Acoustic Radiation Force Impulse Imaging Research Articles

Compound Acoustic Radiation Force Impulse Imaging of Bovine Eye by Using Phase-Inverted Ultrasound Transducer.

In general, it is difficult to visualize internal ocular structure and detect a lesion such as a cataract or glaucoma using the current ultrasound brightness-mode (B-mode) imaging. This is because the internal structure of the eye is rich in moisture, resulting in a lack of contrast between tissues in the B-mode image, and the penetration depth is low due to the attenuation of the ultrasound wave. In this study, the entire internal ocular structure of a bovine eye was visualized in an ex vivo environment using the compound acoustic radiation force impulse (CARFI) imaging scheme based on the phase-inverted ultrasound transducer (PIUT). In the proposed method, the aperture of the PIUT is divided into four sections, and the PIUT is driven by the out-of-phase input signal capable of generating split-focusing at the same time. Subsequently, the compound imaging technique was employed to increase signal-to-noise ratio (SNR) and to reduce displacement error. The experimental results demonstrated that the proposed technique could provide an acoustic radiation force impulse (ARFI) image of the bovine eye with a broader depth-of-field (DOF) and about 80% increased SNR compared to the conventional ARFI image obtained using the in-phase input signal. Therefore, the proposed technique can be one of the useful techniques capable of providing the image of the entire ocular structure to diagnose various eye diseases.

Ultrasound-based quantitative tools in predicting renal involvement in asymptomatic primary hyperparathyroidism.

Asymptomatic primary hyperparathyroidism (aPHPT) has been recognized as a condition that can lead to renal complications. Timely identification of prognostic indicators for renal impairment holds the potential to facilitate proactive monitoring and treatment strategies in these patients. This study aims to investigate the utility of acoustic radiation force impulse (ARFI) imaging and renal resistive index (RRI), in identifying renal parenchymal and vascular changes in patients with aPHPT. Forty-two patients with aPHPT and 42 controls matched for age, sex, and body mass index were included in the study. The presence of renovascular changes was evaluated by RRI measurement with Doppler ultrasonography, and the presence of renal parenchymal involvement was evaluated by ARFI quantification, given as shear wave velocity (SWV). In aPHPT patients, both the mean RRI and mean SWV values exhibited substantial elevation compared to the control group (P < 0.001 for both). Significant associations were observed between SWV values and serum calcium, parathyroid hormone (PTH), and adenoma size within the patient group (P < 0.001, P < 0.001, P = 0.016, respectively). Similarly, the mean RRI demonstrated positive correlations with serum calcium and PTH levels in the patient group (P< 0.001, P = 0.011, respectively). Multivariate linear regression analysis underscored the connection between mean RRI and mean SWV values with serum calcium levels within the patient group. In addition, serum PTH levels affected mean SWV positively and significantly. The use of ARFI imaging and RRI measurements appears to hold potential in identifying renal involvement in patients with aPHPT.

Longitudinal assessment of liver stiffness using ARFI technique does not support increased risk of fibrosis in rheumatoid arthritis patients on methotrexate.

To assess the liver stiffness in patients with rheumatoid arthritis treated with methotrexate monotherapy using non-invasive, ultrasound-based elastography (acoustic radiation force impulse (ARFI) imaging) in a longitudinal approach. In total, 23 MTX-naive patients were longitudinally assessed using acoustic radiation force impulse (ARFI) imaging. Baseline assessments were carried out between July 2018 and April 2019, and the follow-up evaluations took place after an average of 2.6years. The main outcome variable was the mean shear wave velocity as measured by the ARFI method. It was calculated from 10 valid ARFI measurements for each patient. Inferential statistical analyses (within-group comparisons) were performed using t-tests for dependent samples or suitable nonparametric procedures. The main finding was that observed ARFI shear wave velocities did not increase during the observation period. In fact, this parameter decreased over time from 1.07m/s (SD = 0.23) at baseline without MTX exposure to 0.97m/s (SD = 0.16) at follow-up after a mean of 2.6years (P = 0.013). Moreover, the magnitude of the change in shear wave velocity could not be predicted by indicators of inflammation or disease activity, BMI, age, sex or NSAR intake (corresponding regression analysis: corrected R2 = 0.344; P = 0.296). No increased risk of liver fibrosis was found in RA patients treated with MTX monotherapy during observation period.

