Diffusion-weighted Magnetic Resonance Imaging to Predict Response of Hepatocellular Carcinoma to Chemoembolization

Aim: To investigate whether intra-procedural diffusion-weighted magnetic resonance imaging can predict response of hepatocellular carcinoma (HCC) during transcatheter arterial chemoembolization (TACE).

Methods: Sixteen patients (15 male), aged 59 +/- 11 years (range: 42-81 years) underwent a total of 21 separate treatments for unresectable HCC in a hybrid magnetic resonance/interventional radiology suite. Anatomical imaging and diffusion-weighted imaging (b = 0, 500 s/mm(2)) were performed on a 1.5-T unit. Tumor enhancement and apparent diffusion coefficient (ADC, mm(2)/s) values were assessed immediately before and at 1 and 3 mo after TACE. We calculated the percent change (PC) in ADC values at all time points. We compared follow-up ADC values to baseline values using a paired t test (alpha = 0.05).

Results: The intra-procedural sensitivity, specificity, and positive and negative predictive values (%) for detecting a complete or partial 1-mo tumor response using ADC PC thresholds of +/-5%, +/-10%, and +/-15% were 77, 67, 91, and 40; 54, 67, 88, and 25; and 46, 100, 100, and 30, respectively. There was no clear predictive value for the 3-mo follow-up. Compared to baseline, the immediate post-procedure and 1-mo mean ADC values both increased; the latter obtaining statistical significance (1.48 +/- 0.29 mm(2)/s vs 1.65 +/- 0.35 x 10(-3) mm(2)/s, P < 0.014).

Conclusion: Intra-procedural ADC changes of > 15% predicted 1-mo anatomical HCC response with the greatest accuracy, and can provide valuable feedback at the time of TACE.