Multidetector CT angiography in the follow-up of patients treated with renal artery stents: value of different reformation techniques compared with axial source images.

To evaluate the role of 4 different reformation techniques in comparison with axial images from multidetector computed tomographic angiography (MDCTA) in the follow-up of renal artery stents. Data on 40 patients (20 men; mean age 65 years) who underwent MDCTA as part of their routine follow-up after successful primary stenting of a main renal artery were retrospectively analyzed. Multiplanar reformation (MPR), curved planar reformation (CPR), volume rendering threshold (VRT), and virtual angioscopy (VA) were reviewed by 2 independent observers who were blinded to the results of the axial source images, which served as the gold standard. The stenosis degree was scored as I = 0%, II <50%, III = 51%-75%, IV = 76%-99%, or V = occlusion; a stenosis >50% was considered hemodynamically significant. Five hemodynamically significant stenoses were identified on axial images. The correlation with axial images was perfect for both observers using MPR and CPR (kappa = 1 for each observer); corresponding results were kappa = 0.69 and kappa = 0.64 for VRT and kappa = 0.88 and kappa = 0.83 for VA, respectively. The interobserver correlations were excellent for all reformation techniques (kappa = 0.95 to 1). Compared to axial images, MPR and CPR correlated perfectly with axial images; VA performed surprisingly well, while VRT was affected by artifacts and consequently showed inferior results.