Accuracy of Two-Dimensional Shear Wave Elastography and Attenuation Imaging for Evaluation of Patients With Nonalcoholic Steatohepatitis.

BACKGROUND & AIMS: We evaluated the accuracy of a multiparametric approach using attenuation imaging and 2-dimensional shear wave elastography (2D-SWE) for the detection of steatosis and fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). METHODS: We studied 102 patients with increased levels of liver enzymes or suspicion of NAFLD, examined by attenuation imaging and 2D-SWE, immediately before biopsy collection and analysis (reference standard), from January 2018 to July 2019. We collected data on the attenuation coefficient (dB/cm/MHz) from attenuation imaging, liver stiffness measurements, and shear wave dispersion slope (SWDS, [m/s]/kHz) from 2D-SWE. Multivariate linear regression analysis was performed to identify factors associated with each parameter. Diagnostic performance was determined from area under the receiver operating curve (AUROC) values. RESULTS: The attenuation coefficient was associated with steatosis grade (P < .01) and identified patients with steatosis grades S1 or higher, S2 or higher, and S3 or higher, with AUROC values of 0.93, 0.88, and 0.83, respectively. Liver stiffness associated with fibrosis stage (P < .01) and lobular inflammatory activity was the only factor associated with SWDS (P < .01). SWDS detected inflammation grades I1 or higher, I2 or higher, and I3 or higher with AUROC values of 0.89, 0.85, and 0.78, respectively. We developed a risk scoring system to detect steatohepatitis based on the attenuation coefficient (score of 1 for 0.64 < attenuation coefficient ≤ 0.70; score of 2 for 0.70 < attenuation coefficient ≤ 0.73; and score of 3 for attenuation coefficient >0.73) and SWDS (score of 2 for 10.5 [m/s]/kHz < SWDS ≤ 11.7 [m/s]/kHz; and score of 3 for SWDS >11.7 [m/s]/kHz), using an unweighted sum of each score. Based on histopathology analysis, 55 patients had steatohepatitis. Risk scores correlated with NAFLD activity score (rho = 0.73; P < .01). Our scoring system identified patients with steatohepatitis with an AUROC of 0.93-this value was significantly higher than that of other parameters (P < .05), except SWDS (AUROC, 0.89; P = .18). CONCLUSIONS: In the evaluation of patients with suspected NAFLD, the attenuation coefficient can identify patients with steatosis and liver stiffness can detect fibrosis accurately. SWDS was associated significantly with lobular inflammation. We developed a risk scoring system based on the attenuation coefficient and SWDS that might be used to detect steatohepatitis.

Multiparametric US for Identifying Patients with High-Risk NASH: A Derivation and Validation Study.

Background Nonalcoholic fatty liver disease (NAFLD) is common in the general population but identifying patients with high-risk nonalcoholic steatohepatitis (NASH) who are candidates for pharmacologic therapy remains a challenge. Purpose To develop a score to identify patients with high-risk NASH, defined as NASH with an NAFLD activity score (NAS) of 4 or greater and clinically significant fibrosis (stage 2 [F2] or higher). Materials and Methods This was a cross-sectional secondary analysis of data prospectively collected between April 2017 and March 2019 for a group of patients with NAFLD in Japan (Japan NAFLD, the derivation data set) with contemporaneous two-dimensional shear-wave elastography and biopsy-proven NAFLD (age range, 20-89 years). Three US markers (liver stiffness [LS, measured in kilopascals], attenuation coefficient [AC, measured in decibels per centimeter per megahertz], and dispersion slope [DS, measured in meters per second per kilohertz]) were determined, together with aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and the AST-to-ALT ratio. The best-fit multivariate logistic regression model for identifying patients with high-risk NASH was determined. Diagnostic performance was assessed by using the area under the receiver operating characteristic curve (AUC). The findings were validated in an independent data set (Korea NAFLD; age range, 20-78 years). Results The Japan NAFLD data set included 111 patients (mean age, 53 years ± 18 [standard deviation]; 57 men), 84 (76%) with NASH. The Korea NAFLD data set included 102 patients (mean age, 48 years ± 18; 43 men), 55 (36%) with NASH. The most predictive model (LAD NASH score) combined LS, AC, and DS. Performance was satisfactory in both the derivation sample (AUC, 0.86; 95% CI: 0.79, 0.93) and the validation sample (AUC, 0.88; 95% CI: 0.80, 0.95). The LAD NASH score showed a positive predictive value of 86.5% and a negative predictive value of 87.5% for high-risk NASH in the derivation sample. Conclusion A score combining three US markers may be useful for noninvasive identification of patients with high-risk nonalcoholic steatohepatitis for inclusion in clinical trials and pharmacologic therapy. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Lockhart in this issue.

