Neck CTA with Deformable Registration and Subtraction Method: Evaluationin Patients with Stents

Background and purpose: The evaluation of arterial lumen with severe calcification or stent is still challenging. The purpose of the present study was to assess the effectiveness of the new subtraction method for CTA in patients with carotid artery stents. Materials and methods: A total of 35 consecutive neck CTA examinations in patients who had undergone carotid artery stent placement were selected for inclusion in this retrospective study. The CT scanner used was a 320-row MDCT system. The new subtraction method (global non-rigid registration and local rigid refinement subtraction) was used to obtain subtraction images. Two observers visually assessed the subtraction effect for the stents and for bone near the vertebral arteries using a 4-grade scale in order to compare the new subtraction method against the conventional subtraction method and DSA. Results: The arterial lumen could be evaluated in 89% of the stent subtraction images and 100% of the bone subtraction images obtained using the new subtraction method, and the subtraction images were judged to be superior to those obtained using the conventional method. The stenosis ratios showed a high correlation with those obtained by DSA (r = 0.92). Conclusion: The new subtraction method is effective in eliminating stents and bones and is also useful for assessing the arterial lumen after stent placement.