Quantitative Ultrasound Parameters Research Articles

QUS characteristics in Normal Population: a Mini Review and our experience.

Quantitative ultrasound (QUS) is a bone densitometry method that is less expensive and more portable than DXA. It is also noninvasive. QUS parameters include speed of sound (SOS), broad band ultrasound attenuation (BUA), and stiffness index (SI). This study defined normal values of QUS parameters in Iranian men and women. QUS of heels measured in 258 Iranian men and women, aged 20-76 y/o. They were participants of Iranian Multicenter Osteoporosis study (IMOS), selected by randomized sampling. QUS device was an Achilles+ (GE-Lunar) device. Percentiles of SI (2.5%, 50%, and 97.5%) determined. We found a good agreement between the Iranian reference values and western reference (used by device) value in defining normal and osteoporotic people (κ = 0.875). Results from this study suggest that QUS of the heel may be a good method for diagnosis of low bone mass in different regions.

Trabecular bone score and phalangeal quantitative ultrasound are associated with muscle strength and fracture risk in hemodialysis patients.

There is growing interest in the relationship between chronic kidney disease (CKD) and fragility fracture risk. Bone mineral density (BMD) is a major determinant of bone strength, although its role as a predictor of fracture in advanced CKD and hemodialysis is still under debate. We aimed to further investigate surrogates of bone quality and their associations with muscle strength and fracture risk in hemodialysis. Multiple clinical risk factors for fracture and an estimated 10-year probability of fracture, BMD at lumbar spine and femur, trabecular bone score (TBS), X-ray vertebral morphometry, phalangeal bone quantitative ultrasonography (QUS), tibial pulse-echo ultrasonography (PEUS), and handgrip strength were evaluated in a setting of hemodialysis patients in treatment with acetate-free biofiltration (AFB) or bicarbonate hemodialysis. The bone ultrasound measurements, both at phalangeal and tibial sites, were significantly associated with lumbar and femoral DXA values. Handgrip strength was significantly associated with the 10-year probability of fracture (r = −0.57, p < 0.001 for major fractures and r = −0.53, p < 0.001 for hip fracture, respectively), with femur neck, total femur, and L1–L4 BMD values (r = 0.47, p = 0.04; r = 0.48, p = 0.02; r = 0.58, p = 0.007, respectively), with TBS at the lumbar spine (r = 0.71, p < 0.001) and with the phalangeal QUS measure of AD-SoS (r = 0.369, p = 0.023). In the hemodialysis group, 10 participants (24.3%) reported at least one morphometric vertebral fracture (Vfx); conversely, only six participants (15%) showed Vfx in the control group. In the hemodialysis group, participants with Vfx compared with participants without Vfx reported significantly different TBS, bone transmission time (BTT), cortical thickness, and handgrip strength (p < 0.05). At multiple regression analysis, by identifying as dependent variable the 10-year fracture risk for major fracture, after correcting for age, BMI, time since dialysis, AD-SoS, cortical bone thickness, and handgrip strength, only BTT (β = −15.21, SE = 5.91, p = 0.02) and TBS (β = −54.69, SE = 21.88, p = 0.02) turned out as independently associated with fracture risk. In conclusion, hemodialysis patients showed a higher fracture risk and lower surrogate indices of bone strength as TBS and QUS parameters. In this cohort of patients, handgrip strength measurements appeared to be a useful instrument to identify high-fracture-risk subjects.

Quantitative Ultrasound Assessment of Early Osteoarthritis in Human Articular Cartilage Using a High-Frequency Linear Array Transducer.

Quantitative ultrasound (QUS) assessment of osteoarthritis (OA) using high-frequency, research-grade single-element ultrasound systems has been reported. The objective of this ex vivo study was to assess the performance of QUS in detecting early OA using a high-frequency linear array transducer. Osteochondral plugs (n=26) of human articular cartilage were scanned with ExactVu Micro-Ultrasound using an EV29L side-fire transducer. For comparison, the samples were also imaged with SAM200Ex, a custom 40-MHz scanning acoustic microscope with a single-element, focused transducer. Thirteen QUS parameters were derived from the ultrasound data. Magnetic resonance imaging (MRI) data, with T1 and T2 extracted as the quantitative parameters, were also acquired for comparison. Cartilage degeneration was graded from histology and correlated to all quantitative parameters. A maximum Spearman rank correlation coefficient (ρ) of 0.75 was achieved using a combination of ExactVu QUS parameters, while a maximum ρ of 0.62 was achieved using a combination of parameters from SAM200Ex. A maximum ρ of 0.75 was achieved using the T1 and T2 MRI parameters. This study illustrates the potential of a high-frequency linear array transducer to provide a convenient method for early OA screening with results comparable to those of research-grade single-element ultrasound and MRI.