2D shear wave elastography is better than transient elastography in predicting post-hepatectomy complication after resection.

OBJECTIVES: Both transient elastography (TE) and 2D shear wave elastography (SWE) are accurate methods to evaluate liver fibrosis. We aimed to evaluate the diagnostic performance of 2D-SWE in predicting post-hepatectomy complication and to compare it with TE. METHODS: We prospectively enrolled 125 patients with liver tumors. Liver stiffness (LS) (kilopascal [kPa]) was measured using both TE and 2D-SWE before surgery. All post-operative complication was evaluated using the comprehensive complication index (CCI), and CCI ≥ 26.2 was defined as severe complication. Logistic regression analysis was performed to identify predictive factors for severe complication. Receiver operating characteristic analysis was used to evaluate the diagnostic performance of TE/2D-SWE in detecting liver fibrosis and severe complication. RESULTS: Severe complication developed in 18 patients. The median LS in patients with severe complication was significantly higher for both 2D-SWE (11.4 kPa vs. 7.0 kPa, p < 0.001) and TE (8.9 kPa vs. 6.2 kPa, p = 0.009). LS obtained from 2D-SWE was a significant factor correlated with severe complication (odds ratio: 1.27 per kPa [1.10-1.46], p = 0.001). The diagnostic performance of 2D-SWE was significantly higher than that of TE in detecting both ≥F3 (p = 0.024) and F4 (p = 0.048). The area under the curve of 2D-SWE to predict severe complication was 0.854, significantly higher than 0.692 of TE (p = 0.004). The optimal cut-off LS from 2D-SWE to predict severe complication was 8.6 kPa, with sensitivity of 88.9% (16/18) and specificity of 73.8% (79/107). CONCLUSION: LS obtained from 2D-SWE was a significant predictive factor for severe complication, and 2D-SWE showed significantly a better diagnostic performance than TE in detecting liver fibrosis and severe complication. KEY POINTS: • The diagnostic performance of 2D-SWE was significantly higher than that of TE in detecting both ≥ F3 (AUC: 0.853 vs. 0.779, p = 0.024) and F4 (AUC: 0.929 vs. 0.872, p = 0.048). • Liver stiffness value obtained from 2D-SWE was a significant factor correlated with the development of severe complication defined as CCI ≥ 26.2 after hepatic resection for liver tumors (odds ratio: 1.27 per kPa [1.10-1.46], p = 0.001). • 2D-SWE provided significantly a better diagnostic performance in predicting severe complication after hepatic resection than TE (AUC for 2D-SWE: 0.853 vs. AUC for TE: 0.692, p = 0.004).

Quantitative Assessment of Fatty Liver using Ultrasound with Normalized Local Variance Technique.

PURPOSE: To assess the diagnostic performance of the normalized local variance (NLV) ultrasound technique in the detection of the fatty liver using histopathology as a reference standard. MATERIALS AND METHODS: We prospectively enrolled 194 consecutive patients with clinical suspicion of diffuse liver disease or history of liver transplantation. Conventional grayscale ultrasound and NLV examinations were performed and immediately followed by liver biopsies. The degrees of fatty liver, necroinflammatory activity, and fibrosis stage were evaluated by histopathological assessment. The diagnostic performance of the NLV values in detecting each grade of fatty liver was determined using receiver operating characteristics analyses, and multivariate linear regression analyses were performed to identify variables significantly associated with the NLV values. RESULTS: The number of patients in each degree of fatty liver and hepatic fibrosis was 118/37/26/13 and 81/68/24/6/14 for none/mild/moderate/severe steatosis and F0 / F1/F2 / F3/F4 fibrosis on histopathological examinations, respectively. The area under the receiver operating characteristics curve and optimal cut-off NLV value for detecting fatty liver of varying degrees were 0.911 and 1.095 for ≥ S1, 0.974 and 1.055 for ≥ S2, and 0.954 and 1.025 for ≥ S3, respectively. Multivariate analyses revealed that not fibrosis or inflammation but rather the degree of steatosis was associated with the NLV value. CONCLUSION: The NLV value demonstrated excellent diagnostic performance for detecting varying degrees of fatty liver, and the degree of steatosis on histopathological examinations was the only significant factor affecting the NLV value.

Technical success rates and reliability of spin-echo echo-planar imaging (SE-EPI) MR elastography in patients with chronic liver disease or liver cirrhosis.

