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Background & aimsThe Liver Imaging Reporting and Data System (LI-RADS) categorizes observations from imaging analyses of high-risk patients based on the level of suspicion for hepatocellular carcinoma (HCC) and overall malignancy. The categories range from definitely benign (LR-1) to definitely HCC (LR-5), malignancy (LR-M), or tumor in vein (LR-TIV) based on findings from computed tomography or magnetic resonance imaging. However, the actual percentage of HCC and overall malignancy within each LI-RADS category is not known. We performed a systematic review to determine the percentage of observations in each LI-RADS category for computed tomography and magnetic resonance imaging that are HCCs or malignancies.MethodsWe searched the MEDLINE, Embase, Cochrane CENTRAL, and Scopus databases from 2014 through 2018 for studies that reported the percentage of observations in each LI-RADS v2014 and v2017 category that were confirmed as HCCs or other malignancies based on pathology, follow-up imaging analyses, or response to treatment (reference standard). Data were assessed on a per-observation basis. Random-effects models were used to determine the pooled percentages of HCC and overall malignancy for each LI-RADS category. Differences between categories were compared by analysis of variance of logit-transformed percentage of HCC and overall malignancy. Risk of bias and concerns about applicability were assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 tool.ResultsOf 454 studies identified, 17 (all retrospective studies) were included in the final analysis, consisting of 2760 patients, 3556 observations, and 2482 HCCs. The pooled percentages of observations confirmed as HCC and overall malignancy, respectively, were 94% (95% confidence interval [CI] 92%-96%) and 97% (95% CI 95%-99%) for LR-5, 74% (95% CI 67%-80%) and 80% (95% CI 75%-85%) for LR-4, 38% (95% CI 31%-45%) and 40% (95% CI 31%-50%) for LR-3, 13% (95% CI 8%-22%) and 14% (95% CI 9%-21%) for LR-2, 79% (95% CI 63%-89%) and 92% (95% CI 77%-98%) for LR-TIV, and 36% (95% CI 26%-48%) and 93% (95% CI 87%-97%) for LR-M. No malignancies were found in the LR-1 group. The percentage of HCCs and overall malignancies confirmed differed significantly among LR groups 2-5 (P < .00001). Patient selection was the most frequent factor that affected bias risk, because of verification bias and case-control study design.ConclusionsIn a systematic review, we found that increasing LI-RADS categories contained increasing percentages of HCCs and overall malignancy based on reference standard confirmation. Of observations categorized as LR-M, 93% were malignancies and 36% were confirmed as HCCs. The percentage of HCCs found in the LR-2 and LR-3 categories indicate the need for a more active management strategy than currently recommended. Prospective studies are needed to validate these findings. PROSPERO number CRD42018087441.

Background: LI‐RADS version 2018 (v2018) is used for non‐invasive diagnosis of hepatocellular carcinoma (HCC). A recently proposed modification (known as mLI‐RADS) demonstrated improved sensitivity while maintaining specificity and positive predictive value (PPV) of LI‐RADS category 5 (definite HCC) for HCC. However, mLI‐RADS requires multicenter validation. Purpose: To evaluate the performance of v2018 and mLI‐RADS for liver lesions in a large, heterogeneous, multi‐national cohort of patients at risk for HCC. Study Type: Systematic review and meta‐analysis using individual participant data (IPD) [Study Protocol: https://osf.io/duys4]. Population: 2223 observations from 1817 patients (includes all LI‐RADS categories; females = 448, males = 1361, not reported = 8) at elevated risk for developing HCC (based on LI‐RADS population criteria) from 12 retrospective studies. Field Strength/Sequence: 1.5T and 3T; complete liver MRI with gadoxetate disodium, including axial T2w images and dynamic axial fat‐suppressed T1w images precontrast and in the arterial, portal venous, transitional, and hepatobiliary phases. Diffusion‐weighted imaging was used when available. Assessment: Liver observations were categorized using v2018 and mLI‐RADS. The diagnostic performance of each system's category 5 (LR‐5 and mLR‐5) for HCC were compared. Statistical Tests: The Quality Assessment of Diagnostic Accuracy Studies version 2 (QUADAS‐2 was applied to determine risk of bias and applicability. Diagnostic performances were assessed using the likelihood ratio test for sensitivity and specificity and the Wald test for PPV. The significance level was P < 0.05. Results: 17% (2/12) of the studies were considered low risk of bias (244 liver observations; 164 patients). When compared to v2018, mLR‐5 demonstrated higher sensitivity (61.3% vs. 46.5%, P < 0.001), similar PPV (85.3% vs. 86.3%, P = 0.89), and similar specificity (85.8% vs. 90.8%, P = 0.16) for HCC. Data Conclusion: This study confirms mLR‐5 has higher sensitivity than LR‐5 for HCC identification, while maintaining similar PPV and specificity, validating the mLI‐RADS proposal in a heterogeneous, international cohort. Level of Evidence: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Background: Pancreatic cystic lesions (PCLs) are