The Utility of Quantitative Magnetic Resonance Angiography in the Assessment of Intracranial In-Stent Stenosis

Abstract

Background 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 blinded 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.

In Vivo Evaluation of Quantitative MR Angiography in a Canine Carotid Artery Stenosis Model

“…16 The QMRA software has automated the placement of a perpendicular imaging plane and the selection of the appropriate VENC based on the actual flow in the vessel under study. To date, this technique has been used to guide patient management in cerebral revascularization surgery [17][18][19][20] ; assess intracranial and extracranial vessel stenosis pre-and poststent placement 21 ; measure blood flow in cerebral aneurysms 22 ; evaluate subclavian steal syndrome 23 ; assess collateral volume flow in large-vessel cerebrovascular disease 24 ; and predict outcomes of balloon-occlusion testing. 20 Although in vitro validation of QMRA has been performed by using flow phantoms, 16 in vivo evaluation of clinically relevant cerebrovascular flows, in conjunction with progressive arterial stenosis, has not been previously described.…”

Angiographic CT after Intravenous Contrast Agent Application: A Noninvasive Follow-Up Tool after Intracranial Angioplasty and Stenting

“…15 Other noninvasive techniques allowing the detection of ISR include transcranial duplex sonography and quantitative MR angiography. 16,17 However, both of these lack the ability to provide anatomic data of the stent region, and especially duplex sonography is limited due to its dependence on operator experience and the anatomy of the temporal bone window.…”

MR Derived Volumetric Flow Rate Waveforms of Internal Carotid Artery in Patients Treated for Unruptured Intracranial Aneurysms by Flow Diversion Technique

“…29 With the aim of setting an easily usable and reproducible method for physicians, we used 2D pc-MRI technique for flow measurements. This technique has been shown to be an accurate and reliable method for velocity quantification in cervical and intracranial vessels in various cerebrovascular conditions, 11,12,[30][31][32][33] such as aneurysmal disease. 34 It is highly correlated to Laser Doppler Velocimetry as reference method and endovascular Doppler techniques for flow quantifications, especially in large arteries as in ICA.…”