OBJECTIVES: To determine the technical success rates of MR elastography (MRE) according to established gradient-recalled echo (GRE) and spin-echo echo-planar imaging (SE-EPI) sequences and to compare liver stiffness (LS) values between the sequences during expiratory and inspiratory phases in patients with chronic liver disease or liver cirrhosis. METHODS: One hundred and eight patients who underwent MRE were included in this retrospective study. MRE was performed at 3 T based on both sequences during expiration as well as inspiration. Technical failure of MRE was determined if there was no pixel value with a confidence index higher than 95% and/or no apparent shear waves imaged. LS measurements were performed using free-drawing region of interest. To evaluate clinical factors related to the technical success rate of MRE, we assessed etiology of liver disease, ascites, body habitus, iron deposition, and liver morphology of patients. Statistical analysis was performed with the Wilcoxon test, Bland-Altman plot, independent t test, Mann-Whitney test, and McNemar test. RESULTS: The technical success rate of MRE in SE-EPI was significantly higher than that of GRE (98.1% vs. 80.7%, p < 0.0001). On the basis of univariate analysis, height, weight, and BMI were significantly associated with failure of MRE (p < 0.05). There was no significant difference in LS values between GRE and SE-EPI (2.82 kPa vs. 2.92 kPa (p > 0.05)). However, the LS values were significantly higher during inspiration than expiration with both GRE and SE-EPI (p < 0.0001). CONCLUSION: MRE in SE-EPI during expiratory breath-hold can be used as a reliable examination to evaluate liver fibrosis. KEY POINTS: • The technical success rate of MR elastography in spin-echo echo-planar imaging (SE-EPI) was significantly higher than that in gradient-recalled echo (GRE) during both the inspiratory and expiratory phases. • Liver stiffness values were significantly higher during inspiration than during expiration in both GRE and SE-EPI. • MR elastography in SE-EPI during expiratory breath-hold can be used as a reliable examination in patients with liver fibrosis.

Guidelines and Good Clinical Practice Recommendations for Contrast Enhanced Ultrasound (CEUS) in the Liver - Update 2020 - WFUMB in Cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS.

The present, updated document describes the fourth iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS), first initiated in 2004 by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB). The previous updated editions of the guidelines reflected changes in the available contrast agents and updated the guidelines not only for hepatic but also for non-hepatic applications.The 2012 guideline requires updating as previously the differences of the contrast agents were not precisely described and the differences in contrast phases as well as handling were not clearly indicated. In addition, more evidence has been published for all contrast agents. The update also reflects the most recent developments in contrast agents, including the United States Food and Drug Administration (FDA) approval as well as the extensive Asian experience, to produce a truly international perspective.These guidelines and recommendations provide general advice on the use of ultrasound contrast agents (UCA) and are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis to improve the management of patients.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid.

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Assessment of hepatic steatosis by using attenuation imaging: a quantitative, easy-to-perform ultrasound technique.

OBJECTIVES: To evaluate the diagnostic performance of attenuation imaging (ATI) in the detection of hepatic steatosis compared with a histopathology gold standard. METHODS: We prospectively enrolled 108 consecutive patients (35 males; median age, 54.0 years) who underwent percutaneous liver biopsy for evaluation of diffuse liver disease between January 2018 and November 2018 in a tertiary academic center. Grayscale ultrasound examination with ATI was performed just before biopsy, and an attenuation coefficient (AC) was obtained from each patient. The degree of hepatic steatosis, fibrosis stage, and necroinflammatory activity were assessed on histopathologic examination. The significant factor associated with the AC was found by a linear regression analysis, and the diagnostic performance of the AC for the classification into each hepatic steatosis stage was evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The distribution of hepatic steatosis grade on histopathology was 53/11/22/16/6 for none/mild (< 10%)/mild (≥ 10%)/moderate/severe steatosis, respectively. The area under the ROC curve, sensitivity, specificity, and optimal cutoff AC value for detection of hepatic steatosis ranged from 0.843-0.926, 74.5-100.0%, 77.4-82.8%, and 0.635-0.745, respectively. Multivariate analysis revealed that the degree of steatosis was the only significant determinant factor for the AC. CONCLUSIONS: The AC from ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis. The degree of steatosis was the only significant factor affecting the AC, whereas fibrosis and inflammation were not. KEY POINTS: • Attenuation imaging (ATI) is based on two-dimensional grayscale ultrasound images that can incorporate into routine ultrasound examinations with less than 2 min of acquisition time. • ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis with an area under the ROC curves ranging from 0.843 to 0.926, and there was no technical failure in this study indicating high applicability of this technique. • The degree of hepatic steatosis was the only significant factor affecting the result of ATI examination.

