Coronal reformatted CT images contribute to the precise evaluation of the radiofrequency ablative margin for hepatocellular carcinoma

Abstract

The purpose of the present study was to evaluate the usefulness of coronal reformatted images obtained from 64-slice multi-detector computed tomography to assess the ablative margin (AM) in hepatocellular carcinoma (HCC) treated with radio frequency ablation (RFA). Ninety-five HCC nodules were analyzed in 66 HCC patients treated with RFA. Two radiologists and one hepatologist independently reviewed axial CT images with or without coronal reformatted images in HCC treated with RFA. Nodules were determined as AM-sufficient (≥5mm) or AM-insufficient (<5mm). The level of interobserver agreement was measured using the weighted kappa test. The sensitivity, specificity, and positive and negative predictive values (NPVs) of an insufficient AM (<5mm) to predict local recurrence were evaluated. The numbers of AM-sufficient nodules judged by readers 1-3 based on axial images and both axial and coronal images were 56, 49, and 58, and 47, 33, and 48, respectively. Excellent agreement and good to excellent agreement were obtained among the three readers on axial image readings and both axial and coronal image readings, respectively. The mean sensitivity, specificity, and positive and NPVs of an insufficient AM on axial images and both axial and coronal images to predict local recurrence were 64%, 60%, 17%, and 93%, and 95%, 50%, 20%, and 97%, respectively. Coronal reformatted CT images should be utilized to evaluate the AM in HCC treated with RFA in order to decrease the risk of local recurrence following treatment.