context to investigate adult women of variable age. A total of 384 female patients (46-65 years; body mass index < 25 kg/m²) underwent a spinal dual X-ray absorptiometry (DXA) and an abdominal US scan of lumbar spine, acquiring both echographic images and unprocessed radiofrequency signals. US data were analyzed through a new fully automatic algorithm, which performed a series of spectral and statistical analyses to calculate the parameter called Osteoporosis Score (O.S.). Diagnostic effectiveness of O.S. was assessed through a direct comparison with DXA measurements (assumed as the gold standard reference), quantifying the agreement between the two methods through accuracy calculation, Cohen's kappa (k) and Pearson correlation coefficient (r). The overall accuracy of O.S.-based diagnoses resulted 84.6%, ranging from a minimum of 81.7% for the oldest patients (aged in 61-65 y) to a maximum of 87.2% for the youngest patients (aged in 46-50 y). Cohen's kappa showed an analogous trend, confirming a significant agreement between DXA and US-based diagnoses along the whole considered age interval (k=0.758, p<0.0001). A good correlation was also found between O.S.-derived BMD values and corresponding DXA measurements (r=0.72, p<0.001). These results demonstrated that US-measured O.S. is significantly correlated with spinal BMD in normal-and under-weight adult women belonging to a wide age interval. Therefore, the routine clinical application of this innovative approach to osteoporosis diagnosis can be envisioned.

Current methods for ultrasound (US) molecular imaging suffer the lack of image processing techniques specifically designed to identify the newer nanosized contrast agents (CAs). The available pulse sequences and signal analysis methods for US contrast detection, in fact, were developed for the older microbubble CAs, whose acoustic properties differ significantly from those of nanoparticles. This work illustrates the implementation and experimental testing of a new contrast detection scheme, tailored to enhance the contribution of solid nanosized CAs in echographic images. The proposed protocol, including a novel pulse sequence and a two-step image processing algorithm, was evaluated on a phantom consisting of silica nanospheres dispersed into an agarose gel matrix that was imaged through a conventional echographic transducer. Obtained results demonstrated the capability of selectively suppressing non-contrast echoes, without any loss in spatial resolution and maintaining the characteristics of real-time imaging, therefore showing very promising perspectives for clinical applications.

Vertebral morphometry is a commonclinically-used method for vertebral fracture detection andclassification, based on height measurements of vertebralbodies in radiographic images. This method is quantitativeand does not require specific operator skills, but its actualaccuracy is affected by errors made during the timeconsumingmanual or semi-automatic measurements. In thispaper, we propose an innovative fully automatic approach tovertebral morphometry. A novel algorithm, based on a localphase symmetry measure and an "Active Shape Model",was implemented and tested on lateral X-ray radiographs of50 patients. Thoracic and lumbar vertebral bodies in eachimage were independently segmented and measured by boththe automatic algorithm and an experienced radiologist,whose manually-obtained results were assumed as theground truth. The algorithm showed reasonably low errorrates regarding both vertebral localization and morphometricmeasurements with a sensitivity of 86.5% and a perfectspecificity of 100%, because no false positive were present.Furthermore, its performance did not appreciably worsen onpoor quality images, emphasizing a significant potential fora prompt translation into clinical routine.

We investigated the possible clinical feasibility and accuracy of an innovative ultrasound (US) method for diagnosis of osteoporosis of the spine. A total of 342 female patients (aged 51-60 y) underwent spinal dual X-ray absorptiometry and abdominal echographic scanning of the lumbar spine. Recruited patients were subdivided into a reference database used for US spectral model construction and a study population for repeatability and accuracy evaluation. US images and radiofrequency signals were analyzed via a new fully automatic algorithm that performed a series of spectral and statistical analyses, providing a novel diagnostic parameter called the osteoporosis score (O.S.). If dual X-ray absorptiometry is assumed to be the gold standard reference, the accuracy of O.S.-based diagnoses was 91.1%, with k = 0.859 (p < 0.0001). Significant correlations were also found between O.S.-estimated bone mineral densities and corresponding dual X-ray absorptiometry values, with r(2) values up to 0.73 and a root mean square error of 6.3%-9.3%. The results obtained suggest that the proposed method has the potential for future routine application in US-based diagnosis of osteoporosis. (C) 2015 World Federation for Ultrasound in Medicine & Biology.

Current imaging methods for catheter position monitoring during minimally invasive surgery do not provide an effective support to surgeons, often resulting in the choice of more invasive procedures. This study was conducted to demonstrate the feasibility of non-ionizing monitoring of endovascular devices through embedded quantitative ultrasound (QUS) methods, providing catheter self-localization with respect to selected anatomical structures. QUS-based algorithms for real-time automatic tracking of device position were developed and validated on in vitro and ex vivo phantoms. A trans-esophageal ultrasound probe was adapted to simulate an endovascular device equipped with an intravascular ultrasound probe. B-mode images were acquired and processed in real time by means of a new algorithm for accurate measurement of device position. After off-line verification, automatic position calculation was found to be correct in 96% and 94% of computed frames in the in vitro and ex vivo phantoms, respectively. The average errors of distance measurements (bias +/- 2SD) in a 41-step 10-cm-long parabolic pathway were 0.76 +/- 3.75 mm or 0.52 +/- 3.20 mm, depending on algorithm implementations. Our results showed the effectiveness of QUS-based tracking algorithms for real-time automatic calculation and display of endovascular system position. The method, validated for the case of an endoclamp balloon catheter, can be easily extended to most endovascular surgical systems.

Aim of this paper was to assess the discrimination power of a novel ultrasound (US) parameter, called theFragility Score (F.S.), in the early identification of subjects prone to osteoporotic fractures. A total of 102female patients were recruited: 49 with a recent osteoporotic fracture (''frail" subjects), 53 were controlswithout fracture history (''non-frail" subjects). All the patients underwent a spinal DXA (dual X-rayabsorptiometry) and an abdominal US scan of lumbar vertebrae. Acquired US data were analyzed by anovel algorithm, which calculated the F.S. through spectral and statistical analyses involving both echographicimages and corresponding ''raw" signals. F.S. showed a good performance in discriminating ''frail"from ''non-frail" subjects (sensitivity = 76%, specificity = 68%), resulting even slightly more effective thanDXA-measured BMD (sensitivity = 73%, specificity = 66%). This methodology has a potential to become aneffective tool for the early identification, and timely treatment, of ''frail" subjects.

In the last decades, minimally invasive technologies have experienced a significant diffusion in various clinical specialties, finding their application in diagnosis and therapy of acute and chronic diseases. In particular early and effective cancer diagnosis is amongst the goals of recent studies focused on the improvement of innovative medical instruments. Moreover, several research projects are currently operating on the optimization of novel diagnostic paradigms, seeking to minimal exposure of the patient to ionizing radiations, considered highly health threatening. Therefore, the aim of this study was to assess the accuracy of a prototypal software algorithm for advanced spectral analysis on echographic images (RULES, ELEN SpA, Florence, Italy) in the automatic segmentation of a simulated tumour mass with variable physical conditions (position, shape, pressure exerted by the surrounding tissues). Different phantoms were used to mimic specific pathological conditions: an early stage cancer and a hard tumour mass. Specificity and sensitivity of the procedure were calculated throughout the condition variation cycle for each model and compared. Results demonstrated the possibility of selecting an appropriate configuration of the algorithm to perform an automatic echographic monitoring of a tissue mass of given mechanical properties while it experiences variations of position, shape and pressure exerted by the surrounding tissues. Clinical implications of the reported findings could be crucial for management of cancer patients and for disease assessment in absence of contrast agent injection.

Prototypal software algorithms for advanced spectral analysis of echographic images were developed to perform automatic detection of simulated tumor masses at two different pathological stages. Previously published works documented the possibility of characterizing macroscopic variation of mechanical properties of tissues through elastographic techniques, using different imaging modalities, including ultrasound (US); however, the accuracy of US-based elastography remains affected by the variable manual modality of the applied compression and several attempts are under investigation to overcome this limitation. Quantitative US (QUS), such as Fourier- and wavelet-based analyses of the RF signal associated with the US images, has been developed to perform a microscopic-scale tissue-type imaging offering new solutions for operator-independent examinations. Because materials able to reproduce the harmonic behavior of human liver can be realized, in this study, tissue-mimicking structures were US imaged and the related RF signals were analyzed using wavelet transform through an in-house-developed algorithm for tissue characterization. The classification performance and reliability of the procedure were evaluated on two different tumor stiffnesses (40 and 130 kPa) and with two different applied compression levels (0 and 3.5 N). Our results demonstrated that spectral components associated with different levels of tissue stiffness within the medium exist and can be mapped onto the original US images independently of the applied compressive forces. This wavelet-based analysis was able to identify different tissue stiffness with satisfactory average sensitivity and specificity: respectively, 72.01% ± 1.70% and 81.28% ± 2.02%.

The aim of this paper was to investigate the clinical feasibility and the accuracy in femoral neck densitometryof the Osteoporosis Score (O.S.), an ultrasound (US) parameter for osteoporosis diagnosis that has beenrecently introduced for lumbar spine applications. A total of 377 female patients (aged 61-70 y) underwent both afemoral dual X-ray absorptiometry (DXA) and an echographic scan of the proximal femur. Recruited patientswere sub-divided into a reference database used for ultrasound spectral model construction and a study populationfor repeatability assessments and accuracy evaluations. Echographic images and radiofrequency signals wereanalyzed through a fully automatic algorithm that performed a series of combined spectral and statistical analyses,providing as a final output the O.S. value of the femoral neck. Assuming DXA as a gold standard reference, theaccuracy of O.S.-based diagnoses resulted 94.7%, with k 5 0.898 (p , 0.0001). Significant correlations werealso found between O.S.-estimated bone mineral density and corresponding DXA values, with r2 up to 0.79 androot mean square error 5 5.9-7.4%. The reported accuracy levels, combined with the proven ease of use andvery good measurement repeatability, provide the adopted method with a potential for clinical routine applicationin osteoporosis diagnosis. (

The aim of this paper was to optimize the employment of a novel algorithm for acquisition and processing of medical ultrasound (US) signals to facilitate its clinical translation. The implemented procedure is dedicated to selective enhancement of nanoparticle (NP) contrast agents in echographic images and is based on the differences in US signal backscatter between NP-containing targets and more homogeneous objects. Previous preliminary studies verified the feasibility of this approach on silica nanospheres (SiNSs) dispersed at a constant volume concentration (0.7%) in agarose gel samples. The present extended these evaluations, addressing two issues of direct clinical interest: 1) safety: SiNSs were coated with a biocompatible layer made of polyethylene glycol (PEG) and the adopted NP volume concentration was reduced to 0.2%, which is in the nontoxic range and 2) reproducibility: a different phantom configuration was used, to verify the independence of algorithm performance from a specific target region shape. The obtained results demonstrated that the proposed method can be effectively applied to enhance the presence of PEG-coated SiNSs in the diameter range 160--660 nm at a low and biocompatible volume concentration: the combined employment of a phantom with a different geometry and a lower concentration of PEG-coated NPs, in fact, caused only slight variations in the suppression patterns of noncontrast echoes, without affecting the final diagnostic effectiveness of the investigated contrast detection scheme. This approach also provides specific advantages with respect to the available measurement techniques dedicated to the enhancement of targeted US contrast agents for molecular imaging purposes.

The clinical significance of osteoporosis liesin the relevant occurrence of fractures. Osteoporosis affectsabout 200 million people in the world and is responsible for8.9 million fractures each year worldwide. Hip fractures area major public health burden, from both social andeconomic point of view, since they represent one of the mostimportant causes of morbidity, disability, decreased qualityof life and mortality for the elderly population. It has beendemonstrated that bone mineral density (BMD)measurements on lumbar spine or proximal femur,standardly evaluated by dual-energy X-ray absorptiometry(DXA) examinations, are the most reliable available tool topredict the general risk of osteoporotic fractures. However,DXA, bearing X-ray related issues, is inadequate forpopulation screening purposes and early diagnosis. In thepresent work, we present a new ultrasound (US)-basedmethod and evaluate its performance for the prediction ofosteoporotic fractures. We enrolled 40 women with recentnon-vertebral osteoporotic fractures (frail subjects) and 44controls without fracture history (non-frail subjects): thissample was used to compare the discriminatory power of thenovel US methodology applied on spine with lumbar DXAby building the corresponding Receiver OperatingCharacteristic (ROC) curves. Obtained results showed thatthe new proposed US parameter (named Fragility Score,F.S.) is suitable for population screening purposes, since itsArea Under the Curve (AUC) was the same of DXAmeasuredBMD (0.77) but it was coupled with a bettersensitivity (83% vs 68%) in identifying patients at high riskof osteoporotic fracture.