Comparison and Combination of Strain and Shear Wave Elastography of Breast Masses for Differentiation of Benign and Malignant Lesions by Quantitative Assessment: Preliminary Study.

OBJECTIVES: To compare the diagnostic performance of strain and shear wave elastography of breast masses for quantitative assessment in differentiating benign and malignant lesions and to evaluate the diagnostic accuracy of combined strain and shear wave elastography. METHODS: Between January and February 2016, 37 women with 45 breast masses underwent both strain and shear wave ultrasound (US) elastographic examinations. The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) final assessment on B-mode US imaging was assessed. We calculated strain ratios for strain elastography and the mean elasticity value and elasticity ratio of the lesion to fat for shear wave elastography. Diagnostic performances were compared by using the area under the receiver operating characteristic curve (AUC). RESULTS: The 37 women had a mean age of 47.4 years (range, 20-79 years). Of the 45 lesions, 20 were malignant, and 25 were benign. The AUCs for elasticity values on strain and shear wave elastography showed no significant differences (strain ratio, 0.929; mean elasticity, 0.898; and elasticity ratio, 0.868; P > .05). After selectively downgrading BI-RADS category 4a lesions based on strain and shear wave elastographic cutoffs, the AUCs for the combined sets of B-mode US and elastography were improved (B-mode + strain, 0.940; B-mode + shear wave; 0.964; and B-mode, 0.724; P < .001). Combined strain and shear wave elastography showed significantly higher diagnostic accuracy than each individual elastographic modality (P = .031). CONCLUSIONS: These preliminary results showed that strain and shear wave elastography had similar diagnostic performance. The addition of strain and shear wave elastography to B-mode US improved diagnostic performance. The combination of strain and shear wave elastography results in a higher diagnostic yield than each individual elastographic modality.

Distinguishing benign from malignant thyroid nodules using thyroid ultrasonography: utility of adding superb microvascular imaging and elastography.

OBJECTIVE: Thyroid nodules are common; however, malignancy is less than 7%. Therefore, additional techniques such as Doppler ultrasonography or elastography are used to improve diagnostic performance of conventional ultrasonography. We want to prospectively investigate the use of additional superb microvascular imaging (SMI) and strain elastography to B-mode ultrasound in thyroid nodules in distinguishing benign from malignant thyroid nodules. METHODS: We analyzed 52 thyroid nodules (malignant = 26, benign = 26) and reviewers scored the likelihood of malignancy for three data sets (i.e., B-mode ultrasonography alone, B-mode ultrasonography + SMI, and B-mode ultrasonography + strain elastography). The area under the receiver-operating characteristic curve (Az) values, sensitivities, and specificities were compared. RESULTS: A comparison of the data sets revealed that area under the receiver-operating characteristic curve values were similar without statistical difference. However, on comparing sensitivity and specificity based on the management decision of whether to conduct fine-needle aspiration (FNA) after combining information from all three types of imaging (B-mode ultrasonography + SMI + strain elastography), specificity was significantly higher for the combined technique (34.6%) than for B-mode ultrasonography alone (11.5%), without decrease in sensitivity (P = 0.032). CONCLUSION: Additional use of SMI and strain elastography could potentially lead to increase in specificity in thyroid ultrasonography.

Prediction of Therapeutic Response of Hepatocellular Carcinoma to Transcatheter Arterial Chemoembolization Based on Pretherapeutic Dynamic CT and Textural Findings.

OBJECTIVE: The objective of our study was to assess the value of CT texture analysis for prediction of therapeutic response of hepatocellular carcinoma (HCC) to transcatheter arterial chemoembolization (TACE) with pretherapeutic dynamic CT. MATERIALS AND METHODS: We retrospectively analyzed 132 HCCs in 96 patients treated with TACE who underwent dynamic CT before initial TACE. Imaging findings and arterial enhancement ratios were analyzed. All HCCs were manually segmented, and their texture features were quantitatively extracted using in-house software. CT texture was quantified with 2D and 3D analysis. HCCs were classified as with and without complete response (CR) according to modified Response Evaluation Criteria in Solid Tumors. Predictive factors for CR were assessed with multivariate analysis. Radiologic responses were correlated with time to progression (TTP). RESULTS: Of the 132 HCCs, CR was achieved in 75 (56.8%). Tumor size, subjective arterial tumor attenuation, and arterial enhancement ratios were significantly associated with CR. On 2D and 3D analysis, tumors with CR showed significantly lower homogeneity and higher mean attenuation, gray-level co-occurrence matrix (GLCM) moments, and CT number percentiles (p < 0.05). On multivariate analysis, higher subjective tumor attenuation (adjusted odds ratio [OR] = 23.35), arterial enhancement ratio (OR = 14.07), GLCM moments (OR = 6.57), smaller tumor size (OR = 17.26), and lower homogeneity (OR = 0.69) were significant predictors of CR compared with incomplete response (p < 0.05). Median survival value for TTP was significantly longer in tumors with CR (p < 0.001). CONCLUSION: Pretherapeutic dynamic CT texture analysis can be valuable to predict CR of HCC to TACE. Higher arterial enhancement and GLCM moments, lower homogeneity, and smaller tumor size are significant predictors of CR after TACE.

