Acoustic Radiation Force Impulse Technique Research Articles

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.

The diagnostic value of the different ARFI (acoustic radiation force impulse)-technique for solid thyroid nodules with different diameters: A case–control study

This study aims to explore the diagnostic value of the acoustic radiation force impulse (ARFI) technique for solid thyroid nodules with different diameters. A total of 212 solid thyroid nodules with pathological results in 191 patients from March to December 2017 were retrospectively reviewed. These nodules were divided into two groups according to their diameter: 117 nodules were ≥1.0cm and 95 were <1.0cm. Before the operation, the nodules were evaluated using conventional ultrasound and different ARFI technique, including virtual touch tissue imaging (VTI), virtual touch tissue quantification (VTQ), and virtual touch tissue imaging and quantification (VTIQ). Further, receiver operating characteristic (ROC) curves were drawn to analyze the diagnostic value of the ARFI technique for solid thyroid nodules with different diameters. For the three methods used in the diagnosis of solid thyroid cancer, VTI, VTQ, and VTIQ, the sensitivity, specificity, accuracy, and area under the ROC curve were 91.03%, 76.92%, 86.32%, and 0.840; 73.08%, 100%, 82.05%, and 0.865; and 91.03%, 100%, 94.02% and 0.955, respectively for nodules with a diameter ≥1.0cm, and 84.62%, 70.00%, 80.00%, and 0.773; 61.54%, 80.00%, 67.37%, and 0.708; 75.38%, 90.00%, 80.00%, and 0.827, respectively for nodules with a diameter <1.0cm. For nodules with a diameter ≥1.0cm, the diagnostic efficacy of VTIQ is higher than VTI and VTQ. For nodules with a diameter <1.0cm, the diagnostic efficacy of VTI and VTIQ are higher than VTQ.

Ultrasound elastography.

Physicians have used palpation as a diagnostic examination to understand the elastic properties of pathology for a long time since they realized that tissue stiffness is closely related to its biological characteristics. US elastography provided new diagnostic information about elasticity comparing with the morphological feathers of traditional US, and thus expanded the scope of the application in clinic. US elastography is now widely used in the field of diagnosis and differential diagnosis of abnormality, evaluating the degree of fibrosis and assessment of treatment response for a range of diseases. The World Federation of Ultrasound Medicine and Biology divided elastographic techniques into strain elastography (SE), transient elastography and acoustic radiation force impulse (ARFI). The ARFI techniques can be further classified into point shear wave elastography (SWE), 2D SWE, and 3D SWE techniques. The SE measures the strain, while the shear wave-based techniques (including TE and ARFI techniques) measure the speed of shear waves in tissues. In this review, we discuss the various techniques separately based on their basic principles, clinical applications in various organs, and advantages and limitations and which might be most appropriate given that the majority of doctors have access to only one kind of machine.

Update to the Society of Radiologists in Ultrasound Liver Elastography Consensus Statement.

This multidisciplinary update of the Society of Radiologists in Ultrasound consensus statement on liver elastography incorporates the large volume of new information available in the literature since the initial publication. The recommended procedure for acquiring stiffness measurements is reviewed. There has been substantial improvement in the acoustic radiation force impulse (ARFI) technology-most notably the addition of a quality assessment of the shear wave propagation. Due to the efforts of the Quantitative Imaging Biomarkers Alliance, or QIBA, the variability of liver stiffness measurements between systems had decreased. There are now effective treatments for hepatitis B and hepatitis C, and follow-up after effective treatment should be based on the use of the delta change of the value obtained at viral eradication or suppression. Because the detection of compensated advanced chronic liver disease (cACLD) is very important, the new guidelines are made based on the probability of cACLD for given stiffness values. The panel recommends a vendor-neutral rule of four for interpretation for ARFI techniques. This new method simplifies interpretation of liver stiffness results and is more clinically relevant.