Halloysite Nanotubes (HNTs) are nanomaterials composed of double layered aluminosilicate minerals with a predominantly hollow tubular structure in submicron range. HNTs are characterized by a wide range of applications in anticancer therapy, sustained agent delivery, being particularly interesting because of their tunable release rates and fast adsorption rates. However systematic investigations of their acoustic properties are still poorly documented. This paper shows a quantitative assessment of the effectiveness of HNTs as scatterers at conventional ultrasonic frequencies (5.7 -7 MHz) in low range of concentrations (1.5-5 mg/mL). Different samples of HNT (diameter: 40-50 nm; length: 0.5 to 2 microns, empty lumen diameter: 15-20 nm) containing agarose gel were imaged through a commercially available echographic system and acquired data were processed through a dedicated prototypal platform in order to extract the average ultrasonic signal amplitude associated to the considered sample. Relationships have been established among backscatter, HNT concentration and the employed echographic frequency. Our results demonstrated that improvement in image backscatter could be achieved incrementing HNT concentration, determining a non-linear signal enhancement due to the fact that they are poly-disperse in length. On the other hand the effect of different echographic frequencies used was almost constant at all concentrations, specifically using higher values of echographic frequency allows yielding a signal enhanced of a factor 1.75±0.26. © 2013 IEEE.

Aim of this work was to investigate the automatic echographic detection of an experimentaldrug delivery agent, halloysite clay nanotubes (HNTs), by employing an innovative methodbased on advanced spectral analysis of the corresponding "raw" radiofrequency backscattersignals. Different HNT concentrations in a low range (5.5-66  1010 part/mL, equivalent to0.25-3.00 mg/mL) were dispersed in custom-designed tissue-mimicking phantoms and imagedthrough a clinically-available echographic device at a conventional ultrasound diagnostic frequency(10 MHz). The most effective response (sensitivity = 60%, specificity = 95%), was found ata concentration of 33  1010 part/mL (1.5 mg/mL), representing a kind of best compromisebetween the need of enough particles to introduce detectable spectral modifications in thebackscattered signal and the necessity to avoid the losses of spectral peculiarity associated tohigher HNT concentrations. Based on theoretical considerations and quantitative comparisonswith literature-available results, this concentration could also represent an optimal concentrationlevel for the automatic echographic detection of different solid nanoparticles when employinga similar ultrasound frequency. Future dedicated studies will assess the actual clinical usefulness ofthe proposed approach and the potential of HNTs for effective theranostic applications.

Labor progression is routinely assessed through transvaginal digital inspections, meaning that the clinical decisions taken during the most delicate phase of pregnancy are subjective and scarcely supported by technological devices. In response to such inadequacies, we combined intrapartum echographic acquisitions with advanced tracking algorithms in a new method for noninvasive, quantitative, and automatic monitoring of labor. Aim of this work is the preliminary clinical validation and accuracy evaluation of our automatic algorithm in assessing progression angle (PA) and fetal head station (FHS). A cohort of 10 parturients underwent conventional labor management, with additional translabial echographic examinations after each uterine contraction. PA and FHS were evaluated by our automatic algorithm on the acquired images. Additionally, an experienced clinical sonographer, blinded regarding the algorithm results, quantified on the same acquisitions of the two parameters through manual contouring, which were considered as the standard reference in the evaluation of automatic algorithm and routine method accuracies. The automatic algorithm (mean error +/- 2SD) provided a global accuracy of 0.9 +/- 4.0 mm for FHS and 4 degrees +/- 9 degrees for PA, which is far above the diagnostic ability shown by the routine method, and therefore it resulted in a reliable method for earlier identification of abnormal labor patterns in support of clinical decisions.

Halloysite clay Nanotubes (HNTs) are nanomaterials composed of double layered aluminosilicate minerals with a hollow tubular structure in the submicron range. They are characterized by a wide range of applications in anticancer therapy as agent delivery. In this work we aim to investigate the automatic detection features of HNTs through advanced quantitative ultrasound imaging employing different concentrations (3-5 mg/mL) at clinical conventional frequency, i.e. 7 MHz. Different tissue mimicking samples of HNT containing agarose gel were imaged through a commercially available echographic system, that was opportunely combined with ultrasound signal analysis research platform for extracting the raw ultrasound radiofrequency (RF) signals. Acquired data were stored and analyzed by means of an in-house developed algorithm based on wavelet decomposition, in order to identify the specific spectrum contribution of the HNTs and generate corresponding image mapping. Sensitivity and specificity of the HNT detection were quantified. Average specificity (94.36%) was very high with reduced dependency on HNT concentration, while sensitivity showed a proportional increase with concentration with an average of 46.78%. However, automatic detection performances are currently under investigation for further improvement taking into account image enhancement and biocompatibility issues.

Quantitative ultrasound (QUS) methods forosteoporosis diagnosis potentially provide information aboutthe bone quality and its elastic properties. In this context, anovel ultrasound-based method for spinal and femoraldensitometry was developed by our research group. In orderto maximize its accuracy, it is very important to properlydetect the bone interfaces that will be analyzed as regions ofinterest (ROIs). A fully automatic segmentation algorithmwas developed to select lumbar vertebral interfaces inechographic images and its actual accuracy was assessed inthe present work by means of a visual checking carried outby an expert operator. Abdominal US scans of lumbar spine(from L1 to L4) were performed on 100 female subjects(60.5±3.0 years old) with different ranges of body massindex (BMI) (25.8±4.6 kg/m2). During each US scan, 100frames of radiofrequency (RF) data were stored on a PChard disk for offline analysis. The operator scanned eachvertebra, moving the probe to the next vertebra after 20seconds. For each acquired RF data frame, the implementedalgorithm generated a sectorial echographic image and, if avertebral interface was detected, it was highlighted on thesaved image. The validation procedure was performed by anexpert operator previously trained to detect the "optimal"vertebral interfaces for osteoporosis diagnosis. Resultsshowed that the segmentation algorithm had a highspecificity (93.4%), which reached its maximum on subjectswith BMI < 25 kg/m2 (94.2%), thus avoiding the selectionof false vertebral interfaces and allowing a good accuracy ofosteoporosis diagnosis.

Aim of this study was to perform a detailed clinical validation of a novel fully automatic method for vertebralmorphometry. About 80 spine lateral radiographs were evaluated both automatically, by the proposed algorithm, andmanually, by an experienced radiologist. The following metrics were used for algorithm performance assessment:sensitivity and specificity in vertebra detection; errors in the localisation of characteristic points of vertebral border;errors in the measurement of six diagnostic parameters; level of agreement and correlation between manual andautomatic morphometric measurements; overall accuracy of automatic diagnoses with respect to manual ones.Obtained results showed a very good performance in vertebra detection (sensitivity = 89.1% and specificity = 100.0%).Average errors in the localisation of vertebral characteristic points were always smaller than 3 mm (range 0.85-2.79mm),causing relative errors in diagnostic parameter values ranging from -5.01 to +6.10%. Bland-Altman analysis documenteda mean error in automatic measurements of diagnostic ratios of 0.01 ± 0.18 (bias ± 2 SDs), while Pearson's correlationcoefficient resulted r = 0.71 (p < 0.001). Finally, an optimal diagnostic coincidence (92.8%) was found between automaticand manual diagnoses. Therefore, the adopted method has a potential for an effective employment in clinical routinefor reliable diagnosis of vertebral fractures.

Core-shell iron oxide-gold nanoparticles (Fe3O4@Au) can be considered a smart platform for polyvalent presentation on account of their globular shape, tunable size, facile surface chemistry, and biocompatibility. We reported the synthesis and the characterization of Fe3O4@Au nanoparticles with transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet visible spectroscopy (UV-Vis), and we investigated their applicability as contrast agents for Magnetic Resonance Imaging (MRI). The measurement of longitudinal and transverse relaxation times of water protons in homogeneous aqueous dispersions of Fe3O4@Au nanoparticles with biocompatible coating at different concentrations allowed the assessment of longitudinal (r1) and transverse (r2) relaxivities at 1.5 and 3 T. The use of conjugated Fe3O4@Au nanoparticles as negative contrast agents could open up new perspectives for the development of novel tools for nanomedicine and for targeted delivery-MRI contrast enhancement systems and photo-optical applications in biomedicine.

Aim of this work was to study the dissolution behaviour of the phospholipid-shelled perfluorobutanemicrobubbles of an experimental contrast agent for echographic imaging through an innovative methodologybased on time-scheduled size distribution measurements. Two different contrast handling procedures wereemployed and temporal evolution of corresponding microbubble populations was monitored for several hours.Dissolution behaviour of shelled microbubbles resulted to be qualitatively analogous to that theoreticallypredicted for unshelled perfluorobutane bubbles, with a much longer lifetime due to the shell effect. In particular,mean microbubble diameter, initially around 2 ?m, first increased to more than 2.6 ?m and then graduallyreduced to less than 1.7 ?m, with corresponding variations of the effectively employable ultrasound frequenciesfor imaging purposes. We also demonstrated that excess lipid material is diffused as submicron particleshedding. Finally, we discussed the implications of these results for diagnostic and therapeutic applicationsinvolving the studied microbubbles.

Osteoporosis and overweight/obesityconstitute major worldwide public health burdens that areassociated with aging. The gold standard for osteoporosisdiagnosis is currently represented by bone mineral density(BMD) measurement through dual-energy X-rayabsorptiometry (DXA). However, DXA cannot be used forearly diagnosis through population mass screenings due toionizing radiation employment. Because of this, generally,only people considered at high risk of fracture (underweightwomen after the menopause) undergo to osteoporosisscreening. In fact, a significant risk factor for fracture is thelow body mass index (BMI), while the tendency tooverweight or obesity delays osteoporosis onset.Nevertheless, a high proportion of women after themenopause develop intra-abdominal adiposity, which leadsto metabolic disorders and osteoporosis. This paperdescribes the diagnostic accuracy of a novel ultrasound(US)-based method to perform spinal densitometry. Theproposed innovative methodology is based on a combinedanalysis of both echographic images and "raw"radiofrequency US signals. The diagnostic output isrepresented by the same parameters provided by DXA(BMD, T-score, Z-score). The efficiency of the proposedmethodology was evaluated on a cohort of 280 overweightor obese (BMI > 25 kg/m2) female patients in the age range45-65 years. For 81.4% of the patients, US diagnosis(osteoporotic, osteopenic, healthy) was the same of thecorresponding DXA one, showing the high accuracy of theproposed US technique, especially in the youngest patients(86.4% of correct diagnoses in the age range 45-50 y). Agood correlation was also found between the diagnosticparameters provided by both US and DXA methods: allobtained values of Pearson coefficient (r) were within theinterval 0.66-0.76 (p<0.001). Then, this new non-ionizingapproach to spinal bone densitometry has the potential forbeing extremely useful for early osteoporosis diagnosisthrough population mass screenings.

Multimodal contrast agents (CAs) allow theenhancement of medical images acquired through differenttechniques by employing a single contrast injection, withsignificant benefits for diagnostic outcome. The present study isfocused on the characterization of the magnetic behavior of anovel CA class, consisting of silica (Si) nanoparticles (NPs)covered by either superparamagnetic iron oxide (SPIO) NPs orFePt-IO nanocrystals and designed to be detected through bothultrasound and magnetic resonance imaging (MRI). The usemultimodal nanoparticles as negative MRI contrast agents couldopen up new perspectives for the development of novel tools fornanomedicine, combining different non-ionizing techniques fortargeted imaging of specific diseased cells. In this work, wesimulated the MRI signal of a blood vessel in presence of the newbimodal CAs and compared it with the response of thesuperparamagnetic NPs alone. The performed numericalsimulations showed that the magnetic response of the novel nanocomposites,in terms of signal magnitude, was similar to that ofthe conventional superparamagnetic NPs for values of echo time(TE) shorter than 0.4 ms, while for longer TE values it was evenbetter, showing a stronger vessel enhancement leading to aneasier detection of the smaller vessels. Therefore, the testedbimodal NPs have the potential for an effective employment asMRI CAs.