Radiologic Findings in Extrapancreatic Solid Pseudopapillary Tumor with Aggressive Behavior: a Case Report.

Solid pseudopapillary tumor (SPT) is a low grade malignant tumor in the pancreas, and extrapancreatic SPT is extremely rare. We report a case of a 61-year-old woman who complained abdominal pain with diffuse tenderness. She was diagnosed with extrapancreatic SPT with extensive peritoneal dissemination and hepatic metastases. Although a few cases have reported imaging findings of extrapancreatic SPT, there have been no reports of extrapancreatic SPT with aggressive tumor behavior and dismal prognosis. Although imaging features closely resembled those of classical pancreatic SPTs, malignant transformation of extrapancreatic SPT should be considered when focal discontinuity of the tumor capsule with ill-defined margin and invasion of adjacent structures were identified.

Monitoring Vascular Disrupting Therapy in a Rabbit Liver Tumor Model: Relationship between Tumor Perfusion Parameters at IVIM Diffusion-weighted MR Imaging and Those at Dynamic Contrast-enhanced MR Imaging.

PURPOSE: To investigate whether perfusion-related intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance (MR) imaging parameters correlate with dynamic contrast material-enhanced MR imaging parameters in between-subject and/or within-subject longitudinal settings for monitoring the therapeutic effects of a vascular disrupting agent (VDA) (CKD-516) in rabbit VX2 liver tumors. MATERIALS AND METHODS: With institutional Animal Care and Use Committee approval, 21 VX2 liver tumor-bearing rabbits (treated, n = 15; control, n = 6) underwent IVIM DW imaging with 12 b values (0-800 sec/mm(2)) and dynamic contrast-enhanced MR imaging performed before (baseline) CKD-516 administration and 4 hours, 24 hours, and 7 days after administration. Perfusion-related IVIM DW imaging parameters of the tumors, including the pseudodiffusion coefficient (D*) and perfusion fraction (f), as well as dynamic contrast-enhanced MR imaging parameters, including the volume transfer coefficient (K(trans)) and initial area under the gadolinium concentration-time curve until 60 seconds (iAUC), were measured. IVIM DW imaging parameters were correlated with dynamic contrast-enhanced MR imaging parameters by using Pearson correlation analysis between subjects at each given time and by using a linear mixed model for within-subject longitudinal data. RESULTS: In the treated group, D*, f, K(trans), and iAUC significantly decreased (-40.7% to -26.3%) at 4-hour follow-up compared with these values in the control group (-6.9% to +5.9%) (P < .05). For longitudinal monitoring of CKD-516 treatment, D* and f showed significant positive correlations with K(trans) and iAUC (P = .004 and P = .02; P < .001 and P = .006, respectively), while no significant correlations were observed between IVIM DW imaging and dynamic contrast-enhanced MR imaging parameters between subjects at any given time (P > .05). CONCLUSION: In a rabbit tumor model, perfusion parameters serially quantified with IVIM DW imaging can be used as alternatives to dynamic contrast-enhanced MR imaging parameters in reflecting the dynamic changes in tumor perfusion during the within-subject longitudinal monitoring of VDA treatment.

Pancreatic Steatosis and Fibrosis: Quantitative Assessment with Preoperative Multiparametric MR Imaging.