Value of the New Elastography Technique using Acoustic Radiation Force Impulse in Differentiation between Hashimoto’s Thyroiditis and Graves’ Disease

Background and Aim:This study was performed to evaluate the role and accuracy of shear wave elastography in the differentiation between Graves’ disease (GD) and Hashimoto’s thyroiditis (HT), in comparison with the B-mode ultrasound and color Doppler ultrasound.Materials and Methods:This study was non-randomized prospective study. The study included 30 patients with GD, 65 patients with HT, and 35 patients with normal thyroid glands. Assessment of ultrasonographic criteria, color Doppler flow pattern, and shear patterns differed significantly between the control group and the group of diffuse thyroid disease (P < 0.001). The most specific sign for diagnosing HT was nodularity (97.87%), and the most sensitive sign was coarse echotexture (81.54%). Color Doppler flow (CDF) showed sensitivity of 91.8%, specificity of 56.92%, positive predictive value of 52.54%, negative predictive value of 92.5%, and diagnostic accuracy of 68.69% in the differentiation between GD and HT. The mean shear wave velocity (SWV) was 2.61 ± 0.32 m/s in the GD group (range: 2.1–3.21 m/s), 2.85 ± 0.52 m/s in the HT group (range: 2.31–3.82 m/s), and 1.75 ± 0.37 m/s in the control group (range: 1.24–2.36 m/s). The mean SWVs in the GD and HT groups were significantly higher than that in the control group (P < 0.001). The mean SWV in the HT group was higher than that in the GD group (P = 0.03).Conclusion:Quantitative and qualitative SWE is useful for diagnosing diffuse thyroid disease and evaluating the degree of fibrosis in autoimmune thyroiditis. However, acoustic radiation force impulse techniques cannot differentiate between HT and GD reliably.

Evaluation of rat liver with ARFI elastography: In vivo and ex vivo study.

ObjectiveThe aim of this study was to compare in vivo vs ex vivo liver stiffness in rats with acoustic radiation force impulse (ARFI) elastography using the histological findings as the gold standard.MethodsEighteen male Wistar rats aged 16–18 months were divided into a control group (n = 6) and obese group (n = 12). Liver stiffness was measured with shear wave velocity (SWV) using the ARFI technique both in vivo and ex vivo. The degree of fibrosis, steatosis and liver inflammation was evaluated in the histological findings. Pearson’s correlation coefficient was applied to relate the SWV values to the histological parameters.ResultsThe SWV values acquired in the ex vivo study were significantly lower than those obtained in vivo (P < 0.004). A significantly higher correlation value between the degree of liver fibrosis and the ARFI elastography assessment was observed in the ex vivo study (r = 0.706, P < 0.002), than the in vivo study (r = 0.623, P < 0.05).ConclusionAssessment of liver stiffness using ARFI elastography yielded a significant correlation between SWV and liver fibrosis in both the in vivo and ex vivo experiments. We consider that by minimising the influence of possible sources of artefact we could improve the accuracy of the measurements acquired with ARFI.

Ultrasonic assessment of liver stiffness and carotid artery elasticity in patients with chronic viral hepatitis