A novel denoising strategy for ultrasound elastography

Ultrasound imaging, while offering real-time tissue monitoring, portability, and other benefits, often suffers from poor signal to noise ratio (SNR). Noise has a particularly detrimental effect in US elastography since it gets amplified during the elastic modulus reconstruction process due to computation of high-order spatial derivatives of the deformation field needed to calculate the shear wave velocity within the sample. In this work, we introduce a novel scheme to denoise deformation fields using physically motivated “compatibility conditions,” which are imposed as constraints. These conditions, well established in the solid mechanics literature, ensure that the deformation field remains continuous without exhibiting cracks, folds, or slips. Spatially uncorrelated noise gets significantly reduced when we apply them. Importantly, this approach avoids unnecessary smoothing and the ensuing loss of accuracy commonly observed in other denoising methods. We demonstrate the efficacy of this method using planar deformation fields obtained from simulations and those measured on an elasticity quality assurance (QA) phantom using acoustic radiation force impulse imaging (ARFI). Our pipeline results in smoother elasticity maps with 2x improved SNR, confirming the effectiveness of the approach.

Evaluation of Myocardial Stiffness in Cardiac Amyloidosis Using Acoustic Radiation Force Impulse and Natural Shear Wave Imaging.

Increased myocardial stiffness (MS) is an important hallmark of cardiac amyloidosis (CA) caused by myocardial amyloid deposition. Standard echocardiography metrics assess MS indirectly via downstream effects of cardiac stiffening. The ultrasound elastography methods acoustic radiation force impulse (ARFI) and natural shear wave (NSW) imaging assess MS more directly. This study compared MS in 12 healthy volunteers and 13 patients with confirmed CA using ARFI and NSW imaging. Parasternal long-axis acquisitions of the interventricular septum were obtained using a modified Acuson Sequoia scanner and a 5V1 transducer. ARFI-induced displacements were measured through the cardiac cycle, and ratios of diastolic-over-systolic displacement were calculated. NSW speeds from aortic valve closure were extracted from echocardiography-tracked displacement data. ARFI stiffness ratios were significantly lower in CA patients than controls (mean ± standard deviation: 1.47 ± 0.27 vs. 2.10 ± 0.47, p < 0.001), and NSW speeds were significantly higher in CA patients than controls (5.58 ± 1.10 m/s vs. 3.79 ± 1.10 m/s, p < 0.001). A linear combination of the two metrics exhibited greater diagnostic potential than either metric alone (area under the curve=0.97 vs. 0.89 and 0.88). MS was measured to be significantly higher in CA patients using both ARFI and NSW imaging. Together, these methods have potential utility to aid in clinical diagnosis of diastolic dysfunction and infiltrative cardiomyopathies.

Combined model with acoustic radiation force impulse to rule out high-risk varices in HBV-related cirrhosis with viral suppression.