Deep Estimation of Speckle Statistics Parametric Images.

Quantitative Ultrasound (QUS) provides important information about the tissue properties. QUS parametric image can be formed by dividing the envelope data into small overlapping patches and computing different speckle statistics such as parameters of the Nakagami and Homodyned K-distributions (HK-distribution). The calculated QUS parametric images can be erroneous since only a few independent samples are available inside the patches. Another challenge is that the envelope samples inside the patch are assumed to come from the same distribution, an assumption that is often violated given that the tissue is usually not homogenous. In this paper, we propose a method based on Convolutional Neural Networks (CNN) to estimate QUS parametric images without patching. We construct a large dataset sampled from the HK-distribution, having regions with random shapes and QUS parameter values. We then use a well-known network to estimate QUS parameters in a multi-task learning fashion. Our results confirm that the proposed method is able to reduce errors and improve border definition in QUS parametric images.

Relationship between clinical severity and hemodynamic impact of great saphenous vein incompetence using strain gauge plethysmography and duplex ultrasound.

To evaluate the relation of quantitative Duplex ultrasound (DUS) and strain gauge plethysmography (SGP) parameters with clinical severity and quality of life in patients with superficial venous incompetence. DUS volume flow and distal SGP refilling times (T50 and T90) were evaluated in 152 patients (164 Limbs) with superficial incompetence. Clinical severity and quality of life were evaluated with C of the CEAP classification, venous clinical severity score (VCSS), Aberdeen varicose vein questionnaire (AVVQ), and EuroQol 5D-3L. Higher DUS volume flow was associated with higher C in CEAP scores. Volume flow was also related to T50 and T90. Shorter T50 and T90 were associated with higher C in CEAP and VCSS. T50 was also associated with EQ-5DVAS. Reflux extension to the foot wase associated with shorter T50 and T90 and higher DUS volume flow. DUS volume flow and SGP refilling times are related with clinical severity and provide quantitative information regarding venous function in patients with superficial incompetence.

Ultrasound-Estimated Bladder Weight Correlates With Videourodynamic Studies in Neurogenic Bladder Dysfunction.

This retrospective study was designed to evaluate which lower urinary tract ultrasound parameter(s) could predict the results of invasive urodynamic testing which are the current reference standard in the evaluation of bladder dysfunction in children with spina bifida. Fifty eight children with spina bifida undergoing video urodynamic evaluation and a renal bladder ultrasound as their standard of care were evaluated. Quantitative and qualitative ultrasound parameters were then correlated with the videourodynamic study results which served as the reference standard. For bladders with ending storage pressures above 15 cm H2 O, there were increases in these ultrasound measured parameters: 1) bladder mass (P=.00019), 2) bladder/body mass ratio (P=.0059), and 3) wall thickness (P=.01). We defined the storage cost as the final storage pressure divided by the percentage of expected bladder capacity attained. These data were analyzed to compute receiver operating curves with assuming end storage pressures cutoff points of 15, 20, 30, and 40 cm H2 O. The optimal area under the curve was found for a bladder weight of 65 g and a pressure cutoff of 30 cm H2 O with a sensitivity of 75% with a specificity of 84%. Bladder weight is independent of luminal volume, can be normalized to body weight, and may serve as a clinically valuable tool for noninvasive screening to define a subset of patients with neurogenic bladder with a higher likelihood of having abnormal videourodynamic results.