BackgroundThis study investigated the relationship between liver stiffness and carotid artery elasticity in patients with chronic viral hepatitis. We used an acoustic radiation force impulse (ARFI) technique to measure stiffness, and a radio frequency (RF) vascular quantitative ultrasound technique to measure changes in common carotid artery elasticity and vascular function.MethodsTwo-hundred seventeen patients with chronic viral hepatitis caused by either hepatitis B virus (HBV) or hepatitis C virus (HCV) were enrolled. We divided the patients into two groups, one comprising 147 patients with chronic hepatitis B (CHB) (98 men and 49 women, average age 46.5 ± 12.2 years) and another comprising 70 patients with chronic hepatitis C (CHC) (47 men and 23 women, average age 47.6 ± 12.1 years). Additionally, 64 healthy age- and sex-matched participants (43 men and 21 women, average age 47.8 ± 5.1 years) were selected as the control group. The ARFI technique was used to measure liver stiffness and the RF ultrasound technique was used to measure carotid artery elasticity parameters including intima-media thickness (IMT), pulse wave velocity (PWV), arterial wall dilation coefficient (DC), compliance coefficient (CC), sclerosis indices α and β, and augmentation index (Aix). Clinical indicators, liver stiffness, and carotid artery elasticity parameters were observed and compared between the different age groups to investigate the correlation between carotid artery elasticity parameters and liver stiffness.ResultsThe ARFI values for the CHB and CHC groups were significantly higher than those for the control group (1.84 ± 0.52 vs. 1.04 ± 0.11 m/s; 1.86 ± 0.37 vs. 1.04 ± 0.11 m/s, respectively; P < 0.001). When compared to the control group, both CHB and CHC groups showed an IMT of the same order, but had significantly higher elasticity parameters, such as α and β, as well as lower DC and CC values (P < 0.001). The PWV of the CHC group was significantly higher than that of the control group (7.98 ± 1.42 vs. 6.09 ± 0.90 m/s, P < 0.001). In the CHB group, all parameters including ARFI, IMT, PWV, DC, CC, α and β, were significantly different between the two age groups (P < 0.05). Within the CHC group, all parameters including IMT, PWV, DC, α and β, were significantly different between the two age groups (P < 0.05), except for ARFI, wherein the difference was not statistically significant. The correlation analysis and stepwise multiple linear regression analysis indicated that for patients with CHB, age was an independent predictor of common carotid artery IMT (R2 = 0.468, F = 54.635, and P < 0.001). For patients with CHC, age and blood sugar were independent predictors of common carotid artery IMT (R2 = 0.465, F = 29.118, and P < 0.001).ConclusionAlthough based on ARFI and RF ultrasound, the carotid artery IMT in patients with CHB and CHC was not significantly higher than that in the control group, their functional elasticity parameters had already changed. This finding serves as a useful reference for the clinical diagnosis of vascular diseases in patients with viral hepatitis.Trial registrationClinicalTrials: ChiCTR1800015859 25/04/2018.

Role of acoustic radiation force impulse imaging elastography in the assessment of steatohepatitis and fibrosis in rat models

Acoustic radiation force impulse (ARFI) elastography is a non-invasive method for performing liver assessment via liver shear wave velocity (SWV) measurements. The aim of this study was to evaluate the performance of the ARFI technique in the diagnosis of nonalcoholic steatohepatitis (NASH) and fibrosis and to investigate the effect of steatosis and inflammation on liver fibrosis SWV measurements in a rat model of nonalcoholic fatty liver disease (NAFLD). The ex vivo right liver lobes from 110 rats were processed and embedded in a fabricated gelatin phantom, and the other lobes were used for histologic assessment. The SWV induced by acoustic radiation force was derived to evaluate liver stiffness. The experimental results showed that the liver SWV value could be used to differentiate non-NASH rats from NASH-presenting rats and NASH from cirrhosis, and these comparisons showed areas under the receiver operating characteristic curves (AUROC) of 0.951 and 0.980, respectively. The diagnostic performances of ARFI elastography in predicting severe fibrosis (F ≥ 3) and cirrhosis (F ≥ 4) showed AUROC values of 0.997 and 0.993, respectively. In rats with mild fibrosis (F0–F1), severe steatosis had a significant effect on the mean SWV values. In rats with significant fibrosis (F2–F4), severe lobular inflammation had significant effects on the mean SWV values. Our findings indicate that ARFI elastography is a promising method for differentiating non-NASH rats from NASH rats and for staging hepatic fibrosis in NASH. The presence of severe steatosis and severe lobular inflammation are significant factors for evaluating fibrosis stages.

Acoustic radiation force impulse (ARFI) elastography in a cohort of alpha-1 antitrypsin-deficient individuals and healthy volunteers.

BackgroundAcoustic radiation force impulse (ARFI) elastography has been used to assess liver stiffness non-invasively. However, its usefulness in alpha-1 antitripsin-deficient (AATD) individuals is unknown.PurposeTo assess if liver fibrosis is present in a cohort of AATD individuals using ARFI elastography.Material and MethodsEighty-three participants aged 38–39 years, except for two who were aged 40 years, underwent ultrasound elastography of the liver with ARFI technique. Twenty-nine were homozygote ZZ genotype, PiZZ (14 men, 15 women); 12 were SZ genotype, Pi SZ (8 men, 4 women), and 42 were healthy volunteers, PiMM (16 men, 26 women). Three specific liver anatomical regions were examined: segments 2/3 (left lobe) in the subcostal plane, and 5/6 and 7/8 (right lobe) in the intercostal space. In each region, three measurements were registered.ResultsThere was no statistically significant difference between ARFI-median in the AATD group and the control group (P value = 0.877) and neither between AATD groups (PiZZ and PiSZ) with a P value = 0.259. The ARFI-median was lower in the right liver lobe than in the left lobe in all groups and the difference between both lobes was statistically significant (P = 0.001). No statistically significant difference was found in ARFI-median of the right liver lobe between the AATD group and the control group (P = 0.759), nor between the AATD group (P = 0.384). No gender difference was found in ARFI-median.ConclusionsARFI values in AATD individuals aged 38–39 years showed no difference compare to healthy participants.

