Acoustic Radiation Force Impulse Imaging Values Research Articles

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.

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<0.001), and APRI values (r=0.704, p<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.

Ultrasound elastography in diagnosis and follow-up for patients with sialolithiasis.

This study aims to answer whether acoustic radiation force impulse imaging (ARFI) can reasonably be employed in initial examination and follow-up during therapy in patients with sialolithiasis, one of the most common non-malignant disorders of the salivary glands. Mechanical tissue properties of affected and contralateral healthy salivary glands were analyzed by ARFI in 129 patients with sialolithiasis. In different subgroup analyses, ARFI shear wave velocity values were compared between healthy and diseased submandibular or parotid glands, salivary glands with calculi exhibiting different sizes, as well as before and after therapy. The patients' symptoms were evaluated by a standardized questionnaire. The t-test (2 groups) or the One-way ANOVA test (>2 groups) was used for the estimation of stochastic probability in intergroup comparisons. Submandibular or parotid glands affected by sialolithiasis were found to exhibit significant lower ARFI values as compared to the healthy contralateral glands in the same individuals. ARFI values in submandibular glands with a single calculus of more than 5 mm in diameter or with multiple calculi as well as in parotid glands with calculi exhibiting diameters of more than 5 mm were significantly higher as compared to the respective healthy contralateral glands. No significant differences in ARFI values of affected salivary glands were detected between patients with low or high symptom perception. ARFI provides an easy, quick and reliable diagnostic tool for the objective assessment of disease severity and progression in patients with sialolithiasis that can simply be implemented in pre-existing ultrasound protocols.

Low Pretreatment Acoustic Radiation Force Impulse Imaging (ARFI) Values Predict Sustained Virological Response in Antiviral Hepatitis C Virus (HCV) Therapy.

BackgroundNon-invasive procedures such as acoustic radiation force impulse imaging (ARFI) shear-wave elastography are currently used for the assessment of liver fibrosis. In the course of chronic hepatitis C, significant liver fibrosis or cirrhosis develops in approximately 25% of patients, which is a negative predictor of antiviral treatment response. Cirrhosis can be prevented by successful virus elimination.In this prospective study, a pretreatment ARFI cutoff value of 1.5 m/s was evaluated in relation to sustained virological response to anti-HCV therapy.Material/MethodsIn 23 patients with chronic hepatitis C, liver stiffness was examined with ARFI at defined times before and under antiviral triple therapy (peginterferon, ribavirin in combination with a first-generation protease inhibitor, and telaprevir or boceprevir). Patients were stratified into 2 groups based on pretreatment ARFI values (<1.5 m/s and ≥1.5 m/s) for the assessment of virological response.ResultsThe liver stiffness at baseline for all patients was 1.57±0.79 m/s (ARFI median ± standard deviation; margin: 0.81 m/s to 3.45 m/s). At week 4 of triple therapy, patients with low pretreatment ARFI values had higher rates of HCV-RNA negativity (69% vs. 43%), reflecting an early rapid virological response (eRVR). Sustained virological response (SVR) was found in 75% (12/16) of patients with an ARFI value <1.5 m/s and only 57% (4/7) of patients with ARFI value ≥1.5 m/s.ConclusionsPatients with chronic hepatitis C and pretreatment ARFI <1.5 m/s showed earlier virus elimination and better response to treatment.

The performance of acoustic radiation force impulse imaging in predicting liver fibrosis in chronic liver diseases