To prospectively evaluate the performance of spleen stiffness measurement (SSM) and liver stiffness measurement (LSM) via acoustic radiation force impulse (ARFI) imaging combined with platelet counts (PLT) in ruling out HRV in HBV-related cirrhotic patients with viral suppression. Patients with cirrhosis enrolled between June 2020-March 2022 were divided into a derivation cohort and validation cohort. LSM and SSM ARFI-based, and esophagogastroduodenoscopy (EGD) were performed at enrollment. In the derivation cohort, overall, 236 HBV-related cirrhotic patients with maintained viral suppression were enrolled, and the prevalence of HRV was 19.5% (46/236). With the aim of identifying HRV, the most accurate LSM and SSM cut-offs were chosen of 1.46m/s and 2.28m/s, respectively. The combined model (LSM<1.46m/s and PLT>150×109/L strategy combined with SSM ≤ 2.28m/s) can spare 38.6% of EGDs and 4.3% of HRV cases were misclassified. In the validation cohort, we analysed 323 HBV-related cirrhotic patients with maintained viral suppression and validated the combined model can spare 33.4% (108/323) of EGD, and the HRV missed rate was 3.4%. A non-invasive prediction model combining LSM<1.46m/s and PLT>150×109/L strategy with SSM ≤ 2.28m/s exhibited excellent performance in ruling out HRV and avoided a significantly large number (38.6% vs 33.4%) of unnecessary EGDs in HBV-related cirrhotic patients with viral suppression.

Combined ARFI and Shear Wave Imaging of Prostate Cancer: Optimizing Beam Sequences and Parameter Reconstruction Approaches.

This study demonstrates the implementation of a shear wave reconstruction algorithm that enables concurrent acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) of prostate cancer and zonal anatomy. The combined ARFI/SWEI sequence uses closely spaced push beams across the lateral field of view and simultaneously tracks both on-axis (within the region of excitation) and off-axis (laterally offset from the excitation) after each push beam. Using a large number of push beams across the lateral field of view enables the collection of higher signal-to-noise ratio (SNR) shear wave data to reconstruct the SWEI volume than is typically acquired. The shear wave arrival times were determined with cross-correlation of shear wave velocity signals in two dimensions after 3-D directional filtering to remove reflection artifacts. To combine data from serially interrogated lateral push locations, arrival times from different pushes were aligned by estimating the shear wave propagation time between push locations. Shear wave data acquired in an elasticity lesion phantom and reconstructed using this algorithm demonstrate benefits to contrast-to-noise ratio (CNR) with increased push beam density and 3-D directional filtering. Increasing the push beam spacing from 0.3 to 11.6 mm (typical for commercial SWEI systems) resulted in a 53% decrease in CNR. In human in vivo data, this imaging approach enabled high CNR (1.61-1.86) imaging of histologically-confirmed prostate cancer. The in vivo images had improved spatial resolution and CNR and fewer reflection artifacts as a result of the high push beam density, the high shear wave SNR, the use of multidimensional directional filtering, and the combination of shear wave data from different push beams.

PD22-08 ACOUSTIC RADIATION FORCE IMPULSE IMAGE FOR EVALUATION OF PARENCHYMA ELASTICITY IN ACUTE HYDRONEPHROTIC KIDNEY: A PRELIMINARY REPORT

