Simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging: Comparison with contrast‐enhanced MR angiography for measuring carotid stenosis

摘要

Purpose To evaluate in a proof‐of‐concept study the feasibility of Simultaneous Noncontrast Angiography and intraPlaque hemorrhage (SNAP) imaging as a clinical magnetic resonance angiography (MRA) technique for measuring carotid stenosis. There is a growing interest in detecting intraplaque hemorrhage (IPH) during the clinical management of carotid disease, yet luminal stenosis has remained indispensable during clinical decision‐making. SNAP imaging has been proposed as a novel IPH imaging technique that provides carotid MRA with no added scan time. Flowing blood shows negative signal on SNAP because of phase‐sensitive inversion recovery. Materials and Methods In all, 58 asymptomatic subjects with 16–79% stenosis on ultrasound were scanned at 3T by SNAP with 0.8?mm isotropic resolution and 16?cm longitudinal coverage. Two readers measured luminal stenosis of bilateral carotid arteries ( n ?=?116) on minimum intensity projections of SNAP using the NASCET criteria. In the subset (48 arteries) with contrast‐enhanced (CE) MRA available for comparison, luminal stenosis was also measured on maximum intensity projections of CE‐MRA. Results Intraclass correlation coefficients (ICCs) with 95% confidence intervals were 0.94 (0.90–0.96) and 0.93 (0.88–0.96) for intra‐ and interreader agreement on stenosis measurements, respectively. Corresponding kappas for grading stenosis (0–29%, 30–69%, 70–99%, and 100%) were 0.79 (0.67–0.89) and 0.80 (0.68–0.90). Agreement between SNAP and CE‐MRA was high (ICC: 0.95 [0.90–0.98]; kappa: 0.82 [0.71–0.93]). Conclusion As a dedicated IPH‐imaging sequence, SNAP also provided carotid stenosis measurement that showed high intra‐ and interreader consistency and excellent agreement with CE‐MRA. Further comparisons with digital subtraction angiography and other noninvasive techniques are warranted. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1045–1052.