Value of Acoustic Radiation Force Impulse Imaging Elastography for Non-invasive Evaluation of Patients with Nonalcoholic Fatty Liver Disease

The goals of the work described here were to evaluate the clinical utility of acoustic radiation force impulse (ARFI) elastography in differentiating non-alcoholic fatty liver disease (NAFLD) histologic subtypes and to determine if ARFI elastography measurements correlate with the severity of liver fibrosis. We compared ARFI elastography measurements with clinical, biologic and histologic features (simple steatosis or steatohepatitis) in 64 patients with histologically proven NAFLD. ARFI elastography is suitable for distinguishing patients with non-alcoholic steatohepatitis from those with simple steatosis, with an area under the receiver operating characteristic curve (AUROC) of 0.867 (95% confidence interval = 0.782–0.953). There was a highly significant correlation (r = 0.843) between ARFI elastography measurements and fibrosis (p < 0.001). In patients with non-alcoholic steatohepatitis, the diagnostic performance of ARFI elastography in predicting significant fibrosis (F ≥ 2) had an AUROC of 0.944. ARFI elastography better predicted F = 4 fibrosis (AUROC = 0.984). In conclusion, ARFI elastography is a promising method for differentiating patients with non-alcoholic steatohepatitis from patients with simple steatosis and can also predict significant fibrosis in these patients.     

慢性乙型肝炎肝硬化患者超声辐射力脉冲成像参数与肝功能Child-Pugh分级的相关性

目的 探讨乙型肝炎肝硬化患者肝功能Child-Pugh分级与声辐射力脉冲成像(ARFI)定量参数剪切波速度(SWV)之间的相关性.方法 对临床诊断为肝硬化的40例慢性乙型肝炎患者及40名健康体检者行ARFI,测量肝脏SWV;检测肝硬化患者血清学指标,根据结果及临床表现进行肝功能Child-Pugh分级.比较肝硬化患者与健康人及不同Child-Pugh分级患者间SWV的差异,分析肝脏SWV与Child-Pugh分级及血清学指标之间的相关性.结果 健康人肝脏SWV 显著低于肝硬化患者;随Child-Pugh分级上升,SWV明显增加(P<0.001),SWV与Child-Pugh分级呈正相关(r=0.62,P<0.001).肝硬化患者SWV与凝血酶原时间呈正相关(r=0.65,P<0.001),与血清白蛋白水平呈负相关(r=-0.59,P<0.001).结论 肝硬化患者SWV显著高于健康人,并与肝功能Child-Pugh分级呈正相关.     

Comparison of Acoustic Radiation Force Impulse Imaging and Transient Elastography for Non-invasive Assessment of Liver Fibrosis in Patients with Chronic Hepatitis B

The aims of this study were to compare the performance of acoustic radiation force impulse (ARFI) elastography and transient elastography (TE) in the assessment of liver fibrosis in patients with chronic hepatitis B and to evaluate the impact of elevated alanine transaminase levels on liver stiffness assessment using ARFI elastography. One hundred eighty consecutive patients with chronic hepatitis B were enrolled in this study and evaluated with respect to histologic and biochemical features. All patients underwent ARFI elastography and TE. ARFI elastography and TE correlated significantly with histologically assessed fibrosis (r = 0.599, p < 0.001, for ARFI elastography; r = 0.628, p < 0.001, for TE) and necro-inflammatory activity (r = 0.591, p < 0.001, for ARFI elastography; r = 0.616, p < 0.001, for TE). Areas under the receiver operating characteristic curves for ARFI elastography and TE were 0.764 and 0.813 (p = 0.302, ≥stage 2), 0.852 and 0.852 (p = 1.000, ≥stage 3) and 0.825 and 0.799 (p = 0.655, S = 4), respectively. The optimum cutoff values for ARFI elastography were 1.63 m/s for stage ≥2, 1.74 m/s for stage ≥3 and 2.00 m/s for stage 4 in patients for whom alanine transaminase levels were evaluated. The cutoff values decreased to 1.24 m/s for ≥ stage 2, 1.32 m/s for ≥ stage 3 and 1.41 m/s for stage 4 in patients with normal alanine transaminase levels. ARFI elastography may be a reliable method for diagnosing the stage of liver fibrosis with diagnostic performance similar to that of TE in patients with chronic hepatitis B. In addition, liver stiffness values obtained with ARFI elastography, like those obtained with TE, may be influenced by alanine transaminase levels.     