You have accessJournal of UrologyCME1 Apr 2023PD22-08 ACOUSTIC RADIATION FORCE IMPULSE IMAGE FOR EVALUATION OF PARENCHYMA ELASTICITY IN ACUTE HYDRONEPHROTIC KIDNEY: A PRELIMINARY REPORT Jen-Chieh Chen, Shih-Yen Lu, Tzu-Ping Lin, and William J. Huang Jen-Chieh ChenJen-Chieh Chen More articles by this author , Shih-Yen LuShih-Yen Lu More articles by this author , Tzu-Ping LinTzu-Ping Lin More articles by this author , and William J. HuangWilliam J. Huang More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003295.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The acoustic radiation force impulse (ARFI) imaging is a new technique with great promise in the field of elastography. It had been used widely in evaluation of various disease involving tissue stiffness, such as liver fibrosis, thyroid nodules, subcutaneous lymph nodes, and breast lesions. However, in kidney, the blood flow is thought to affect the elasticity more than tissue stiffness. To date, the utility of ARFI imaging in acute hydronephrotic kidney remains unexplored. In this study, we aim to compare the shear wave velocity (SWV) measured by ARFI ultrasound elastography of hydronephrotic kidneys caused by ureteral stones and the normal contralateral kidneys. METHODS: A total of 31 patients presented to our emergency room (ER) due to unilateral renal colic caused by ureteral stone with hydronephrosis from April 2020 to September 2022 were prospectively recruited. The patient’s character was recorded. The kidney ultrasound with ARFI imaging of the affected kidney and the contralateral side was performed by a single experienced technician immediately after the diagnosis was made. The SWV value, expressed as speed (m/sec.) of wave propagation through the tissue, was calculated for each kidney in its outer renal cortex. To each of the kidney, the SWV value was assigned through the average of ten different measurements. The Wilconxon signed rank test was used to compare the SWV value of affected and contralateral kidney in an individual. All P values less than 0.05 were considered statistically significant. RESULTS: Among 31 patients, 16 patients presented to our ER at acute/intermediate phase (<24 hours of symptoms onset) and 15 patients at late phase (≥ 24 hours). The SWV value showed variable changes between the affected and contralateral kidneys in patients who came to our ER within 24 hours of symptoms onset. However, in patients who presented to our ER at late phase, the SWV value was significantly lower in their affected kidney (p=0.043). Subsequent analysis found that the SWV value did not showed any significant correlations with age, side of the affected kidney, pain score, stone size, degree of hydronephrosis, presence of urinary tract infection, or presence of acute kidney injury. All patients received stone management successfully afterward. After a mean follow-up of 3 months, there was no evidence of significant sequelae. CONCLUSIONS: The SWV value showed variable changes in patients whose interval between the onset of the symptoms and the kidney stiffness measurement was less than 24 hours. However, SWV value decreased significantly in patients whose interval was greater than 24 hours. This finding may compatible with the concept that the renal blood flow decreases after 24 hours of obstructive uropathy. To our knowledge, this is the first study to evaluate the ARFI image in acute hydronephrotic kidney. Source of Funding: Nil © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e667 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jen-Chieh Chen More articles by this author Shih-Yen Lu More articles by this author Tzu-Ping Lin More articles by this author William J. Huang More articles by this author Expand All Advertisement PDF downloadLoading ...

Fontan Hepatopathy - Managing Unknowns.

How to best monitor Fontan associated liver disease (FALD) remains unclear. We describe results from a prospective liver care pathway in adults (n=84) with a Fontan circulation. Routine assessment of the liver, by acoustic radiation force frequency and ultrasound was undertaken. Results, including liver biochemistry, systemic ventricular function (echocardiography), functional class, medication use and clinical endpoints (varices, hepatocellular carcinoma, heart transplantation and death) were collated. Most individuals returned a cirrhotic range acoustic radiation force impulse imaging (ARFI) result. ARFI values were greater in the proportion of individuals with hepatic nodularity (p=0.024). Univariate analysis demonstrated moderate correlation with platelet number (Spearmans rho= -0.376, p=0.049). Patients with clinical endpoints had lower platelets (p=0.012) but only a trend to hepatic nodularity (p=0.057). Clinical endpoints were more common in those with ventricular dysfunction (p=0.011). Multivariate analysis revealed that age at Fontan and being on angiotensin converting enzyme inhibitors (ACEI) predicted ARFI score (β=0.06 (95% CI 0.01-0.09), p=0.007 and β=0.53 (95% CI 0.17-0.89), p=0.005, respectively). However, these associations were not significant once adjusted for Fontan type, age at ARFI, systemic ventricle morphology, ventricle function, or Model for End-stage Liver Disease (MELD-XI) excluding international normalised ratio (INR) (p>0.05 for all). Ideal FALD monitoring remains unclear. ARFI has utility as a binary non-invasive indicator of cirrhosis, highlighting individuals who may need more frequent ongoing monitoring for hepatocellular carcinoma. However, no definite advantage to serial ARFI, once cirrhotic range ARFI results are present, has been identified.