The assessment of osteoporotic fracture riskrequires the measurement of bone mineral density (BMD)on reference sites (hip and spine) and the evaluation ofclinical risk factors (CRFs) for fracture. The Fracture RiskAssessment algorithm (FRAX®), internationally recognizedby official guidelines for osteoporotic patient management,represents a tool for estimating 10-year probability of hipand major fragility fractures by integrating CRFs andfemoral neck BMD or T-score, when available. In this workwe presented an innovative ultrasound (US)-based methodfor estimating fracture risk by means of a safe and radiationfreeapproach. From abdominal ultrasound scans performedon 64 female patients, we defined and quantified a new USdiagnostic parameter named Fragility Score (F.S.), whichestimates bone fragility. Obtained results showed an highPearson correlation coefficient between fractureprobabilities calculated by FRAX® and F.S. (r up to 0.75 inthe case of FRAX® estimates including femoral neck BMDand r=0.71 in the case of FRAX® estimates based onfemoral neck T-score). The present study demonstrated thefeasibility of a novel US approach for fracture riskprediction and prevention, directly applicable on spine andindependent from BMD measurements and CRFassessments. The proposed methodology could represent avalid alternative to both FRAX® and BMD for earlyassessment of fracture risk.

Nanosized contrast agents for medical imaging arebeing increasingly studied because of their potential for directand selective targeting of diseased cells located in theextravascular compartment. Recently, our research group hasexperimentally investigated the echogenicity of silicananospheres (SiNSs), potentially useful for tumor targetingpurposes, demonstrating their contrast enhancement power onconventional ultrasound (US) images in a wide range of sizesand concentrations. In the present work, we evaluated the "invitro" cytotoxicity of SiNSs at variable concentration in humancervical cancer cell line (HeLa). Toxicity of SiNSs with diameterin our investigated range (160-330 nm) had never beenpreviously quantified, although this is the most promising sizeinterval for US targeted imaging. Our reported results indicateda SiNS concentration range which does not cause appreciabledecrements in cell survival, being therefore safely exploitable forcontrast-enhanced US imaging.

Halloysite Clay nanotubes (HNTs) are naturally occurring nanotubes composed of double layered aluminosilicate minerals with a hollow tubular structure in the nanometer range. In recent years, HNTs have attracted specific research attention as a possible new material for various biological applications, including drug and gene delivery vehicles, ultrasound contrast agents, cancer and stem cells isolation. Therefore, assessment of HNT biocompatibility has gained importance to demonstrate its suitability for clinical purposes. In this study, HNTs were densely coated with poly(ethylene glycol) (PEG) and MTT measurements were performed on MCF-7 (breast cancer) and HeLa (cervical cancer) cells to quantify the biocompatibility of PEG-coated HNTs as a function of nanotube dosage and incubation time. PEG-coated HNTs resulted fully biocompatible for both cell lines at concentrations up to 0.1 mg/mL (>70% of cells survived after 72-h incubation), making them suitable candidates for nanomedicine applications at moderate levels of exposure.

Currently, osteoporosis is mainly diagnosedthrough dual-energy X-ray absorptiometry (DXA). However,DXA cannot be used for early diagnoses through populationmass screenings because of issues related to ionizingradiation employment. This paper describes the diagnosticaccuracy of a novel ultrasound (US)-based method toperform spinal densitometry without employing X-rays. Theproposed innovative methodology is based on a combinedanalysis of both echographic images and "raw"radiofrequency US signals. The diagnostic output isrepresented by the same parameters of DXA (bone mineraldensity (BMD), T-score, Z-score). The actual effectivenessof the proposed methodology was evaluated on a cohort of350 normal-weight or underweight (body mass index (BMI)< 25 kg/m2) female patients in the age range 45-65 years bya direct comparison with DXA assumed as gold standard.The accuracy of US-based diagnoses ranged from amaximum of 90.5% to a minimum of 74.1%, correspondingto the youngest and oldest patient age category, respectively,with an average of 84.9%. A good correlation was alsofound between US-estimated BMD and DXA related values(r=0.69, p<0.001). Obtained results demonstrated the highaccuracy of the proposed US approach to spinal bonedensitometry compared with DXA. This technique has thepotential to become a useful and effective tool in clinicalpractice improving the current approach to osteoporosisdiagnosis.

Since the recognition of disease molecular basis, it has become clear that the keystone moments of medical practice, namely early diagnosis, appropriate therapeutic treatment and patient follow-up, must be approached at a molecular level. These objectives will be in the near future more effectively achievable thanks to the impressive developments in nanotechnologies and their applications to the biomedical field, starting-up the nanomedicine era. The continuous advances in the development of biocompatible smart nanomaterials, in particular, will be crucial in several aspects of medicine. In fact, the possibility of manufacturing nanoparticle contrast agents that can be selectively targeted to specific pathological cells has extended molecular imaging applications to non-ionizing techniques and, at the same time, has made reachable the perspective of combining highly accurate diagnoses and personalized therapies in a single theranostic intervention. Main developing applications of nanosized theranostic agents include targeted molecular imaging, controlled drug release, therapeutic monitoring, guidance of radiation-based treatments and surgical interventions. Here we will review the most recent findings in nanoparticles contrast agents and their applications in the field of cancer molecular imaging employing non-ionizing techniques and disease-specific contrast agents, with special focus on recent findings on those nanomaterials particularly promising for ultrasound molecular imaging and simultaneous treatment of cancer.

Purpose: To evaluate the diagnostic performance of gold nanorod (GNR)-enhanced optoacoustic imaging employing a conventional echographic device and to determine the most effective operative configuration in order to assure optoacoustic effectiveness, nanoparticle stability, and imaging procedure safety.Methods: The most suitable laser parameters were experimentally determined in order to assure nanoparticle stability during the optoacoustic imaging procedures. The selected configuration was then applied to a novel tissue-mimicking phantom, in which GNR solutions covering a wide range of low concentrations (25-200 pM) and different sample volumes (50-200 ?L) were exposed to pulsed laser irradiation. GNR-emitted optoacoustic signals were acquired either by a couple of single-element ultrasound probes or by an echographic transducer. Off-line analysis included: (a) quantitative evaluation of the relationships between GNR concentration, sample volume, phantom geometry, and amplitude of optoacoustic signals propagating along different directions; (b) echographic detection of "optoacoustic spots," analyzing their intensity, spatial distribution, and clinical exploitability. MTT measurements performed on two different cell lines were also used to quantify biocompatibility of the synthesized GNRs in the adopted doses.Results: Laser irradiation at 30 mJ/cm2 for 20 seconds resulted in the best compromise among the requirements of effectiveness, safety, and nanoparticle stability. Amplitude of GNR-emitted optoacoustic pulses was proportional to both sample volume and concentration along each considered propagation direction for all the tested boundary conditions, providing an experimental confirmation of isotropic optoacoustic emission. Average intensity of echographically detected spots showed similar behavior, emphasizing the presence of an "ideal" GNR concentration (100 pM) that optimized optoacoustic effectiveness. The tested GNRs also exhibited high biocompatibility over the entire considered concentration range.Conclusion: An optimal configuration for GNR-enhanced optoacoustic imaging was experimentally determined, demonstrating in particular its feasibility with a conventional echographic device. The proposed approach can be easily extended to quantitative performance evaluation of different contrast agents for optoacoustic imaging.

Among the various nanosized particles developed forinnovative biomedical applications, like selective molecularimaging and targeted drug delivery, silica nanoparticles (SiNPs)seem to be particularly attractive since of their low cost, lowtoxicity, ease of functionalization and acoustic properties. In fact,SiNPs have been demonstrated to effectively enhance ultrasoundcontrast at clinical diagnostic frequencies and, therefore, theymight be potentially employed in non-ionizing echographicmolecular imaging. Aim of this work was the development of asilica nanoparticle based system for in vitro molecular imaging ofhepatocellular carcinoma, using both ultrasound and laserscanningconfocal microscopy, by exploiting the particularfeature of these tumor cells to express on their surface high levelsof Glypican-3 protein (GPC-3). At this regard, we have designedand characterized novel GPC-3 ligand peptide-functionalizedfluorescent silica nanoparticles and tested them on GPC-3positive HepG2 cells, a human hepatocarcinoma cell line. Laserscanning confocal microscopy analysis showed that GPC-3-targeted fuorescent SiNP, in the concentration range used forexperimental ultrasound detection, did not exert significantcytotoxic effects and were effectively bound and taken up byHepG2 cells. These results suggest that silica nanoparticles mightbe a very promising contrast agents for non-ionizing ultrasoundmolecular imaging since of their high biocompatibility, targetingeffectiveness and ultrasound enhancement power.

Successful employment of multimodal molecular imaging for cancer targeting entails the development of safe nanoparticle contrast agents (NPCAs), detects at least by two nonionizing imaging techniques. This paper presents a quantitative assessment of the effectiveness of both pure silica nanospheres (SiNSs) and composite silica/superparamagnetic NPCAs as scatterers for low-frequency diagnostic ultrasound (US) (3 MHz) in very low range of concentrations (1.5-5 mg/mL). Iron oxide (IO) and FePt-IO nanocrystals are employed for SiNS magnetic coating. Different samples of NPCA-containing agarose gel are US imaged through a commercially available system and acquired data are processed through a dedicated prototypal platform to extract image backscatter information and perform evaluation of the image gray level. The pure silica NPCAs confirms recent reports for higher concentrations at higher frequencies. The FePt-IO- coated NPCAs show similar behavior, although with lower values of image backscatter, with a marked effectiveness peak for 330-nm SiNSs, particularly useful for tumor targeting purposes. Finally, the IO-coated SiNSs presented a marked lowering of US enhancement potential and a peak efficiency for a particle diameter of 660 nm. The extent of US backscatter reduction is found to be a function of the number of magnetic nanoparticles per mL of NPCA-containing gel and decreased with increasing NPCA concentrations. These results broadened our knowledge of dual-mode molecular imaging of deep tumors, employing US, and magnetic resonance techniques for the accurate, safe and early detection of cancer cells located in internal organs.

Electroencephalogram (EEG) remains the most immediate, simple, and rich source of information for understanding phenomena related to brain electrical activities. It is certainly a source of basic and interesting information to be extracted using specific and appropriate techniques. The most important aspect in processing EEG signals is to use less co-lateral assets and instrumentation in order to carried out a possible diagnosis; this is the approach of early diagnosis. Advanced estimate spectral analysis can reveal new information encompassed in EEG signals by means of specific parameters or indices. The research proposes a multidimensional approach with a combined use of decimated signal diagonalization (DSD) as basis from which it is possible to work by finding appropriate signal windows for revealing expected information and overcoming signal processing limitations encountered in quantitative EEG. Important information, about the state of the patient under observation, must be extracted from calculated DSD bispectrum. For this aim, it is useful to define an assessment index about the dynamic process associated with the analyzed signal. This information is measured by means of entropy, since the degree of order/disorder of the recorded EEG signal will be reflected in the obtained DSD bispectrum. The general advantage of multidimensional approach is to reveal eventual stealth frequencies "in space and in time" giving a topological vision to be correlated to physical areas which these frequencies emerge from. Long term and sleeping EEG recorded are analyzed, and the results obtained are of interest for an accurate diagnosis of the patient's clinical condition.

