Dynamic changes in magnetic resonance imaging (MRI) features improve sensitivity for diagnosing small recurrent...

To establish improved diagnostic criteria for small recurrent hepatocellular carcinoma (HCC) (<20 mm) presenting with indeterminate findings on postoperative surveillance magnetic resonance imaging (MRI).

Patients who underwent curative resection for primary HCC between January and December 2018 were retrospectively reviewed. Newly detected hepatic nodules with atypical imaging features on surveillance MRI were included. Logistic regression analyses were performed to identify imaging features independently associated with recurrent HCC at the time of initial detection. The diagnostic performance of newly emerged MRI features (newly emerged arterial phase hyperenhancement, washout, enhancing 'capsule', threshold growth, mild-to-moderate T2 hyperintensity, restricted diffusion, and T1 hypointensity), threshold growth on 3-month follow-up MRI, and the liver imaging reporting and data system (LI-RADS) category were assessed and compared.

A total of 398 patients with 460 newly detected nodules were analysed, of which 351 (76.3%) were confirmed as recurrent HCC. Restricted diffusion (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.20-3.95; P = 0.01) and T1 hypointensity (OR, 20.48; 95% CI, 11.53-36.36; P < 0.001) were independent predictors of recurrence at initial detection. Compared with threshold growth alone (sensitivity, 60.6%) and LI-RADS 5 (sensitivity, 45.6%), newly emerged MRI features demonstrated significantly higher sensitivity (94.9%; P < 0.001 for both) while maintaining comparable specificity (96.3% vs. 98.2% vs. 98.2%; P > 0.99). The area under the receiver operating characteristic (ROC) curve for newly emerged features was 0.96 (0.94 after excluding LI-RADS 5 nodules).

Newly emerged MRI features offer higher sensitivity than threshold growth and LI-RADS 5 categorisation, while maintaining high specificity for the early diagnosis of recurrent HCC.