Sonography-based noninvasive liver fibrosis assessment is promising in the prediction of treatment efficacy and prognosis in chronic liver disease (CLD) patients. Acoustic radiation force impulse imaging (ARFI) is a newly-developed transient elastography (TE) method integrated into a conventional ultrasound machine. The study aimed to assess the performance of ARFI imaging in the diagnosis of liver fibrosis in Taiwanese CLD patients. We also aimed to search for the optimal cut-off values in different fibrosis stages. A total of 60 CLD patients (40 males; mean age, 51.8±11 years) were consecutively included. They received standard ARFI measurement within 2 weeks at the time of liver biopsy. There were eight patients with Metavir fibrosis stage 0 (F0), 16 patients with F1, 20 patients with F2, eight patients with F3, and eight patients with F4, respectively. The mean values among patient with F0, F1, F2, F3, and F4 were 1.17±0.13, 1.30±0.17, 1.31±0.24, 2.01±0.45, and 2.69±0.91, respectively (p<0.001). The optimal cut-off ARFI value for significant fibrosis (F≥2) was 1.53 with the accuracy of 0.733, while it was 1.66 for advanced fibrosis (F≥3) with the accuracy of 0.957. Our study demonstrated that ARFI imaging is competent for fibrosis diagnosis, particularly in CLD patients with advanced fibrosis.

Diagnosing native liver fibrosis and esophageal varices using liver and spleen stiffness measurements in biliary atresia: a pilot study.

Biliary atresia commonly leads to liver fibrosis and cirrhotic complications, including esophageal varices. To evaluate liver and spleen stiffness measurements using acoustic radiation force impulse (ARFI) imaging for diagnosing grade of liver fibrosis and predicting the presence of esophageal varices in patients treated for biliary atresia. ARFI imaging of the spleen and native liver was performed in 28 patients with biliary atresia. We studied the relation between ARFI imaging values and liver histology findings (n=22), upper gastrointestinal endoscopy findings (n=16) and several noninvasive test results. Diagnostic accuracy was assessed using receiver operating characteristic curve analyses. Liver stiffness measurements exhibited a significant difference among the different grades of liver fibrosis (P=0.009), and showed higher values in patients with high-risk esophageal varices than in the other patients (P=0.04). The areas under the receiver operating characteristic curves of liver stiffness measurements for liver fibrosis grades ≥ F2, ≥F3 and = F4 were 0.83, 0.93 and 0.94, respectively. Patients with high-risk esophageal varices were preferentially diagnosed by the combined liver and spleen stiffness measurements (area under the curve, 0.92). Liver and spleen stiffness measurements using ARFI imaging are potential noninvasive markers for liver fibrosis and esophageal varices in patients treated for biliary atresia.

Acoustic radiation force impulse imaging elastography is efficacious in detecting hepatic fibrosis in children

ObjectiveTo evaluate the diagnostic performance of acoustic radiation force impulse imaging (ARFI) in detecting significant hepatic fibrosis in children. Material and methodsOur hospital's ethics committee approved the study and all patients or their representatives provided informed written consent. We included 96 children (50 boys, 46 girls; mean age, 8 years). We also studied 16 volunteers without liver disease as controls and 80 patients with diseases that can lead to fibrosis and cirrhosis of the liver. The final sample included 31 patients with biopsies and the 16 controls. All patients underwent abdominal ultrasonography including Doppler imaging and elastography with ARFI. The ARFI value, expressed as velocity (m/s) of shear wave propagation through the tissue, was calculated by averaging 16 measurements in both liver lobes. We used one-way analysis of variance to compare means between groups; we set statistical significance at P<0.05. We used Student's t-tests and chi-square tests for categorical data. ResultsThe ARFI value in children with fibrosis ≥F2 was higher (1.80±0.45m/s) than in controls and higher than in patients with F0–F1 (1.38±0.22m/s). The difference was significant (P<0.001) for detecting ≥F2. Steatosis was not related with the ARFI value (Student's t-test, P>0.84). Necroinflammatory activity was strongly associated with the ARFI value (Student's t-test, P<0.01). Fibrosis and necroinflammatory activity were strongly associated with each other (chi-square test, P<0.0001). ConclusionThe speed of shear wave propagation is significantly associated with the degree of hepatic fibrosis in children.

