Diagnostic performance of CT versus MRI Liver Imaging Reporting and Data System category 5 for hepatocellular carcinoma: a systematic review and meta-analysis of comparative studies

Objective: To compare the performance of Liver Imaging Reporting and Data System category 5 (LR-5) for diagnosing HCC between CT and MRI using comparative studies. Methods: The MEDLINE and EMBASE databases were searched from inception to April 21, 2021, to identify studies that directly compare the diagnostic performance of LR-5 for HCC between CT and MRI. A bivariate random-effects model was fitted to calculate the pooled per-observation sensitivity and specificity of LR-5 of each modality, and compare the pooled estimates of paired data. Subgroup analysis was performed according to the MRI contrast agent. Results: Seven studies with 1145 observations (725 HCCs) were included in the final analysis. The pooled per-observation sensitivity of LR-5 for diagnosing HCC was higher using MRI (61%; 95% confidence interval [CI], 43–76%; I² = 95%) than CT (48%; 95% CI, 31–65%; I² = 97%) (p < 0.001). The pooled per-observation specificities of LR-5 did not show statistically significant difference between CT (96%; 95% CI, 92–98%; I² = 0%) and MRI (93%; 95% CI, 88–96%; I² = 16%) (p = 0.054). In the subgroup analysis, extracellular contrast agent–enhanced MRI showed significantly higher pooled per-observation sensitivity than gadoxetic acid–enhanced MRI for diagnosing HCC (73% [95% CI, 55–85%] vs. 55% [95% CI, 39–70%]; p = 0.007), without a significant difference in specificity (93% [95% CI, 80–98%] vs. 94% [95% CI, 87–97%]; p = 0.884). Conclusions: The LR-5 of MRI showed significantly higher pooled per-observation sensitivity than CT for diagnosing HCC. The pooled per-observation specificities of LR-5 were comparable between the two modalities. Key Points: • The pooled sensitivity of LR-5 using MRI was higher than that using CT (61% versus 48%), but the pooled specificities of LR-5 were not significantly different between CT and MRI (96% versus 93%). • Subgroup analysis according to the MRI contrast media showed a significantly higher pooled per-observation sensitivity using ECA-enhanced MRI than with EOB-enhanced MRI (73% versus 55%), and comparable specificities (93% versus 94%). • Although LI-RADS provides a common diagnostic algorithm for CT or MRI, the per-observation performance of LR-5 can be affected by the imaging modality as well as the MRI contrast agent.