Predictive value of acoustic radiation force impulse imaging in breast cancer after neoadjuvant chemotherapy

ABSTRACT To investigate the predictive value of acoustic radiation force impulse imaging for neoadjuvant chemotherapy in breast cancer. Seventy-eight breast cancer patients treated in our hospital from March 2019 to March 2022 were recruited. They received neoadjuvant chemotherapy and were examined by conventional ultrasound and acoustic radiation force impulse imaging before chemotherapy and after two cycles of chemotherapy. The lesion diameter, intralesional blood flow pulsatility index (PI), resistance index (RI), shear wave velocity (SWV), and change rate (Δlesion diameter, ΔPI, ΔRI, ΔSWV) were compared between the two groups before and after chemotherapy. The receiver operating characteristic curve was drawn to evaluate the predictive power of related parameters on the efficacy of neoadjuvant chemotherapy in breast cancer. After two cycles of neoadjuvant chemotherapy, according to the Miller-Payne grading, 57 cases (73.08%) with significant neoadjuvant chemotherapy response were classified as the response group, and 21 cases (26.92%) with non-significant response were classified as the non-response group. Before and after chemotherapy, the difference in lesion diameter, PI, RI, SWV, and change rate (Δlesion diameter, ΔPI, ΔRI, and ΔSWV) was statistically significant between the two groups (P < 0.05). The area under the curve of ΔSWV in predicting the efficacy of neoadjuvant chemotherapy 0.876 (95%CI 0.781 ~ 0.939) was significantly higher than that of Δlesion diameter 0.652 (95%CI 0.535 ~ 0.756), that of ΔPI 0.712 (95%CI 0.599 ~ 0.809), and that of ΔRI 0.678 (95%CI 0.563 ~ 0.780) (P < 0.05). The change rate of tissue stiffness has a relatively high predictive value for the effect of neoadjuvant chemotherapy in breast cancer.

A comparison of transient elastography with acoustic radiation force impulse elastography for the assessment of liver health in patients with chronic hepatitis C: Baseline results from the TRACER study.

Liver stiffness measurements can be used to assess liver fibrosis and can be acquired by transient elastography using FibroScan® and with Acoustic Radiation Force Impulse imaging. The study aimed to establish liver stiffness measurement scores using FibroScan® and Acoustic Radiation Force Impulse in a chronic hepatitis C cohort and to explore the correlation and agreement between the scores and the factors influencing agreement. Patients had liver stiffness measurements acquired with FibroScan® (right lobe of liver) and Acoustic Radiation Force Impulse (right and left lobe of liver). We used Spearman's correlation to explore the relationship between FibroScan® and Acoustic Radiation Force Impulse scores. A Bland-Altman plot was used to evaluate bias between the mean percentage differences of FibroScan® and Acoustic Radiation Force Impulse scores. Univariable and multivariable analyses were used to assess how factors such as body mass index, age and gender influenced the agreement between liver stiffness measurements. Bland-Altman showed the average (95% CI) percentage difference between FibroScan® and Acoustic Radiation Force Impulse scores was 27.5% (17.8, 37.2), p < 0.001. There was a negative correlation between the average and percentage difference of the FibroScan® and Acoustic Radiation Force Impulse scores ( r (95% CI) = -0.41 (-0.57, -0.21), p < 0.001), thus showing that percentage difference gets smaller for greater FibroScan® and Acoustic Radiation Force Impulse scores. Body mass index was the biggest influencing factor on differences between FibroScan® and Acoustic Radiation Force Impulse (r = 0.12 (0.01, 0.23), p = 0.05). Acoustic Radiation Force Impulse scores at segment 5/8 and the left lobe showed good correlation (r (95% CI) = 0.83 (0.75, 0.89), p < 0.001). FibroScan® and Acoustic Radiation Force Impulse had similar predictive values for the assessment of liver stiffness in patients with chronic hepatitis C infection; however, the level of agreement varied across lower and higher scores.

