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



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.



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]).



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.



2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1045-1052.
Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China.|Department of Radiology, University of Washington, Seattle, Washington, USA.
Hongge
H
Shu
Department of Radiology, University of Washington, Seattle, Washington, USA.
Jie
J
Sun
Department of Surgery, University of Washington, Seattle, Washington, USA.
Thomas S
TS
Hatsukami
Department of Radiology, University of Washington, Seattle, Washington, USA.
Niranjan
N
Balu
Department of Radiology, University of Washington, Seattle, Washington, USA.
Daniel S
DS
Hippe
Department of Bioengineering, University of Washington, Seattle, Washington, USA.
Haining
H
Liu
Department of Surgery, University of Washington, Seattle, Washington, USA.|Surgery and Perioperative Care, VA Puget Sound Health Care System, Seattle, Washington, USA.
Ted R
TR
Kohler
Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China.
Wenzhen
W
Zhu
Department of Radiology, University of Washington, Seattle, Washington, USA.|Department of Bioengineering, University of Washington, Seattle, Washington, USA.
Chun
C
Yuan
D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000503:physiopathology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006470:Hemorrhage / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media
NASCET; carotid disease; intraplaque hemorrhage; magnetic resonance angiography