Transient hepatic attenuation difference (THAD) following transcatheter arterial chemoembolization for hepatic malignancy: changes on serial CT examinations

The purpose of this study was to investigate the natural history of transcatheter arterial chemoembolization (TACE)-induced, transient hepatic attenuation difference (THAD). Among the patients who underwent TACE for treatment of hepatocellular carcinomas during a 32-month period, 32 patients with 40 newly developed THADs defined as localized, transient, peripheral hepatic parenchymal enhancement during the hepatic arterial phase of dynamic CT (axial dimension, 1.9-8.8 cm; mean, 4.9 cm) in the vicinity of iodized-oil accumulation were subjected to a retrospective analysis of serial follow-up CT examinations. Among the 40 TACE-induced THADs, 18 (45%) and 9 (23%) were accompanied with arterial-portal venous fistula (APF) and portal venous stenosis (PVS), respectively, while 2 (5%) THADs showed both APF and PVS simultaneously. Thirty-eight (95%) THADs disappeared spontaneously during the follow-up period (range, 4-26 months; mean, 9 months), and 11 (29%) of them showed progressive atrophy of the corresponding hepatic parenchyma. Regardless of the presence of APF, 10 (91%) of 11 THADs of following parenchymal atrophy had shown PVSs (P < 0.001). During the long-term follow-up period after TACE, almost all of the TACE-induced THADs spontaneously disappeared and either had or did not have corresponding parenchymal atrophy, which is strongly related to the presence of PVS. Understanding the nature of these CT features would be helpful for radiologists in determining the prognosis of the TACE-induced hepatic injuries as well as in distinguishing them from the recurrent tumour.