Use of ARFI elastography in the prediction of placental invasion anomaly via a new Virtual Touch Quantification Technique

We aimed to evaluate the efficiency of placental elasticity in predicting a placental invasion anomaly with the Virtual Touch Quantification (VTQ) technique. Pregnant women in the third trimester with suspected placental invasion anomaly were enrolled into the research (n = 58). The placenta was evaluated and divided into three equal parts as foetal edge (inner 1/3 of placenta), maternal edge (outer 1/3 of placenta) and the central part (central 1/3 of placenta). Shear wave velocity (SWV) measurements were used in the elastographic evaluation of placentas by VTQ. We performed the measurements at the different regions of placenta for sampling the variety areas of the placenta. Acoustic Radiation Force Impulse (ARFI) Elastography scores were significantly higher in the group in which an invasion was detected during the surgery of patients with preoperative placental invasion suspicion. A significant difference in the measurements of the inner, central and outer third of the placenta between the groups was found (p < .001). In this study, we have shown higher SWV scores of placental measurements of the patients with preoperative suspected anomalies and an invasion detected during their surgery. These findings may reflect an event at the tissue elasticity level and we hope that the use of the VTQ technique may contribute to an early prediction of placental invasions before surgery in the future via new research.Impact statementWhat is already known on this subject? Placenta invasion anomalies (PIA’s) are characterized by haemorrhages which can threat the mother’s life. Placental invasion anomalies are among the most important causes of maternal mortality and morbidity. Early diagnosis is very important condition in reducing the mortality and morbidity. Gray scale ultrasonography (US) is mostly used in early diagnosis of PIA’s. Acoustic radiation force impulse elastography (ARFI) is a new elastographic ultrasonography technic. We aimed to evaluate a new method in the early diagnosis of PIA’s using ARFI technique. There is no study in the diagnosis of PIA’s by ARFI in the literature to our knowledge. We think that this original study will contribute to the literature.What do the results of this study add? We showed the accuracy of ARFI in determination of PIA’s. ARFI scores were significantly higher in the group in which invasion was detected during surgery of patients with preoperative placental invasion suspicion.What are the implications are of these findings for clinical practice and/or further research? Our findings may reflect an event at the tissue elasticity level and we hope that the use of VTQ technique may contribute to early predict of placental invasions before surgery in the future via new researches. Early diagnosis of placental invasion anomalies may reduce mortality and morbidity.

Is Acoustic Radiation Force Impulse (ARFI) Ultrasound Elastography Valuable in the Assessment of Cervical Lymphadenopathy?

Cervical lymphadenopathy frequently poses a diagnostic challenge as neither clinical nor imaging assessment can reliably differentiate between benign and malignant lymphadenopathy. Non-invasive differentiation between the two may help to reduce the number of FNAC or biopsy. The purpose of this study was to evaluate whether the new ARFI technique (Virtual Touch Quantification), in conjunction with gray scale sonography and Doppler, can help in the characterization and differentiation of benign from malignant cervical lymphadenopathy. Fifty adult patients with cervical lymphadenopathy were included in the study and sonoelastography was done. Sonoelastographic findings were compared to the gold standard histopathology or cytopathology. ARFI measurements in benign and malignant enlarged lymph nodes were compared using the Student t test and ROC curve was used to arrive at the Youden index, sensitivity, specificity, PPV, NPV and diagnostic accuracy. Sonographic patterns indicative of malignancy includes heterogenous echopattern, short axis/long axis ratio > 0.5, absent echogenic fatty hilum and mixed vascular pattern. Sensitivity, specificity, PPV, NPV and accuracy in differentiation between the benign and malignant lymph nodes using ARFI elastography was 79.17, 100, 100, 83.9 and 89.9% respectively. ROC curve analysis of SWVs for differentiation between the malignant and benign lymph nodes gave a cut-off value of 2.8m/s with an area under curve of 0.892. ARFI imaging technique quantifies the tissue stiffness of the cervical lymph nodes non-invasively and aids in characterisation and differentiation of benign from malignant cervical lymphadenopathy in conjunction with conventional sonography.