frequent on MRI and are thought to be associated with pancreatic adenocarcinoma (PDAC) necessitating long‐term surveillance based on older studies suffering from selection bias. Purpose: To establish the percentage of patients with PCLs on MRI with a present or future PDAC. Study Type: Systematic review, meta‐analysis. Population: Adults with PCLs on MRI and a present or future diagnosis of PDAC were eligible. MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Scopus were searched to April 2022 (PROSPERO:CRD42022320502). Studies limited to PCLs not requiring surveillance, <100 patients, or those with a history/genetic risk of PDAC were excluded. Field Strength/Sequence: ≥1.5 T with ≥1 T2‐weighted sequence. Assessment: Two investigators extracted data, with discrepancies resolved by a third. QUADAS‐2 assessed bias. PDAC was diagnosed using a composite reference standard. Statistical Tests: A meta‐analysis of proportions was performed at the patient‐level with 95% confidence intervals (95% CI). Results: Eight studies with 1289 patients contributed to the percentage of patients with a present diagnosis of PDAC, and 10 studies with 3422 patients to the percentage with a future diagnosis. Of patients with PCLs on MRI, 14.8% (95% CI 2.4–34.9) had a PDAC at initial MRI, which decreased to 6.0% (2.2–11.3) for studies at low risk of bias. For patients without PDAC on initial MRI, 2.0% (1.1–3.2) developed PDAC during surveillance, similar for low risk of bias studies at 1.9% (0.7–3.6), with no clear trend of increased PDAC for longer surveillance durations. For patients without worrisome features or high‐risk stigmata, 0.9% (0.1–2.2) developed PDAC during surveillance. Of 10, eight studies had a median surveillance ≥3 years (range 3–157 months). Sources of bias included retrospectively limiting PCLs to those with histopathology and inconsistent surveillance protocols. Data Conclusion: A low percentage of patients with PCLs on MRI develop PDAC while on surveillance. The first MRI revealing a PCL should be scrutinized for PDAC. Level of Evidence: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Medical imaging diagnostic test accuracy research is strengthened by adhering to best practices for study design, data collection, data documentation, and study reporting. In this review, key elements of such research are discussed, and specific recommendations provided for optimizing diagnostic accuracy study execution to improve uniformity, minimize common sources of bias and avoid potential pitfalls. Examples are provided regarding study methodology and data collection practices based on insights gained by the liver imaging reporting and data system (LI‐RADS) individual participant data group, who have evaluated raw data from numerous MRI diagnostic accuracy studies for risk of bias and data integrity. The goal of this review is to outline strategies for investigators to improve research practices, and to help reviewers and readers better contextualize a study's findings while understanding its limitations. Level of Evidence: 5 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Background: Pancreatic cystic lesions (PCLs) are followed for years due to older and likely biased works demonstrating a strong association with pancreatic carcinoma; more recent data are needed clarifying this relationship. Purpose: To determine the association between PCLs on MRI and a synchronous or future diagnosis of pancreatic carcinoma. Study type: Single‐center retrospective cohort. Population: A total of 192 patients (111 female, 58%) with median age 66 years (range 26–87 years) with PCLs on abdominal MRI from 2011 to 2016. Field Strength/Sequences: 1.5 T and 3 T, including T2WI, T1WI, diffusion weighted imaging and contrast‐enhanced T1WI. Assessment: Each PCL was reviewed independently by 2 of 10 fellowship‐trained abdominal radiologists. Fukuoka guideline worrisome features and high‐risk stigmata were evaluated. Follow‐up imaging and clinical notes were reviewed within a system that captures pancreatic carcinoma for the region, for a median follow‐up of 67 months (interquartile range: 43–88 months). Statistical Tests: Pancreatic carcinoma prevalence and incidence rate for future carcinoma with 95% confidence intervals (95% CI). Fisher exact test, logistic regression with odds ratios (OR) and the Wilcoxon rank‐sum test were used to assess PCL morphologic features with the Kolmogorov–Smirnov test used to assess for normality. P < 0.05 defined statistical significance. Results: The prevalence of pancreatic carcinoma on initial MRI showing a PCL was 2.4% (95% CI: 0.9%, 5.2%). Thickened/enhancing cyst wall was associated with pancreatic carcinoma, OR 52 (95% CI: 4.5, 1203). Of 189 patients with a PCL but without pancreatic carcinoma at the time of initial MRI, one developed high‐grade dysplasia and none developed invasive carcinoma for an incidence rate of 0.97 (95% CI: 0.02, 5.43) and 0 (95% CI: 0, 3.59) cases per 1000 person‐years, respectively. Data Conclusion: A low percentage of patients with a PCL on MRI had a pancreatic carcinoma at the time of initial evaluation and none developed carcinoma over a median 67 months of follow‐up. Evidence Level: 3 Technical Efficacy: 5 [ABSTRACT FROM AUTHOR]