and Purpose-Noninvasive screening for intracranial in-stent stenosis is often limited by artifact because of the stent or associated coils. We aimed to determine the utility of quantitative MRA (QMRA) as a screening tool for detecting intracranial in-stent stenosis. Methods-We reviewed 14 patients who had intracranial stent placement with follow-up QMRA and conventional angiography at our institution. Socio-demographic, medical, clinical, and imaging data were abstracted from medical charts. A

more »

... linded interventional neurologist reviewed all angiograms for presence of Ͼ50% in-stent stenosis. We tested QMRA (mL/min) at varying thresholds as a predictor of angiographic results. Results-Among 14 patients (mean age, 62 years; 12 female, 2 male), 13 patients had Neuroform stents placed for wide-neck cerebral aneurysms and 1 patient had a Wingspan stent placement for atherosclerotic stenosis. Lesions were located in the intracranial internal carotid artery in 57.2% (nϭ8), the middle cerebral artery in 14.3% (nϭ2), and vertebrobasilar arteries in 28.6% (nϭ4). On follow-up angiography, 2 patients (14.3%) had Ͼ50% in-stent stenosis on angiography. Time-of-flight MRA was nondiagnostic in each case because of artifact from the stent or coils. A Ͼ20% reduction in vessel-specific blood flow by QMRA was associated with presence of Ͼ50% in-stent stenosis on angiography (Pϭ0.033). As a screening tool to predict Ͼ50% angiographic in-stent stenosis, the sensitivity, specificity, positive predictive value, and negative predictive value of QMRA were 100%, 92%, 67%, and 100%, respectively. Conclusion-We found that QMRA is a promising screening tool to detect intracranial in-stent stenosis. Future prospective studies should focus on whether QMRA has a role in the detection of radiographic restenosis and prediction of clinical events. (Stroke. 2009;40:991-993.)