PURPOSE: To evaluate the diagnostic performance of multiparametric pancreatic magnetic resonance (MR) imaging, including the T2*-corrected Dixon technique and intravoxel incoherent motion (IVIM) diffusion-weighted (DW) imaging, in the quantification of pancreatic steatosis and fibrosis, with histologic analysis as the reference standard, and to determine the relationship between MR parameters and postoperative pancreatic fistula. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board, and the informed consent requirement was waived. A total of 165 patients (93 men, 72 women; mean age, 62 years) underwent preoperative 3-T MR imaging and subsequent pancreatectomy (interval, 0-77 days). Fat fractions, IVIM DW imaging parameters (true diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]), pancreas-to-muscle signal intensity ratios on unenhanced T1-weighted images, and pancreatic duct sizes were compared with the fat fractions and fibrosis degrees (F0-F3) of specimens. In 95 patients who underwent pancreatoenteric anastomosis, MR parameters were compared between groups with clinically relevant postoperative pancreatic fistula and those without. The relationship between postoperative pancreatic fistula and MR parameters was evaluated by using logistic regression analysis. RESULTS: Fat fractions at MR imaging showed a moderate relationship with histologic findings (r = 0.71; 95% confidence interval: 0.63, 0.78). Patients with advanced fibrosis (F2-F3) had lower D*([39.72 ± 13.64] ×10(-3)mm(2)/sec vs [32.50 ± 13.09] ×10(-3)mm(2)/sec [mean ± standard deviation], P = .004), f (29.77% ± 8.51 vs 20.82% ± 8.66, P < .001), and unenhanced T1-weighted signal intensity ratio (1.43 ± 0.26 vs 1.21 ± 0.30, P < .001) than did patients with F0-F1 disease. Clinically relevant fistula developed in 14 (15%) of 95 patients, and f was significantly associated with postoperative pancreatic fistula (odds ratio, 1.17; 95% confidence interval: 1.05, 1.30). CONCLUSION: Multiparametric MR imaging of the pancreas, including imaging with the T2*-corrected Dixon technique and IVIM DW imaging, may yield quantitative information regarding pancreatic steatosis and fibrosis, and f was shown to be significantly associated with postoperative pancreatic fistulas.

Portal Vein Thrombosis in Patients with Hepatocellular Carcinoma: Diagnostic Accuracy of Gadoxetic Acid-enhanced MR Imaging.

Purpose To assess the diagnostic performance of gadoxetic acid-enhanced magnetic resonance (MR) imaging in the evaluation of portal vein thrombosis (PVT) in patients with hepatocellular carcinoma (HCC). Materials and Methods This retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. A total of 366 patients with HCC who underwent gadoxetic acid-enhanced MR imaging between January 2007 and May 2013, including 134 with malignant PVT, 49 with benign PVT, and 183 without PVT matched for age and sex, comprised our study population. PVTs were complete in 125 patients and partial in 58 and were located in a major portal vein (n = 159) or segmental portal vein (n = 24). Two radiologists independently reviewed the MR images and assessed the sensitivity, specificity, and accuracy in the detection and characterization of PVT according to location (major vs segmental) and type (complete vs partial). The Fisher exact or χ(2) test was used to evaluate sensitivity difference between the subsets. Results Gadoxetic acid-enhanced MR imaging showed good sensitivity (reviewer 1, 84% [154 of 183 patients]; reviewer 2, 70% [129 of 183 patients]) and high specificity (reviewer 1, 89% [163 of 183 patients]; reviewer 2, 96% [176 of 183 patients]) in the detection of PVT. Diagnostic accuracy for differentiating malignant PVT from benign PVT was high (reviewer 1, 92% [141 of 154 patients]; reviewer 2, 95% [122 of 129 patients]). However, there was slightly lower sensitivity for detecting segmental PVT compared with that of major PVT in the malignant PVT group (reviewer 1, 95% [104 of 110 patients] vs 88% [21 of 24 patients]; reviewer 2, 82% [90 of 110 patients] vs 79% [19 of 24 patients]; P = .203 and .775 for reviewers 1 and 2, respectively). Conclusion Gadoxetic acid-enhanced MR imaging provided good diagnostic performance in the detection of PVT and the differentiation of malignant from benign PVT in patients with HCC. However, caution is needed when evaluating potential candidates for curative treatment because of the low sensitivity for segmental PVT in the malignant PVT group. (©) RSNA, 2016 Online supplemental material is available for this article.

Radiofrequency Ablation with an Internally Cooled Monopolar Directional Electrode: Ex Vivo and in Vivo Experimental Studies in the Liver.

