Early response of hepatocellular carcinoma to transcatheter arterial chemoembolization: Choline levels and MR diffusion constants initial experience

Purpose: To prospectively investigate the apparent diffusion coefficient (ADC) and choline levels measured at hydrogen 1 (H-1) magnetic resonance (MR) spectroscopy, to monitor therapeutic responses of hepatocellular carcinoma (HCC) to transcatheter arterial chemoembolization (TACE). Materials and Methods: Institutional review board approval was obtained, and all patients and control subjects provided informed consent. Histologically proved large HCCs (> 3 cm in diameter) were evaluated in 20 patients (16 men and four women; mean age, 59 years; range, 34-80 years) before TACE and 2-3 days after TACE. A control group of eight adults (five men and three women; mean age, 43 years; range, 24-76 years) with normal livers was examined by using the same protocol. Hepatic choline levels were measured by means of an external phantom replacement method, quantifying the peak at 3.2 ppm at H-1 MR spectroscopy. ADCs were measured for all lesions. A Wilcoxon rank sum test was used to compare absolute choline concentrations and ADCs at baseline between HCCs and normal liver parenchyma. Changes in choline levels and ADCs in the tumors before and after TACE were analyzed by using the Wilcoxon signed rank test. Results: The median preoperative choline level in patients with HCC (measured in 18 of the 20 patients) was 4.0 mmol/L (range, 0.0-17.2 mmol/L), which was significantly higher than that in patients with normal livers (n = 8) (median, 1.6 mmol/L; range, 0.0-2.1 mmol/L; P < .01). Among 18 patients with HCC, choline levels decreased significantly from before TACE to after TACE (P < .01). A significant increase in ADC from before TACE to after TACE in the 20 patients with HCC was also found (P < .01). Conclusion: Hepatic choline levels and ADCs may allow monitoring of therapeutic responses of HCC to TACE although larger, more definitive and quantitative studies with clinical end points are needed.