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Background: According to the Liver Imaging Reporting and Data System (LI-RADS), the LI-RADS category M (LR-M), which are probably or definitely malignant but are not specific for hepatocellular carcinomas (HCCs), does not exclude HCCs. A gap in knowledge remains, including their characteristics and recurrence of HCCs categorized as LR-M.Purpose: To compare the characteristics of HCCs categorized as LR-M with HCCs categorized as LR-4 or LR-5 (LR-4/5) using the LI-RADS version 2018 and evaluate the relationship of these categories with the risk of early recurrence after curative resections of single HCCs.Study Type: Retrospective.Subjects: Two hundred and eighty-one patients (mean age, 57 years; 191 men and 90 women) who underwent curative resections for single HCCs and preoperative contrast-enhanced MRI between 2015 and 2017.Field Strength/sequence: 3T Dual gradient-echo T1 WI with in- and opposed-phase, turbo spin-echo T2 WI, diffusion-weighted echo-planar images, and three-dimensional gradient-echo T1 WI before and after administration of contrast agent.Assessment: MRI features according to the LI-RADS version 2018 were evaluated and LI-RADS category were assigned for each observation. Clinical, imaging, and histopathological features were compared based on LI-RADS categorization. Early recurrence rates (<2 years) and associated factors were also evaluated.Statistical Tests: Fisher's exact test, two-sample t test after satisfying assumption of normality through Shapiro-Wilk test, Fleiss κ coefficient, Cox proportional hazards regression analysis, Kaplan-Meier method, and log-rank test.Results: Forty-one HCCs (14.6%) were categorized as LR-M and 240 HCCs (85.4%) were categorized as LR-4/5. LR-M HCCs showed poorer differentiation than LR-4/5 HCCs. In the multivariate analysis, the LR-M category was an independent predictor for early recurrence (hazard ratio, 1.904; 95% confidence interval, 1.024-3.542; P < 0.05). Early recurrence rates were significantly higher in patients with LR-M HCCs than in patients with LR-4/5 HCCs (32.0% vs. 18.4%, respectively, P < 0 05).Data Conclusion: Compared to LR-4/5 HCCs, LR-M HCCs were associated with poorer tumor differentiation and higher early recurrence rates after curative resections of single HCCs.Level Of Evidence: 3 Technical Efficacy Stage: 2. [ABSTRACT FROM AUTHOR]

Background & Aims: The liver Imaging Reporting and Data System (LI‐RADS) is a comprehensive system for standardizing liver imaging in patients at high risk for hepatocellular carcinoma (HCC). We performed a meta‐analysis to determine the diagnostic performance of the LR‐5 category for HCC and the pooled proportions of HCCs in each LI‐RADS category using CT/MRI LI‐RADS v2017. Methods: We searched multiple databases for original studies reporting on the diagnostic accuracy of CT/MRI LI‐RADS v2017. Random‐effects models were used to determine the summary estimates of the diagnostic performance of the LR‐5 category and the pooled proportions of HCCs for each LI‐RADS category. Risk of bias and concerns regarding applicability were evaluated with the Quality Assessment of Diagnostic Accuracy Studies‐2 tool. Results: Fourteen studies (3 prospective studies and 11 retrospective studies) were included in the final analysis, consisting of 2056 patients, 2589 observations, and 1693 HCCs. The pooled per‐observation sensitivity was 67% (95% confidence interval [CI], 62%‐72%) with specificity of 92% (95% CI, 88%‐95%) in the LR‐5 category of CT/MRI LI‐RADS v2017 for diagnosing HCC. The pooled proportions of HCCs were 0% (95% CI, 0%‐0%) for LR‐1, 4% (95% CI, 0%‐8%) for LR‐2, 34% (95% CI, 23%‐44%) for LR‐3, 67% (95% CI, 53%‐81%) for LR‐4, and 92% (95% CI, 87%‐96%) for LR‐5. The proportions of HCCs were significantly different among LI‐RADS categories 1‐5 (P =.034). Conclusions: The LR‐5 category of CT/MRI LI‐RADS v2017 shows moderate sensitivity and high specificity for diagnosing HCC. Higher LI‐RADS categories contained higher proportions of HCCs. [ABSTRACT FROM AUTHOR]