PURPOSE: To evaluate the feasibility of using an internally cooled directional electrode (ICDE) to create sufficient directional ablation in the desired area and to investigate whether use of the ICDE reduces thermal injury to the adjacent organs. MATERIALS AND METHODS: The animal care and use committee approved this animal study. In ex vivo studies of bovine livers and colons, temperature was measured in both ablation and nonablation directions with the ICDE, temperature at the liver-colon interface and the presence of burns on the colon were evaluated with each ICDE and internally cooled conventional electrode (ICCE), and the ablation area with the use of three ICDEs in the switching multichannel mode was evaluated. In an in vivo study of 10 pigs, 11 ablations were performed by using three ICDEs in the switching multichannel mode. In addition, the difference in thermal injury to the gallbladder and stomach was compared between use of the ICDE and the ICCE. Mann-Whitney test and the Fisher exact test were used for statistical analysis. RESULTS: In the ex vivo study, the hepatic temperature in the nonablation direction was lower than 50°C; temperature higher than 47°C was maintained for less than 3 minutes, even 0.5 cm away from the ICDE; and the temperature at the liver-colon interface did not increase above 50°C. In the switching multichannel mode, a fused coagulation zone was created. In the in vivo study, confluent ablation was created in the inner circle of three ICDEs with a mean interelectrode distance of less than 2.6 cm. Use of the ICDE did not create a moderate-to-severe gallbladder wall injury in any of the pigs, but use of the ICCE caused injury in three of the five pigs (P > .05). The ICDE caused moderate-to-severe gastric wall injury at one of eight ablations, and the ICCE caused injury at eight of nine ablations (P < .05). CONCLUSION: Use of an ICDE can create a sufficient ablation in the desired direction and can decrease thermal injury to the adjacent organs.

Hepatic Steatosis: Assessment with Acoustic Structure Quantification of US Imaging.

PURPOSE: To investigate the diagnostic performance of acoustic structure quantification (ASQ) for the assessment of hepatic steatosis by using hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopy as the reference standard and to compare ASQ with hepatorenal ratio. MATERIALS AND METHODS: This prospective study was approved by an institutional review board, and informed written consent was obtained from all participants. ASQ and MR spectroscopy were performed in 89 participants (mean age, 41.48 years ± 14.16; 35 men, 54 women) without history of chronic liver disease. Obtained were focal disturbance (FD) ratio by using ASQ, hepatic fat fraction (HFF) by using MR spectroscopy, and hepatorenal ratio by using a histogram. Correlation coefficient, intraclass correlation coefficient, and receiver operating curve analyses were performed. RESULTS: FD ratio measured with ASQ had a strong linear correlation with HFF measured with MR spectroscopy after logarithmic transformation of both variables (r = -0.87; P < .001). By using HFF of 5.79% as a cutoff value of 10% hepatic steatosis, 29 of 89 participants (32.6%) were categorized into the group with hepatic steatosis of 10% or greater (mean HFF, 13.18% ± 4.89). The area under curve of the FD ratio for diagnosing hepatic steatosis 10% or greater was 0.959 (95% confidence interval: 0.895, 0.990) with sensitivity of 86.2% (95% confidence interval: 68.3%, 96.0%) and specificity of 100% (95% confidence interval: 94.0%, 100.0%) by using a cutoff value of 0.1; the area under curve and specificity of the FD ratio were significantly higher than those of the hepatorenal ratio (respectively, 0.772 and 73.3%; respective P values, .001 and <.001). CONCLUSION: This pilot study in a cohort of patients with hepatic steatosis without other parenchymal disease suggested ASQ may be valuable for the quantification of hepatic steatosis and detection of hepatic steatosis 10% or greater in living liver donors.

Assessment of Malignant Potential in Intraductal Papillary Mucinous Neoplasms of the Pancreas: Comparison between Multidetector CT and MR Imaging with MR Cholangiopancreatography.

PURPOSE: To compare the diagnostic performance of multidetector computed tomography (CT) and magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP) in identifying the malignant potential of pancreatic intraductal papillary neoplasms (IPMNs) and evaluate their intermodality agreement. MATERIALS AND METHODS: Institutional review board approval was obtained, and the requirement for informed consent was waived for this retrospective study. In 129 patients with pathologically proved pancreatic IPMNs, three reviewers independently evaluated their preoperative CT and MR imaging with MRCP findings. Intermodality agreement between multidetector CT and MR imaging with MRCP, as well as interobserver agreement of each imaging modality, for depicting high-risk stigmata and worrisome features were assessed. Diagnostic values of other signs of overt malignancy, including the presence of a parenchymal mass and local-regional extension, were analyzed. Diagnostic performance and intermodality agreement were assessed by using receiver operating characteristics (ROC) curve analysis and weighted κ statistics. RESULTS: Overall, multidetector CT and MR imaging with MRCP were similar in their ability to depict signs suspicious or indicative of malignancy in patients with IPMN (area under the ROC curve [AUC] = 0.82 for both), with good intermodality agreement (κ = 0.75) and moderate interobserver agreement (κ = 0.47-0.59) when high-grade dysplasia was used as the cutoff for malignancy. When parenchymal masses and local-regional extensions were also considered as overt signs of malignancy, the ability to identify invasive IPMNs significantly increased (AUC = 0.87 for CT and AUC = 0.88 for MR imaging), with high sensitivity (94.3%), while maintaining specificity (69.1%). CONCLUSION: The diagnostic performance of multidetector CT and MR imaging with MRCP for identifying the malignant potential of pancreatic IPMNs was similar and showed good intermodality agreement, suggesting that follow-up with either modality may be used.

