[Three-dimensional DSA imaging and 3-dimensional measurement of cross section for internal carotid artery stenosis]

We have performed rotational DSA for internal carotid artetry (ICA) stenosis and examined cross sectional imaging of the stenosis. Then, we compared the area stenosis rate (ASR) with stenosis rate by NASCET method and with results of duplex carotid ultrasonography. Of consecutive 451 patients who underwent digital subtraction angiography, 28 patients with ICA stenosis were selected for this study. Imaging data were transmitted to a workstation, and three-dimension (3-D) images were prepared, and cross sectional images of the highest-grade stenotic portion were obtained. ASRs were calculated [1-(the area of highest stenotic portion of ICA/the area of distal ICA)] x 100, which were compared with stenosis rates by NASCET method, as well as peak systolic velocity ratios (PSVR) of ICA to common carotid artery (CCA) determined by duplex carotid ultrasonography (USG). Cross sectional images in all patients were made except for restless patients, thereby morphology of the stenosis was feasible and measurements of cross section and diameter were possible. ASR and stenosis rate by NASCET method showed a very high correlation, and ASR was obtained by formula of (12.886 + 1.037 x stenosis rate by NASCET method). In patients with distorted stenosis, the stenosis rate was overestimated by NASECT method. ICA/CCA PSVR could predict stenosis to some extent, and in particular, all the patients with ICA/CCA PSVR of 3.1 or greater were found to have high grade stenosis. However duplex carotid USG failed to detect stenosis in a patient with high-grade stenosis at high position. In conclusion, as to ICA stenosis, 3-D image could show the stenosis precisely, and was considered to be useful as a routine examination.