Value of the unenhanced phase for detection of hepatocellular carcinomas 3 cm or less when performing multiphase computed tomography in patients with cirrhosis

Objective: To determine whether unenhanced images are of added benefit to dual-phase computed tomography (CT) for detection of hepatocellular carcinomas (HCCs) 3 cm or less. Methods: Thirty-six patients with cirrhosis underwent unenhanced, arterial and portal venous phase CT, 17 with pathologically proven HCCs 3 cm or less and 19 without HCC. Two radiologists reviewed dual-phase images with and without unenhanced images. Presence or absence of HCC in each segment (n = 324) and subjective added benefit of unenhanced images were recorded. Results: For readers 1 and 2, unenhanced CT was subjectively helpful in 16 (5%) of 324 and 23 (7%) of 324 segments. Sensitivity and area under the receiver operating characteristic curve were identical for dual-phase versus triple-phase images for reader 1 (82.4% and 0.882) and reader 2 (100% and 0.997). Conclusions: Addition of unenhanced to dual-phase CT does not statistically significantly increase the diagnostic accuracy or sensitivity for HCCs 3 cm or less.