Acoustic Radiation Force Impulse Technology Research Articles

Efficacy of Virtual Touch Quantification Technique for Differentiating Patients with Immunoglobulin A Nephropathy (IgAN) from Healthy Controls

Background: The virtual touch quantification (VTQ) using acoustic radiation force impulse (ARFI) is a type of ARFI technology, which has been widely used against many diseases. The sensitivity and specificity of VTQ in differentiating immunoglobulin A nephropathy (IgAN) patients from healthy controls remain unestablished. Objectives: The present study aimed to measure the VTQ values of renal parenchyma in patients with IgAN and to evaluate the efficacy of these values in distinguishing IgAN patients from healthy individuals. Patients and Methods: Ultrasound examinations were performed for the experimental and control groups. All routine ultrasound data, including the renal parenchymal thickness, renal volume, resistive index (RI) of interlobar renal arteries, and peak velocity of interlobar renal arteries, were collected. The VTQ values were measured in the middle and lower renal parenchyma using the VTQ technique. A receiver operating characteristic (ROC) curve was plotted to evaluate the efficacy of VTQ in differentiating IgAN patients from healthy individuals. Results: The VTQ values, RI values of interlobar arteries, and peak velocity of interlobar arteries were significantly different between patients with IgAN and the controls (2.14 ± 0.31 vs. 2.62 ± 0.24 m/s, 0.68 ± 0.05 vs. 0.63 ± 0.03 m/s, and 0.56 ± 0.59 vs. 0.60 ± 0.58 m/s; P < 0.05 for all). The VTQ values were associated with the renal parenchymal thickness, peak flow velocity of interlobular arteries, and Lee’s grade (P < 0.05 for all). The ROC curve analysis revealed that VTQ values might be used as a diagnostic method for differentiating IgAN patients (area under the curve [AUC] = 0.909) from healthy controls. Conclusion: The VTQ values significantly decreased in patients with IgAN and might play an important role in distinguishing IgAN patients from healthy individuals, with high sensitivity and specificity.

Diagnostic Performance of Point Shear Wave Elastography Using Acoustic Radiation Force Impulse Technology in Peripheral Pulmonary Consolidations: A Feasibility Study.

The aim of the study described here was to evaluate the diagnostic performance of lung ultrasound point shear wave elastography using acoustic radiation force impulse (ARFI) in peripheral pulmonary consolidations (PPCs). A total of 87 patients with PPCs diagnosed from April to December 2020 were included retrospectively in the study. The inclusion criteria were (i) a PPC >1 cm; (ii) valid ARFI measurements; and (iii) confirmation of the diagnosis of a PPC by histocytological examination and/or clinical and radiological follow-up. The presence of pleural effusions and mean ARFI velocities (MAVs) of PPCs were evaluated. To examine the MAV for potential cutoff values between benign and malignant PPCs, a receiver operating characteristic analysis was implemented. In total, 48 of 87 PPCs (55.2%) were accompanied by pleural effusions. Benign PPCs had significantly lower MAVs than malignant PPCs (1.82 ± 0.97 m/s vs. 3.05 ± 0.73 m/s, p < 0.001). Selecting 2.21 m/s as a cutoff value yielded a sensitivity and specificity of 89.7% and 75.9%, respectively, in diagnosing malignant PPCs (area under the curve=0.852, 95% confidence interval: 0.773-0.931). In summary, ARFI elastography may be an additional non-invasive tool for differentiating benign from malignant PPCs. Furthermore, the feasibility of using ARFI elastography in PPCs associated with pleural effusions was proved. However, there is some degree of overlap between different disease entities, and diagnosis should always take into account the clinical background.

The possibilities of ultrasound elastography in diagnostics of lymphomatous changes of superficial lymph nodes

