Intrahepatic cholangiocarcinoma treated with local-regional therapy: quantitative volumetric apparent diffusion coefficient maps for assessment of tumor response

Abstract

Purpose: To evaluate volumetric changes in apparent diffusion coefficient (ADC) and contrast material enhancement on contrast-enhanced (CE) magnetic resonance (MR) images in hepatic arterial and portal venous phases for assessing early response in cholangiocarcinoma treated with transcatheter arterial chemoembolization (TACE).

Materials and methods: Twenty-nine patients with unresectable cholangiocarcinoma, including 11 men (mean age, 60 years; standard deviation, 16.8) and 18 women (mean age, 63 years; standard deviation, 11.5) were included in this retrospective institutional review board-approved, HIPAA-compliant study; informed consent was waived. Sixty-nine TACE procedures were performed during the observational time (range, one to five TACE sessions). No patients received another form of therapy after treatment with TACE. MR Imaging was performed before and 3-4 weeks after TACE, and images were analyzed with a semiautomatic volumetric software package. Patients were stratified as responders and nonresponders on the basis of overall survival (OS) as the primary end point. Differences between responders and nonresponders were analyzed with paired t tests, and OS was calculated with the Kaplan-Meier method. Significant differences were analyzed with the log-rank test.

Results: Mean volumetric ADC increased from 1.54×10(-3) mm2/sec to 1.92×10(-3) mm2/sec (P<.0001), with no significant decrease in mean volumetric enhancement in hepatic arterial (40.6% vs 37.5%, P=.546) and portal venous (79.0% vs 70.0%, P=.105) phases. Patients who demonstrated improved survival of 10 months or more had a significant increase in mean volumetric ADC and volumetric ADC above the threshold level of 1.60×10(-3) mm2/sec (P<.002). Patients with 45% or greater (n=21; log-rank test, P<.02) and 60% or greater (n=12; log-rank test, P<.009) ADC changes for the whole tumor volume demonstrated better OS compared with patients in whom these ADC changes were not achieved.

Conclusion: Patients with percentage tumor volume increase in ADC of 45% or greater and 60% or greater above the threshold level of 1.60×10(-3) mm2/sec had favorable response to therapy and improved survival.