Nanosized particles are receiving increasingattention as future contrast agents (CAs) forultrasound (US) molecular imaging, possibly decoratedon its surface with biological recognition agentsfor targeted delivery and deposition of therapeutics. Inparticular, silica nanospheres (SiNSs) have beendemonstrated to be feasible in terms of contrastenhancement on conventional US systems. In thiswork, we evaluated the cytotoxicity of SiNSs on breastcancer (MCF-7) and HeLa (cervical cancer) cellsemploying NSs with sizes ranging from 160 to 330 nmand concentration range of 1.5-5 mg/mL. Cell viabilitywas evaluated in terms of size, dose and timedependence, performing the MTT reduction assaywith coated and uncoated SiNSs. Whereas uncoatedSiNSs caused a variable significant decrease in cellviability on both cell lines mainly depending on sizeand exposure time, PEGylated SiNSs (SiNSs-PEG)exhibit a high level of biocompatibility. In fact, after72-h incubation, viability of both cell types was abovethe cutoff value of 70 % at concentration up to 5 mg/mL. We also investigated the acoustical behavior ofcoated and uncoated SiNSs within conventionaldiagnostic US fields in order to determine a suitableconfiguration, in terms of particle size and concentration,for their employment as targetable CAs. Ourresults indicate that the employment of SiNSs withdiameters around 240 nm assures the most effectivecontrast enhancement even at the lowest testedconcentration, coupled with the possibility of targetingall tumor tissues, being the SiNSs still in a size rangewhere reticuloendothelial system trapping effect isrelatively low.

Plasmon-resonant gold nanorods (AuNRs) are of great interest for optoacoustic imaging, due to their capacity of generating ultrasound (US) signals when irradiated by Near Infrared light. In fact, detection of emitted acoustic waves could lead to micron-scale resolution imaging and early diagnosis of tumor masses. Nonetheless, until now, no relevant studies have assessed the optoacoustic behavior of AuNRs under repeatable experimental conditions. A new experimental set-up including a novel custom-designed tissue-mimicking phantom was developed for this study, in order to quantify the contribution of independent parameters to the optoacoustic signal (OAS) produced by AuNRs. Analysis of the OAS recorded by 2 US probes demonstrated a direct proportionality between signal amplitude and both AuNR concentration and laser intensity. Moreover, the optimal and maximum duration of laser exposure were determined through a quantitative analysis of progressive degradation of AuNRs under irradiation.

Contrast agents for ultrasound (US) imaging are currently used for several clinical applications, such as blood signal enhancement, myocardial perfusion imaging and characterization of liver lesions. During the last years, research in targeted microbubble contrast agents has opened new exciting perspectives in this field.: US molecular imaging (which relies on the detection of disease-targeted contrast particles), effective combination of echographic methods with other non-invasive imaging techniques to perform multimodal diagnostic studies, novel "theranostic" strategies based on the site-targeted delivery of drugs operated by smart contrast agents.

The purpose of this work was to study the relationships between quantitative ultrasound (QUS) parameters and the microstructure properties of human proximal femur samples. QUS data acquisition was achieved by means of a custom-developed experimental set-up, which allowed the insonification of excised femoral heads along 30 different directions, each time including both the trabecular region and the cortical layer in their physiologic morphological configuration. Two QUS parameters, Integrated Reflection Coefficient (IRC) and Apparent Integrated Backscatter (AIB), were measured by means of both single-element transducers at two different frequencies (2.25 MHz and 3.5 MHz) and a clinically-available 128-element convex probe. The obtained data were compared with local structural properties of the bone samples as quantified by high-resolution micro-computed tomography (micro-CT). The corresponding results showed a strong correlation between trabecular bone volume fraction and AIB (r up to 0.81) and an appreciable linear correlation between cortical bone density and IRC (r up to 0.59). QUS parameter values measured by single-element transducers were optimally reproduced when the clinically-available probe was employed. This provides the proposed approach with an interesting potential for a prompt clinical translation as a possible new tool for osteoporosis diagnosis, especially considering that the insonification of the whole femoral head was performed in its physiological shape with all its components (cartilage, cortical layer, trabecular region).

An adaptive initialization method was developed to produce fully automatic processing frameworks based on graph-cut and gradient flow active contour algorithms. This method was applied to abdominal Computed Tomography (CT) images for segmentation of liver tissue and hepatic tumours. 25 anonymized datasets were randomly collected from several radiology centres without specific request on acquisition parameter settings nor patient clinical situation as inclusion criteria. Resulting automatic segmentations of liver tissue and tumours were compared to their reference standard delineations manually performed by a specialist. Segmentation accuracy has been assessed through the following evaluation framework: dice similarity coefficient (DSC), false negative ratio (FNR), false positive ratio (FPR) and processing time. Regarding liver surfaces, graph-cuts achieved a DSC of 95.49% (FPR=2.35% and FNR=5.10%), while active contours reached a DSC of 96.17% (FPR=3.35% and FNR=3.87%). The analyzed datasets presented 52 tumours: graph-cut algorithm detected 48 tumours with a DSC of 88.65%, while active contour algorithm detected only 44 tumours with a DSC of 87.10%. In addition, in terms of time performances, less time was requested for graph-cut algorithm with respect to active contour one. The implemented initialization method allows fully automatic segmentation leading to superior overall performances of graph-cut algorithm in terms of accuracy and processing time. The initialisation method here presented resulted suitable and reliable for two different segmentation techniques and could be further extended.

Aim of the present work was to evaluate the performance of a novel fully automatic algorithm for 3D segmentation and volumetric reconstruction of liver vessel network from contrast-enhanced computed tomography (CECT) datasets acquired during routine clinical activity. Three anonymized CECT datasets were randomly collected and were automatically analyzed by the new vessel segmentation algorithm, whose parameter configuration had been previously optimized on a phantom model. The same datasets were also manually segmented by an experienced operator that was blind with respect to algorithm outcome. Automatic segmentation accuracy was quantitatively assessed for both single 2D slices and 3D reconstruction of the vessel network, accounting manual segmentation results as the reference "ground truth". Adopted evaluation framework included the following two groups of calculations: 1) for 3D vessel network, sensitivity in vessel detection was quantified as a function of both vessel diameter and vessel order; 2) for vessel images on 2D slices, dice similarity coefficient (DSC), false positive ratio (FPR), false negative ratio (FNR), Bland-Altman plots and Pearson correlation coefficients were used to judge the correctness of single pixel classifications. Automatic segmentation resulted in a 3D vessel detection sensitivity of 100% for vessels larger than 1 mm in diameter, 64.6% for vessels in the range 0.5-1.0 mm and 27.8% for smaller vessels. An average area overlap of 99.1% was obtained between automatically and manually segmented vessel sections, with an average difference of 0.53 mm(2). The corresponding average values of FPR and FNR were 1.8% and 1.6%, respectively. Therefore, the tested method showed significant robustness and accuracy in automatic extraction of the liver vessel tree from CECT datasets. Although further verification studies on larger patient populations are required, the described algorithm has an exciting potential for supporting liver surgery planning and intraoperative resection guidance.

Photoacoustic (PA) imaging is based on the detection of ultrasound signals emitted by physiological targets that underwent a pulsed laser irradiation. Gold nanoparticles are being currently studied by several research groups as potential molecular contrast agents for PA imaging. Aim of this paper was to test whether a highly biocompatible PEG (polyethylene glycol) coating can improve the stability of gold nanorods (GNRs) under laser irradiation and their effectiveness as contrast agents for PA imaging with respect to uncoated GNRs. Uncoated GNRs and PEG-coated GNRs were synthesized with the same size (48x7 nm) and very similar absorption spectra (main peak at 1055 nm). GNR stability was evaluated as a function of both laser fluence (range 40-100 mJ/cm2) and exposure duration (30-60 s), monitoring optical and morphological GNR changes. PAeffectiveness was then tested using a custom-designed phantom which allowed laser irradiation of GNR solutions of variable concentration contained in a tissue-mimicking hydrogel and acquisition of the corresponding PA signals through a clinically-available ultrasound device. Obtained results showed that absorption spectrum of uncoated GNRs was significantly deteriorated after laser exposure already in the mildest adopted conditions (30-s exposure to 40-mJ/cm2 laser), while PEG-coated GNRs always resulted much more stable, with negligible peakintensity decrements in the mildest irradiation conditions. TEM analysis confirmed the higher morphological stability of PEG-coated GNRs, which also resulted more effective as PA contrast enhancers, since their PA signal intensity was always significantly higher than the corresponding value measured for uncoated GNRs.

The aim of the present work was to demonstrate the possibility of selective detection of nanoparticle contrast agents (NPCAs) on diagnostic echographic images by exploiting the second harmonic component they introduce in the spectra of corresponding ultrasound signals, as a consequence of nonlinear distortion during ultrasound propagation. We employed silica nanospheres (SiNSs) of variable diameter (160 nm, 330 nm, and 660 nm) dispersed in different volume concentrations (range 0.07-0.8%) in agarose gel samples that were automatically scanned through a digital ecograph using narrow-band ultrasound pulses at 6.6 MHz and variable mechanical index (MI range 0.2-0.6). In the first part of the study, the intensity peaks of four different spectral components of the backscattered signal were considered: fundamental (detected in correspondence of the incident ultrasound frequency), subharmonic (detected at half of the fundamental frequency), ultra harmonic (detected at 1.5 times the fundamental frequency), and second harmonic (detected at twice the fundamental frequency). Subsequently, based on the experimental results of the first part of the study and on our recently reported findings, the focus was moved to a detailed comparison between subharmonic and second harmonic trend, which were determined as a function of nanoparticle composition, sample concentration, and MI. The experiments were also repeated on different agarose samples, containing SiNSs covered by an outer shell of smaller magnetic nanoparticles, made of either iron oxide (IO) or FePt-IO nanocrystals. Obtained results show that this new ultrasound-based method for NPCA imaging has a detection sensitivity similar to that of our previously introduced subharmonic-based technique in the presence of 330-nm SiNSs, but performs significantly better in the detection of both the types of "dual mode" NPCAs. The fact that the reported detection method was optimized for identification of 330-nm SiNSs (a sort of "ideal" size for the development of novel tumor-targeting NPCAs) and that the magnetically coated particles are detectable also through magnetic resonance imaging makes the presented second harmonic ultrasound method a valuable solution for the introduction of new protocols for multimodal molecular diagnoses employing only nonionizing radiations.

Rationale and Objectives: The aim of this study was to identify the optimal parameter configuration of a new algorithm for fully automaticsegmentation of hepatic vessels, evaluating its accuracy in view of its use in a computer system for three-dimensional (3D) planning of liversurgery.Materials and Methods: A phantom reproduction of a human liver with vessels up to the fourth subsegment order, corresponding toa minimum diameter of 0.2 mm, was realized through stereolithography, exploiting a 3D model derived from a real human computed tomographicdata set. Algorithm parameter configuration was experimentally optimized, and the maximum achievable segmentation accuracywas quantified for both single two-dimensional slices and 3D reconstruction of the vessel network, through an analytic comparison of theautomatic segmentation performed on contrast-enhanced computed tomographic phantom images with actual model features.Results: The optimal algorithm configuration resulted in a vessel detection sensitivity of 100% for vessels > 1 mm in diameter, 50% in therange 0.5 to 1 mm, and 14% in the range 0.2 to 0.5 mm. An average area overlap of 94.9% was obtained between automatically andmanually segmented vessel sections, with an average difference of 0.06 mm2. The average values of corresponding false-positive andfalse-negative ratios were 7.7% and 2.3%, respectively.Conclusions: A robust and accurate algorithm for automatic extraction of the hepatic vessel tree from contrast-enhanced computedtomographic volume images was proposed and experimentally assessed on a liver model, showing unprecedented sensitivity in vesseldelineation. This automatic segmentation algorithm is promising for supporting liver surgery planning and for guiding intraoperativeresections.

Halloysite Clay nanotubes (HNTs) are naturallyoccurring nanomaterials composed of double layeredaluminosilicate minerals with a hollow tubular structure. Due totheir interesting structural characteristics, chemically activeexternal and internal surfaces, cheap and abundant availability,HNTs have recently become the subject of research attention as anew type of material for various biological applications, includingdrug and gene delivery vehicles, cancer cells isolation, boneimplants, ultrasound contrast agents, cancer and stem cellsisolation and cosmetics. Therefore, assessment of HNTbiocompatibility has gained importance to demonstrate itssuitability for clinical purposes. In this study, HNTs were denselycoated with poly(ethylene glycol) (PEG) and MTT measurementswere carried out on two different human cancer cell lines, namelyHeLa (cervical cancer) cells and HepG2 (hepatocarcinoma) cells,to quantify the biocompatibility of PEG-coated HNTs as afunction of nanotube dosage and incubation time. While noncoatednanotubes exhibited significant concentration- and timedependenttoxicity, PEG-coated HNTs resulted fullybiocompatible for concentrations up to 0.5 mg/mL and forincubation time up to 72 h, making them suitable candidates fornanomedicine applications.