ARFI elastography in patients with chronic autoimmune liver diseases: A preliminary study

ObjectiveAcoustic radiation force impulse (ARFI) is a new software-based technique that evaluates liver stiffness during B-mode ultrasonography. The purpose of this study was to evaluate the accuracy of ARFI in distinguishing patients with chronic autoimmune liver disease from healthy subjects.Material and methodsWe enrolled 9 adult patients (8 women, 1 man; age 48.1 ± 12.8 years) with chronic autoimmune disease (primary biliary cirrhosis (PBC, n = 3), autoimmune hepatitis (AIH, n = 2), primary sclerosing cholangitis (PSC, n = 1) and overlap syndromes, (n = 3) who underwent a liver biopsy and 11 healthy volunteers (age 34.7 ± 10.4 years; 7 women, 4 men). Liver stiffness was evaluated and expressed as the shear wave velocity (SWV) in m/sec. We used a US scanner Siemens-Acuson S2000, evaluating the right liver lobe and the left liver lobe.ResultsThe SWV was significantly higher in cases (right lobe: 1.51 ± 0.44; left lobe: 1.57 ± 0.40) than in controls (right lobe: 1.08 ± 0.10; left lobe: 1.12 ± 0.13) (right lobe: P = 0.002; left lobe: P = 0.013). We found no significant correlation between right and left lobe SWVs in cases (P = 0.779) or controls (P = 0.385). The SWV cut-off that best distinguished cases from controls was 1.25 m/sec (accuracy: AUC=0.885; sensitivity: 70.6%; specificity: 95.5%).ConclusionsARFI elastography is a noninvasive ultrasonographic technique that can differentiate healthy subjects from patients with fibrotic stages of chronic liver disease.     

The Influence of Food Intake on Liver Stiffness Values Assessed by Acoustic Radiation Force Impulse Elastography—Preliminary Results

The present study assessed the influence of food intake on acoustic radiation force impulse elastography (ARFI) measurements. Seventy-three healthy volunteers were included: 57 subjects in the study group (on whom ARFI measurements were performed first in fasting condition, followed by measurements made 1h and 3h after food intake); and 16 subjects in the control group (on whom ARFI measurements were performed 3 times during a 3-h interval without eating). All subjects included in the study group received the same standard solid meal. In the study group, the mean liver stiffness (LS) values by ARFI increased significantly 1 h after food intake (1.51 ± 0.40 m/s vs. 1.27 ± 0.23, p = 0.003), but 3 h after the meal the differences were no longer significant (1.46 ± 0.51 vs. 1.27 ± 0.23, p = 0.06). In the control group, the mean LS values were similar in all 3 measurements. In conclusion, food intake significantly increased the LS values, thus ARFI measurements should be performed in fasting conditions.     

Preliminary Results of Acoustic Radiation Force Impulse (ARFI) Ultrasound Imaging of Breast Lesions

The aim of this study was to determine the appearance of breast lesions using acoustic radiation force impulse imaging (ARFI) and to correlate the ARFI values with the pathologic results. The area ratio (AR) and virtual touch tissue quantification (VTQ) values were analyzed in 86 patients (mean age 45.6 years, range 17-78 years) with 92 breast lesions (65 benign, 27 malignant; mean size 25.7 mm). The diagnostic performance of ultrasound (US) alone and US plus ARFI values were compared with respect to sensitivity, specificity and area under the curve (AUC) using a receiver operating characteristic curve analysis. The mean AR of the benign lesions (1.08 ± 0.21) differed from that of the malignant lesions (1.99 ± 0.63; p < 0.0001), as did the mean VTQ values (3.25 ± 2.03 m/s vs. 8.22 ± 1.27 m/s; p < 0.0001). In conclusion, ARFI provides quantitative elasticity measurements, which may complement B-mode US and potentially improve the characterization of breast lesions.     

