Quantitative flow measurement by digital subtraction angiography in cerebral carotid stenosis using optical flow method

OBJECTIVE: We analyzed intracranial regional blood flows using an optical flow method (OFM) and digital subtraction angiography in patients with internal carotid artery (ICA) stenosis. We also retrospectively explored the correlation between the patients' diagnoses and the severity of the ICA stenoses. MATERIALS AND METHODS: OFM, an image-processing algorithm to estimate motion, was applied to determine the mean velocity V-mean in the vessels. A group of 40 patients without vascular anomalies acted as the control group. The patients were classified as having either moderate stenosis (< 80%, n = 14) or severe stenosis (> 80%, n = 23). RESULTS: The V-mean of the ICAs was significantly lower in the stenotic group compared with the control group (p < 0.01). The V-mean of the ICAs was inversely correlated with the severity of the stenosis (p < 0.05). The receiver operating characteristic curve of the V-mean in an AP view showed substantial discriminatory power, with an optimal cutoff value of 3.48 pixels/frame for the detection of patients with carotid stenosis. The sensitivity and specificity were 84% and 50%, respectively. On a lateral view, the best cutoff for the V-mean was 4.01 pixels/frame, and the sensitivity and specificity were 92% and 43%, respectively. CONCLUSIONS: Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.