Diagnostic value of acoustic radiation force impulse imaging for evaluating the degree of liver fibrosis in chronic hepatitis B

Objective To investigate the clinical value of the acoustic radiation force impulse imaging (ARFI) in the quantitative evaluation of fibrosis staging in chronic hepatitis B. Methods A total of 373 patients with chronic hepatitis B were grouped in accordance with the depth of the right anterior lobe and posterior lobe of the liver and underwent ARFI to measure ARFI values. Liver biopsy was performed in all patients to investigate the relationship between liver fibrosis stages and ARFI values in different groups. Results The ARFI values in different pathological grades with the same depth of the right anterior and right posterior lobe of the liver were statistically significant (P<0.001); the ARFI values between the middle and deep parts of the right anterior lobe and the same location of the right posterior lobe were statistically significant (P<0.01); for the right anterior lobe, the ARFI value of the shallow part showed statistical significance from that of the middle and the deep part (P<0.05). Receiver operating characteristic (ROC) curve analysis for different sampling locations showed that the largest area under the ROC curve, which was 0.818, existed in the middle part of the right anterior lobe, indicating that it could be the optimal sampling location for the measurement of ARFI values. Liver stiffness at ARFI imaging was significantly correlated with liver fibrosis stage in chronic hepatitis B and spearman coefficient of correlation was 0.530 (P<0.001). The areas under the ROC curves for the chronic hepatitis B patients with severe liver fibrosis (≥S3) and early cirrhosis (=S4) were 0.818 and 0.860, respectively. Conclusions ARFI imaging was promising for clinical application and could be utilized as a noninvasive method for the quantitative evaluation of fibrosis staging in chronic hepatitis B. Key words: Ultrasonography; Hepatitis B, chronic; Liver cirrhosis; Acoustic radiation force impulse

La elastografía mediante técnica Acoustic radiation force impulse es eficaz en la detección de fibrosis hepática en el niño

ObjectiveTo evaluate the diagnostic performance of acoustic radiation force impulse imaging (ARFI) in detecting significant hepatic fibrosis in children. Material and methodsOur hospital's ethics committee approved the study and all patients or their representatives provided informed written consent. We included 96 children (50 boys, 46 girls; mean age, 8 y). We also studied 16 volunteers without liver disease as controls and 80 patients with diseases that can lead to fibrosis and cirrhosis of the liver. The final sample included 31 patients with biopsies and the 16 controls.All patients underwent abdominal ultrasonography including Doppler imaging and elastography with ARFI. The ARFI value, expressed as velocity (m/s) of shear wave propagation through the tissue, was calculated by averaging 16 measurements in both liver lobes.We used one-way analysis of variance to compare means between groups; we set statistical significance at P<.05. We used Student's t-tests and chi-square tests for categorical data. ResultsThe ARFI value in children with fibrosis ≥ F2 was higher (1.80±0.45m/s) than in controls and higher than in patients with F0-F1 (1.38±0.22m/s). The difference was significant (P<.001) for detecting F ≥ 2. Steatosis was not related with the ARFI value (Student's t-test, P>.84). Necroinflammatory activity was strongly associated with the ARFI value (Student's t-test, P<.01). Fibrosis and necroinflammatory activity were strongly associated with each other (chi-square test, P<.0001). ConclusionThe speed of shear wave propagation is significantly associated with the degree of hepatic fibrosis in children.

Assessment of Spleen Stiffness Using Acoustic Radiation Force Impulse Imaging (ARFI): Definition of Examination Standards and Impact of Breathing Maneuvers

Spleen elastography is a promising method for the characterization of portal hypertension in cirrhotic individuals. However, standardized examination procedures for spleen stiffness measurement have not been defined yet. We analyzed the distribution characteristics of spleen shear-wave velocity (ARFI) and assessed the influence of the respiratory position on spleen stiffness measured by ARFI. 25 healthy probands and 25 patients with Child A liver cirrhosis were prospectively characterized with conventional ultrasound, transient elastography, liver ARFI, and underwent spleen ARFI in two respiratory positions: breath hold after expiration (exp) and deep inspiration (insp). For each position 20 single measurements were performed. The distribution of spleen ARFI values was analyzed for normality and the appropriate number of measurements for spleen stiffness estimation was investigated. Spleen ARFI results were normally distributed in > 95 % of cases. Performing 20 instead of 10 single measurements resulted in < 5 % deviation from the mean value after 20 measurements in the majority of cases. Cirrhotic patients had a higher spleen stiffness compared to healthy probands (exp: 3.25 ± 0.58 vs. 2.46 ± 0.35 m/s; p < 0.001). Deep inspiration caused an overall increase in spleen stiffness in both groups: probands 2.46 ± 0.35 m/s (exp) vs. 2.66 ± 0.36 m/s (insp), p = 0.01; cirrhotics 3.25 ± 0.58 m/s (exp) vs. 3.46 ± 0.38 m/s (insp), p = 0.03. However, cases with high spleen stiffness values (exp) show decreasing ARFI values in deep inspiration. ARFI values of the spleen are normally distributed and the mean of 10 valid measurements can be used as a representative value. Deep inspiration significantly modulates spleen stiffness. Therefore, the respiratory position needs careful standardization.