Probability Mass Function-Based Adaptive Median Filtering for Acoustic Radiation Force Impulse Imaging: A Feasibility Study

Probability Mass Function-Based Adaptive Median Filtering for Acoustic Radiation Force Impulse Imaging: A Feasibility Study

声脉冲辐射力成像对2型糖尿病周围神经病变胫神经的研究

声脉冲辐射力成像对2型糖尿病周围神经病变胫神经的研究

Malign ve benign tiroid nodüllerinin ayrımında ARFI elastografi

Aim: To examine the diagnostic performance of virtual touch tissue quantification (VTQ) mode of Acoustic Radiation Force Impulse (ARFI) elastography imaging in differentiating benign and malignant thyroid nodules. Materials and Methods: Two hundred four solid and mostly solid nodules &amp;gt;5mm were prospectively evaluated with ultrasonography, VTQ mode of ARFI elastography, fine needle aspiration biopsy, and when indicated with tissue pathology. Three shear-wave velocities (SWV) measurements were done in 196 nodules. The SWV ratio for each nodule was calculated as the mean value of the SWV of the nodule divided by the mean value of the adjacent parenchyma. The diagnostic performance of SWV value and SWV-ratio were assessed by a receiver-operating characteristic (ROC) curve analysis. Results: The mean SWV value in the normal parenchyma, in benign and malign thyroid nodules, were 2.13±0.44 m/s, 2.06±0.80 m/s, and 2.06±0.88 m/s respectively. The SWV-ratios were 0.97±0.37 for benign thyroid nodules and 1.02±0.40 for malignant thyroid nodules. There was no significant difference between benign and malign nodules in terms of mean SWV values (t=0.008) (P=0.994) or SWV-ratios (t =0.596; P=0.527). No cut-off point was found to predict malignancy. In subgroup analysis, AUCs for the SWV and SWV-ratio were significantly different between nodules ˂10 mm and those ≥10 mm, but not with any other two groups (all P&amp;gt;0.05) (Table-2). The cutoff points for the differential diagnosis were 2.59 m/s for SWV and 1.0 for SWV- ratio respectively for nodules &amp;lt;10 mm. Conclusion: VTQ mode of ARFI imaging does not have a good diagnostic performance for detecting malignancy and cannot contribute to reducing unnecessary thyroid biopsies.

Spleen and Liver Stiffness Evaluation by ARFI Imaging: A Reliable Tool for a Short-Term Monitoring of Portal Hypertension?

Background Assessment of hepatic venous pressure gradient (HVPG) is the most reliable, though invasive method for evaluation of portal hypertension. Non-invasive, elastography-based techniques are well established in diagnosis, but not in monitoring of portal hypertension. The aim of our prospective study was to determine the value of acoustic radiation force impulse (ARFI) elastography technique of the liver and spleen in diagnosis and monitoring of portal hypertension. Methods We prospectively assessed portal hypertension by HVPG and corresponding elastography of the liver and spleen in 31 patients with liver cirrhosis and an indication for primary prophylaxis by non-cardio selective beta-blockers. Investigations were performed at baseline and a follow-up visit after 6-8 weeks. To address the known large variability of values for spleen elastography, well-defined corresponding areas in the spleen were used for baseline and follow-up elastography. Sensitivity, specificity, and AUC-ROC values for both spleen and liver elastography monitoring of portal hypertension were calculated. Results Liver but not spleen elastography significantly correlated with HVPG results and was suitable for initial evaluation of portal hypertension. However, changes in HVPG results did not show any correlation with alterations of ARFI values from baseline to follow-up visits both for liver and spleen elastography. Spleen stiffness results were not homogeneous across the whole organ differing significantly between the upper, hilar, and bottom placed investigation areas. Conclusions In this prospective study ARFI-based assessment of liver elastography showed itself suitable for initial assessment but not for monitoring of portal hypertension. Spleen elastography was not appropriate for both, evaluation and monitoring of portal hypertension. A possible explanation for this new data that are in some contrast to previously published results is the degree of portal hypertension in our study, a comparatively short follow-up period, and well-defined investigation areas for spleen elastography in repetitive ARFI investigations. This trial is registered with NCT03315767.

