Abbreviated MRI with optional multiphasic CT as an alternative to full-sequence MRI: LI-RADS validation in a HCC-screening cohort

Abstract

Objective: To compare the diagnostic performance of abbreviated MRI (AMRI) combined with multiphasic CT (mCT) with that of full-sequence gadoxetic acid-enhanced MRI (EOB-MRI) in a hepatocellular carcinoma (HCC)-screening cohort Methods: Consecutive patients at risk of HCC who underwent EOB-MRI and mCT within 3 months for evaluation of new 0.5–3-cm hepatic observations were retrospectively recruited from 3 centers. An AMRI protocol comprising hepatobiliary phase, T2- and diffusion-weighted imaging, and dual-echo sequence was reconstituted from EOB-MRI. Two radiologists independently reviewed each observation in AMRI plus mCT (set 1) and EOB-MRI (set 2) per LI-RADS v2018. Per-lesion sensitivity, accuracy, and positive predictive value (PPV) for HCC were calculated and compared between image sets. Results: In 267 patients, 306 histologically confirmed observations (280 HCCs, 20 combined hepatocellular-cholangiocarcinomas, 1 cholangiocarcinoma, and 5 benignities) were assessed. Set 1 yielded higher sensitivity (96.4% vs. 92.9%, p = 0.013) and comparable accuracy (91.2% vs. 87.6%) and PPV (94.1% vs. 93.5%) to set 2 using LI-RADS category (LR)-4/5 criteria. The sets showed comparable sensitivity (66.4% vs. 70.4%), accuracy (67.7% vs. 70.6%), and PPV (97.4% vs. 96.6%) using LR-5 criteria. A similar substantial number of non-HCC malignancies were categorized as LR-4 or LR-5, as was the number of HCCs categorized as LR-M in both sets. Conclusions: AMRI combined with mCT showed diagnostic performance similar or superior to that of EOB-MRI for HCC diagnosis using LI-RADS. Therefore, mCT holds potential as a sequential examination for HCC diagnosis in AMRI-detected hepatic observation in patients at risk of HCC. Key Points: • AMRI plus multiphasic CT showed comparable accuracy (91.2%) and PPV (94.1%) to full-sequence gadoxetic acid-enhanced MRI using LR-4/5 criteria. • AMRI plus multiphasic CT was significantly more sensitive than full-sequence gadoxetic acid-enhanced MRI (96.4% vs. 92.9%) using LR-4/5 criteria. • Multiphasic CT is a potential sequential modality for HCC diagnosis after AMRI. © 2019, European Society of Radiology.