In vivo assessment of pulmonary edema and fibrosis in rats using separation of single and multiple scattering contributions and quantitative ultrasound

The application of spectral quantitative ultrasound (QUS) and envelope statistical methods to lung ultrasound is complicated due to the presence of multiple scattering (MS). In this study, the relationship between QUS assessment of lung disease and scattering regime was explored by applying QUS to lung ultrasound data, where the single scattering (SS) and MS components were separated. Data were acquired by a Verasonics Vantage ultrasound scanner from 15 healthy rats, 19 edematous rats, and 20 fibrotic rats. SS and MS components of the data were separated by a random matrix theory approach. Spectral QUS and envelope statistical parameters were then estimated from the SS and MS data separately. Initial results were obtained using the healthy and pulmonary edema data, where the extracted QUS parameters were correlated to the wet-to-dry (W/D) weight ratio, a gold standard measurement of edema. Several QUS parameters were significantly correlated to W/D ratio for both the SS and MS data, and the highest correlation coefficient was 0.53 using the SS data and 0.48 using the MS data. These results demonstrate the utility of QUS for assessing lung disease and provide further insight on the effects of SS and MS on spectral QUS and envelope statistical parameters.

Robust Scatterer Number Density Segmentation of Ultrasound Images.

Quantitative ultrasound (QUS) aims to reveal information about the tissue microstructure using backscattered echo signals from clinical scanners. Among different QUS parameters, scatterer number density is an important property that can affect the estimation of other QUS parameters. Scatterer number density can be classified into high or low scatterer densities. If there are more than ten scatterers inside the resolution cell, the envelope data are considered as fully developed speckle (FDS) and, otherwise, as underdeveloped speckle (UDS). In conventional methods, the envelope data are divided into small overlapping windows (a strategy here we refer to as patching), and statistical parameters, such as SNR and skewness, are employed to classify each patch of envelope data. However, these parameters are system-dependent, meaning that their distribution can change by the imaging settings and patch size. Therefore, reference phantoms that have known scatterer number density are imaged with the same imaging settings to mitigate system dependency. In this article, we aim to segment regions of ultrasound data without any patching. A large dataset is generated, which has different shapes of scatterer number density and mean scatterer amplitude using a fast simulation method. We employ a convolutional neural network (CNN) for the segmentation task and investigate the effect of domain shift when the network is tested on different datasets with different imaging settings. Nakagami parametric image is employed for multitask learning to improve performance. Furthermore, inspired by the reference phantom methods in QUS, a domain adaptation stage is proposed, which requires only two frames of data from FDS and UDS classes. We evaluate our method for different experimental phantoms and in vivo data.

In Vivo Quantitative Ultrasound on Dermis and Hypodermis for Classifying Lymphedema Severity in Humans.

This study investigated the ability of in vivo quantitative ultrasound (QUS) assessment to evaluate lymphedema severity compared with the gold standard method, the International Society of Lymphology (ISL) stage. Ultrasonic measurements were made around the middle thigh (n=150). Radiofrequency data were acquired using a clinical scanner and 8-MHz linear probe. Envelope statistical analysis was performed using constant false alarm rate processing and homodyned K (HK) distribution. The attenuation coefficient was calculated using the spectral log-difference technique. The backscatter coefficient (BSC) was obtained by the reference phantom method with attenuation compensation according to the attenuation coefficients in the dermis and hypodermis, and then effective scatterer diameter (ESD) and effective acoustic concentration (EAC) were estimated with a Gaussian model. Receiver operating characteristic curves of QUS parameters were obtained using a linear regression model. A single QUS parameter with high area under the curve (AUC) differed between the dermis (ESD and EAC) and hypodermis (HK) parameters. The combinations with ESD and EAC in the dermis, HK parameters in the hypodermis and typical features (dermal thickness and echogenic regions in the hypodermis) improved classification performance between ISL stages 0 and ≥I (AUC=0.90 with sensitivity of 75% and specificity of 91%) in comparison with ESD and EAC in the dermis (AUC=0.82) and HK parameters in the hypodermis (AUC=0.82). In vivo QUS assessment by BSC and envelope statistical analyses can be valuable for non-invasively classifying an extremely early stage of lymphedema, such as ISL stage I, and following its progression.

Efficacy and safety of an orally administered DGAT2 inhibitor alone or coadministered with a liver-targeted ACC inhibitor in adults with non-alcoholic steatohepatitis (NASH): rationale and design of the phase II, dose-ranging, dose-finding, randomised, placebo-controlled MIRNA (Metabolic Interventions to Resolve NASH with fibrosis) study

IntroductionSmall molecule inhibitors of the terminal step in intrahepatic triglyceride synthesis (diacylglycerol acyltransferase 2 inhibitor (DGAT2i, PF-06865571, ervogastat)) and upstream blockade of de novo lipogenesis via acetyl-coenzyme A carboxylase inhibitor...