Comparison Between Different Manufacturers’ 2-D and Point Shear Wave Elastography Techniques in Staging Liver Fibrosis in Chronic Liver Disease Using Liver Biopsy as the Reference Standard: A Prospective Study

The purpose of this study was to assess the utility of 2-D shear wave elastography (SWE) in assessing liver fibrosis in patients with chronic liver disease by comparing its performance with that of point shear wave elastography (pSWE) using liver histological staging as the reference standard. In this ethics committee-approved, single-institution prospective study, pSWE and 2-D SWE velocity measurements were obtained in 121 adult patients (age: 18–70 y, median: 45 y) immediately before a liver biopsy for chronic liver disease. Shear wave velocity (SWV) and Ishak scores were compared using the Kruskal–Wallis test, Spearman's correlation and receiver operating characteristic (ROC) curve analysis. Youden's index was used to determine the optimal cutoff point. There was no technical failure using pSWE and 2-D SWE. The mean difference for SWV between pSWE and 2-D SWE was 0.0223 (limits of agreement: –1.1009, 1.1145). Values for both pSWE and 2-D SWE were significantly correlated with fibrosis stage (Spearman's ρ = 0.606, p < 0.0001; ρ = 0.722, p < 0.001 respectively). The area under the ROC curve differentiating F ≥3 was 0.855 (95% confidence interval: 0.778–0.932) for pSWE and 0.884 (95% CI: 0.817–0.951) for 2-D SWE. The AUC for differentiating F ≥5 was 0.890 (95% CI: 0.826–0.954) for pSWE and 0.926 (95% CI: 0.88–0.973) for 2-D SWE. This study indicates that 2-D SWE provides feasible and accurate assessment of liver fibrosis, comparable to that provided by pSWE from two different manufacturers’ machines.     

Liver Fibrosis Assessment Using Transient Elastography Guided with Real-Time B-mode Ultrasound Imaging: A Feasibility Study

Liver fibrosis is a kind of chronic damage of the liver and can lead to cirrhosis, one of the top 10 causes of death in the Western world. However, there is still a lack of noninvasive methods for diagnosing liver fibrosis. Fibroscan (Echosens, Paris, France), a device based on A-mode transient elastography, has shown promising results. In this study, a transient elastography system with real-time B-mode imaging for non-invasive liver fibrosis assessment, named Liverscan, was developed; its performance was tested and compared with that of the Fibroscan. A specific measurement probe was designed and fabricated with a B-mode ultrasound transducer fixed along the axis of a mechanical vibrator. It was integrated with the Liverscan to measure liver stiffness based on the shear wave propagation in liver tissues. The system was validated by mechanical indentation test using custom-made agar-gelatin phantoms with different stiffness. To further test its feasibility, in vivo measurements were conducted in 67 volunteers (age, 34 ± 3 years; body mass index, 21.3 ± 2.8 kg/m²; Mean ± SD., 34 male and 33 female), including 20 patients with various liver diseases, and 28 (19 male and 9 female) being tested by both Liverscan and Fibroscan. A significant linear correlation between the stiffness measured by the mechanical indentation test and that by the Liverscan (r = 0.973; p < 0.001) was obtained. The in vivo liver stiffness measured by Liverscan was also correlated with that by Fibroscan significantly (r = 0.886; p < 0.001). There was a significant difference in liver stiffness between the 20 patients and the other healthy subjects (14.1 ± 3.4 kPa vs. 10.5 ± 2.1 kPa; p = 0.001). The intra- and inter-observer tests indicated that the measurements were repeatable with intra-class correlation coefficients being 0.987 (p < 0.001) and 0.988 (p < 0.001), respectively. This study demonstrated that Liverscan with a specifically designed probe was able to measure and differentiate liver of different stiffness using the established measurement protocol under the guidance of real-time B-mode ultrasound imaging.     