Osteoporosis is considered as a major publichealth problem, second only to cardiovascular diseases. Thegold standard for its diagnosis is currently represented bydual energy X-ray absorptiometry (DXA), which, however,suffers from some important drawbacks. In order toovercome such limitations, the use of ultrasound (US)techniques has been proposed. In this paper, a novelapproach to the diagnosis of osteoporosis through US scanson lumbar spine and proximal femur is described. Theapproach relies on the estimation of diagnostic parametersby measuring the degree of similarity between the spectra ofthe raw radiofrequency (RF) echo signals and referencespectral models of osteoporotic or healthy bones. Referencemodels are representative of the features of eitherosteoporotic or healthy bone structures and are matchedwith subject age, sex, ethnic group and body mass index totake into account variations in bone physiological conditionand subject anatomy. In this paper, the methodsimplemented to build the database of reference models andto estimate diagnostic parameters are presented. Theperformance of the approach was assessed on a total of 145Caucasian underweight and normal-weighted women withage in the range from 46 to 55. Performance was assessedthrough direct comparison with DXA results. The obtainedmedian relative error in the estimation of bone mineraldensity was as low as 9.1% on women aged 51 to 55 yearsand 12.0% on women with age in the range from 46 to 50years. Moreover, for the two groups, the estimation errorwas lower than 20% for 81% and 78.6% of subjects,respectively. Therefore, the proposed method combines theadvantages of the use of US techniques with a remarkablediagnostic accuracy, thus lending itself to the possibility ofbeing used for population mass screenings.

In recent years, intensive investigations have been undertaken to develop nanoparticle-based cancer targeting agents for various imaging modalities, including ultrasound. Thus, diagnostic paradigms are needed to correctly detect the presence of nanoparticles (NPs) in the anatomic districts. Furthermore, it would be desirable to have algorithms for the automatic recognition of areas where NPs are localized. In this work an experimental optimization of an algorithm for automatic segmentation of nanoparticle-containing tissues is presented and is based on time-frequency processing of the radiofrequency (RF) signals derived from conventional echographic acquisitions. The employed prototypal software (RULES, Radiofrequency Ultrasonic Local Estimator, developed by ELEN SpA, Florence, Italy) correlates spectral parameters to the mechanical and physical properties of the object examined. The effectiveness of the algorithm was evaluated for different configurations of the spectral parameters and tested for different NP size (330 and 660 nm). Accuracy of the algorithm has been quantified through two parameters: sensitivity and specificity. Specifically, the possibility to improve selective identification of NPs disperse in tissue-mimicking layer was investigated. Through subsequent refinement, the most promising results were obtained with algorithm parameter configuration for 330-nm nanoparticles. In particular, it was found that an increase in sensitivity up to 13.9% (from 63% to 76.9%) is achievable by accepting a decrease of 1.5% in specificity (from 99.6 % to 98.1%).

Recent literature has reported increasing interest in using contrast agents for ultrasound imaging, in the form of shelled gas microbubbles, for innovative advanced purposes such as noninvasive targeted imaging and drug delivery. Effectiveness of such agents is time-dependent and is determined by microbubble dissolution behavior, a complex phenomenon whose knowledge is still limited. In the present study, we monitored the microbubbles of an experimental phospholipid-shelled perfluorobutane contrast agent through time-scheduled size distribution measurements. The diameter-time curve we obtained for shelled perfluorobutane microbubbles showed a rapid diameter increment up to about 1.4 times the initial value, followed by a slow decrement towards bubble disappearance. This behavior is qualitatively similar to the one theoretically predicted by Kabalnov's model for unshelled bubbles, with an extended lifetime due to shell effect. Kabalnov's model, devised for spontaneous dissolution of unshelled microbubbles, was consequently modified in order to get a proper prediction of experimental results also in the case of encapsulated bubbles. A theoretical diameter-time curve was then derived from this new model and fitted to our experimental data points, to estimate microbubble surface tension and to determine the value of an empirical parameter accounting for the shell effect. The proposed model has the potential to predict the dissolution behavior of all kinds of microbubble contrast agents for ultrasound imaging and the adopted experimental methodology represents a new and simple way to estimate microbubble surface tension, essential also for predicting microbubble oscillation performance.

The aim of this study was to investigate the relationships between selected quantitative ultrasound (QUS)parameters and human femur microstructure properties, as quantified by micro-computed tomography (micro-CT). Theauthors employed an innovative custom-designed experimental set-up, which allowed the insonification of eachportion of an excised femoral head sample, simultaneously including trabecular region, cortical layer and cartilage intheir physiologic morphological configuration. Thirty different, uniformly distributed, regions of interest were analysedfor the calculation of apparent integrated backscatter (AIB), integrated reflection coefficient (IRC) and several micro-CTparameters. QUS data acquisitions were performed through both single-element ultrasound transducers at twodifferent frequencies (2.25 and 3.5 MHz) and a clinically available 128-element echographic probe. Obtained resultsshowed that AIB was strongly correlated with trabecular network properties (r up to 0.80) and IRC had appreciablelinear correlations with cortical bone density (r up to 0.57). The agreement between single-element transducers andechographic probe, combined with the innovative approach of considering the entire femoral head in its physiologicalshape with all its components (cartilage, cortical layer, trabecular region), encourages the clinical translation of theproposed approach as a possible new method for early osteoporosis diagnosis.

An in vitro investigation based on QuantitativeUltrasound (QUS) has been carried out in this paper on asample of human femoral head, aiming at microstructurecharacterization and bone quality assessment. Two QUSparameters, Integrated Reflection Coefficient (IRC) andApparent Integrated Backscatter (AIB) were measured byaccurately analyzing ultrasonic signals backscattered fromthe target bone when immersed in water and insonified at2.25 MHz. In particular, US data were acquired from 22different positions along the maximum sectionperpendicular to the axial direction (head-neck axis) of thetarget sample. The obtained data were compared with localstructural properties gathered at each considered positionfrom a high-resolution micro-computed tomography(microCT) scan of the same sample. A linear regressionanalysis showed an appreciable correlation between QUSparameters and some of the micro-structural parameters. Asexpected, IRC correlated better with cortical bone volumefraction (r = -0.53), and AIB with trabecular bone volumefraction (r = -0.60) and trabecular spacing (r = 0.47). Theseresults are particularly encouraging in view of a possibleclinical translation of the proposed approach for earlyosteoporosis diagnosis.

The aim of this study is to assess the accuracy of a novel ultrasound (US) approach for lumbar spine densitometry on overweight and obese women of variable age through a clinical validation study. The US method was originally developed in women with body mass index (BMI) < 25 kg/m2. In this study, 382 female patients were recruited (45-80 years, BMI > 25 kg/m2) and underwent dual X-ray absorptiometry (DXA) of lumbar spine (L1-L4) and an US scan of the same vertebrae L1-L4, performed with a dedicated device providing both echographic images and 'raw' radiofrequency signals. Acquired US data were analysed through a novel automatic algorithm that performed a series of spectral and statistical analyses to calculate bone mineral density employing an innovative method. Diagnostic accuracy of US investigations was quantitatively assessed through a direct comparison with DXA results. The average agreement between US and DXA diagnoses was acceptable for patients aged 45-65 years (81.5%), while a slight decrement was observed for older patients (69.6%), which can be partially due to a decrease in DXA accuracy because of age-related degenerations. The adopted method has a potential for early osteoporosis diagnosis in people younger than 65 years, independent of their BMI.

Nanoparticles (NPs) are emerging as a potential medical tool for novel diagnostic, drug delivery, and therapeutic approaches. Among them, a spherical NP with a core-shell structure is a way to combine multiple functionalities on the nanoscale. In this paper, we describe the preparation characterization and applications of core-shell iron oxide-gold nanoparticles (Fe3O 4@Au NPs). A comprehensive set of experiments, including transmission electron microscopy, dynamic light scattering, small angle neutron scattering, and ultraviolet visible spectroscopy is applied to characterize their chemical, physical, and optical properties. We also study their applicability as contrast agents for magnetic resonance imaging (MRI): the measurement of longitudinal and transverse relaxation times of Fe3O4@Au NPs in vitro and in vivo allowed the assessment of longitudinal (R1) and transverse (R2) relaxivities at 1.5 and 3 T. Finally, a procedure for functionalizing NPs with integrin targeting cyclic Arginine-Glycine-Aspartate peptidomimetic is reported, leading to the development of nanoscale probes for ?v?3 integrin, particularly attractive in terms of resolution and 3-D imaging capabilities. The resulting multifunctional nanoprobes offer suitable blood-circulation time and contrast for microimaging as well as for gradient-echo MRI, and could enable new imaging magnetoplasmonic applications.

The aim of the present work is to assess the effects of different laser fluence and exposure time values on the signal enhancement obtained using of Gold Nanorods (AuNRs) as contrast agent for optoacoustic imaging. In fact, until now, extremely few relevant studies have assessed the optoacoustic behavior of AuNRs under repeatable experimental conditions. A dedicated experimental set-up was developed in order to quantify the contribution of independent parameters to the optoacoustic signal (OAS) produced by 100-mu l solution of AuNR at different concentrations (50, 100 and 200 pM), deposited in a custom-designed tissue-mimicking phantom and irradiated by an appropriate Near Infrared (NIR) light source at variable working conditions in order to generate plasmonic resonance in the AuNRs. Analysis of the OAS recorded by a single-channel ultrasound (US) probe allowed the identification of the optimal and maximum duration of laser exposure, determined through a quantitative analysis of the progressive degradation of the signal emitted by AuNRs under irradiation and at different laser fluence levels. Similarly the effect of rising AuNR concentrations on OAS characteristics was verified, finding a direct proportionality between signal amplitude and AuNR concentration. We found the optimal and maximum laser exposure duration, in order to preserve the AuNR optoacoustic efficiency, were respectively equal to 20 s and 60 s for laser fluence up to 50 mJ/cm(2). Furthermore, the OAS generated upon laser irradiation of AuNRs was found directly proportional to the concentration employed and the optimal concentration of 200 pM was identified.

In recent years, intensive studies have been conducted on the development of nanosized contrast agents (CAs) for multimodal molecular imaging. In this context, we have demonstrated the possibility of realizing a shell of magnetic nanoparticles (NPs) on acoustically-visible silica nanospheres (SiNSs), in order to obtain new dual-mode CAs detectable through both ultrasound (US) and magnetic resonance imaging (MRI). In the present work we performed the first experimental investigation of the low-frequency acoustical behavior of one of these novel CAs, made of SiNSs of different diameters (range 160-660 nm) coated by FePt-iron oxide NPs. Magnetically-coated SiNSs were insonified with low-frequency US pulses (2.5, 3.5 and 4.5 MHz) and the results were compared with those of pure SiNSs. Magnetic shell addition was shown to produce only slight variations in acoustical response of SiNSs and the detection ability of each considered US frequency was quantified as a function of NP size.

HRV (Heart Rate Variability) is an indicator that can be related to different human organs and systems: breathing, heart, brain, pulmonary system, etc. In cardiac clinic, physical exertion can be pre-assessed thanks to HR (Heart Rate) response using appropriate tests to rule out eventual cardiac dysfunction prior to undergo patient to further exams, surgical operations and rehabilitation activities. HR assessment must determine the capability of patient to continue exertion up to a certain level without having angina pain symptoms and brain dysfunctions. The variability of HR is a marker of dynamic load because it is sensitive and responsive to acute stress. Moreover it is also a marker of a cumulative wear and tear because it declines with advancing age. In this paper we propose combined measurements of EEG-Ergospirometry and ECG for patient's cardio-pulmonary condition assessment for allowing doctors to make a decision on rehabilitation or surgical operation for people suspected of suffering from epilepsy seizures. Measurements assessed using frequency domain parameters have permitted the determination of low and high frequencies that are related to sympathetic and parasympathetic activities respectively. (C) 2012 Elsevier Ltd. All rights reserved.