Objective: to evaluate the possibilities of strain elastography (SE) in eSie Touch mode and shear wave elastography (SWE) with ARFI (Acoustic Radiation Force Impulse) technology in Virtual TouchTM Tissue Imaging (VTI) for diagnostics lymphomatous superficial lymph nodes (LN).Materials and methods. The prospective study included 168 patients with enlarged superficial LN. Based on a previous histological examination, patients were divided into three groups: group 1 (n = 108) – patients with lymphomas; group 2 (n = 30) – patients with metastatic superficial LN; group 3 (n = 30) – patients with reactive (inflammatory) changes in superficial LN. All patients underwent SE and SWE elastography of the enlarged LN using eSie Touch and VTI modes respectively.Results. The SE data: reactive LN was characterized by elastotypes 1 and 2 with a predominance of elastic structure in 90.0 % of cases. In patients with lymphomas, the elastotype 3 was more often determined (58.3 %). The stiffest LN with the elastotype 4 were metastatic LN, detected in 66.7 % of patients from this group. The results of VTI elastography showed that the stiffest structure is typical for metastatic LN (elastotypes 5–6 in 63.3 % of cases). Lymphomas had an intermediate degree of stiffness (elastotypes 3–4 in 81.5 % of cases). The lowest indicators of elasticity were found in patients with reactive LN (elastotypes 1–2 in 73.4 % of cases).Conclusion. The qualitative assessment of superficial LN stiffness, both using SE and VTI elastography, demonstrated statistically significant differences in the frequency of various types of superficial LN elastograms with lymphomatous, metastatic and reactive changes, which allows for more accurate differential diagnosis between these types of lymphadenopathy.

SAT270 - Virtual touch quantification using acoustic radiation force impulse technology versus transient elastography for the non-invasive assessment of liver fibrosis in patients with chronic hepatitis B or C using liver biopsy as gold standard

SAT270 - Virtual touch quantification using acoustic radiation force impulse technology versus transient elastography for the non-invasive assessment of liver fibrosis in patients with chronic hepatitis B or C using liver biopsy as gold standard

Evaluation of acoustic radiation force impulse (ARFI) elastography as a tool for non invasive detection and grading of liver fibrosis with histopathology correlation

Background: Chronic insult caused by viral infection, autoimmune disease, alcohol and other toxins can damage the liver parenchyma and ultimately lead to liver fibrosis and cirrhosis. Acoustic Radiation Force Impulse (ARFI) elastography is emerging as a valuable tool in the detection and grading of fibrosis in liver. Materials and Methods: It is a prospective comparative study performed in 36 patients between December 2016 and March 2018 who presented with deranged liver function test and referred for ultrasonography, ARFI elastography of liver followed by liver biopsy. The findings of Elastography were correlated with histopathology. Results: When compared with histopathology ARFI had a sensitivity of 82%, specificity of 85%, positive predictive value of 90% and negative predictive value of 75% in detecting liver fibrosis when we used optimum cut values of ARFI. Conclusion: ARFI elastography is a valuable tool in non-invasively detecting liver fibrosis and can be included as part of routine ultrasonic examination protocol of liver. ARFI technology allows the quantification of liver fibrosis and can be effectively used to stage fibrosis. Hence ARFI can be used as an alternative to liver biopsy and it might substitute liver biopsy in future.

Normal values of shear wave velocity in liver tissue of healthy children measured using the latest acoustic radiation force impulse technology.

BACKGROUNDSeveral studies have demonstrated the feasibility and effectiveness of using ultrasound elastography to assess liver tissue stiffness. Virtual touch imaging quantification (VTIQ) based on acoustic radiation force impulse imaging has been developed as a latest and noninvasive method for assessing liver stiffness in children.AIMTo determine the standard value in healthy children, and to identify possible factors that might influence the VTIQ measurement.METHODSWith the ethical approval, 202 children between 1 month and 15 years old were included in this study. None of them had any liver or systematic diseases. All children had a normal ultrasound scan and normal body mass index (BMI) range. The subjects were divided into four age and BMI groups. The effects of gender, age, liver lobe, measurement depth, and BMI on liver elasticity were investigated.RESULTSA significant correlation was found between age and shear wave velocity (SWV) value. At measurement depths of 1.5 cm and 2.0 cm in the left lobe, there were significant differences among the age groups. SWV values were significantly negatively correlated with the measurement depth. Gender, liver lobe, and BMI showed no significant effect on the SWV values. Age and BMI may influence the quality of the elastogram.CONCLUSIONVTIQ is a noninvasive technique that is feasible to measure liver stiffness in children. The afore-mentioned velocity value obtained utilizing VTIQ method could be used as reference value for normal liver stiffness in children.