Neck Muscle Stiffness Quantified by Sonoelastography is Correlated with Body Mass Index and Chronic Neck Pain Symptoms

This study aimed to quantify neck muscle stiffness in the normal population with ultrasound elastography. We applied the acoustic radiation force impulse technique and measured shear wave velocities (SWVs) as representative values. The mean ± standard deviation values of SWV in 20 healthy volunteers were 2.09 ± 0.45, 1.21 ± 0.30, 1.12 ± 0.17 and 0.97 ± 0.10 m/s for the trapezius, levator scapulae, scalene anterior and sternocleidomastoid muscles, respectively. The SWV values of the four muscles significantly differed (Kruskal-Wallis test, p < 0.001). The SWV values for the trapezius muscle correlated with body mass indexes (Pearson's correlation, p = 0.034). Subjects with chronic neck pain symptoms had significantly stiffer trapezius muscle (Mann–Whitney U test, p = 0.008). This study demonstrated the technique and feasibility of quantifying neck muscle stiffness using acoustic radiation force impulse elastography and shear wave velocity detection. Further study is necessary to evaluate its diagnostic power in assessing various neck muscle diseases.     

声脉冲辐射力成像技术鉴别诊断肝脏良恶性局灶性病变

目的探讨声脉冲辐射力成像技术(ARFI)对肝脏良恶性局灶性病变的鉴别诊断价值。方法对64例患者76个肝脏局灶性病变进行ARFI检查并分析,包括声触诊组织成像技术(VTI)和声触诊组织量化技术(VTQ)。所有患者均经手术或穿刺病理证实或两种增强影像学检查(CEUS、CT、MRI)确诊。采用ROC曲线评价剪切波速(SWV)对肝脏局灶性病变良恶性的鉴别诊断价值,并确定临界点。结果 VTI声像图中,31个(31/40,77.50%)恶性病灶和13个(13/36,36.11%)良性病灶呈灰黑色(P<0.05);良性病灶SWV明显低于恶性病灶[(1.67±0.61)m/s vs(2.80±1.07)m/s,P<0.01)。以SWV=2.04m/s为临界点鉴别肝脏局灶性病变的良恶性,其敏感度、特异度和准确率分别是82.50%、80.60%和81.58%。结论 ARFI有助于鉴别诊断肝脏良恶性局灶性病变,具有良好的临床应用前景。     

Serial change of liver stiffness measured by acoustic radiation force impulse imaging in chronic liver disease: correlation with biochemical markers

Purpose

In patients with chronic diffuse liver diseases, liver fibrosis severity is an important element for prognosis and for selecting therapy. Acoustic radiation force impulse (ARFI) imaging techniques were recently developed to measure liver fibrosis, but their specificity is impaired by cholestasis, inflammation, or edema in acute hepatitis. Herein, our objectives were to evaluate serial changes in shear wave velocity (SWV) and to correlate these changes with biochemical activity.

Methods

This study included 108 patients who underwent ARFI because of viral hepatitis [hepatitis B (HBV) or C (HCV)] with serial follow-up after 3–6 months at our institution between August 2011 and May 2013. Based on baseline and follow-up ARFI, we divided patients with HBV and HCV into two groups: a decreasing SWV group and a non-decreasing SWV group. We evaluated serial SWV changes and correlated these changes with biochemical activity changes.

Results

The patients were divided into SWV groups as follows: decreasing SWV group (HBV, n = 23; HCV, n = 7) and non-decreasing SWV group (HBV, n = 40; HCV, n = 38). In both HBV and HVC patients, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly decreased at follow-up in the decreasing SWV group.

Conclusions

The liver stiffness value assessed by ARFI became lower over time in patients who had decreasing AST and ALT levels. According to this study, ARFI overestimates fibrosis grade in patients with high AST and ALT. Thus, assessment of liver fibrosis by ARFI elastography should include consideration of biochemical markers such as AST and ALT levels and additional follow-up using ARFI elastography.     

