Ablation margin assessment of liver tumors with intravenous contrast-enhanced C-arm computed tomography

AIM:To evaluate the feasibility of intravenous contrastenhanced C-arm computed tomography(CT) for assessing ablative areas and margins of liver tumors.METHODS:Twelve patients(5 men,7 women;mean age,69.5 years) who had liver tumors(8 hepatocellular carcinomas,4 metastatic liver tumors;mean size,16.3 mm;size range,8-20 mm) and who underwent percutaneous radiofrequency ablations(RFAs) with a flatdetector C-arm system were retrospectively reviewed.Intravenously enhanced C-arm CT and multidetector computed tomography(MDCT) images were obtained at the end of the RFA sessions and 3-7 d after RFA to evaluate the ablative areas and margins.The ablated areas and margins were measured using axial plane images acquired by both imaging techniques,with prior contrast-enhanced MDCT images as the reference.The sensitivity,specificity,and positive and negative predictive values of C-arm CT for detecting insufficient ablative margins(< 5 mm) were calculated.Statistical differences in the ablative areas and margins evaluated with both imaging techniques were compared using a paired t-test.RESULTS:All RFA procedures were technically successful.Of 48 total ablative margins,19(39.6%) and 20(41.6%) margins were found to be insufficient with C-arm CT and MDCT,respectively.Moreover,there were no significant differences between these 2 imaging techniques in the detection of these insufficient ablative margins.The sensitivity,specificity,and positive and negative predictive values for detecting insufficient margins by C-arm CT were 90.0%,96.4%,94.7% and 93.1%,respectively.The mean estimated ablative areas calculated from C-arm CT(462.5 ± 202.1 mm 2) and from MDCT(441.2 ± 212.5 mm 2) were not significantly different.The mean ablative margins evaluated by C-arm CT(6.4 ± 2.2 mm) and by MDCT(6.0 ± 2.4 mm) were also not significantly different.CONCLUSION:The efficacy of intravenous contrastenhanced C-arm CT in assessing the ablative areas and margins after RFA of liver tumors is nearly equivalent to that of MDCT.