Study On Characteristics Of Lower Extremity Artery Athero-sclerotic Plaque Using High-Resolution Magnetic Resonance Vessel Wall Imaging

Part I:Methodology of Lower Extremity Artery Magnetic Resonance Vessel Wall Imaging and Image AnalysisThis study aimed to investigate the imaging characteristics of lower extremity artery atherosclerosis using 3D high resolution magnetic resonance vessel wall imaging techniques. The imaging protocol includes three sequences, such as 3D MERGE,3D T2-VISTA and 3D SNAP sequences. The black-blood techniques were applied to all those three sequences for better delineation of vessel wall and plaque features. The components of atherosclerotic plaques in femoral arteries were identified according to the signal patterns on different imaging sequences. To ensure sufficient longitudinal coverage when imaging the femoral artery, moving-table techniques and custom-made slidable supporting plate were used to acquire two stacks with 40mm overlap.The MR images were analyzed by trained reviewers using custom-designed semi-automatic software (3D-CASCADE). The burden (wall thickness and normalized wall index) and the distribution of atherosclerotic plaques in femoral arteries were measured. The plaque compositional characteristics including calcification, lipid-rich necrotic core, and intraplaque hemorrhage or thrombus were also determined on multi-contrast 3D vessel wall images. To determine the plaque distribution, the femoral arteries were divided into four segments:common femoral artery (CFA), proximal segment of superficial femoral artery (pSFA), adductor canal segment (AC), and popliteal artery segment (PA).Part II:Study on Correlation of Lower Extremity Artery Atherosclerosis with Carotid Plaque and Cerebral Ischemic LesionsObjective To evaluate the relationship of lower extremity artery atherosclerosis with carotid plaque and cerebral ischemic lesions.Materials and Methods A total of 48 old subjects (≥60 years old) without recent cardiovascular symptoms (within 6 months) were recruited into this study. All subjects underwent MR imaging for femoral arteries, carotid arteries and brain. Two trained reviewers interpreted the MR images using 3D CASCADE software. The wall thickness and normalized wall index of femoral and carotid arteries and the volume of ischemic lesions in basal ganglia area were measured. Presence or absence of carotid plaque and lipid-rich necrotic core was assessed. The correlations between femoral artery plaque burden and carotid plaque features and cerebral ischemic lesions were analyzed.Results Of 48 recruited subjects,71.4% were found to have lower extremity atherosclerosis. The prevalence of atherosclerotic plaque in CFA, pSFA, AC and PA was 45.8%,41.7%,37.5 and 50.0%, respectively. Among four segments of femoral artery, the AC (55.2%) and PA (55.6%) segments showed the highest NWI. For plaque burden measurement of maximum wall thickness, a significant correlation between carotid artery and CFA can be observed (r=0.304, p=0.036). There was significant correlation of atherosclerosis between femoral and carotid arteries. The presence of atherosclerotic plaque in CFA was significantly associated with left carotid atherosclerosis (r=0.745, p<0.001). In addition, presence of lipid-rich necrotic core in left and right carotid artery was found to be correlated with atherosclerosis in pSFA (r=0.314, p=0.030) and PA (r=0.300, p=0.038), respectively. We found the femoral artery maximum wall thickness was significantly associated with the volume of ischemic lesions in basal ganglia area (r=0.446, p=0.009).Conclusions Lower extremity atherosclerotic disease is prevalent in asymptomatic old adults, particularly in popliteal segment. The association of femoral atherosclerosis with carotid plaque and cerebral ischemic lesions suggests that the femoral artery atherosclerosis might be an indicator for carotid plaque and cerebral ischemic disease.PartⅢ:Study on Characteristics of Lower Extremity Atherosclerosis in Diabetic Patients by MR imagingObjectives To assess the characteristics of burden, compositions, and distribution of femoral artery atherosclerotic disease in patients with diabetes.Materials and Methods A total of 19 diabetic patients (Mean age:64.1±8.1; 9 males) with evidence of femoral artery disease were included in this study. A 3D multi-contrast MR imaging protocol, including 3D MERGE,3D T2-VISTA, and 3D SNAP sequences, was performed for all subjects. The MR images were interpreted by two trained reviewers using custom-designed software of 3D CASCADE. The plaque burden, compositional features (calcification, lipid-rich necrotic core, and intraplaque hemorrhage/thrombus), and the distribution of femoral artery atherosclerosis were evaluated.Results In femoral artery of patients with diabetes, atherosclerotic disease was found in 94.7% of CFAs,89.5% of pSFAs,84.2% of ACs, and 94.7% of PAs, respectively. Among four segments of femoral artery, PA and AC showed the highest plaque burden. In addition, the prevalence of femoral artery calcification, lipid-rich necrotic core, and intraplaque hemorrhage/thrombus was 89.5%,94.7%, and 21.1%, respectively.Conclusions In diabetic patients, the most severe femoral artery atherosclerotic disease tends to involve the popliteal artery and adductor canal segments. The calcified and lipid-rich atherosclerotic plaques are prevalent in patients with diabetes.