Evaluation of Visibility by Metal Artifact Reduction during Stent-assisted Coil Embolization

Objective: In cases of stent-assisted coil (SAC) embolization, visualization of stents with cone-beam CT is interfered significantly by the coil mass with streak artifacts. Metal artifact reduction (MAR), which is the algorithm for contrastenhanced cone-beam CT, improves visualization of stents. We analyzed our cases of SAC embolization and report efficacy of MAR. Materials and Methods: We reviewed 37 images of cone-beam CT of 37 aneurysms treated with SAC embolization between 2011 and 2013 in our institution. The 80 kV high-resolution XperCT was performed, and stent images were reconstructed with and without MAR. Neuroradiologists evaluated the following findings using a 3-point scale: stent apposition, stent lumen, and stent strut and anatomy of surrounding small vessels. Results: By applying MAR, scores of findings listed above were improved at least by 1 point in 83.8%, 86.5%, 89.2%, and 29.7% of the cases, respectively, and overall visibility was improved in all of the cases. Improvement of the total score with MAR did not significantly correlate with aneurysm size (r = 0.079). Conclusion: It was significantly valuable to apply MAR for the images after the SAC embolization treatment to observe stent apposition, stent lumen, and stent strut and surrounding vessels. This technique will also provide valuable information for cases of re-treatment or risk analysis for ischemic complications.