Abstract: Background and purpose: Early evaluating the therapeutic efficacy of transcatheter arterial chemoembolization (TACE) in patients with hepatic cancer is still a difficult clinical problem. The purpose of this study was to evaluate the ability of the apparent diffusion coefficient (ADC) to help predict early disease progression after TACE. Methods: Institutional review board approval was obtained, and all patients signed informed consent. Magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) (b=50, 500, 1 000 mm²/s) were performed before and 1 month after initiating TACE for 23 patients with hepatic cancer (14 were male, 9 were female; mean age: 53.3 years; range: 21-85 years). Contrast-enhanced MRI was performed 3 months after initiating TACE. Patients were classified as either progressing or non-progressing according to RECIST 1.1. The preoperative ADC values of tumor and the ADC values of tumor 1 month after TACE were analyzed by paired t-test in both progressing and non-progressing group. Unpaired t-test was used to compare ADC parameters between progressing and non-progressing group. In all the 23 hepatic cancer patients, receiver operating characteristic (ROC) curve analysis was performed to determine a threshold ADC ratio (ADC%) to differentiate progressing from non-progressing patients. Results: Thirteen progressing and 9 non-progressing patients were evaluated. Increase in ADCs of tumor was observed in non-progressing patients at 1 month after TACE compared with preoperative ADCs. There was a significant difference between the 2 groups (P=0.01). In progressing group, preoperative ADCs of tumor were similar to those at 1 month after TACE (P=0.221). There was no significant difference in preoperative ADCs of tumor and ADC% between the progressing and non-progressing groups. In patients with hepatic cancer, 1 month ADC ratio in non-progressing patients were significantly higher than those of progressing patients (P=0.029). Using ROC to evaluate the ability of ADC% could predict early disease progression after TACE. Using -6.455% as the threshold, the area under the ROC curve was 0.867 (95%CI: 0.643-1.000). The sensitivity was 100%, and the specificity was 66.7%. Conclusion: One month after TACE, the increases in ADCs of tumor were observed only in the non-progressing group; and the ADC ratio seems to be a promising tool for helping predict the early disease progression after TACE in patients with hepatic cancer.

Key words: Diffusion-weighted imaging, Hepatic cancer, Transcatheter arterial chemoembolization, Follow-up, Apparent diffusion coefficient, Progress