Placental elasticity on patients with gestational diabetes: Single institution experience

BackgroundGestational diabetes is defined as glucose intolerance which is first recognized in pregnancy. Oral glucose tolerance test (OGTT) is the cornerstone in diagnosing gestational diabetes. Placental elasticity evaluation is relatively new concept and is principally used for research purposes. We aimed to find any relation between placental elasticity evaluation and patients of gestational diabetes diagnosed by 75 g OGTT. MethodsThere were 91 patients took part in study, forming two groups as gestational diabetic patients (21 patients) and control group (70 patients). Elasticity of placenta was determined by acoustic radiation force impulse technology utilized by two blinded radiology specialists. ResultsWe were not able to find any correlation between 75 g OGTT values and placental elasticity measurements (p > .05). Also placental elasticity was not found to be significantly different in two groups (p > .05). ConclusionPlacental elasticity measurement on the 24th–28th weeks does not seem to be a marker for identification of gestational diabetes.

Concordance of non-invasive mechanical and serum tests for liver fibrosis evaluation in chronic hepatitis C.

AIMTo determine the sensitivity and specificity of liver stiffness measurement (LSM) and serum markers (SM) for liver fibrosis evaluation in chronic hepatitis C.METHODSBetween 2012 and 2014, 81 consecutive hepatitis C virus (HCV) patients had METAVIR score from liver biopsy compared with concurrent results from LSM [transient elastography (TE) [FibroScan®/ARFI technology (Virtual Touch®)] and SM [FIB-4/aspartate aminotransferase-to-platelet ratio index (APRI)]. The diagnostic performance of these tests was assessed using receiver operating characteristic curves. The optimal cut-off levels of each test were chosen to define fibrosis stages F ≥ 2, F ≥ 3 and F = 4. The Kappa index set the concordance analysis.RESULTSFifty point six percent were female and the median age was 51 years (30-78). Fifty-six patients (70%) were treatment-naïve. The optimal cut-off values for predicting F ≥ 2 stage fibrosis assessed by TE were 6.6 kPa, for acoustic radiation force impulse (ARFI) 1.22 m/s, for APRI 0.75 and for FIB-4 1.47. For F ≥ 3 TE was 8.9 kPa, ARFI was 1.48 m/s, APRI was 0.75, and FIB-4 was 2. For F = 4, TE was 12.2 kPa, ARFI was 1.77 m/s, APRI was 1.46, and FIB-4 was 3.91. The APRI could not distinguish between F2 and F3, P = 0.92. The negative predictive value for F = 4 for TE and ARFI was 100%. Kappa index values for F ≥ 3 METAVIR score for TE, ARFI and FIB-4 were 0.687, 0.606 and 0.654, respectively. This demonstrates strong concordance between all three screening methods, and moderate to strong concordance between them and APRI (Kappa index = 0.507).CONCLUSIONGiven the costs and accessibility of LSM methods, and the similarity with the outcomes of SM, we suggest that FIB-4 as well as TE and ARFI may be useful indicators of the degree of liver fibrosis. This is of particular importance to developing countries.

Role of Acoustic Radiation Force Impulse (ARFI) Elastography in Determination of Severity of Benign Prostate Hyperplasia.

BackgroundThe aim of this study was to investigate the potential contribution of acoustic radiation force impulse (ARFI) elastography to the determination of the severity of benign prostate hypertrophy (BPH) by performing shear wave velocity (SWV) measurements of the prostate using ARFI technology.Material/MethodsSixty BPH patients and 40 healthy volunteers were included in this study. SWV measurements of the prostate were performed by transabdominal ultrasonography (US), both in the BPH patients and control subjects. The BPH patients also underwent uroflowmetry measurements. Using the International Prostate Symptom Score (IPSS), the BPH patients were divided into two subgroups, a mild-to-moderate BPH group and a severe BPH group, to compare SWV values.ResultsThe BPH patients had higher SWV values for the central area of the prostate compared to the control subjects (2.52±0.59 m/s and 1.47±0.42 m/s, p<0.01). The SWV values of the central area of prostate were higher in the severe BPH group compared to the mild-to-moderate BPH group (2.62±0.58 and 2.25±0.55, p=0.02).ConclusionsOur ARFI elastography results indicated that the central prostate SWV values of BPH patients were significantly higher relative to those of a healthy control group. The central prostate SWV values increased in proportion to the increased severity of BPH. Measurement of SWV by ARFI technology constitutes a non-invasive alternative to other methods for the determination of BPH severity.