Influence of different frequencies and insertion depths on the diagnostic accuracy of liver elastography by acoustic radiation force impulse imaging (ARFI)

BackgroundAcoustic Radiation Force Impulse Imaging (ARFI) is an innovative elastography for staging of liver fibrosis. We evaluated the diagnostic accuracy of different probes to perform ARFI at different insertion depths. MethodsIn a prospective study, 89 chronic HCV infected patients underwent ARFI elastography using both available probes (c-ARFI: C4-1-MHz; l-ARFI: L9-4 MHz) in comparison to Fibroscan®. Variability of ARFI elastography at different insertion depths was systematically evaluated in 39 patients (44%). According to Fibroscan® elastography, 32 patients (36%) presented with liver cirrhosis, 23 patients (26%) had significant fibrosis and 34 patients (38%) had no significant fibrosis. ResultsMean propagation velocity with c-ARFI was 1.70±0.67m/s and 1.91±0.87m/s with l-ARFI. Results of both probes were correlated to each other (p<0.001; r=0.70) and to Fibroscan® (p<0.001, r=0.82 and 0.84, respectively). In patients with significant fibrosis or with cirrhosis, mean values by l-ARFI were significantly higher than by c-ARFI (p<0.001). For detection of liver cirrhosis, AUROC was 0.97 for c-ARFI (cut-off level 1.72m/s) and 0.90 for l-ARFI (cut-off 2.04m/s). Correlation coefficients of c-ARFI with Fibroscan® were highest at an insertion depth of 5–6cm (r=0.882 and 0.864, respectively, p<0.001) and at 3–4cm for l-ARFI (r=0.850 and 0.838, respectively, p<0.001). ConclusionsARFI elastography with the linear and with the convex probes showed comparable validity and accuracy in the estimation of liver stiffness. The linear probe gave higher ARFI values. The most accurate insertion depth was 5–6cm for c-ARFI and 3–4cm for l-ARFI indicating that measurements should not be performed close to the liver capsule.

Acoustic radiation force impulse imaging as noninvasive marker of hepatic fibrosis

Background: Acoustic Radiation Force impulse Imaging (ARFI) is a novel non-invasive technique studying the localized mechanical properties of tissue by utilizing short, high intensity acoustic pulses (shear wave pulses) to assess the mechanical response(tissue displacement), providing a measure of tissue elasticity. Aims: To investigate the feasibility of ARFI imaging as a noninvasive method for assessing liver fibrosis compared to liver biopsy scores in patients with suspected chronic liver disease. Method: A prospective comparison study of ARFI elastography (Virtual Touch imaging, ACUSON S2000 ultrasound unit, Siemens) in a consecutive series of patients who underwent liver biopsy for assessment of liver stiffness was measured in meters per second. Mean ARFI velocities were compared with Modified Ishak scores and Brunt score for fibrosis in liver biopsy findings. Results: Study included 40 patients of suspected chronic liver disease who underwent liver biopsy and ARFI Elastography from the same segment of liver between the age group of 38.7 ± 14.4 years with predominant male gender (80%) over a period of 1 year. Cryptogenic cause for chronic hepatitis (32.5%) was the leading cause followed by NASH (22.5%) and then contributed equally by viral etiology of HCV and HBV (20%) each. The median ARFI value is 1.55mt/sec and there is an increasing trend of ARFI values as Childs score increases. ARFI proved to be a better predictor of advanced fibrosis (F3 or F4). The spearman rho correlation coefficients between median values of ARFI measurements and the histological fibrosis stage of the Metavir score and Brunt score were both highly significant (P< 0.01) with rho of 0.523 and 0.69 respectively. Conclusion: Our study showed that ARFI sonoelastography stands out on account of its very good correlation with liver biopsy (gold standard for evaluating liver fibrosis).

