4:21 PM Abstract No. 331 Quantitative analysis of Lipiodol washout rates in intrahepatic cholangiocarcinoma and hepatic metastasis from neuroendocrine tumors and colorectal cancer after chemoembolization

Abstract

To evaluate Lipiodol washout time after conventional transarterial chemoembolization (cTACE) in different hepatic malignancies including intrahepatic cholangiocarcinoma (ICC) as well as hepatic metastatic neuroendocrine tumors (NET) and colorectal carcinoma (CRC). This retrospective study included 41 patients, who underwent cTACE for the treatment of ICC (n = 9), NET (n = 14) or CRC metastases to the liver (n = 12). Lipiodol volume (LV) in cm3 was analyzed on follow-up non-contrast CT imaging obtained within 24 hours (LV1) as well as 40-220 days (LV2) after cTACE using a volumetric segmentation and image analysis software (qEASL; Medisys, Philips Research, Suresnes, France). The lipiodol washout rate was calculated as the ratio of (LV1-LV 2) to the interval (in days) between both CT scans. Additionally, tumor response on contrast-enhanced MRI was assessed 1 month after cTACE according to qEASL criteria. Lipiodol was visible on all follow-up CT scans. The LV2 was significantly lower than LV1 in all three tumors types (p<0.001). The mean lipiodol washout rate was -0.034 for ICC, -0.045 for NET, and -0.034 cm3/day for CRC metastases. No significant difference in lipiodol washout rates was observed between the three types of tumors (p>0.05). As for tumor response, 2/9 ICC patients, 4/14 NET patients and 5/18 CRC patients demonstrated response to cTACE according to qEASL criteria. However, no difference in lipiodol washout rate was revealed between responders and non-responders (p>0.05). This study showed that lipiodol washout rates after cTACE were similar for different hepatic malignancies including ICC, NET and CRC metastases. All observed tumors showed consistent washout regardless of response suggesting that lipiodol washout rate may not be predictive of tumor response to treatment.