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The following is an illustrative review of common pitfalls in liver MRI that may challenge interpretation. This article reviews common technical and diagnostic challenges encountered when interpreting dynamic multiphasic T1 -weighted imaging, hepatobiliary phase imaging, and diffusion-weighted imaging of the liver. Additionally, each section includes suggestions for avoiding diagnostic and technical errors. Level of Evidence: 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:41-58.

Author(s): Kielar, Ania Z; Chernyak, Victoria; Bashir, Mustafa R; Do, Richard K; Fowler, Kathryn J; Mitchell, Donald G; Cerny, Milena; Elsayes, Khaled M; Santillan, Cynthia; Kamaya, Aya; Kono, Yuko; Sirlin, Claude B; Tang, An | Abstract: The computed tomography / magnetic resonance imaging (CT/MRI) Liver Imaging Reporting a Data System (LI-RADS) is a standardized system for diagnostic imaging terminology, technique, interpretation, and reporting in patients with or at risk for developing hepatocellular carcinoma (HCC). Using diagnostic algorithms and tables, the system assigns to liver observations category codes reflecting the relative probability of HCC or other malignancies. This review article provides an overview of the 2017 version of CT/MRI LI-RADS with a focus on MRI. The main LI-RADS categories and their application will be described. Changes and updates introduced in this version of LI-RADS will be highlighted, including modifications to the diagnostic algorithm and to the optional application of ancillary features. Comparisons to other major diagnostic systems for HCC will be made, emphasizing key similarities, differences, strengths, and limitations. In addition, this review presents the new Treatment Response algorithm, while introducing the concepts of MRI nonviability and viability. Finally, planned future directions for LI-RADS will be outlined.Level of evidence5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;47:1459-1474.

SummaryBackground Magnetic resonance imaging (MRI) is the gold standard for assessment of perianal fistulising Crohn's disease (CD). The Van Assche index is the most commonly used MRI fistula index. Aims To assess the reliability of the Van Assche index, and to modify the instrument to improve reliability and create a novel index for fistulising CD. Methods A consensus process developed scoring conventions for existing Van Assche index component items and new items. Four experienced radiologists evaluated 50 MRI images in random order on three occasions. Reliability was assessed by estimates of intraclass correlation coefficients (ICCs). Common sources of disagreement were identified and recommendations made to minimise disagreement. A mixed effects model used a 100 mm visual anologue scale (VAS) for global severity as outcome and component items as predictors to create a modified Van Assche index. Results Intraclass correlation coefficients (95% confidence intervals) for intra-rater reliability of the original and modified Van Assche indices and the VAS were 0.86 (0.81-0.90), 0.90 (0.86-0.93) and 0.86 (0.82-0.89). Corresponding ICCs for inter-rater reliability were 0.66 (0.52-0.76), 0.67 (0.55-0.75) and 0.58 (0.47-0.66). Sources of disagreement included number, location, and extension of fistula tracts, and rectal wall involvement. A modified Van Assche index (range 0-24) was created that included seven component items. Conclusions Although “almost perfect” intra-rater reliability was observed for the assessment of MRI images for fistulising CD using the Van Assche index, inter-rater reliability was considerably lower. Our modification of this index should result in a more optimal instrument.

Author(s): Kielar, Ania Z; Chernyak, Victoria; Bashir, Mustafa R; Do, Richard K; Fowler, Kathryn J; Santillan, Cynthia; Sirlin, Claude B; Mitchell, Donald G; Cerny, Milena; Tang, An; Elsayes, Khaled M; Kamaya, Aya; Kono, Yuko; Arora, Sandeep S

The Liver Imaging Reporting and Data System (LI-RADS) is an American College of Radiology (ACR)-endorsed diagnostic system of standardized terminology, interpretation, and reporting for imaging examinations of the liver in patients at high risk for hepatocellular carcinoma (HCC). LI-RADS assigns a category to observations in the liver indicating the likelihood of benignity or HCC. LI-RADS categories include LR-1: Definitely Benign, LR-2: Probably Benign, LR-3: Intermediate Probability for HCC, LR-4: Probably HCC, LR-5: Definite HCC, LR-5V: Definite HCC with Tumor in Vein, LR-Treated: Treated HCC, LR-M Probable Malignancy, not specific for HCC. This article reviews the types of nodules seen in the cirrhotic liver, examines core LI-RADS concepts and definitions, and utilizes the LI-RADS v2014 algorithm to categorize representative observations depicted at magnetic resonance imaging in a case-based approach.