A simple and effi cient method for synthesizing a range of hybrid nanocompositesbased on a core of silica nanospheres (160, 330, and 660 nm indiameter) covered by an outer shell of superparamagnetic nanoparticles,either iron oxide or heterodimeric FePt-iron oxide nanocrystals, is presented.The magnetic and ultrasound characterization of the resulting nanocompositesshows that they have great potential as contrast agents for dual-modeimaging purposes, combining magnetic resonance imaging (MRI) and ultrasonography(US).

To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents (NPCAs) for echographic medical imaging at low ultrasound (US) frequency.METHODS: We synthesized three different nanosized structures: (1) pure silica nanospheres (SiNSs); (2) FePt-iron oxide (FePt-IO)-coated SiNSs; and (3) IO-coated SiNSs, employing three different diameter of SiNS-core (160, 330 and 660 nm). Tissue mimicking phantoms made of agarose gel solution containing 5 mg of different NPCAs in 2 mL-Eppendorf tubes, were insonified by a commercial echographic system at three different low US pulse values (2.5, 3.5 and 4.5 MHz). The raw radiofrequency signal, backscattered from each considered NPCA containing sample, has been processed in order to calculate the US average backscatter intensity and compare the acoustic behavior of the different NPCA types.RESULTS: The highest US contrast was exhibited by pure SiNSs; FePt-IO-coated SiNSs acoustical behavior followed a similar trend of pure SiNSs with a slight difference in terms of brightness values. The acoustic response of the examined NPCAs resulted function of both SiNS diameter and US frequency. Specifically, higher US frequencies determined higher value of the backscatter for a given SiNS diameter. Frequency-dependent enhancement was marked for pure SiNSs and became less remarkable for FePt-IO-coated SiNSs, whereas IO-coated SiNSs resulted almost unaffected by such frequency variations. Pure and FePt-IO-coated SiNSs evidenced an image backscatter increasing with the diameter up to 330 nm. Conversely, among the types of NPCA tested, IO-coated SiNSs showed the lowest acoustical response for each synthesized diameter and employed US frequency, although a diameter-dependent raising trend was evidenced.CONCLUSION: The US characterization of magnetically covered SiNS shows that FePt-IO, rather than IO, was the best magnetic coating for realizing NPCAs suitable for dual mode imaging of deep organs, combining US and magnetic resonance imaging.

Osteoporosis is a silent disease without any evidenceof disease until a fracture occurs. Approximately 200million people in the world are affected by osteoporosisand 8.9 million fractures occur each year worldwide.Fractures of the hip are a major public health burden,by means of both social cost and health condition ofthe elderly because these fractures are one of the maincauses of morbidity, impairment, decreased quality oflife and mortality in women and men. The aim of thisreview is to analyze the most important factors relatedto the enormous impact of osteoporotic fractures onpopulation. Among the most common risk factors, lowbody mass index; history of fragility fracture, environmentalrisk, early menopause, smoking, lack of vitaminD, endocrine disorders (for example insulin-dependentdiabetes mellitus), use of glucocorticoids, excessivealcohol intake, immobility and others represented themain clinical risk factors associated with augmentedrisk of fragility fracture. The increasing trend of osteoporosisis accompanied by an underutilization of theavailable preventive strategies and only a small numberof patients at high fracture risk are recognized andsuccessively referred for therapy. This report providesanalytic evidences to assess the best practices inosteoporosis management and indications for theadoption of a correct healthcare strategy to significantlyreduce the osteoporosis burden. Early diagnosis is thekey to resize the impact of osteoporosis on healthcaresystem. In this context, attention must be focused onthe identification of high fracture risk among osteoporoticpatients. It is necessary to increase nationalawareness campaigns across countries in order toreduce the osteoporotic fractures incidence.

Diagnosis by imaging is one of the most important findings in biomedical imaging because it allows not only the diagnosing of a specific pathology but to perform online and offline surgical operations using imaging as it is noticed in interventional radiology. This paper illustrates the use Hough transform in identifying pathological structures included in CT (Computer Tomography) and HRCT (High Resolution Computer Tomography) images related to patients suffering from lung disease. These abnormal areas appear as bulges of the trophic vessels and they are similar to circular structures with level of lighter gray near to white. Circular Hough transform (CHT) identifies regions with a circular shape. However, a metrics is defined in order to understand if the pointed out area has a pathological morphology. CHT is used here for helping to detect possible events of indolent tumors or undetermined significance pathologies for lung apparatus. For this aim, we use entropy approach with CHT because it measures the scatter of the directional elements in an image. In fact a high entropy value is related to areas with a strong contrast in grayscale, and abnormalities in the image are present as a set of points with more lighter than the dark background. The results have shown, by means of an accuracy true table, rendering a comparison between clinicians'diagnosis and CHT detection, it is possible to indicate, with a better accuracy, potential areas of undetermined significance pathologies. Finally, a receiver operational curve (ROC) is used as an accuracy index for evaluating the positive impact of entropy on diagnosis.

Thermotherapy is often used for diverse biomedical applications. One of them is treating human body area under pain, for example, lumbar pain. Thermotherapy can be used for such purpose by means of, for instance, metal-based bands that produce heat on the area under treatment. The heat delivered by such bands end after a specific time. This is a thermotherapy system based on a contact between dedicated bands and human body area under pain. The bands generally contain materials as polyester, iron or copper, salt, cellulose, active carbons, etc. The paper presents an energy harvesting system based on Seebeck's effect using micro-thermogenerators (TEGs) that convert heat from neck to electrical energy to be used on lumbar area with a further conversion from electrical to heat. This approach, even apparently complicated, allows to use a system that can be utilized every time and for a long period. It is useful because the heat produced by human body is displaced from neck to another area of the same body.

Electroencephalogram (EEG) is a source ofinteresting information if one is able to extract them accordingto appropriate techniques. The conditions of individual underEEG test is a key issue. In general, EEG feature extraction canbe associated to other information like Electrocardiogram(ECG), ergospirometry and electromyogram (EMG). However,in some cases, a multidimensional representation is used;bispectrum is an example of such a representation. HOS (highorder statistics), for instance, include the bispectrum and thetrispectrum (third and fourth order statistics, respectively).Advanced estimate spectral analysis can reveal newinformation encompassed in EEG signals. That is the reasonthe author propose an algorithm based on DSD (DecimatedSignal Diagonalization) that is able of processing exponentiallydumped signals like those that regard EEG features. Theversion proposed here is a multidimensional one.

Aim of the present work was to perform a detailed experimental investigation on the applicability ranges of a novel ultrasound (US) imaging method, that has been recently proposed by our research group in order to facilitate the detection of targeted nanosized contrast agents on diagnostic echographic images. In our previous investigation, in fact, we demonstrated the possibility of selectively suppressing non-contrast echoes in US images through a new contrast detection protocol, including a novel broadband pulse sequence employing two different US frequencies and a two-step image processing algorithm. Feasibility of this approach was preliminarily verified on 330-nm silica nanospheres (SiNSs) dispersed in agarose gel phantoms. In the present work, we investigated the effectiveness of the same approach employing a different clinically-available echographic device and adding the following new experimental conditions: 1) two further sizes of SiNSs (160 nm and 660 nm) were tested; 2) the effects of lower levels of incident acoustic pressure were studied; 3) a different couple of lower US frequencies was employed. Obtained results demonstrated that the proposed method can be effectively applied to enhance the presence of SiNSs in the whole range 160-660 nm employing US pulses at conventional diagnostic frequencies and it seemed particularly suited to be employed in combination with low acoustic pressures. Furthermore, the tested imaging technique shows very promising perspectives for a prompt translation into clinical contexts, given its suitability for real-time imaging with constant spatial resolution employing commercially-available echographic devices.

Halloysite nanotubes (HNTs) are nanomaterials composed of double layered aluminosilicate minerals characterized by a wide range of medical applications. Nonetheless, systematic investigations of their imaging potential are still poorly documented. This paper shows a parametric assessment of the effectiveness of HNTs as scatterers for safe ultrasound (US)-based molecular imaging. Quantitative evaluation of average signal enhancement produced by HNTs with varying set up configuration was performed. The influence of different levels of power (20%, 50%, and 80%) of the signal emitted by clinical equipment was determined, to assess the efficacy of different HNT concentrations (1.5, 3, and 5 mg/mL) at conventional ultrasonic frequencies (5.7-7 MHz), even in case of specific limitation regarding US mechanical interaction with target tissues. Different samples of HNT containing agarose gel were imaged through a commercially available echographic system and acquired data were processed through a dedicated prototypal platform to extract the average ultrasonic signal amplitude. The rate of signal enhancement achieved by different concentration values was quantified and the contribution of frequency increment was separately evaluated. Despite influencing the level of mechanical excitation on HNTs and tissues, our results demonstrated how increasing the power of the emitted signal negatively affected the measured backscatter. Conversely, noticeable improvements in signal backscatter could be achieved incrementing HNT concentration and the echographic frequency employed; specifically the signal enhancement over the used concentration range could be improved by averagely 20%, corresponding to 4.86 ± 0.80 (a.u.), when employing the higher value of echographic frequency. © 2013 IEEE.

The detection of neurophysiological features by means of electroencephalogram (EEG) is one of the most recurrent medical exams to be performed on human beings. As it stands, EEG trials are not always sufficient to deliver a clear and precise diagnosis for much pathology. Hence, it must be integrated with other exams. However, we can use all additional instrumental exams to improve the quality of the diagnosis because there are other constraints, namely, financial, medical, and individual. This paper presents an original implementation of EEG signal processing using filter diagonalization method to build a bispectrum and contour representation to discover possible abnormalities hidden in the signal for aided-diagnosis. Two different EEG signals are used for this scope. EEG signals are acquired simultaneously with electrocardiograms (ECG) and ergospirometric ones. ECG signals are also processed along with EEGs. A comparison is made with high order spectra approach. All experimental data regarding EEG, ECG, and ergospirometry are acquired during suspected-patient walking along a path of similar to 32 m for verifying the impact of fatigue on neurophysiological processes and vice versa.

Bio-implantable circuits always raise interestbecause it is already the frontier of overcoming differentdeficiencies of human body physiological limitations andimpairments. They allow, on one hand the operating mode ofinternal organs, and the contact with outside, at the other hand,thanks to wired and/or wireless architectures. EEG(Electroencephalogram) signals are an example of a topic wherescientists and researchers have been working to use them forpreventing general and specific pathologies regarding namelycentral nervous system and other physiological aspects. Thispaper illustrates preliminary results of nanocircuits used for abio-implantable neuro-case encompassing circuits useful forsignal processing and measurement.

Early and accurate diagnosis of tumors requires the combined adoption of different imaging modalities with molecular sensitivity. A successful employment of multimodal molecular imaging is related to the development of smart fully-biodegradable nanoparticle contrast agents (NPCAs), detectable by at least two non-ionizing imaging techniques and suitably sized for tumor targeting. After a short overview of recent findings obtained by our research group in the development and characterization of novel NPCAs, this paper shows for the first time a quantitative assessment of the effectiveness of both a pure silica NPCA and a composite silica/superparamagnetic NPCA as scatterers of low-frequency diagnostic ultrasound (3 MHz) in very low volume concentrations (0.1-0.2%). The pure silica NPCA confirmed the behavior recently reported for higher concentrations at higher frequencies. The composite NPCA followed the same behavior, showing a marked effectiveness peak for a particle diameter of 330 nm, which represents a particularly useful size for tumor targeting purposes. These results open new exciting perspectives for dual-mode molecular imaging of deep tumors, combining ultrasound and magnetic resonance techniques for the accurate, safe and early detection of cancer cells located in internal organs.

