Fig. 2

Case (1) (A) CT study, A 60-year-old female patient with cirrhosis and mild ascites had shown an HCC lesion with CR according to mRECIST accompanied by incomplete lipiodol retention. a Pre-TACE baseline post-contrast axial CT image showed heterogenous enhanced HCC lesion at segment VII measuring 2.5 × 2 × 1 cm (white arrow). b, c On initial follow-up CT, the lesion displayed incomplete lipiodol retention (yellow arrow) on a pre-contrast image (b), whereas the hepatic arterial phase image (c) did not exhibit any residual enhancement. Non-enhanced CT image obtained on the 6th month post-cTACE (d) showed a reduced size of retained lipiodol (blue arrow). Case (1) (B) (e–n) On 1st-month follow-up DCE-MRI serial images, the lesion showed in-phase (e) and out-of-phase (f) T1WI hypointensity, no contrast enhancement in all contrast phases (g–k); arterial (h), portal (i), venous (j), and delayed (k) phases. Lesion displayed T2WI (l) hyperintensity and free diffusion in DWI (m) and ADC (n) images, denoting complete response. Case (1) (C) On 6th-month follow-up DCE-MRI serial images, the HCC lesion showed in-phase (o) and out-of-phase (p) T1WI hypointensity, pre-contrast phase (q) hypointensity, while in contrast phases (r–u) it showed faint enhancement in the arterial phase (r), with washout in the portal (s), venous (t), and delayed (u) phases (yellow arrows). Lesion displayed faint high signal intensity in T2WI (v). On DWI (w) and ADC (x) images, it showed restricted diffusion (blue arrows), denoting recurrence. A newly developed high-grade dysplastic nodule (red arrow) has emerged into segment VII, with rounded shape, measured less than 1 cm, showed in-phase (o) and out-of-phase (p) T1WI hyperintensity, pre-contrast phase (q) hyperintensity, while in contrast phases (r–u) it showed faint enhancement in the arterial phase (r), without washout in the portal (s), venous (t), or delayed (u) phases. It displayed hypointensity in T2WI (v) with free diffusion on DWI (w) and ADC (x) images