Role of acoustic radiation force impulse and shear wave velocity in prediction of preterm birth: a prospective study.

Background Preterm birth is one of the important causes of neonatal morbidity where we rely on subjective criteria such as modified Bishop's scoring and contemporary sonographic measurement of cervical length. Acoustic radiation force impulse (ARFI) is a technological advancement in elastography that can be employed in prediction of cervical softening and preterm labor. Purpose To evaluate the role of ARFI technique and shear wave velocity (SWV) estimates as a predictor of preterm birth and its comparison with other clinical and sono-elastographic measures. Material and Methods Thirty-four pregnant women (gestation age = 28-37 weeks age) showing features suggestive of preterm labor were included and evaluated with modified Bishop's score, cervical length by ultrasound (US), ARFI to derive Elastography index (EI), and SWV of the cervix. The patients were later divided into two groups, using the clinical outcome of preterm or term delivery. Results Twenty patients delivered at term (gestational age > 37 weeks) and 14 were preterm. Receiver operating characteristics (ROC) curves showed SWV with highest sensitivity and specificity (93% and 90%, respectively) for the prediction of preterm birth at a cutoff value of 2.83 m/s. EI and modified Bishop's score were comparable to each other, but were less sensitive techniques. Conclusion Elastographic assessment of antenatal cervix is a novel technique of virtual palpation of internal os and can be utilized as an objective criterion for preterm birth prediction.

Acoustic radiation force impulse imaging for detection of liver fibrosis in overweight and obese children.

Background Acoustic radiation force impulse (ARFI) is a non-invasive alternative to a liver biopsy for the evaluation of liver fibrosis (LF). Purpose To investigate the potential usefulness of acoustic radiation force impulse ARFI for detecting LF in overweight and obese children Material and Methods A cross-sectional study was conducted in 148 schoolchildren. A diagnosis of non-alcoholic fatty liver disease (NAFLD) and LF was based on ultrasound (US) and ARFI shear wave velocity (SWV). Results The laboratory parameters were normal in all the children. NAFLD was observed in 50 children (33.8%). The median SWV was 1.18 ± 0.28 m/s. Differences between ARFI categories and hepatic steatosis grades were observed (χ2 = 43.38, P = 0.0005). No fibrosis or insignificant fibrosis (SWV ≤ 1.60 m/s) was detected in 137 children (92.5%), and significant fibrosis (SWV > 1.60 m/s) in 11 children (7.5%), nine of whom had normal US or mild steatosis. Conclusion The present study is the first to evaluate the utility of the ARFI technique for detecting LF in overweight and obese children. The results of the study suggest that children with normal laboratory parameters such as normal liver ultrasound or mild steatosis may present with significant LF.

Acoustic radiation force impulse (ARFI) elastography of adrenal glands in healthy adult dogs

ABSTRACT To describe the ARFI elastography in the evaluation of the adrenal glands in adult dogs, to evaluate the stiffness of adrenal parenchyma and to determine the qualitative and quantitative standards of the ARFI technique, which have not yet been described in veterinary medicine. Sixty adrenal glands from thirty healthy adult dogs were evaluated by B-mode and qualitative and quantitative ARFI elastography to assess the stiffness of healthy parenchyma and to determine the quality and quantity (shear velocity) standards of ARFI technique in body, cranial and caudal adrenal poles. Findings of ultrasonography evaluations were normal. Qualitative elastography showed that adrenal glands were not deformable and presented homogeneous middle-gray areas. The results of shear wave velocity were similar statically (P = 0.3087): 1) left adrenal - 1.42 m/s for cranial polar, 1.31 m/s for body region, and 1.71 m/s for caudal polar; 2) right adrenal - 1.42 m/s for cranial polar, 1.74 m/s for body region and 1.63 m/s for caudal pole. Quantitative and qualitative ARFI elastography of dogs' adrenal glands is feasible, well tolerated, easily implemented and may provide baseline data in the study of this structure to allow the use of ARFI.