Currently, the accepted "gold standard" method for bone mineral density (BMD) measurement and osteoporosis diagnosis is dual-energy X-ray absorptiometry (DXA). However, actual DXA effectiveness is limited by several factors, including intrinsic accuracy uncertainties and possible errors in patient positioning and/or post-acquisition data analysis. DXA employment is also restricted by the typical issues related to ionizing radiation employment (high costs, need of dedicated structures and certified operators, unsuitability for population screenings). The only commercially-available alternative to DXA is represented by "quantitative ultrasound" (QUS) approaches, which are radiation-free, cheaper and portable, but they cannot be applied on the reference anatomical sites (lumbar spine and proximal femur). Therefore, their documented clinical usefulness is restricted to calcaneal applications on elderly patients (aged over 65 y), in combination with clinical risk factors and only for the identification of healthy subjects at low fracture risk. Literature-reported studies performed some QUS measurements on proximal femur, but their clinical translation is mostly hindered by intrinsic factors (e.g., device bulkiness). An innovative ultrasound methodology has been recently introduced, which performs a combined analysis of B-mode images and corresponding "raw" radiofrequency signals acquired during an echographic scan of the target reference anatomical site, providing two novel parameters: Osteoporosis Score and Fragility Score, indicative of BMD level and bone strength, respectively. This article will provide a brief review of the available systems for osteoporosis diagnosis in clinical routine contexts, followed by a synthesis of the most promising research results on the latest ultrasound developments for early osteoporosis diagnosis and fracture prevention.

Osteoporosis is the most common disorder of bone metabolism. The main consequence of this disease is theincreased risk of fracture. Osteoporotic fractures represent a serious problem in terms of social and economiccosts. Then, there is a strong need for the assessment of the best practices in prevention and treatment of osteoporosis.Dual X-ray absorptiometry (DXA) represents the current "gold standard" method for osteoporosisdiagnosis. However, DXA cannot be employed for population mass screenings, because of required expositionto ionizing radiation and high management costs. The aim of this paper was to review the currently availabletechniques for osteoporosis diagnosis and also to illustrate the feasibility of an innovative quick, cheap andnon-invasive ultrasound-based methodology. The results recently published by the authors' research groupsuggest that the proposed approach has the potential for routine application in early diagnosis, which is thekey to resize the impact of osteoporosis on healthcare systems.

To experimentally investigate the acoustical behavior of silica nanoparticles within conventional diagnostic ultrasound fields and to determine a suitable configuration, in terms of particle size and concentration, for their employment as targetable contrast agents. We also assessed the effectiveness of a novel method for automatic detection of targeted silica nanoparticles for future tissue typing applications. MATERIALS AND METHODS: Silica nanospheres of variable size (160, 330, and 660 nm in diameter) and concentration (1010-1013 part/mL) were dispersed in different custom-designed agarose-based gel samples and imaged at 7.5 MHz with a conventional echograph linked to a research platform for radiofrequency signal acquisition. Off-line analysis included evaluation of backscattered ultrasound amplitude, image brightness, and nanoparticle automatic detection through radiofrequency signal processing. RESULTS: Amplitude of nanoparticle-backscattered signals linearly increased with particle number concentration, but image brightness did not show the same trend, because the logarithmic compression caused the reaching of a "plateau" where brightness remained almost constant for further increments in particle concentration. On the other hand, both backscatter amplitude and image brightness showed significant increments when particle diameter was increased. Taking into account particle size constraints for tumor targeting (pore size of tumor endothelium and trapping effects because of reticuloendothelial system limit the dimension of effectively employable particles to less than 380 nm), a suitable compromise is represented by the employment of 330-nm silica nanospheres at a concentration of about 1 to 2 x 10^11 part/mL. These particles, in fact, showed the best combination of number concentration and diameter value to obtain an effective enhancement on conventional echographic images. Furthermore, also the sensitivity of the developed method for automatic nanoparticle detection had a maximum (72.8%) with 330-nm particles, whereas it was lower with both bigger and smaller particles (being equal to 64.1% and 17.5%, respectively). CONCLUSIONS: Silica nanoparticles at a diameter of about 330 nm are very promising contrast agents for ultrasound imaging and specific tumor targeting at conventional diagnostic frequencies, being in particular automatically detectable with high sensitivity already at low doses. Future studies will be carried out to assess the acoustic behavior of nanoparticles with different geometries/sizes and to improve sensitivity of the automatic detection algorithm.

The knowledge of ultrasound contrast agent (UCA) behaviour is continuously improving, mainly thanks to "invitro" measurements performed by means of specific phantoms, mimicking the acoustic properties of severalhuman body districts. For such purposes, it is necessary to develop experimental setups able to minimisechemical and physical effects due to environmental conditions. In this paper we discuss the design of a newtissue-mimicking phantom, specifically evaluating the sound-absorption properties of three synthetic materials(Polyurethane, Airex©, ethylene vinyl acetate (EVA©)) laid on the bottom of the phantom. Our goal is toestablish the best material to use in order to minimise the artefacts within the tissue-mimicking matrix.Polyurethane showed the best sound-absorbent behaviour for every tested ultrasound frequency, so itsemployment in covering the bottom of tissue-mimicking phantoms is suggested in order to allow experimentalinvestigations of acoustic properties of different UCAs without additional aspects due to environmentalboundary conditions.

Osteoporosis is the most common disorder ofbone metabolism, with a high rate of diffusion, especially inthe elderly population. The main consequence ofosteoporosis is bone fragility, with the consequentlyincreased risk of fracture. Vertebral and hip fracturesrepresent one of the most important causes of morbidity anddisability and cause also high economic costs for theNational Healthcare Systems. The currently accepted "goldstandard" method for osteoporosis diagnosis is representedby the evaluation of bone mineral density (BMD) throughdual X-ray absorptiometry (DXA). However, DXA presentssome considerable limitations such as the exposition toionizing radiations, employment of bulky devices and highcosts of management. This paper gives an overview of themost widely used X-ray based techniques to performosteoporosis diagnosis and describes the working principlesof non-invasive ultrasound (US) based methods for bonedensitometry, underlining the corresponding advantages andlimitations for their use in the clinical practice. Moreover,the article illustrates the effectiveness of an innovative UStechnique, directly applicable on the main anatomicalreference sites, in terms of diagnostic accuracy and fracturerisk prediction. Early diagnosis is the key to resize theimpact of osteoporosis on healthcare systems. Therefore, itwould be necessary to encourage the widespread use ofquick, cheap and non-invasive screening techniques.

Osteoporosis affects about 200 millionsubjects in the world and is responsible for 8.9 millionfractures each year. The combined annual cost of allosteoporotic fractures in Europe has been estimated to be 30billion Euros. The frequency of osteoporotic fractures isrising in many countries, in particular because of theincreased longevity of the population. In Italy, around 4million of women and more than 800,000 men are exposedto a high fracture risk. The National Healthcare Systemspends about 500 million Euros for hospitalization andchirurgical treatment of hip fractures and costs related torehabilitation are even greater. The situation is more criticalin southern Italy, where the incidence of elderly people ishigher than in the other regions. Therefore, there is a strongneed for the assessment of the best practices in preventionand treatment of osteoporosis. In this paper, after anoverview of the socioeconomic impact of osteoporosis inItaly, with particular focus on Apulia region, the mostimportant techniques used to assess the fracture risk arebriefly described. In general, they fall into two majorcategories: physical measurement of skeletal mass andassessment of clinical risk factors. Moreover, the mostcommonly used pharmacological agents for the treatment ofosteoporosis are reported. In conclusion, for a correctmanagement of the disease, it would be necessary toencourage the widespread use of cheap and non-invasivescreening techniques for early diagnosis of osteoporosis.

Hip fracture has been recognized as the worstconsequence of osteoporosis, as it represents one of the mostimportant causes of disability and mortality in elderlypeople. An accurate knowledge of the osteoporotic fracturerisk in asymptomatic individuals through population massscreenings may be the only way to reduce the occurrence ofhip fractures. Aim of this study was to perform apreliminary clinical validation of a new ultrasound (US)-based method for bone densitometry directly applicable onfemoral neck. A total of 112 female patients were enrolledfor this study (61-75 years of age, body mass index(BMI)<40 kg/m2) and all of them underwent two differentdiagnostic investigations: a conventional DXA (dual-energyX-ray absorptiometry) of the femoral neck and an US scanof the same bone district, acquiring both echographic imagesand unfiltered radiofrequency signals. US data wereanalyzed by a new algorithm that calculated the samediagnostic parameters obtained from DXA examination(BMD, T-score, Z-score). Accuracy of each parametercalculated by this algorithm was then evaluated through adirect comparison with DXA results as a function of bothpatient age and BMI. For 81.3% of the patients USdiagnosis (osteoporotic, osteopenic, healthy) coincided withthe corresponding DXA one and this accuracy level was notappreciably influenced by patient age nor by BMI. Theillustrated method has the potential to be used for routinepopulation screening programs for early osteoporosisdiagnosis and hip fracture prevention.

Molecular imaging techniques play an increasingly important role in the deep understading of pathologies.They represent a direct spotlight on the molecular correlates of diseases and can be used for assessing earlier the state of health and decide the treatment of each patient in a personalized way. This article will show the basis of several imaging techniques, and give examples on the application and development of molecular imaging tracers. Particular attention will be pointed on the use of nanostructured materials, that has a promising role in the finding of new tracers, on the use of novel methodological approaches (multimodality, theranostics, pretargeting) and on the possibility of translational applications.

Nowadays the decision between Caesarean Sections (CS), natural or operative child delivery is taken upon interpretation of manually measured anatomical parameters and recorded fetal heart rate, exposing the clinical staff and patients to human errors and determining the continuously rising rate of CS above the ideal 15% recommended by the World Health Organization. This study introduces a new method for non-invasive, quantitative and automatic monitoring of childbirth labor progression. We combined an ultrasound system with a real-time tracking algorithm in order to automatically measure labor progression parameters, like head station, head position, progression angle, based on patient specific anatomical references [Patent no. PCT/EP2009/008321]. A 2D digital echograph connected to a PC for real-time image processing was employed to measure fetal head station (FHS) and progression angle (PA). A quantitative validation study was carried out on a birth simulator, consisting of fetal and maternal mannequins immersed in water. Then, a preliminary intrapartum B-mode imaging study was conducted on patients by means of the developed methods and corresponding algorithms. In the birth simulator, the automatic identification was correct in 98% of the computed images providing high visual reliability for the operator. The average errors (expressed as bias +/- SD) were 0.8 +/- 1.9 mm for FHS and 3 degrees +/- 4 degrees for the PA. Accuracies improve of about 30% by reducing the frame-rate to be processed, i.e. from 1 fps to 0.2 fps, which is still suitable for the purpose. The methodology has been successfully validated in preliminary intrapartum echographic monitoring.

Effective prevention and management of osteoporosis would require suitable methods for population screenings and early diagnosis. Current clinically-available diagnostic methods are mainly based on the use of either X-rays or ultrasound (US). All X-ray based methods provide a measure of bone mineral density (BMD), but it has been demonstrated that other structural aspects of the bone are important in determining fracture risk, such as mechanical features and elastic properties, which cannot be assessed using densitometric techniques. Among the most commonly used techniques, dual X-ray absorptiometry (DXA) is considered the current "gold standard" for osteoporosis diagnosis and fracture risk prediction. Unfortunately, as other X-ray based techniques, DXA has specific limitations (e.g., use of ionizing radiation, large size of the equipment, high costs, limited availability) that hinder its application for population screenings and primary care diagnosis. This has resulted in an increasing interest in developing reliable pre-screening tools for osteoporosis such as quantitative ultrasound (QUS) scanners, which do not involve ionizing radiation exposure and represent a cheaper solution exploiting portable and widely available devices. Furthermore, the usefulness of QUS techniques in fracture risk prediction has been proven and, with the last developments, they are also becoming a more and more reliable approach for assessing bone quality. However, the US assessment of osteoporosis is currently used only as a pre-screening tool, requiring a subsequent diagnosis confirmation by means of a DXA evaluation. Here we illustrate the state of art in the early diagnosis of this "silent disease" and show up recent advances for its prevention and improved management through early diagnosis.

