Arterial enhancement on triphasic computed tomography scan predicts response of colorectal liver metastases to chemoembolization: A case–control study

Objectives: The arterial enhancement fraction (AEF), a simple calculation based on a standard triple-phase computed tomography (CT) scan, has been shown to predict treatment response in radioembolization of colorectal liver metastases (CRLM). The current study aims to determine if arterial enhancement also predicts treatment response in transarterial chemoembolization (TACE) of CRLM, which uses a larger particle size and exerts an ischemic effect. Materials and Methods: A retrospective analysis of our experience with TACE for CRLM between 2013 and 2022 yielded 97 TACE treatments for CRLM. The study included the first TACE treatment patients having a triple-phase CT scan before and after TACE, yielding 62 tumors treated with TACE of irinotecan drug-eluting beads in 36 patients. Tumors with complete response or partial response based on CT-based modified RECIST criteria were considered to be “responders,” whereas tumors that had progressive disease or stable disease were considered to be “non-responders.” Results: The responders differed from the non-responders in terms of arterial phase enhancement (APhE) (9.5 [interquartile range, IQR 6, 17] vs. 2 [IQR 1, 5] Hounsfield units [HUs], P < 0.001) and AEF (0.7 [IQR 0.5, 1] vs. 0.3 [IQR 0.1, 1], P = 0.01), both validated measures of hepatic arterial perfusion. Receiver operating characteristic curve analysis yielded a 5.5 HU cutoff for APhE. Those tumors with APhE >5.5 HU had a response rate of 72%, whereas those <5.5 HU had a response rate of 21%. Median overall survival for patients with tumors having APhE >5.5 HU was 22.4 months (IQR 13, 32) versus 14.5 months (IQR 10, 19) for those with APhE ≤5.5 HU, but this did not achieve statistical significance ( P = 0.14). Conclusion: CRLM with greater hepatic arterial blood supply as measured by the APhE and AEF have a higher probability of TACE treatment response.