Quantitative assessment of muscle stiffness with acoustic radiation force impulse elastography after botulinum toxin A injection in children with cerebral palsy

Our objective in this study was to assess the changes in medial gastrocnemius muscle (GCM) stiffness after botulinum toxin A (BTA) injection in children with cerebral palsy (CP) by using acoustic radiation force impulse (ARFI) elastography and to research the usability of this technique in clinical practice. Twenty-four spastic lower extremities of 12 children with CP were assessed. BTA injection treatment was applied to the medial GCM. Muscle stiffness was measured with the ARFI technique before the procedure and a month after the procedure. The patients were assessed with the modified Ashworth scale (MAS) in the physiotherapy department at about the same time. Shear wave velocity (SWV) values and MAS scores before and after the treatment were compared. Mean SWV values were measured as 3.20±0.14m/s before BTA and as 2.45±0.21m/s after BTA, and the difference between them was found to be statistically significant (p<0.001). Mean MAS score (2.33±0.70) after BTA decreased significantly when compared to the score before BTA (2.96±0.62) (p=0.001). SWV values positively correlated with MAS scores (ρ=0.578, p=0.003). The interobserver agreement expressed as interclass correlation coefficient (ICC) was 0.65 (95% CI 0.33-0.84, p<0.001). ARFI elastography for identifying structural changes that occur in the spastic muscle after BTA injection in children with CP can yield more valuable information with combined use of MAS.

Clinical value of acoustic radiation force impulse technique to predict esophageal and gastric varices in patients with biliary atresia

Objective: To investigate the clinical value of acoustic radiation force impulse (ARFI)technique in predicting esophageal and gastric varices in patients with biliary atresia after Kasai portoenterostomy. Methods: A total of 42 patients with biliary atresia after Kasai portoenterostomy were collected from September 2015 to May 2016 in Tianjin First Central Hospital.ARFI technique was used to measure the stiffness of liver and spleen, and 28 healthy children as control.According to the result of CT examination , patients with biliary atresia were divided into two groups , twenty-three patients with esophageal and gastric varices(A group) and nineteen patients without esophageal and gastric varices (B group), Comparing the difference of liver and spleen stiffness between the two groups.The ROC curve analysis was carried out to test the diagnostic power of effective parameter. Results: The ARFI value of liver (2.98±0.80) m/s and spleen (3.00±0.33) m/s of patients with biliary atresia was significantly higher than that of control group((1.10±0.16) m/s, (2.12±0.32) m/s), the differences had statistical significance (both P<0.01). Between group A and group B, the spleen ARFI value of group A(3.16±0.26) m/s was higher than group B(2.83±0.32) m/s, the difference had statistical significance (P<0.01), whereas there was no statistical difference of liver ARFI value between two group((2.93±0.65), (3.02±0.96) m/s)(P>0.05). The cut-off ARFI value of spleen to diagnose esophageal and gastric varices in biliary atresia was 3.02 m/s, and the biggest area under the ROC curve, sensitivity, and specificity were 0.81, 78.6% and 84.5%, respectively. Conclusion: ARFI can be used as a noninvasive method to predict the presence of esophageal and gastric varices in patients with biliary atresia after Kasai portoenterostomy.

Differences of standard values of Supersonic shear imaging and ARFI technique - in vivo study of testicular tissue.

To investigate the difference of standard values of Supersonic shear imaging (SSI) and Acoustic Radiation Force Impulse (ARFI) technique in the evaluation of testicular tissue stiffness in vivo. 58 healthy male testes were examined using B-mode sonography and ARFI and SSI. B-mode sonography was performed in order to scan the testis for pathologies followed by performance of real-time elastography in three predefined areas (upper pole, central portion and lower pole) using the SuperSonic® Aixplorer ultrasound device (SuperSonic Imagine, Aix-en-Provence, France). Afterwards a second assessment of the same testicular regions by elastography followed using the ARFI technique of the Siemens Acuson 2000™ ultrasound device (Siemens Health Care, Germany). Values of shear wave velocity were described in m/s. Parameters of elastography techniques were compared using paired sample t-test. The values of SSI were all significantly higher in all measured areas compared to ARFI (p < 0.001 to p = 0.015). Quantitatively there was a higher mean SSI wave velocity value of 1,1 compared to 0.8 m/s measured by ARFI. SSI values are significantly higher than ARFI values when measuring the stiffness of testicular tissue and should only be compared with caution.