Early Changes in Quantitative Ultrasound Imaging Parameters during Neoadjuvant Chemotherapy to Predict Recurrence in Patients with Locally Advanced Breast Cancer.

Simple SummaryPatients diagnosed with breast cancer treated with chemotherapy before surgery were included in this study. The tumor was imaged using ultrasound before the chemotherapy was started and in the middle of chemotherapy treatment (one month after starting). After treatment completion, patients were followed up according to standard clinical practice and categorized into two groups based on disease recurrence until the last follow-up. The ultrasound imaging was analyzed using advanced computational techniques, and artificial intelligence was used to develop models to differentiate between the two outcomes. We demonstrated that using the ultrasound image data, the final outcomes can be predicted as early as within one month of the start of chemotherapy.Background: This study was conducted to explore the use of quantitative ultrasound (QUS) in predicting recurrence for patients with locally advanced breast cancer (LABC) early during neoadjuvant chemotherapy (NAC). Methods: Eighty-three patients with LABC were scanned with 7 MHz ultrasound before starting NAC (week 0) and during treatment (week 4). Spectral parametric maps were generated corresponding to tumor volume. Twenty-four textural features (QUS-Tex1) were determined from parametric maps acquired using grey-level co-occurrence matrices (GLCM) for each patient, which were further processed to generate 64 texture derivatives (QUS-Tex1-Tex2), leading to a total of 95 features from each time point. Analysis was carried out on week 4 data and compared to baseline (week 0) data. ∆Week 4 data was obtained from the difference in QUS parameters, texture features (QUS-Tex1), and texture derivatives (QUS-Tex1-Tex2) of week 4 data and week 0 data. Patients were divided into two groups: recurrence and non-recurrence. Machine learning algorithms using k-nearest neighbor (k-NN) and support vector machines (SVMs) were used to generate radiomic models. Internal validation was undertaken using leave-one patient out cross-validation method. Results: With a median follow up of 69 months (range 7–118 months), 28 patients had disease recurrence. The k-NN classifier was the best performing algorithm at week 4 with sensitivity, specificity, accuracy, and area under curve (AUC) of 87%, 75%, 81%, and 0.83, respectively. The inclusion of texture derivatives (QUS-Tex1-Tex2) in week 4 QUS data analysis led to the improvement of the classifier performances. The AUC increased from 0.70 (0.59 to 0.79, 95% confidence interval) without texture derivatives to 0.83 (0.73 to 0.92) with texture derivatives. The most relevant features separating the two groups were higher-order texture derivatives obtained from scatterer diameter and acoustic concentration-related parametric images. Conclusions: This is the first study highlighting the utility of QUS radiomics in the prediction of recurrence during the treatment of LABC. It reflects that the ongoing treatment-related changes can predict clinical outcomes with higher accuracy as compared to pretreatment features alone.

A Study on Correlation between Contrast-Enhanced Ultrasound Parameters and Pathological Features of Diabetic Nephropathy.

The objective of this study was to evaluate the correlation between contrast-enhanced ultrasound (CEUS) parameters and histopathological features in patients with diabetic nephropathy (DN). Sixty-two patients with DN (44 men, mean age: 52.61 ± 10.63 y) were enrolled. They underwent renal biopsy for DN at the Department of Ultrasound, PLA Hospital, between May 2017 and February 2020. Renal tissue was obtained by ultrasound-guided percutaneous needle biopsy. CEUS was performed, and time-intensity curves (TICs) and renal perfusion parameters were analyzed. Differences in CEUS parameters were analyzed according to the glomerular classification and interstitial fibrosis-tubular atrophy (IFTA) score. Continuous variables were evaluated using the analysis of variance or Mann-Whitney U-test. Discontinuous variables were compared with the χ2-test. Spearman correlation analyses evaluated associations among quantitative ultrasound perfusion parameters and histopathological characteristics. Peak enhancement (PE), wash-in rate (WiR), wash-in perfusion index (WiPI) and wash-out rate (WoR) of the cortex, and their cortex/medulla ratios, decreased with increasing glomerular classification grade (p < 0.05). The fall time (FT) of the cortex, and their cortex/medulla ratios, increased with increasing glomerular classification grade (p < 0.05). There were no significant differences in the CEUS parameters for different IFTA scores. The perfusion volume-relevant parameters (such as PE, WiR and WiPI) had a negative correlation (p < 0.05), while the perfusion time-relevant parameters (such as RT and FT) had a positive correlation (p < 0.05), with the severity of glomerular lesions, glomerulosclerosis rate and number of Kimmelstiel-Wilson lesions. The CEUS parameters of the cortex could reflect pathological characteristics, especially changes in glomerular lesions.