Acoustic radiation force impulse imaging—normal values of liver stiffness in healthy children

Acoustic radiation force impulse imaging (ARFI) is a recent ultrasound technique to assess tissue stiffness. Our aim was to describe the feasibility and to define normal ARFI values in liver in children. ARFI values were measured in 103 children (ages 2weeks to 17years) divided into four age groups, at a minimum depth of 3cm. In 20 children, measurements were done at 3-, 4- and 5-cm depth in the liver to assess the suitability of measurement location. The impact of age groups and of depth groups was examined using multilevel models. The precision of the measurements was determined using intraclass correlation coefficient (ICC). There was no statistical difference between measurements taken at different ages, with a mean propagation velocity of 1.12m/s (range: 0.73 to 1.45m/s). There was no significant difference according to the depth of the regions of interest (up to 5cm). The ICC was 0.77 (95% CI 0.69-0.83). ARFI is feasible in children at any age with an acceptable reliability. The depth of measurements in the liver seems to have no influence on test results. We set the standard ARFI elastography values for healthy liver in children.

Standard value of ultrasound elastography using acoustic radiation force impulse imaging (ARFI) in healthy liver tissue of children and adolescents.

Ultrasound elastography by acoustic radiation force impulse imaging (ARFI) is used in adults for non invasive measurement of liver stiffness, indicating liver diseases like fibrosis. To establish ARFI in children and adolescents we determined standard values of healthy liver tissue and analysed potentially influencing factors. 132 patients between 0 and 17 years old were measured using ARFI. None of them had any liver disease or any other disease that could affect the liver secondarily. All patients had a normal ultrasound scan, a normal BMI and normal liver function tests. The mean value of all ARFI measurements was calculated and potentially influencing factors were analysed. The mean value of all ARFI elastography measurements was 1.16 m/sec (SD ± 0.14 m/sec). Neither age (p = 0.533) nor depth of measurement (p = 0.066) had no significant influence on ARFI values, whereas a significant effect of gender was found with lower ARFI values in females (p = 0.025), however, there was no significant interaction between age groups (before or after puberty) and gender (p = 0.276). There was an interlobar difference with lower values in the right liver lobe compared to the left (p = 0.036) and with a significantly lower variance (p < 0.001). Consistend values were measured by different examiners (p = 0.108), however, the inter examiner variance deviated significantly (p < 0.001). ARFI elastography is a reliable method to measure liver stiffness in children and adolescents. In relation to studies which analyse liver diseases, the standard value of 1.16 m/sec (± 0.14 m/sec) allows a differentiation of healthy versus pathological liver tissue.

Non-invasive evaluation of hepatic manifestation in Wilson disease with transient elastography, ARFI, and different fibrosis scores

Objective. Noninvasive investigation of liver fibrosis with ultrasound-based elastography and laboratory-based fibrosis indices have been established in various chronic liver diseases within the last years. We aimed to evaluate feasibility and diagnostic value of transient elastography (TE), acoustic radiation force impulse imaging (ARFI), and different serologic fibrosis indices in Wilson's disease (WD). Materials and methods. TE and ARFI were performed in 50 Wilson patients. In addition, AST/Platelet Ratio Index (APRI), FIB-4, and Forns score were calculated. Hepatic fibrosis was classified by a clinical score. Results. Of the 50 Wilson patients 41 had hepatic manifestation of WD. TE results were significantly increased in advanced hepatic fibrosis (7.0 ± 2.2 kPa; p < 0.05) and cirrhosis (10.1 ± 6.73 kPa; p < 0.05) compared to individuals without hepatic manifestation (5.0 ± 1.4 kPa). Right liver lobe ARFI (R-ARFI) values were only increased in cirrhotic patients (1.43 ± 0.28 vs. 1.19 ± 0.14 m/s; p < 0.05). The cutoff values to best discriminate cirrhosis were 6.1 kPa for TE and 1.29 m/s for R-ARFI. Left lobe ARFI failed to provide additional diagnostic benefit. Elastography methods displayed a significant correlation with APRI, FIB-4, and Forns indices (Pearson's rho > 0.33; p < 0.03). Conclusions. TE displayed a gradual increase between different stages of hepatic manifestation in WD and could significantly discriminate cirrhosis. The TE cutoff for cirrhosis may be clinically more relevant than the R-ARFI value.

