Superparamagnetic iron oxide-enhanced MR imaging for early and late radiation-induced hepatic injuries

Superparamagnetic iron oxide (SPIO)-enhanced MRT was performed in twenty-on e patients undergoing proton-beam radiotherapy for hepatocellular carcinoma s. Patients were divided into two groups: early and late phase hepatic inju ries. Each group was investigated 3 to 9 weeks and 4 to 65 months after the start of irradiation, respectively. T-1-weighted, T-2-weighted, and T-2*-w eighted images were obtained before and after SPIO administration. In all p ostcontrast sequences in the early phase, irradiated livers demonstrated re latively higher intensity than nonirradiated livers and the radiation-to-li ver contrast-to-noise ratio (C/N) was improved. Postcontrast T-2*-weighted images showed the highest C/N. In the late phase, the irradiated areas show ed high intensity on T-2-weighted images and low intensity on T-1-weighted images without SPIO, while high intensity on T-1-weighted images with SPIO. The C/N increased with SPIO in all sequences and postcontrast T-2-weighted images showed the highest C/N in the late phase. SPIO-enhanced MRI is usef ul to evaluate this entity both in the early and late phase of clinical stu dies. (C) 2000 Elsevier Science Inc. All rights reserved.