CT FINDINGS AFTER HEPATIC CHEMOEMBOLIZATION

Hepatic arterial chemoembolization (CE) with a mixture of particulate collagen and chemotherapeutic agents was evaluated as therapy for hepatic metastases from colorectal carcinoma. This article describes the characteristic sequential pattern of change seen on liver CT scans following CE. Thirty CT scans were performed on seven patients who had undergone a total of 11 CE procedures. All patients had baseline, immediate postprocedural, and follow-up CT exams at 1 to 2 month intervals following CE. Immediate postprocedural CT scans mapped the area of embolization owing to the density of the contrast mixed with the CE agents. Some lesions seen easily on baseline were more difficult to see as they became isodense with normal liver. Reflux of embolic material into the cystic artery and gallbladder wall was also observed on postprocedural scans in three patients. In all patients, early follow-up scans (1 month after CE) demonstrated changes in lesions seen on baseline scans consistent with tumor necrosis. This was corroborated by a decrease in carcinoembryonic antigen (CEA) levels. In three patients, however, low attenuation regions developed in areas in which there had been no lesion before. The significance of these is uncertain, but the low CEA values and the subsequent evolution in appearance of these sites on CT suggest that they were regions of hepatic ischemia/infarction as opposed to heretofore unidentifiable metastases, now "unmasked." Intermediate follow-up scans (2-3 months) revealed maximal effect on tumor volume, with a decrease of greater-than-or-equal-to 25% in five of seven patients (71%). Late follow-up scans (greater-than-or-equal-to 3 months after the last CE) confirmed recurrent disease and new lesions in all cases.