Acoustic radiation force impulse imaging of kidneys - a phantom study.

Aim of the studySince there have been only few works reporting the diagnosis of kidneys using Acoustic Radiation Force Impulse technique and those works do not provide consistent results of shear wave velocity measurements in renal tissue, we have decided to use kidney phantoms with known properties to examine the reliability of the method itself in a controlled setup similar to kidneys examination.Materials and methodsFour gelatin-based phantoms imitating different clinical situations were manufactured – two with thick and two with thin renal cortex, each type at a depth similar to a normal-weight or overweight patient. For each phantom, a series of interest points was chosen and for each point 20 Shear Wave Velocity measurements were taken using the build-in Virtual Touch Tissue Quantification™ tool in a Siemens Acuson S2000 ultrasound scanner equipped with a 6C1 HD Transducer (Siemens Mountainview, USA).ResultsMean Shear Wave Velocity values obtained for all the examined points ranged from 2.445 to 3.941 m/s, with standard deviation exceeding 0.1 in only one case out of 29 points, but differing significantly between all points.ConclusionsThe obtained results indicate that the method is highly reliable as long as the measurement volume contains a uniform tissue region. If the measurement window covers a region with different properties even partially, the obtained results are affected. The variance of measured values on the other hand is not affected by the said non-uniformity of material under examination. Furthermore, the variance of measured values does not show a clear dependency on the depth at which the shear wave velocities are measured.

Comparison of placental elasticity in normal and pre-eclamptic pregnant women by acoustic radiation force impulse elastosonography.

The aim of this research was to study and compare placental elasticity with acoustic radiation force impulse (ARFI) elastography in pre-eclamptic and normal pregnancies. A total of 107 singleton pregnancies in the third trimester (38 healthy control subjects, 34 patients with gestational hypertension, and 35 pre-eclampsia patients) were included in the study. ARFI elastography was used to determine the placental elasticity in the three predetermined regions of the placenta (the fetal edge, maternal edge, and central part of the placenta). The obstetrical data regarding grayscale and Doppler ultrasonography and perinatal outcomes were reviewed. A mean placental shear wave velocity cut-off value that predicts the presence of pre-eclampsia was determined. The shear wave elasticity values in the pre-eclampsia group in all three regions were significantly higher than in the gestational hypertension and healthy control groups (P=0.001). The most significant difference was found in the peripheral edge of the placenta from the fetal surface in the pre-eclampsia group (P=0.001). The stiffness of the placenta determined by the ARFI technique is significantly higher in pre-eclampsia patients. ARFI elastography of the placenta might be used as a non-invasive and easy method in the diagnosis and evaluation of pre-eclampsia as a supplement to the already existing methods.

Renal shear wave velocity and estimated glomerular filtration rate in children with chronic kidney disease.

A shear wave velocity (SWV) value obtained by the acoustic radiation force impulse technique depends on tissue elasticity. We investigated the relationship between SWV values and the estimated glomerular filtration rate (eGFR) in children with chronic kidney disease. A total of 29 patients were enrolled in the study. There were 18 primary and 11 secondary cases of vesicoureteral reflux. eGFR was calculated using Schwartz's formulas (2012). Partial eGFR for each kidney was assessed by multiplying the eGFR by the percentage of renal function measured by means of renal (99m)Tc-dimercaptosuccinic acid scintigraphy. All ultrasound tests were done by a single qualified technician using a convex probe (frequency 4 MHz) on an S-2000 system. The mean SWV values of the two kidneys were significantly and negatively correlated with eGFR calculated with both univariate (cystatin C [Cys C] and multivariate (creatinine, Cys C, and nitrogen) equations. Of all the formulae, the strongest correlation was obtained with eGFR (Cys C). SWV of the renal cortex correlates with the eGFR of patients affected by malformative uropathies. Nevertheless, this technique needs standardization and validation.