Acoustic radiation force impulse imaging (ARFI) for non-invasive detection of liver fibrosis: examination standards and evaluation of interlobe differences in healthy subjects and chronic liver disease

Objective.Acoustic radiation force impulse imaging (ARFI) is a non-invasive method for the quantification of liver stiffness. We aimed to develop standards for the measuring procedure and studied the impact of different measuring sites. Materials and Methods.ARFI was tested in a tissue phantom and in 50 healthy volunteers. In addition, 116 patients with chronic liver disease underwent ARFI. The results were compared with histological staging (non-viral liver disease) and transient elastography (hepatitis C). ARFI diagnostic performance was evaluated with receiver operating characteristic curves. Results.ARFI results were not normally distributed in >20% of cases. Deep inspiration significantly increased ARFI values by 13% (p < 0.05). The mean shear-wave velocity in healthy individuals was 1.28 ± 0.19 m/s in the left liver lobe and 1.15 ± 0.17 m/s in the right liver lobe (p < 0.001). Similarly, in 79/116 patients with chronic liver disease a significant difference of shear-wave velocity between both liver lobes was detected. The histological staging correlated with ARFI results of the biopsy site (r = 0.661, p < 0.001) in non-viral liver disease (n = 47). The mean shear-wave velocity in cases with F1 and F2 fibrosis was increased in the left compared with the right liver lobe (2.1 ± 0.73 m/s vs. 1.75 ± 0.89 m/s, p = 0.041). Similar results were obtained in patients with hepatitis C (n = 69). Conclusion.Our study strengthens the necessity for definition of examination standards and demonstrates the usefulness of ARFI in non-viral liver disease. Interlobe variations of liver stiffness demand further investigation.

Comparing Acoustic Radiation Force Impulse Imaging to transient elastography to assess liver stiffness in healthy volunteers with and without valsalva manoeuvre

Acoustic Radiation Force Impulse Imaging (ARFI) is a new ultrasound elastography technology (Siemens ACUSON S2000 Virtual Touch™ Tissue Quantification), which is integrated in conventional ultrasound equipment. In preliminary studies, ARFI sheer wave speed (SWS) in liver tissue correlated well with transient elastography (TE) values and liver fibrosis stages. Sixty-eight healthy male and female volunteers were measured with ARFI with two ultrasound tranducers, three measuring positions and during valsalva manoeuvre. A TE (FibroScan™, Echosens, France) was performed in 60 volunteers. Volunteers had a mean age of 28 years and a mean BMI of 22.3. There was no significant difference of ARFI SWS between the 4C1 and 4V1 ultrasound probes in either intercostal or abdominal approach to liver segment 8 but a higher variance of ARFI SWS with the 4V1/abdominal compared to the intercostal approach (p = 0.0368). The 4C1/intercostal approach had the highest success rates (97.2%), comparable to those of TE (97.18%). Left liver lobe measurements obtained both significantly higher ARFI SWS and value variance (p = 0.0016 and p = 0.0198) compared to 4C1/intercostal approach. Mean ARFI SWS was 1.19 m/s (range 0.77-1.63). Mean TE was 5.39 kPa (range 3.3-9.0 kPa). Valsalva manoeuvre did not significantly alter ARFI SWS and variance. Skin-liver distance significantly influenced ARFI SWS (p < 0.05), while age and gender did not. These results might constitute a first impression of the chances of ARFI SWS to assess liver stiffness, especially in patients with liver diseases due to increased venous pressure.