Completeness of treatment in hepatocellular carcinomas treated with image-guided tumor therapies: Evaluation of positive predictive value of contrast-enhanced CT with histopathologic correlation in the explanted liver specimen.

OBJECTIVE: To evaluate the positive predictive value of contrast-enhanced multiphase computed tomography (CT) in determining the completeness of treatment, after radiofrequency (RF) ablation and/or transcatheter arterial chemoembolization, based on histopathologic correlation in the explanted liver specimen.
MATERIALS AND METHODS: During a recent 10-year period, 84 consecutive patients who had a history of RF ablation and/or transcatheter arterial chemoembolization for hepatocellular carcinoma (HCC) underwent liver transplantation in our institution. Among them, we selected the patients in whom complete treatment had been considered at periodic follow-up CT (29 tumors in 20 patients, M:F = 18:2, mean age, 47.2 years). The mean size of the tumor at the initial CT was 2.2 cm (range, 0.7-3.6 cm). We investigated the necrosis rate of HCC on the basis of microscopic examinations of the explanted liver specimen and calculated the positive predictive value of CT in determining the completeness of treatment.
RESULTS: The last CT examinations had been obtained 1-37 days before surgery. The overall necrosis rate of HCC for both RF ablation and transcatheter arterial chemoembolization on microscopic examination was 92.9% +/- 12.3%. The positive predictive value of contrast-enhanced CT in determining completeness of treatment was 69.0% (20/29). The tumor necrosis rate for the RF ablation-only group (n = 12) was 91.5% +/- 15.2% with a positive predictive value of 58.3% (7/12) and that of the transcatheter arterial chemoembolization-only group (n = 11) was 91.4% +/- 19.2% with a positive predictive value of 72.7% (8/11).
CONCLUSIONS: Our results suggest that contrast-enhanced CT is limited in accurately determining the completeness of treatment after image-guided tumor ablation for HCC.