Liver Fibrosis Staging with MR Elastography: Comparison of Diagnostic Performance between Patients with Chronic Hepatitis B and Those with Other Etiologic Causes.

Purpose To evaluate the diagnostic performance of magnetic resonance (MR) elastography in staging liver fibrosis in patients with chronic hepatitis B (CHB) and other etiologic causes. Materials and Methods This retrospective study was institutional review board-approved and the requirement for informed consent was waived. Before surgery, MR elastographic imaging was performed in 352 patients with chronic liver diseases (281 patients with CHB, 71 patients without CHB) and hepatocellular carcinomas and 64 living liver donor candidates. Liver stiffness (LS) values were measured on quantitative shear-stiffness maps of MR elastography, and the diagnostic performance of MR elastography in staging liver fibrosis was evaluated by using receiver operating characteristic curve analysis and the Obuchowski measure with the histopathologic analysis of liver fibrosis in the CHB group and in the group composed of other etiologic causes. In 120 patients (97 with CHB, 23 without CHB) and 51 donors, diagnostic performance of MR elastography was validated. Results Areas under the curve of LS values for the diagnosis of significant fibrosis (≥stage F2), severe fibrosis (≥stage F3), and cirrhosis (stage F4) in the CHB group were 0.972 (95% confidence interval: 0.948, 0.987), 0.946 (95% confidence interval: 0.916, 0.968), and 0.920 (95% confidence interval: 0.885, 0.947), respectively. Obuchowski measures were similarly high in the CHB group and in the group composed of other etiologic causes (0.970 vs 0.977). However, the estimated cutoff value for stage F4 in the group with CHB was substantially lower than in the participants with other etiologic causes: 3.67 kPa versus 4.65 kPa. In the validation study for stage F1 or greater, stage F2 or greater, stage F3 or greater, and stage F4, the Youden indexes were 0.807, 0.842, 0.806, and 0.639, respectively, in the group with CHB, and 0.783, 0.900, 1.000, and 0.917, respectively, in the group without CHB. Conclusion The diagnostic performance of MR elastography in liver fibrosis staging was similarly high in the groups with and without CHB, but the cutoff LS values for diagnosing liver cirrhosis differed between the groups with and without CHB. (©) RSNA, 2016 Online supplemental material is available for this article.

Quantitative assessment of hepatic function: modified look-locker inversion recovery (MOLLI) sequence for T1 mapping on Gd-EOB-DTPA-enhanced liver MR imaging.

OBJECTIVES: To determine whether multislice T1 mapping of the liver using a modified look-locker inversion recovery (MOLLI) sequence on gadoxetic acid-enhanced magnetic resonance imaging (MRI) can be used as a quantitative tool to estimate liver function and predict the presence of oesophageal or gastric varices. METHODS: Phantoms filled with gadoxetic acid were scanned three times using MOLLI sequence to test repeatability. Patients with chronic liver disease or liver cirrhosis who underwent gadoxetic acid-enhanced liver MRI including MOLLI sequence at 3 T were included (n = 343). Pre- and postcontrast T1 relaxation times of the liver (T1liver), changes between pre- and postcontrast T1liver (ΔT1liver), and adjusted postcontrast T1liver (postcontrast T1liver-T1spleen/T1spleen) were compared among Child-Pugh classes. In 62 patients who underwent endoscopy, all T1 parameters and spleen sizes were correlated with varices. RESULTS: Phantom study showed excellent repeatability of MOLLI sequence. As Child-Pugh scores increased, pre- and postcontrast T1liver were significantly prolonged (P < 0.001), and ΔT1liver and adjusted postcontrast T1liver decreased (P < 0.001). Adjusted postcontrast T1liver and spleen size were independently associated with varices (R (2) = 0.29, P < 0.001). CONCLUSIONS: T1 mapping of the liver using MOLLI sequence on gadoxetic acid-enhanced MRI demonstrated potential in quantitatively estimating liver function, and adjusted postcontrast T1liver was significantly associated with varices. KEY POINTS: • T1 mapping using MOLLI sequence can be achieved within a breath-hold. • T1liver measured by MOLLI sequence provided excellent short-term repeatability. • Precontrast and postcontrast T1liver were significantly prolonged as Child-Pugh scores increased. • Adjusted postcontrast T1liver and spleen size were independently associated with varices.