Ultrasound Scattering From Cell-Pellet Biophantoms and Ex Vivo Tumors Provides Insight Into the Cellular Structure Involved in Scattering.

The histologically identifiable cellular structure(s) involved in ultrasonic scattering is(are) yet to be uniquely identified. The study quantifies six possible cellular scattering parameters, namely, cell and nucleus radii and their respective cell and nucleus volume fractions as well as a combination of cell and nucleus radii and their volume fraction. The six cellular parameters are each derived from four cell lines (4T1, JC, LMTK, and MAT) and two tissue types (cell-pellet biophantom and ex vivo tumor). Optical histology and quantitative ultrasound (QUS), both independent approaches, are used to yield these cellular parameters. QUS scatterer parameters are experimentally determined using two ultrasonic scattering models: the spherical Gaussian model (GM) and the structure factor model (SFM) to yield insight about scattering from nuclei only and cells only. GM is a classical ultrasonic scattering model to evaluate QUS parameters and is well adapted for diluted media. SFM is adapted for dense media to estimate reasonably well scatterer parameters of cellular structures from ex vivo tissue. Nucleus and cell radii and volume fractions are measured optically from histology. They were used as inputs to calculate BSC for scattering from cells, nuclei, and both cells and nuclei. The QUS-derived scatterers (radii and volume fractions) distributions were then compared to the optical histology scatterer parameters derived from these calculated BSCs. The results suggest scattering from cells only (LMTK and MAT) or both cells and nuclei (4T1 and JC) for cell-pellet biophantoms and scattering from nuclei only for tumors.

Diagnostic value of calcaneal quantitative ultrasound in the evaluation of osteoporosis in middle-aged and elderly patients.

To study the correlation between calcaneal quantitative ultrasound (QUS) and dual-energy X-ray absorptiometry (DXA), and analyze the diagnostic value of calcaneal QUS in the evaluation of middle-aged and elderly osteoporosis.We assessed bone mineral density (BMD) at the femoral neck and intertrochanteric of left hip and lumbar spine (L1–L4) sites with DXA and QUS parameters of the right and left calcanei in a cohort of 82 patients over the age of 50 years. Using DXA parameters as the gold standard for the diagnosis of osteoporosis, the correlation coefficient between BMD and QUS parameters was calculated. Receiver operating characteristic curve was generated and areas under the curves were evaluated. Cut-off values for QUS were defined.In men, there was a moderate correlation between calcaneal QUS and proximal femoral BMD (P < .05), but no significant correlation between calcaneal QUS and lumbar BMD (P > .05). In women, calcaneal QUS were moderately correlated with lumbar spine and proximal femoral BMD (P < .05). Using DXA as the gold standard, the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of calcaneal QUS in the diagnosis of osteoporosis were 90.2%, 89.2%, 100%, 100%, and 50.0%, respectively. According to the receiver operating characteristic curve, when the QUS T-score of calcaneum was –1.8, the area under the curve was 0.888, the sensitivity was 73.21%, and the specificity was 92.31% (P < .05). When the QUS T-score of calcaneum was –2.35, the sensitivity was 37.2% and the specificity was 100%.Calcaneal QUS can be used to predict proximal femoral BMD in middle-aged and elderly people, as well as lumbar BMD in women. As a screening method for osteoporosis, calcaneal QUS has good specificity, so it can be recommended to use it as a pre-screening tool to reduce the number of DXA screening. When the QUS T-score of calcaneum is –1.8, it has the greatest diagnostic efficiency for osteoporosis; when the QUS T-score of calcaneum is ≤–2.35, it can be diagnosed as osteoporosis.

Changes in residual kidney Pulsatility Index following living donor nephrectomy.