Usefulness of percutaneous elastography by acoustic radiation force impulse for the non-invasive diagnosis of chronic pancreatitis.

To determine the accuracy of the acoustic radiation force impulse (ARFI) technique for the diagnosis of chronic pancreatitis. We present an observational, single-center study that included patients with suspected chronic pancreatitis in the period between October 2012 and September 2015 who underwent endoscopic ultrasound (EUS) and were classified according to the standard and Rosemont criteria. The same group of patients was assessed by the ARFI technology using ACUSON S2000™ equipment with Virtual Touch™ Quantification software for the assessment of pancreatic stiffness by obtaining the shear wave velocity (SWV) in the head, body and tail of the pancreas. Data were analyzed using ANOVA and nonparametric correlation methods. Diagnostic accuracy was obtained by analyzing receiver operating characteristic (ROC) curve. A total of thirty-three patients were studied (45.5% women); mean age was 58.3 ± 11.8 years. Seventeen with a diagnosis of chronic pancreatitis and sixteen classified as normal according to standard criteria. A significant difference was detected between the means of SWV in pancreatic body of patients without (SWV: 1.27 m/s) and with chronic pancreatitis (SWV 1.57 m/s), p = 0.037. The area under the ROC curve was 71.3% (95% CI 0.532-0.895) and the accuracy of ARFI for diagnosing chronic pancreatitis was 69.7% for a SWV of 1.4 m/s in the pancreatic body. The SWV means in head (r = 0.421, p < 0.05) and body (r = 0.455, p < 0.05) of the pancreas showed a significant correlation with the number of EUS criteria for chronic pancreatitis. Quantification of pancreatic stiffness with ARFI elastography technique has proven to be useful for the non-invasive diagnosis of chronic pancreatitis.

Elastography by acoustic radiation force impulse technology for differentiation of benign and malignant breast lesions: a meta-analysis.

To perform a meta-analysis assessing the ability of elastography by acoustic radiation force impulse (ARFI) technology to differentiate benign and malignant breast lesions. PubMed, the Cochrane Library, and the Web of Knowledge before September 24, 2014 were searched. Published studies that evaluated the diagnostic performance of ARFI for characterization of focal breast lesions were included. A total of fifteen studies, including 1720 patients with 1873 breast lesions (743 cancers, 1130 benign lesions), was analyzed. Among the included studies, virtual touch tissue imaging (VTI) was used in six studies, virtual touch tissue quantification (VTQ) in eight, combined VTI and VTQ in four, and virtual touch tissue imaging quantification (VTIQ) in three. Summary sensitivity and summary specificity for distinguishing malignant from benign breast lesions were 0.913 [95% confidence interval (CI), 0.779-0.969] and 0.871 (95% CI 0.773-0.930) for VTI, 0.849 (95% CI 0.805-0.884) and 0.889 (95% CI 0.771-0.950) for VTQ, and 0.935 (95% CI 0.892-0.961) and 0.881 (95% CI 0.818-0.924) for combined VTI and VTQ, respectively. The area under summary receiver operating characteristic (sROC) curve of VTI, VTQ, and combined VTI and VTQ were 0.95, 0.88, and 0.96, respectively. Significant publication bias was found only in the VTQ assessment (p = 0.025). The obtained sensitivity of VTIQ ranged from 80.4 to 90.3%, while the specificity ranged from 73.0 to 93.0%. The summary diagnostic value of VTIQ could not be evaluated due to insufficient data. Elastography by ARFI technology could be used as a good identification tool for differentiating benign and malignant breast lesions.

Acoustic Radiation Force Impulse Technology in the Differential Diagnosis of Solid Breast Masses with Different Sizes: Which Features Are Most Efficient?

Purpose. To evaluate diagnostic performance of acoustic radiation force impulse (ARFI) technology for solid breast masses with different sizes and determine which features are most efficient. Materials and Methods. 271 solid breast masses in 242 women were examined with ARFI, and their shear wave velocities (SWVs), Virtual Touch tissue imaging (VTI) patterns, and area ratios (ARs) were measured and compared with their histopathological outcomes. Receiver operating characteristic curves (ROC) were calculated to assess diagnostic performance of ARFI for small masses (6–14 mm) and big masses (15–30 mm). Results. SWV of mass was shown to be positively associated with mass size (P < 0.001). For small masses, area under ROC (Az) of AR was larger than that of SWV (P < 0.001) and VTI pattern (P < 0.001); no significant difference was found between Az of SWV and that of VTI pattern (P = 0.906). For big masses, Az of VTI pattern was less than that of SWV (P = 0.008) and AR (P = 0.002); no significant difference was identified between Az of SWV and that of AR (P = 0.584). Conclusions. For big masses, SWV and AR are both efficient measures; nevertheless, for small masses, AR seems to be the best feature.