Factors Which Influence the Accuracy of Acoustic Radiation Force Impulse (ARFI) Elastography for the Diagnosis of Liver Fibrosis in Patients with Chronic Hepatitis C

Our study tried to identify the factors associated with discordance between liver stiffness values assessed by acoustic radiation force impulse (ARFI) elastography and histologic fibrosis in 106 chronic hepatitis C patients. Liver biopsy (LB) and ARFI measurements were performed in the same session. A discordance of at least two stages of fibrosis in the Metavir scoring system between ARFI results and LB was defined as significant. The performance of ARFI elastography was assessed using the following cut-offs: F1-1.19 m/s, F2-1.34 m/s, F3-1.55 m/s and F4-1.80 m/s. Discordance of at least two stages of fibrosis between ARFI results and histologic assessment were observed in 31.7% of the patients. In an univariate analysis, female sex (p = 0.004), interquartile range interval (IQR) ≥30% (p = 0.04), high alanine aminotransferases (p = 0.008) and high aspartate aminotransferases levels (p = 0.003) were associated with discordances. In a multivariate analysis, the female sex (p = 0.006) and IQR ≥30% (p = 0.004) were associated with discordances. Therefore, IQR parameter should be used for ARFI measurements.     

Evaluation of Non-alcoholic Fatty Liver Disease Using Acoustic Radiation Force Impulse Imaging Elastography in Rat Models

The aim of this study is to evaluate the utility of acoustic radiation force impulse (ARFI) elastography for assessing hepatic fibrosis stage and non-alcoholic fatty liver disease (NAFLD) severity, as well as the relationship among hepatic histologic changes using shear wave velocity (SWV). Animal models with various degrees of NAFLD were established in 110 rats. The right liver lobe was processed and embedded in a fabricated gelatin solution (porcine skin). Liver mechanics were measured using SWV induced by acoustic radiation force. Among the histologic findings, liver elasticity could be used to differentiate normal rats from rats with simple steatosis (SS) as well as distinguish SS from non-alcoholic steatohepatitis (NASH), with areas under the receiver operating characteristic curves (AUROC) of 0.963 (95% confidence interval = 0.871–0.973) and 0.882 (95% confidence interval = 0.807–0.956), respectively. For NAFLD rats, the diagnostic performance of ARFI elastography in predicting significant fibrosis (F ≥ 2) had an AUROC of 0.963. For evaluating steatosis severity, we found a progressive increase in ARFI velocity proportional to steatotic severity in NAFLD rat models, but we observed no significant differences for steatotic severity after excluding the rats with fibrosis. ARFI elastography may be used to differentiate among degrees of severity of NAFLD and hepatic fibrotic stages in NAFLD rat models.     

Tissue Elasticity Quantification by Acoustic Radiation Force Impulse for the Assessment of Renal Allograft Function

Acoustic radiation force impulse (ARFI) quantification, a novel ultrasound-based elastography method, has been used to measure liver fibrosis. However, few studies have been performed on the use of ARFI quantification in kidney examinations. We evaluated renal allograft stiffness using ARFI quantification in patients with stable renal function (n = 52) and those with biopsy-proven allograft dysfunction (n = 50). ARFI quantification, given as shear wave velocity (SWV), was performed. The resistance index (RI) was calculated by pulsed-wave Doppler ultrasound, and clinical and laboratory data were collected. Morphologic changes in transplanted kidneys were diagnosed by an independent pathologist. Mean SWV was more significantly negatively correlated with estimated glomerular filtration rate (eGFR) (r = –0.657, p < 0.0001) than was RI (r = –0.429, p = 0.0004) in transplanted kidneys. Receiver operating characteristic curve analysis revealed that the sensitivity and specificity of quantitative ultrasound in the diagnosis of renal allograft dysfunction were 72.0% and 86.5% (cutoff value = 2.625), respectively. The latter values were better than those of RI, which were 62.0% and 69.2% (cutoff value = 0.625), respectively. The coefficient of variation for repeat SWV measurements of the middle part of transplanted kidney was 8.64%, and inter-observer agreement on SWV was good (Bland-Altman method, ICC = 0.890). In conclusion, tissue elasticity quantification by ARFI is more accurate than the RI in diagnosing renal allograft function.     