Nephrectomy in kidney transplant donors provokes a compensatory hyperfiltration process of the residual kidney, characterized by changes in renal vascular hemodynamics. This research aimed to determine the short-term difference in the pulsatility index (PI) of kidney transplant donors' residual kidney before and after nephrectomy. This is a prospective historical study using secondary data from kidney transplant living donors who have undergone nephrectomy at a tertiary referral hospital in Jakarta, Indonesia, from March 2019 to January 2020. PI of renal, segmental, interlobar, and arcuate arteries of the residual kidneys were measured in the preoperative and day-1, day-7, day-30 postoperative period. The pre- and postoperative PI values were statistically analyzed to examine differences between the groups. PI of 40 residual kidneys were obtained. There were no significant mean PI changes in the arteries except for the middle interlobar artery (p = 0.049), which showed no significant difference after post hoc analysis. There is no significant short-term difference in PI of the residual kidney before and after kidney transplant donor nephrectomy. Short-term postoperative PI of the residual kidney arteries may not be suitable as a predictor for chronic kidney disease in kidney transplant donors. Other quantitative Doppler ultrasound parameters must be considered.

Skeletal status in children and adolescents with new-onset type 1 diabetes: a preliminary study based on bone densitometry and quantitative ultrasound.

Type 1 diabetes (T1D) represents a risk factor for bone loss and impaired bone quality. We conducted an exploratory retrospective cross-sectional study involving youths with new-onset T1D, to investigate the relationship between lumbar spine dual-energy X-ray absorptiometry (DXA) and phalangeal quantitative ultrasound (QUS) measurements, along with their correlation with markers of bone turnover, glucose homeostasis, and residual β-cell function. 17 children and adolescents (8 females) with recent-onset T1D were enrolled into this study. Lumbar spine areal bone mineral density (aBMD) and age-adjusted amplitude-dependent speed of sound (AD-SoS) Z-scores were indicative of low BMD status (≤ -2.0 SD) in 11.7% and 17.6% of participants, respectively. Spearman's correlation analysis revealed significant inverse correlations between AD-SoS values and circulating levels of β-CrossLaps, alkaline phosphatase, and osteocalcin, along with a significant positive correlation between bone transmission time (BTT) values and fasting plasma C-peptide (FCP) levels. There was no statistically significant correlation between DXA-QUS parameters, fasting plasma glucose (FPG), and glycated haemoglobin (HbA1c). Finally, there was a significant positive correlation between lumbar spine aBMD and BTT values. Our study suggests that DXA and/or QUS parameters may be altered in a small proportion of T1D children and adolescents at the disease onset. Additionally, residual β-cell function may represent a protective factor against T1D-related detrimental skeletal changes. Large and long-term prospective studies are needed to confirm these preliminary findings since the present study is limited by the retrospective cross-sectional design and by its small sample size.

A multiparametric volumetric quantitative ultrasound imaging technique for soft tissue characterization.

Quantitative ultrasound (QUS) offers a non-invasive and objective way to quantify tissue health. We recently presented a spatially adaptive regularization method for reconstruction of a single QUS parameter, limited to a two dimensional region. That proof-of-concept study showed that regularization using homogeneity prior improves the fundamental precision-resolution trade-off in QUS estimation. Based on the weighted regularization scheme, we now present a multiparametric 3D weighted QUS (3D QUS) method, involving the reconstruction of three QUS parameters: attenuation coefficient estimate (ACE), integrated backscatter coefficient (IBC) and effective scatterer diameter (ESD). With the phantom studies, we demonstrate that our proposed method accurately reconstructs QUS parameters, resulting in high reconstruction contrast and therefore improved diagnostic utility. Additionally, the proposed method offers the ability to analyze the spatial distribution of QUS parameters in 3D, which allows for superior tissue characterization. We apply a three-dimensional total variation regularization method for the volumetric QUS reconstruction. The 3D regularization involving N planes results in a high QUS estimation precision, with an improvement of standard deviation over the theoretical 1/N rate achievable by compounding N independent realizations. In the in vivo liver study, we demonstrate the advantage of adopting a multiparametric approach over the single parametric counterpart, where a simple quadratic discriminant classifier using feature combination of three QUS parameters was able to attain a perfect classification performance to distinguish between normal and fatty liver cases.