Prospective evaluation of acoustic radiation force impulse technology in the differentiation of thyroid nodules: accuracy and interobserver variability assessment.

The aim of this study is to assess the diagnostic efficacy and interobserver agreement of acoustic radiation force impulse (ARFI) elasticity imaging in differentiating thyroid nodules. In our study, 74 consecutive patients (52 females, 22 males; age range 27-77years, mean: 41years) with 82 thyroid nodules (60 benign nodules, and 22 malignant) were examined by two radiologists with different experience. Patients underwent either cytology using fine needle aspiration cytology or thyroid surgery. The diagnostic performance of the two operators at ARFI with sensitivity, specificity, positive predictive and negative predictive value, and ROC curves was estimated. Inter-reader variability between the two operators was defined using Cohen's k. According to receiver operating characteristics ROC curves (AUROC=0.86 for observer 1; 0.81 for observer 2) sensitivity, specificity, PPV and NPV of reader 1 and 2 were respectively: 90, 75, 90.91 and 96.55%; (cut-off value of shear wave: 2.455m/s); 90, 72, 90 and 96.90% (cut-off value shear wave: 2.365m/s). Concordance between the two operators was good (k=0.755). This work is a feasibility study evaluating ARFI imaging. Its results suggest that ARFI imaging is a reproducible method which can be utilized with good diagnostic performance in the thyroid for discriminating benign and malignant nodules using the cut-off value of 2.455m/s. However, larger studies are needed to validate this method.

Preliminary study of the acoustic radiation force impulse imaging in diagnosis and treatment of IgA nephropathy

Objective To investigate the value of acoustic radiation force impulse (ARFI) on evaluating the renal tubular atrophy and interstitial fibrosis of IgA nephropathy(IgAN).Methods 117 patients diagnosed with IgAN,and 80 normal cases were examined with conventional ultrasonography and ARFI,recording the shear wave velocities(SWV),the hemodynamics and the renal biopsy results to quantify the elastic changes of renal cortex,with the aim of assessing AFRI's advantages on early diagnosing the impair of kidney.Results The SWV value of renal cortex,renal medulla of IgAN group were smaller than that of normal group (P ＜0.05),while the collective system SWV value had no difference(P ＞0.05).According to the ROC curve,the cut-off value of SWV in renal cortex was 2.7 cm/s.The accuracy of the diagnosis was 71 ％,which was better than RI (61.9％).The SWV value of the renal cortex decreased with the different stage of 1,2,3,4,but stage 5 was larger than stage 4.The degree of renal tubular atrophy and interstitial fibrosis(T) can be classified by the SWV of renal cortex,and the SWV of T2 was larger than T1 (P ＜0.05).Conclusions By quantifying the elastic change of kidney,ARFI technology is able to distinguish the degree of renal tubular atrophy and interstitial fibrosis,diagnose renal impairment early and judge the clinical stages.Furthermore the sensitivity,specificity,accuracy of it are superior to hemodynamic. Key words: Ultrasonopgraphy; Glomerulonephritis, IgA; Acoustic radiation force impulse

Clinical value of acoustic radiation force impulse imaging for quantitative evaluation of degree of liver fibrosis in chronic hepatitis C patients

