Fig. 4

Superior diagnostic performance of EOB-MRI in detecting < 2 cm-sized viable HCC (LR-TR viable) over CECT. In a 53-year-old man with a history of radiofrequency ablation in segment 3, EOB-MRI (arrows, a) demonstrates a 17-mm nodular enhancement which is more conspicuous on the arterial subtraction image (arrows, b), anterolateral to the treated observation (hollow arrows, a and b), without venous phase washout (c), but with HBP hypointensity (arrow, d) and diffusion restriction (thin arrow, e). The treated observation was assigned a viable HCC category on EOB-MRI. On CECT (f–h), the treated observation (hollow arrow, f-h) was assigned as non-viable due to lack of nodular arterial phase enhancement. A well-differentiated HCC was detected along the treated observation on histopathologic examination of the liver explant. Additionally demonstrated is a non-enhancing 23-mm treated observation (LR-TR non-viable) in segment 7/8 on EOB-MRI and CECT (arrowheads) with proven complete necrosis on histopathology. As a variant of hepatic morphology, the elongated left liver lobe extends laterally to surround the spleen (beaver tail liver), harboring an 18-mm histopathological proven non-treated HCC (thick arrow, f). This lesion manifested typical findings of HCC, including arterial hyperenhancement and washout (LR-5) on both EOB-MRI (not shown) and CECT. Image 5e (thick arrow) depicts the lesion manifesting diffusion restriction. Abbreviations: CECT: contrast-enhanced computed tomography, EOB-MRI: Gadoxetate-enhanced-MRI, HCC: hepatocellular carcinoma, HBP: hepatobiliary phase, LR-TR: Liver Imaging Reporting and Data System-Treatment response