Ex-vivo quantitative ultrasound assessment of cartilage degeneration.

Osteoarthritis is a common disease that implies joint degeneration and that strongly affects the quality of life. Conventional radiography remains currently the most used diagnostic method, even if it allows only an indirect assessment of the articular cartilage and employ the use of ionizing radiations. A non-invasive, continuous and reliable diagnosis is crucial to detect impairments and to improve the treatment outcomes.Quantitative ultrasound techniques have proved to be very useful in providing an objective diagnosis of several soft tissues. In this study, we propose quantitative ultrasound parameters, based on the analysis of radiofrequency data derived from both healthy and osteoarthritis-mimicking (through chemical degradation) ex-vivo cartilage samples. Using a transmission frequency typically employed in the clinical practice (7.5-15 MHz) with an external ultrasound probe, we found results in terms of reflection at the cartilage surface and sample thickness comparable to those reported in the literature by exploiting arthroscopic transducers at high frequency (from 20 to 55 MHz). Moreover, for the first time, we introduce an objective metric based on the phase entropy calculation, able to discriminate the healthy cartilage from the degenerated one.Clinical Relevance- This preliminary study proposes a novel and quantitative method to discriminate healthy from degenerated cartilage. The obtained results pave the way to the use of quantitative ultrasound in the diagnosis and monitoring of knee osteoarthritis.

Shear Wave Elastography and Quantitative Ultrasound as Biomarkers to Characterize Deep Vein Thrombosis In Vivo.

Investigate shear wave elastography (SWE) and quantitative ultrasound (QUS) parameters in patients hospitalized for lower limb deep vein thrombosis (DVT). Sixteen patients with DVT were recruited and underwent SWE and radiofrequency data acquisitions for QUS on day 0, day 7, and day 30 after the beginning of symptoms, in both proximal and distal zones of the clot identified on B-mode scan. SWE and QUS features were computed to differentiate between thrombi at day 0, day 7, and day 30 following treatment with heparin or oral anticoagulant. The Young's modulus from SWE was computed, as well as QUS homodyned K-distribution (HKD) parameters reflecting blood clot structure. Median and interquartile range of SWE and QUS parameters within clot were taken as features. In the proximal zone of the clot, the HKD ratio of coherent-to-diffuse backscatter median showed a significant decrease from day 7 to day 30 (P=.036), while the HKD ratio of diffuse-to-total backscatter median presented a significant increase from day 7 to day 30 (P=.0491). In the distal zone of the clot, the HKD normalized intensity of the echo envelope median showed a significant increase from day 0 to day 30 (P=.0062). No SWE features showed statistically significant differences over time. Nonetheless, a trend of lower median of Young's modulus within clot for patients who developed a pulmonary embolism was observed. QUS features may be relevant to characterize clot's evolution over time. Further analysis of their clinical interpretation and validation on a larger dataset would deserve to be studied.

Quantitative contrast-enhanced ultrasound for the differentiation of kidney allografts with significant histopathological injury.

To identify specific quantitative contrast-enhanced ultrasound (CEUS) parameters that could distinguish kidney transplants with significant histopathological injury. Sixty-four patients were enrolled in this prospective observational study. Biopsies were performed following CEUS and blood examination. 28 biopsy specimens had minimal changes (MC group), while 36had significant injury (SI group). Of these, 12had rejection (RI group) and 24 non-rejection injury (NRI group). In RI and NRI groups, temporal difference in time to peak (TTP) between medulla and cortex (ΔTTPm-c) was significantly shorter compared to the MC group (5.77, 5.92, and 7.94s, P=0.048 and 0.026, respectively). Additionally, RI group had significantly shorter medullary TTP compared to the MC group (27.75 vs. 32.26s; P=0.03). In a subset of 41 patients with protocol biopsy at 1-year post-transplant, ΔTTPm-c was significantly shorter in the SI compared to the MC group (5.67 vs. 7.67s; P=0.024). Area under receiver operating characteristic curves (AUROCs) for ΔTTPm-c was 0.69 in all patients and 0.71 in patients with protocol biopsy. RI and NRI groups had shorter ΔTTPm-c compared to the MC group. AUROCs for both patient groups were good, making ΔTTPm-c a promising CEUS parameter for distinguishing patients with significant histopathological injury.