To investigate the diagnostic value of acoustic radiation force impulse (ARFI) imaging technology for the assessment of liver fibrosis in chronic hepatitis C (CHC) patients. One-hundred-and-eight CHC patients were examined by real-time ultrasound elastography using the Acuson S2000 ARFI instrument (Siemens Healthcare) and underwent liver biopsy for pathohistological analysis. The correlation between liver fibrosis grades determined by the two approaches was analyzed. The cut-off values for diagnosis by ARFI (S more than 2, S more than 3 and S = 4) were determined by generating a receiver operating characteristic (ROC) curve. The spectrum of liver stiffness detected by ARFI sonoelastography included S1 at (1.26+/-0.27) m/s (n = 36), S2 at (1.45+/-0.51) m/s (n = 31), S3 at (2.01+/-0.54) m/s (n = 27), and S4 at (2.28+/-0.82) m/s (n = 14). The ARFI values were significantly different among the four different stages of liver fibrosis (P less than 0.001). The liver stiffness detected by ARFI sonoelastography was significantly correlated with the liver fibrosis stage determined by the gold standard pathohistological analysis (Spearman's rank coefficient: 0.61, P less than 0.001). Using the ARFI technology for assessment of liver fibrosis gave areas under the ROC curve of 0.779 for S more than 2 patients, of 0.863 for S more than 3 patients, and of 0.0880 for S = 4 patients. The real-time ultrasound elastography ARFI technology can show the elasticity modulus of liver, and its data values positively correlate with the patho-histology grade of liver fibrosis in CHC patients. ARFI technology is easy to operate, non-invasive, and quantitative, and has potential clinical value for assessing liver fibrosis in CHC.

The value of acoustic radiation force impulse (ARFI) in the differential diagnosis of thyroid nodules

ObjectivesThe aim of this study was to investigate the value of shear wave velocity value (SWV) and shear wave velocity ratio (SWR) in differentiating between malignant and benign thyroid nodules using virtual touch tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) technology. MethodsThe SWV and SWR were analyzed in 155 thyroid nodules in 155 patients (93 benign and 62 malignant) and eighty normal thyroid glands. The diagnostic performance of SWV and SWR were compared. ResultsThe mean value of SWV of malignant nodules differed significantly from those of the benign nodules (6.34±2.58m/s vs. 2.15±0.59m/s, P<0.05) and the normal thyroid (1.96±0.31m/s, P<0.05). There was no statistically significant difference between the mean value of SWV of benign nodules and normal thyroid (P>0.05). The mean value of SWR of malignant nodules differed significantly from those of the benign nodules (2.99±1.45 vs. 1.07±0.34, P<0.05). The sensitivity, specificity, positive predictive values, negative predictive values and accuracy of SWV in differentiating between malignant and benign nodules were 96.80%, 95.70%, 93.75%, 97.80% and 96.13% respectively based on the cutoff point as 2.84m/s. Those of SWR were 91.90%, 81.70%, 77.03%, 93.83% and 85.83% based on the cutoff point as 1.32. The diagnostic accuracy rate of SWV was statistically higher than that of SWR (P<0.05). ConclusionVTQ of ARFI technology provides the quantitative information of thyroid tissue elasticity and has high accuracy rate in differentiating between malignant and benign nodules. It is a useful complement for conventional ultrasonography.

Evaluation of SWV Measured by ARFI Technology in Hepatic Fibrosis

To explore the application value of the liver shear wave velocity (SWV) measured by acoustic radiation force impulse (ARFI) technology in hepatic fibrosis caused by chronic hepatitis B. The use of ACUSON S2000 color ultrasound system. The measurement of liver SWV in left lateral decubitus were performed on patients with chronic hepatitis B (n=210) and normal volunteers (n=20) and the position were as liver biopsy as possible. All patients with chronic hepatitis B were accepted liver biopsy under ultrasound-guided. SWV values in the cases with chronic hepatitis B increased gradually with the growing degree of hepatic fibrosis. SWV values among each fibrosis groups were remarkably different(P=0.000). Using the cutoff values of 1.43m/s, 1.78m/s, 2.15m/s and 2.45m/s for diagnosis of ≥S1,≥S2,≥S3 and = S4, the corresponding areas under receiver operating characteristic curves (AUROC) were 0.826, 0.829, 0.845 and 0.880 respectively. The sensitivity was 85.3%, 90.6%, 87.1% and 89.1%; the specificity was 87.5%, 90.1%, 82.8% and 87.4%; the accuracy was 89.4%, 84.6%, 88.1% and 83.2% respectively. Undertaking Spearman double variables correlated analysis between the SWV values and the parameters of fibrosis grade, inflammation grade and steatosis grade, the analyses shown were statistically significant between SWV value and fibrosis grade,SWV value and inflammation grade. The correlation coefficient were 0.713 (p = 0.000)and 0.496 (p = 0.001),but there was no obvious correlation between SWV value and steatosis grade in our study, the correlation coefficient was 0.145 (p = 0.368). Multiple linear regression showed that it had correlation relationship between SWV values and fibrosis grade (p = 0.000), the standard regression coefficient was 0.664,but there was no obvious correlation relationship between SWV values and inflammation grade, SWV values and steatosis grade (P>0.05). SWV measurement can directly reflect the elasticity modulus of liver, and the value can reflect the difference of hardness among every S stage. It can also identify hepatic fibrosis degree in a effective, convenient and non-invasive way. SWV measurement can be recommended as a new and to judge hepatic fibrosis degree.

