This study aimed to assess the validity and diagnostic performance of the imaging criteria of Korean Liver Cancer Association-National Cancer Center (KLCA-NCC) 2018 using magnetic resonance imaging (MRI) in high-risk patients for HCC. This retrospective study included 142 treatment-naïve patients (81 patients who underwent MRI with extracellular contrast agent and 61 who underwent MRI with hepatobiliary agent; 183 lesions including 149 HCCs) with a high risk of HCC who underwent multiphasic

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... rast-enhanced MRI from January to December 2015. All lesions were categorized according to the KLCA-NCC 2018 imaging diagnostic criteria by two readers, and per-lesion diagnostic performances were compared. According to the KLCA-NCC 2018, none (0%) of the 13 benign category lesions, 11 (44.0%) of 25 indeterminate category lesions, 15 (93.8%) of 16 probable HCC category lesions, and 97 (99.0%) of 98 definite HCC category lesions were ultimately diagnosed as HCCs. The sensitivity and specificity of definite HCC category were 65.1% and 97.1%, respectively, and those of the combination of definite and probable HCC categories were 75.2% and 94.1%, respectively. The sensitivity of the combination of definite and probable HCC categories was significantly higher than that of definite HCC (P<0.001), but the specificity was not significantly lower (P>0.999). The noninvasive imaging diagnosis of KLCA-NCC 2018 on MRI is reliable and useful for diagnosing HCC in high-risk patients. Combining definite and probable HCC categories of KLCA-NCC 2018 improves the sensitivity while maintaining a high specificity.