Acoustic Radiation Force Impulse Elastography in the Diagnosis of Thyroid Nodules: Useful or Not Useful?

The goal of this study is to evaluate the diagnostic performance of acoustic radiation force impulse (ARFI) elastography for differentiating benign from malignant thyroid nodules. One hundred and seventy-four pathologically proven thyroid nodules (139 benign, 35 malignant) in 154 patients (mean age: 49.2 ± 12.1 y; range: 16–72 y) were included in this study. Conventional ultrasound (US) and ARFI elastography using virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ) were performed to examine the thyroid nodules. Two blinded readers with different amounts of experience independently scored the likelihood of malignancy on the basis of a five-point scale in three different image-reading sets. The diagnostic performances among different image-reading sets and between the two readers were compared. The diagnostic specificity of both readers improved significantly after reading the VTI images or both VTI and VTQ images (all p < 0.05). After review of the results of both VTI and VTQ, the numbers of correctly diagnosed nodules increased in nodules <1.0 cm for both readers and in both nodular goiter and papillary thyroid carcinoma for the junior reader (p < 0.05). The nodules with definite diagnoses (i.e., confidence levels including definite benign and definite malignant cases) increased after review of VTI and VTQ images versus conventional US for the senior reader (p < 0.05). In conclusion, adding ARFI elastography improves the specificity in diagnosing malignant thyroid nodules compared with conventional US on its own. ARFI elastography particularly facilitates the specific diagnosis for thyroid nodules smaller than 1.0 cm. ARFI elastography is also able to increase the diagnostic confidence of the readers.     

Comparison of Strain and Shear Wave Elastography for the Differentiation of Benign From Malignant Breast Lesions,Combined With B-mode Ultrasonography: Qualitative and Quantitative Assessments

Our aim was to compare the diagnostic performance of strain elastography (SE) and shear-wave elastography (SWE), combined with B-mode ultrasonography (US), in breast cancer. For 79 breast lesions that underwent SE and SWE, two radiologists reviewed five data sets (B-mode US, SWE, SE and two combined sets). Qualitative and quantitative elastographic data and Breast Imaging Reporting and Data System (BI-RADS) categories were recorded. The area under the receiver operating characteristic curve (AUC) was evaluated. No significant difference in the AUC between the two elastography methods was noted. After subjective assessment by reviewers, the AUC for the combined sets was improved (SWE, 0.987; SE, 0.982; B-mode US, 0.970; p < 0.05). When SE and SWE were added, 38% and 56% of benign BI-RADS category 4a lesions with a low suspicion of cancer were downgraded without false-negative results, respectively. SE and SWE performed similarly. Therefore, addition of SE or SWE improved the diagnostic performance of B-mode US, potentially reducing unnecessary biopsies.     

Evaluating Biliary Anatomy and Variations in Living Liver Donors by a New Technique: Three-Dimensional Contrast-Enhanced Ultrasonic Cholangiography

Accurate assessment of the biliary anatomy is important for the safety of liver donors in living donor liver transplantation (LDLT). We evaluated the biliary anatomy and variations of 12 living liver donors with 3-D contrast-enhanced ultrasonic cholangiography (3-D CEUSC) by injecting microbubble contrast agents into the common hepatic ducts intraoperatively. Two radiologists assessed the diagnostically adequate, delineation of biliary branch orders, visibility scores (grades 0 to 3) and anatomical patterns of the intrahepatic biliary tree by consensus. The results were compared with findings on intraoperative cholangiography (IOC) and surgery. 3-D CEUSC successfully demonstrated the spatial structure of the intrahepatic biliary tree in all 12 donors. The maximum branching order of intrahepatic bile ducts displayed on 3-D CEUSC was the fifth order in the right lobe and fourth order in the left lobe of the liver, respectively. The visibility scores of the first-order (3.00 ± 0.00) and second-order (2.67 ± 0.69) branches were significantly (p < 0.001) higher than that of the third-order (1.98 ± 1.13) branches, whereas visibility scores of the second-order (2.88 ± 0.34) and third-order (2.44 ± 1.01) branches in the right lobe were significantly (p = 0.040 and p < 0.001, respectively) higher than those in the left lobe (2.46 ± 0.88 and 1.33 ± 0.99). The 3-D CEUSC images of the 12 donors were diagnostically adequate for evaluating the biliary anatomy. Normal biliary pattern in nine donors and biliary variations in three donors were confirmed by both IOC and surgical findings. 3-D CEUSC may be a potential alternative to IOC in the evaluation of biliary anatomical variation before graft harvesting in LDLT. (E-mail: ghchen.gzsums@gmail.com)     

