Multimodality imaging and radiological-pathological analysis of ethiodized oil: Imaging biomarker of tumor necrosis after TACE?

Abstract

TPS503 Background: In transarterial chemoembolization (TACE) for primary and metastatic liver malignancies ethiodized oil (Lipiodol) serves 3 roles: vehicle to deliver high concentration of the chemotherapeutic agent to the tumor, embolic agent to the tumor feeding artery and a contrast agent. The latter allows for intraprocedural visualization during drug delivery. Because of increased retention in liver tumors, Lipiodol can be visualized post-TACE for several weeks to months. Controversial preclinical and clinical data have been published about the role of Lipiodol as an imaging biomarker for treatment success after TACE. Here we investigate whether increased tumor Lipiodol deposition correlates with tumor response and survival using multimodality imaging and radiological/pathological correlation. Methods: This is a prospective phase 2, single center, IRB-approved study. Inclusion criteria include adult patients (Child-Pugh class of A or B and ECOG performance status of 0-2) with unresectable HCC with liver predominant disease or hepatic metastases from any solid tumor. Dynamic contrast-enhanced (DCE) MRI and CT of the liver and PET-CT were obtained before TACE. 24 hours after TACE, a noncontrast CT of the liver was obtained to quantify Lipiodol retention in the targeted tumor. Follow-up imaging consisting of DCE-MRI, CT and PET–CT were also performed approximately 1, 3 and 6 months after the last TACE. Follow up imaging will continue every 2-3 months for up to 4 years. Percent deposition of Lipiodol in the targeted tumor was assessed using 3D quantitative analysis on the 24hr post-TACE CT. Tumor response using RECIST, EASL, modified RECIST, tumor volume (volumetric RECIST), and volumetric tumor enhancement (quantitative EASL) were performed on the DCE-MRI, CT, and PET-CT, and correlated with Lipiodol deposition. Spearman rank correlation coefficient and Pearson’s product-moment correlation were used. The Kaplan-Meier method with the log-rank test was used to assess whether Lipiodol is a biomarker of survival. 12/30 patients with HCC and 12/30 patients with hepatic metastases have been enrolled (#NCT01877187). Clinical trial information: NCT01877187.