Reduction of metal artifact from cryoprobe using tilt CT scanning with metal artifact reduction algorithms for CT-guided cryoablation.

Computed tomography (CT) is a simple and useful method for monitoring during cryoablation; however, image quality is degraded by artifacts caused by the cryoprobe used during treatment. We evaluated the effectiveness of combining tilt scanning and single-energy metal artifact reduction (SEMAR) to improve image quality. A cryoprobe was inserted into an agar phantom, and CT scans were performed at various angles (0°, 5°, 10°, 15°, and 20°) with and without metal artifact reduction. The relative artifact index, calculated using the CT value standard deviation, was used to evaluate the intensity. The strongest tip artifacts occurred at 0°. The relative artifact index decreased with increasing tilt angles. The tilted scanning reduced artifacts extending beyond the cryoprobe tip, but SEMAR demonstrated a limited effect on artifact reduction. The tilted scanning method may be a useful approach for improving the image quality around the cryoprobe without increasing the exposure dose.