Pilot study of the damage degree of Henoch-Schonlein purpura nephritis on children with acoustic radiation force impulse imaging

Objective To assess the value of acoustic radiation force impulse (ARFI) imaging in the pathological damage of Henoch-Schonlein purpura nephritis on children by comparison with renal biopsy.Methods 50 cases of healthy control group as group A; 58 children with HSPN were divided into three groups according to pathological grading:Ⅰ ～ Ⅱ class (group B),Ⅲ class (group C) and Ⅳ ～ Ⅵ class (group D).ARFI was then used to measure the shear wave velocities(SWV) of renal cortex of each group,compared the differences SWV of each group.Results SWV values of children's renal cortex with HSPN were significantly higher (t =5.883,P =0.017) than those in the group A.Pairwise comparisons found that there were statistically significant differences between group D and the other three groups (P ＜0.05).According the ROC curve,the cut-off value of SWV was 2.59 m/s when the maximum area under the curve equal to 0.719,the sensitivity and specificity were 63％ and 67％.Conclusions ARFI technology can quantify the elastic properties of the kidney,which is expected as an important indicator to evaluate the pathological extent of damage of the HSPN. Key words: Ultrasonography; Purpura nephritis; Acoustic radiation force impulse imaging

Acoustic radiation force impulse of the liver

Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualitative or quantitative (wave velocity values) responses. Several non-invasive methods for assessing the staging of fibrosis are used, in order to avoid liver biopsy. Liver function tests and transient elastography are non-invasive, sensitive and accurate tools for the assessment of liver fibrosis and for the discrimination between cirrhotic and non-cirrhotic liver. Many published studies analyse ARFI performance and feasibility in studying diffuse liver diseases and compare them to other diagnostic imaging modalities such as conventional ultrasonography and transient elastography. Solid focal liver lesions, both benign and malignant, are common findings during abdominal examinations. The accurate characterization and differential diagnosis are important aims of all the imaging modalities available today. Only few papers describe the application of ARFI technology in the study of solid focal liver lesions, with different results. In the present study, the existing literature, to the best of our knowledge, about ARFI application on diffuse and focal liver pathology has been evaluated and results and statistical analyses have been compared, bringing to the conclusion that ARFI can be used in the study of the liver with similar accuracy as transient elastography in diagnosing significant fibrosis or cirrhosis and has got some advantages in respect to transient elastography since it does not require separate equipment, better displays anatomical structures and measurements can be successfully carried out almost in every patient.

Comparative Study of Shear Wave Velocities Using Acoustic Radiation Force Impulse Technology in Hepatocellular Carcinoma: The Extent of Radiofrequency Ablation

Background/AimsThe purpose of this study was to assess the value of acoustic radiation force impulse (ARFI) for predicting the extent of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) by correlating the elasticity of HCC and peritumoral parenchyma (as measured by ARFI) with the extent of ablation determined by computed tomography (CT).MethodsFrom September 2009 to June 2011, 158 patients underwent RFA ablation for HCC (single, ≤3 cm). We evaluated the data of a total of 38 prospectively enrolled patients who underwent both ARFI imaging and contrast-enhanced CT after one session of 12 minutes of RFA without a change in needle position. The ARFI imaging indices, including the mean shear wave velocity (SWV) of HCC, mean SWV of the peritumoral parenchyma and tumor size, were evaluated to determine the statistical correlation with RFA extent after one session of 12 minutes of RFA.ResultsA stiffer liver parenchyma in patients with cirrhosis results in a smaller ablation zone.ConclusionsSWV of ARFI in liver parenchyma was well correlated with RFA extent. After evaluating the correlation between ARFI and RFA extent, we suggest that the SWV in liver parenchyma might be a non-invasive supplementary tool for predicting the extent of RFA.