Diagnostic Performance of Acoustic Radiation Force Impulse Imaging in Evaluating Liver Fibrosis in Patients with Chronic Hepatitis B Infection: A Cross-Sectional Study.

Background Acoustic radiation force impulse point shear wave elastography (ARFI-pSWE), measuring shear-wave velocity (SWV), has been utilized to examine the liver stiffness caused by different etiologies. However, information on its reliability in staging liver fibrosis in chronic hepatitis B (CHB) patients is scarce. Purpose The aim of the study is to examine the diagnostic performance of ARFI-pSWE and determine the optimal SWV cut-off values to predict significant fibrosis ( F ≥2) and cirrhosis (F4) in CHB patients. Material and Methods All 114 adult CHB patients visiting the University Medical Center, Ho Chi Minh City, Vietnam between February 2019 and March 2021 underwent liver stiffness measurement using ARFI-pSWE and FibroScan. SWV results were tested against FibroScan for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The area under the receiver operating characteristic (AUROC) curve was used to identify the optimal SWV cut-off values. Results There was a strong agreement between ARFI-pSWE and FibroScan ( r = 0.92, p <0.001). The optimal SWV cut-off value for detecting significant fibrosis was 1.37 m/s with an AUROC of 0.975, sensitivity of 83.3%, specificity of 100%, PPV of 100%, and NPV of 81%. The optimal cut-off value for predicting cirrhosis was 1.70 m/s with an AUROC of 0.986, sensitivity of 97%, specificity of 93%, PPV of 95%, and NPV of 96%. Conclusion ARFI-pSWE could be an effective technique for evaluating liver fibrosis in CHB patients. SWV cut-off values of 1.37 and 1.70 m/s could be used to diagnose significant fibrosis and cirrhosis, respectively.

In Vivo Temperature Rise Measurements of Rabbit Liver and Femur Bone Surface Exposed to an Acoustic Radiation Force Impulse.

Acoustic radiation force impulse (ARFI) imaging and shear wave elastography use a "push pulse." The push pulse, which is referenced as an ARFI in this study, has a longer duration than that of conventional diagnostic pulses (several microseconds). Therefore, there are concerns regarding thermal safety in vivo. However, few in vivo studies have been conducted using living animals. In this study, to suggest a concept for deciding an ARFI output and cooling time while considering thermal safety, the liver (with and without an ultrasound contrast agent) and femur bone surface of living rabbits were exposed to an ARFI, and the maximum temperature rise, temperature rise for 5-min duration, and cooling time were measured via a thermocouple. While testing within the regulation limits of diagnostic ultrasound outputs, a maximum temperature rise on the femur bone surface exceeded the allowable temperature rise (1.5°C) in the British Medical Ultrasound Society (BMUS) statement. However, using the linear relationships between the pulse intensity integral (PII) of a single pulse and the above three temperature parameters, PII may be determined so that the maximum temperature rise is within the allowable temperature rise in the BMUS statement. The cooling time can be estimated from the PII.

