Feasibility of CT-CT fusion imaging for evaluation of the cryoablation margins in visible hepatocellular carcinoma on unenhanced CT images: Initial experience.

Objective: To demonstrate the feasibility of CT-CT fusion imaging for assessment of the cryoablation margins in visible hepatocellular carcinoma (HCC) on unenhanced CT images.

Methods: This retrospective study analyzed 14 patients with 14 HCC lesions treated with CT-guided cryoablation. Nine lesions in nine patients who developed local tumor progression (LTP) during the follow-up period of at least 8 months were reviewed. The unenhanced CT data were used to retrospectively create fusion images of the intraoperative CT images on a workstation. The minimal ablative margin (MAM) was assessed on the fusion images. The concordance between the site of LTP and the MAM area was also assessed.

Results: Eight of the nine lesions with LTP were in the subcapsular region of the liver. Seven of the nine cases were treated by cryoablation combined with transcatheter arterial chemoembolization. The median time required to fuse the images for the nine lesions was 5:17 min (range, 5:04-7:37 min). The site of LTP relative to the HCC lesion was craniocaudal in nine, dorsoventral in six, and lateral in seven lesions. In all lesions, the site of LTP was congruent with the MAM area.

Conclusions: CT-CT fusion imaging enables a real-time intraoperative treatment evaluation for HCC lesions visible on unenhanced CT images. Fused imaging evaluation has proved to be an accurate and useful tool for assessment of the cryoablation margins.