Abstract 17357: Magnetic Resonance Imaging Detected Intraplaque Hemorrhage and Expansive Remodeling in Superficial Femoral Artery

Abstract

Introduction: Compared to coronary and carotid arteries, there is much less knowledge on atherosclerotic plaque characteristics and their clinical relevance in lower-extremity arteries. Magnetic resonance (MR) vessel wall imaging allows for in vivo detection of intraplaque hemorrhage (IPH), which has been consistently associated with increased risks for clinical events in coronary and carotid artery disease. Objective: In a pilot study, we sought to estimate the prevalence of IPH in peripheral artery disease and examine plaque progression in the presence of IPH. Methods: Ten patients with ankle brachial index <0.90 in one or both legs were recruited. A 3D MR imaging protocol with a large coverage (30 or 45 cm in the head-feet direction) and isotropic resolution (voxel size: 0.8x0.8x0.8 mm 3 ) was used to scan bilateral legs in the coronal plane from the common femoral artery bifurcation to the popliteal artery at baseline and 6 months later. Images were reformatted into axial slices for detailed visualization of vessel wall. Following previous publications on carotid MRI, IPH was detected as hyperintense signals on heavily T1-weighted images. Superficial femoral artery (SFA) segments (3 cm in length) with IPH were identified, of which lumen and outer wall were segmented on black-blood images (motion-sensitized flow suppression for improved vessel wall delineation) to measure plaque progression and remodeling. Image analysis was performed in a blinded fashion without knowing time relationship between serial images. Results: Twenty SFAs were analyzed. After excluding 4 arteries with total occlusion, 5 out of the 16 arteries (31%) or 50% of the subjects showed IPH in 1 or more SFA segments. After 6 months, there was significant progression in vessel wall area in SFA segments with IPH (mean ± standard deviation: 43.5 ± 13.9 mm 2 versus 47.3 ± 17.3 mm 2 , p=0.045), which resulted in outer wall expansion (mean [95% confidence intervals]: +3.9 mm 2 [+0.4, +7.4], p=0.035) rather than lumen reduction (-0.02 mm 2 [-2.6, +2.5], p=0.99). Conclusions: MR vessel wall imaging revealed that IPH is likely a common feature in femoral atherosclerosis. SFA segments with IPH showed expansive remodeling in 6 months, of which the clinical significance needs to be further studied.