A prospective study of the correlation between hepatic fibrosis and noninvasively measured fibrosis markers including serum M2BPGi and acoustic radiation force impulse elastography

Background: Mac-2 binding protein glycosylation isomer (M2BPGi) was introduced as a noninvasively measurable serologic marker for liver fibrosis. Acoustic radiation force impulse imaging (ARFI) elastography is another noninvasive method of measuring hepatic fibrosis. There are limited data about the correlations between histologic fibrosis grade and noninvasively measured markers, including M2BPGi and ARFI.Methods: This prospective study was conducted among patients admitted consecutively for liver resection, cholecystectomy, or liver biopsy. ARFI elastography, serum M2BPGi levels, and the AST to Platelet Ratio Index (APRI) score were evaluated before histologic evaluation. Histologic interpretation was performed by a single pathologist using the METAVIR scoring system.Results: In patients with high METAVIR scores, M2BPGi levels and ARFI values showed statistically significant differences between patients with fibrosis and those without fibrosis. In 41 patients with hepatocellular carcinoma, as METAVIR scores increased, M2BPGi levels also tended to increase (p=0.161). ARFI values changed significantly as METAVIR scores increased (p=0.039). In 33 patients without hepatocellular carcinoma, as METAVIR scores increased, M2BPGi levels significantly increased (p=0.040). ARFI values also changed significantly as METAVIR scores increased (p=0.033). M2BPGi levels were significantly correlated with ARFI values (r=0.604, p&lt;0.001), and APRI values (r=0.704, p&lt;0.001), respectively. Conclusions: Serum M2BPGi levels increased with liver fibrosis severity and could be a good marker for diagnosing advanced hepatic fibrosis regardless of the cause of liver disease.

Correlation of spleen stiffness measured by Acoustic Radiation Force Impulse Imaging (ARFI) with Hepatic Venous Pressure Gradient (HVPG) in the prediction of esophageal varices (EVs) grades in cirrhotic patients

Background: measurement of spleen stiffness (SS) by ARFI may predict the presence of EVs. Aim: To assess the correlation of SS measured by ARFI as noninvasive assessment with HVPG in the prediction of presence and grades of EVs in cirrhotic patients. Methods: 30 patients with post HCV liver cirrhosis who underwent biochemical tests, abdominal ultrasound (US) , Doppler , Upper gastrointestinal endoscopy (UGE), liver stiffness (LS) and spleen stiffness (SS) measurements using ARFI elastography and HVPG. Results: statistically significant difference was found between EVs presence and grades in relation to HVPG. In contrary no statistically significant difference was found between EVs presence and grades in relation to SS. Conclusion: HVPG had good significant positive correlation with presence and grades of EVs. There was no significant correlation between non-invasive parameters including the SS and LS (by ARFI) and presence or grades of EVs. There was no significant correlation between HVPG and SS and LS (by ARFI).

Evaluation of change in tumor stiffness measured by acoustic radiation force impulse imaging for early prediction of response to neoadjuvant chemotherapy in breast cancer.

In this study, the role of change in tumor stiffness between pre- and post-two cycles of neoadjuvant chemotherapy (NACT) measured by Acoustic Radiation Force Impulse (ARFI) imaging for predicting the response to NACT in breast cancer was analyzed. Fifty-two adult women with biopsy-proven locally advanced breast cancer and early-stage breast cancer who received NACT followed by either modified radical mastectomy or breast conservation surgery were included in the study. Tumor stiffness represented by shear wave velocity (SWV) in meter per second by ARFI imaging was measured before and after two cycles of NACT. Participants were categorized into responders and nonresponders based on pathological response assessment from the postoperative specimen. The association of change in tumor stiffness between pre- and post-two cycles of NACT with final pathological response status was assessed. The mean change in SWV before and after completion of two cycles of NACT was 0.42 ± 0.16 and 0.17 ± 0.11 m/s in responders and nonresponders, respectively, and this difference was proven to be statistically significant (p < 0.001) suggesting that tumors that exhibit a larger reduction in tumor stiffness, respond better. An SWV reduction cut-off of 0.295 m/s between baseline and post-two cycles of NACT was also arrived at, which can discriminate between responders and nonresponders with a sensitivity and specificity of 88% and 83%, respectively. Difference in tumor stiffness measured by ARFI imaging before and after two cycles of chemotherapy can be used as a reliable early predictor of response to chemotherapy in breast cancer.