From the Department of Medicine (M.M.M.), the Department of Preventive Medicine (M.M.M., K.L., Y.L.), the Department of Surgery and the Division of Vascular Surgery (M.K., W.H.P.), and The Department of Radiology (J.C., T.J.C.), Northwestern University's Feinberg School of Medicine, Chicago, IL; the Department of Family and Preventive Medicine, University of California at San Diego (M.H.C.), San Diego, CA; the Department of Health Research and Policy, Stanford University School of Medicine (L.T.); Cedars-Sinai Hospital, Los Angeles, CA (D.L.); Laboratory of Clinical Epidemiology (L.F.) and Laboratory of Epidemiology, Demography, and Biometry (J.M.G.), National Institute on Aging, Baltimore, MD; the Department of Radiology and Medicine (C.M.K.), University of Virginia Health System, Charlottesville, VA; the Department of Radiology (D.X.) and the Department of Radiology, Electrical Engineering, and Bioengineering (C.Y.), University of Washington School of Medicine, Seattle; Jesse Brown Veterans Affairs Medical Center, Chicago, IL (M.K.); the Department of Medicine (J.B.), University of Texas Southwestern Medical Center, Dallas, TX; University Cardiovascular Surgeons (W.M.) and the Department of Vascular Surgery (J.O., W.M.), Rush University Medical Center, Chicago, IL; and the Departments of Biomedical Engineering and Radiology (T.J.C.), Northwestern University, Chicago, IL.
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Background—The clinical significance of magnetic resonance–imaged plaque characteristics in the superficial femoral artery (SFA) is not well established. We studied associations of the ankle-brachial index (ABI) and leg symptoms with MRI-measured plaque area and percent lumen area in the SFA in participants with and without lower-extremity peripheral arterial disease (PAD).Methods and Results—Four hundred twenty-seven participants (393 with PAD) underwent plaque imaging of the first 30 mm of the SFA. Twelve 2.5-mm cross-sectional images of the SFA were obtained. Outcomes were normalized plaque area, adjusted for artery size (0 to 1 scale, 1=greatest plaque), and lumen area, expressed as a percent of the total artery area. Adjusting for age, sex, race, smoking, statins, cholesterol, and other covariates, lower ABI values were associated with higher normalized mean plaque area (ABI <0.50:0.79; ABI 0.50 to 0.69:0.73; ABI 0.70 to 0.89:0.65; ABI 0.90 to 0.99:0.62; ABI 1.00 to 1.09:0.48; ABI 1.10 to 1.30:0.47 (P trend <0.001)) and smaller mean percent lumen area (P trend <0.001). Compared with PAD participants with intermittent claudication, asymptomatic PAD participants had lower normalized mean plaque area (0.72 versus 0.65, P=0.005) and larger mean percent lumen area (0.30 versus 0.36, P=0.01), adjusting for the ABI and other confounders.Conclusions—Lower ABI values are associated with greater MRI-measured plaque burden and smaller lumen area in the first 30 mm of the SFA. Compared with PAD participants with claudication, asymptomatic PAD participants have smaller plaque area and larger lumen area in the SFA.Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00520312.