Acoustic Radiation Force Impulse and Supersonic Shear Imaging Versus Transient Elastography for Liver Fibrosis Assessment

Our study compared three elastographic methods—transient elastography (TE), acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI)—with respect to the feasibility of their use in liver fibrosis evaluation. We also compared the performance of ARFI imaging and SSI, with TE as the reference method. The study included 332 patients, with or without hepatopathies, in which liver stiffness was evaluated using TE, ARFI and SSI. Reliable measurements were defined as a median value of 10 (TE, ARFI imaging) or 5 (SSI) liver stiffness measurements with a success rate ≥60% and an interquartile range interval <30%. A significantly higher percentage of reliable measurements were obtained using ARFI than by using TE and SSI: 92.1% versus 72.2% (p < 0.0001) and 92.1% versus 71.3% (p < 0.0001). Higher body mass index and older age were significantly associated with inability to obtain reliable measurements of liver stiffness using TE and SSI. In 55.4% of patients, reliable liver stiffness measurements were obtained using all three elastographic methods, and ARFI imaging and TE were similarly accurate in diagnosing significant fibrosis and cirrhosis, with TE as the reference method.     

Acoustic Radiation Force Impulse Imaging for Reactive and Malignant/Metastatic Cervical Lymph Nodes

The aim of this study was to compare lymph node stiffness using acoustic radiation force impulse (ARFI) imaging in patients with cervical lymph node swelling. Forty-two cervical lymph nodes (reactive, n = 22; metastatic, n = 20) from 19 patients (13 men, 6 women; mean age, 63.68 ± 14.9 y; range, 23–85 y) were examined between September 2011 and March 2012. The shear wave velocity (SWV, m/s) of each lymph node was evaluated by ARFI imaging. SWV of reactive lymph nodes was 1.52 ± 0.48 m/s, and that of metastatic/malignant lymph nodes was 2.46 ± 0.75 m/s. A SWV > 1.9 m/s was very useful metastatic lymph node classification, with 95.0% specificity, 81.8% sensitivity and 88.0% overall accuracy. The area under the receiver operating characteristic curve was 0.923 (95% confidence interval, 0.842–1.000). ARFI imaging can be useful in the differentiation of reactive and malignant/metastatic cervical lymph nodes.     

Ultrasound Elastographic Evaluation in the Diagnosis of Carpal Tunnel Syndrome: Initial Findings

The purpose of this study was to investigate ultrasound (US)- and US elastography-detected changes in the median nerve of patients with carpal tunnel syndrome (CTS). Seventy-four wrists of 41 female patients with CTS (mean age, 47.73 ± 11.45 y) and 45 wrists of 24 asymptomatic female controls (mean age, 42.83 ± 10.66 y) were examined with US and US elastography. Electromyography results confirmed the diagnosis of CTS in the patients. The mean median nerve perimeter (MN-P = 15.26 ± 2.18 mm) and median nerve cross-sectional area (MN-CSA = 11.81 ± 4.05 mm²) of patients with CTS were higher than those of controls (12.08 ± 1.54 mm and 7.76 ± 1.40 mm², respectively) (p < 0.05). Mean tissue strain was lower in the patients with CTS (0.094 ± 0.045 than in the controls (0.145 ± 0.068) (p < 0.05). The most sensitive cut-off value for tissue strain was 0.0635, and the most specific was 0.19. US and US elastography, in addition to electromyography, proved to be beneficial in the diagnosis of CTS. US elastography is a new technique that may well find a place in the diagnosis of nerve entrapment syndromes.