Osteoporosis affects about 200 million subjects in the world and is responsible for 8.9 million fractures eachyear. The frequency of osteoporotic fractures is rising in many countries, due to the increased longevity ofthe population. In Europe, the annual cost of all osteoporotic fractures has been estimated to be 30 billion ofEuros. In this paper, after an overview of the socioeconomic impact of osteoporosis in the world and in Italy,with particular focus on Apulia region, the most important techniques used to assess the fracture risk are brieflydescribed. Moreover, the most commonly used pharmacological agents for the treatment of osteoporosis arereported. The aim of this review is to analyze the main factors causing the huge impact of osteoporosis onhealthcare system, in terms of diagnosis and therapies, and to illustrate recent advances for treatment andprevention of this "silent disease".

Fetal malformations are very frequent in industrialized countries. Although advanced maternal age may affect pregnancy outcome adversely, 80%-90% of fetal malformations occur in the absence of a specific risk factor for parents. The only effective approach for prenatal screening is currently represented by an ultrasound scan. However, ultrasound methods present two important limitations: the substantial absence of quantitative parameters and the dependence on the sonographer experience. In recent years, together with the improvement in transducer technology, quantitative and objective sonographic markers highly predictive of fetal malformations have been developed. These markers can be detected at early gestation (11-14 wk) and generally are not pathological in themselves but have an increased incidence in abnormal fetuses. Thus, prenatal ultrasonography during the second trimester of gestation provides a "genetic sonogram", including, for instance, nuchal translucency, short humeral length, echogenic bowel, echogenic intracardiac focus and choroid plexus cyst, that is used to identify morphological features of fetal Down's syndrome with a potential sensitivity of more than 90%. Other specific and sensitive markers can be seen in the case of cardiac defects and skeletal anomalies. In the future, sonographic markers could limit even more the use of invasive and dangerous techniques of prenatal diagnosis (amniocentesis, etc.).

Halloysite clay nanotubes (HNTs) are natural materials with a characteristic hollow tubular structure in the nanometer range. Owing to this feature, they were found to be a suitable nanosized container for the loading of biologically active molecules like biocides and drugs. Also, HNTs have been reported to be of potential interest for other biological applications, such as gene delivery carriers, ultrasound contrast agents, cancer therapy and stem cells isolation. Therefore, biocompatibility of halloysite represents one the main requisites for the employment of HNTs for clinical purposes. Here we present a study aimed at assessing HNTs biocompatibility before and after their surface coating with poly(ethylene glycol) (PEG), a polymer which has been reported to increase biocompatibility, to prolong circulation time and to prevent protein adsorption and aggregation in biological environments. The dose- and time-dependent cytotoxicity of noncoated and PEG-coated HNTs obtained was evaluated in vitro by MTT cell viability assay carried out on both HeLa and HepG2 cells, two different human cancer cell lines. Binding and uptake of nanotubes were also analyzed at ultrastructural level by transmission electron microscopy (TEM). Interestingly, the results obtained showed that both the HNTs tested were actively taken up by the cells but, while noncoated nanotubes exhibited significant concentration- and time-dependent toxicity, PEG-coated HNTs were found to be highly biocompatible, being then suitable candidates for biomedical applications.

Human body has its basal temperature that can be exploited for different uses. Obviously, thermal properties of human tissues allow to retrieve specific characteristics if special attention is paid. Therefore, thermal imaging is a suitable tool for many applications. It could be used in medical issues for checking temperature variations displayed by a volume under investigation during surgery operations related to humans. It plays a double role: imaging and temperature measurements. This paper presents a wide and joint experimental research for determining the decreasing temperature encompassed in a volume during an urological intervention in order to established, in a realtime, which tissues and adherences must be taken in consideration for continuing and optimizing the surgery process. A further processing is performed using Hough transform that exhibits encouraging results for this specific approach. This is very important for some other applications like contour extraction, contour matching and surface spline fitting.

In recent years the understanding of the behaviour of currently available ultrasound contrast agents (UCAs), in the form of gas-filled microbubbles encapsulated in elastic shells, has significantly improved thanks to "ad hoc" designed "in vitro" studies. However, in several studies there has been a tendency to use high UCA concentrations, potentially reducing the safety of microbubbles in clinical applications. In this study we investigated a possible strategy to improve microbubble safety by reducing the injection dose and employing low ultrasound intensities. We measured the achievable contrast enhancement insonifying microbubbles at different low concentrations (range 0.01-0.10 ¼L/mL) using a very low mechanical index (MI=0.08). Our results, based on the use of advanced techniques for signal processing and spectrum analysis, showed that UCA backscatter strongly depends on microbubble concentration also in the considered low range, providing useful indications towards the definition of an optimal low contrast dose, effectively employable at low MIs.

Aim of the present work was, first, to demonstrate feasibility and usefulness of subharmonic imaging of silica nanospheres (SiNSs) at diagnostic ultrasound (US) frequencies and, second, to investigate the acoustic effectiveness of a new class of multimodal nanocomposite contrast agents, towards dual mode investigations combining US and magnetic resonance imaging (MRI). We employed SiNSs of variable diameter (160 nm, 330 nm and 660 nm) dispersed in different volume concentrations (range 0.07-0.8%) in agarose gel samples that were automatically scanned through a digital ecograph using narrow-band US pulses, varying both frequency (range 5-10 MHz) and mechanical index (MI range 0.2-0.6). Raw radiofrequency data were acquired and off-line processed, in order to study the behaviour of fundamental and subharmonic component as a function of incident frequency, MI, SiNS size and concentration. The experiments were also repeated on different agarose samples, containing SiNSs covered by an outer shell of smaller magnetic nanoparticles, made of either iron oxide (FeO) or FePt-FeO nanocrystals. Obtained results show that the highest sensitivity of subharmonic intensity to nanoparticle presence was always found for 330-nm SiNSs, that can be effectively detected at very low volume concentrations (0.07%) by employing a low MI (0.2). These properties were maintained by SiNSs even after a coverage by an outer magnetic shell, so representing a valuable candidate for tasks of dual mode molecular imaging.

Aim of this paper was to assess the clinical effectiveness of a novel ultrasound (US) approach for the estimation of bone fragility. A total of 85 female patients (40-80. years) were recruited and underwent conventional DXA investigations of both lumbar spine and proximal femur, an abdominal US scan of the lumbar spine and the FRAX® questionnaire for the calculation of osteoporotic fracture probabilities. Acquired US data were analyzed through an automatic algorithm that calculated the Fragility Score (F.S.), a parameter that estimates skeletal fragility from dedicated spectral and statistical analyses. F.S. showed a good correlation with the most reliable fracture risk predictions obtained by FRAX® (r = 0.71, p <. 0.001). Since this correlation level with FRAX® outcomes was much better than lumbar BMD one (. r = 0.43) and very similar to that obtained for femoral neck BMD (. r = 0.72), F.S. has the potential to become a simple and non-ionizing method for bone fragility assessment.

Aim of this work was to evaluate the effectiveness of a recently introduced ultrasound (US) parameter for the estimation of bone mineral density (BMD) of the lumbar spine, when extensively used in a clinical context to investigate adult women of variable body mass index (BMI). A total of 414 female patients (aged 51-60 years) underwent a spinal dual X-ray absorptiometry (DXA) and an abdominal echographic scan of the lumbar spine. US images and corresponding unfiltered radiofrequency signals were analyzed through a new fully automatic algorithm, which performed a series of spectral and statistical analyses to calculate the novel diagnostic parameter, called the Osteoporosis Score (O.S.). Effectiveness of O.S. in BMD estimation and subsequent osteoporosis diagnosis was assessed through a direct comparison with DXA measurements (assumed as the gold standard reference), by quantifying the agreement between the two methods through accuracy calculation and Pearson correlation coefficient (r). A very good and significant correlation was found between O.S.-estimated BMDs and corresponding DXA values over the whole considered study population (r=0.81, p<0.001). The subsequent diagnostic classifications of patients as osteoporotic, osteopenic or healthy on the basis of O.S.-estimated BMD values resulted in an overall accuracy of 90.1%. Interestingly, both the adopted metrics (r value and accuracy) were not appreciably influenced by patient BMI, demonstrating that US-measured O.S. is significantly correlated with spinal BMD in adult women independently of their BMI. Therefore, the clinical translation of this innovative method for osteoporosis diagnosis can be envisioned.

Aim of this work was to investigate the effect ofultrasound incident frequency on the echographic contrastenhancement power of an experimental drug delivery agent,halloysite clay nanotubes (HNTs), and to determine a suitableconfiguration in terms of both insonification frequency andparticle concentration for an effective employment as targetedcontrast agent. Various HNT concentrations (range 0.25-3.00mg/mL) were dispersed in custom-designed tissue-mimickingphantoms and exposed to different ultrasound frequencies (7-11MHz) through a conventional clinically-available echographicdevice. Off-line analysis included the evaluation of bothamplitude of backscattered ultrasound signals and imagebrightness. Amplitude of HNT-backscattered signals showed alinear increase with particle concentration, while imagebrightness enhancement was limited by logarithmic compressioneffects. On the other hand, backscatter amplitude showedsignificant increments with increasing ultrasound frequency upto 10 MHz, then showing a concentration-dependent behaviorwithout further enhancements. Overall, the most effectiveresponse was found when a 10-MHz ultrasound frequency wasemployed to insonify HNTs at a concentration of 1.5 mg/mL. Inconclusion, the present study optimized the combination ofincident ultrasound frequency and HNT concentration, in orderto obtain an echographic image enhancement suitable for medicalapplications. Future dedicated studies will assess the feasibility ofautomatic detection of HNTs within echographic images andtheir possible employment as theranostic agents.

Aim of this study was to perform a detailed clinical validation of a new fully automatic algorithm for vertebral interface segmentation in echographic images. Abdominal echographic scans of lumbar vertebrae L1-L4 were carried out on 150 female subjects with variable age and body mass index (BMI). Acquired datasets were automatically processed by the algorithm and the accuracy of the obtained segmentations was then evaluated by three independent experienced operators. Obtained results showed a very good specificity in vertebra detection (93.3%), coupled with a reasonable sensitivity (68.1%), representing a suitable compromise between the detection of a sufficient number of vertebrae for reliable diagnoses and the limitation of the corresponding computation time. Importantly, there was only a minimum presence of 'false vertebrae' detected (2.8%), resulting in a very low influence on subsequent diagnostic analyses. Furthermore, the algorithm was specifically tuned to provide an improved sensitivity (up to 73.1%) with increasing patient BMI, to keep a suitable number of correctly detected vertebrae even when the acquisition was intrinsically more difficult because of the augmented thickness of abdominal soft tissues. The proposed algorithm will represent an essential added value for developing echographic methods for the diagnosis of osteoporosis on lumbar vertebrae.

Positioning system for endovascular devices and the like comprising a catheter (A) having a possibly inflatable element (B), provided with ultrasonic probes (C,C',C"), a control algorithm and characterised in that at least one of said probes is arranged inside (C) the element (B) and at least one further probe is arranged outside the element (B), upstream (C) and/or downstream (C"), in order to allow an accurate spatial localisation - and in real time - of the inflatable element.

An apparatus (10) for measuring one or more labor progress parameters (25) as the dilation of the endocervical canal (8), the rotation and the position of the head (4) of the foetus (3) during the descent, the duration and the intensity of the uterine contractions, other morphological and physiological parameters, without introducing foreign objects into the body of a pregnant woman (2) and independently from the sensitivity of the operator. The apparatus (10) comprises automatic means for tracking, in a sequence of ultrasound images (11,12) that are obtained by an ultrasound probe (1), one or more regions of interest (ROI, 21), that may be both two-dimensional or three-dimensional and are centred about anatomic reference points (28) that define said parameters selected in a reference image by a displaying unit (14). The tracking means comprises: a) a means for calculating a function (f) at the pixels of the ROI of the reference image and of images preferably sampled among the images of the sequence, b) a means for calculating iteratively at the positions of the ROI in subsequent images, by a means of comparison between the values of the function (f) calculated in the pixels of the ROI of a current image and the values of the function (f) calculated in the pixels of the ROI of a subsequent ultrasound image; c) a means for comparing each position of the ROI with the position of the ROI in the reference image and for calculating the labor progress parameter responsive to said comparison. The new position of the region of interest may be defined as a domain in which a predetermined object function assumes a minimum value.