Imaging Study Of Vascular Wall Of LEPAD HRMR In The Elderly

Part one:The study on methodology of high-resolution magnetic resonance vessel wall imaging for lower extremity arteriesIn this study, a magnetic resonance (MR) black-blood vessel wall imaging sequence of3DMERGE, with blood suppression technique of iMSDE was used to image the femoral artery. The MR data of femoral artery were acquired coronally with two stacks. After the MR images were obtained, the images in two stacks will be fused at MR workstation. Femoral arteries were divided into three segments:bifurcation, adductor canal and distal. The MR vessel wall images of femoral artery were analyzed by using a custom-designed semi-automatic software. Five subjects with lo femoral arteries were randomly selected for intra-reader reproducibility study. By using semi-automatic software, an experienced radiologist reviewed the femoral artery MR images of5subjects twice with2month time interval. The intraclass correlation coefficient within two measurements of was0.972(95%confidence interval,0.941-0.986, p≤0.001).Part two:High-resolution magnetic resonance vessel wall imaging of lower extremity peripheral artery disease (LEPAD) in older populationOBJECTIVE:To evaluate the imaging characteristics of LEPAD in older population using high-resolution magnetic resonance vessel wall imaging.MATERIALS AND METHODS:Forty-four old subjects (≥60years old) without clinical symptoms underwent femoral artery MR vessel wall imaging with3D MERGE sequence. The femoral artery was divided into three segments:bifurcation, adductor canal and distal segment. The prevalence of plaque and calcification in femoral artery was analyzed. The maximum wall thickness (MWT) at axial images after2D reconstruction was measured. The stenosis and plaque eccentricity index at the location of MWT for each plaque were determined. The plaque burden measurements were compared among three segments of femoral artery and between left and right side. The correlation coefficient between MWT and luminal stenosis was calculated using Pearson correlation analysis.RESULTS:The prevalence of plaques in this study was63.6%, of which50.0%occurred in the bifurcation segment and its plaque burden was significantly greater than that in other segments (p<0.05). In addition, the MWT was found to be significantly correlated with degree of stenosis (r=0.769, p<0.001). Particularly,11.1%of subjects with0%stenosis had plaques in the femoral artery. The plaque burden in the right side was higher than that in left side, but the difference was not statistically significant. The MWT in the bifurcation segment (2.26±0.80mm) was significantly greater than that in the adductor canal (1.64±0.29mm) and distal segments (1.88±0.69mm)(all p≤0.001).CONCLUSIONS:The prevalence of plaques in this study was63.6%, the MWT was found to be significantly correlated with degree of stenosis. The MWT in the bifurcation segment was significantly greater than that in the adductor canal and distal segments.Part three:The study on correlation between LEPAD and clinical and laboratory risk factorsAIM:To assess the correlation between femoral artery atherosclerotic lesions and clinical/laboratory indicators in asymptomatic older population using high-resolution magnetic resonance vessel wall imaging.MATERIALS:Forty-four old subjects (≥60years old) without clinical symptoms underwent femoral artery MR vessel wall imaging with3D MERGE sequence. The femoral artery was divided into three segments:bifurcation, adductor canal and distal segment. The prevalence of plaque and calcification in femoral artery was analyzed. The maximum wall thickness (MWT) at axial images after2D reconstruction was measured. The stenosis and plaque eccentricity index at the location of MWT for each plaque were determined. The correlation coefficient between lesions and clinical risk factors were calculated using Regression analysis. RESULTS:Gender and maximum wall thickness, stenosis, eccentricity index were significantly correlated (p=0.002,0.033,0.006). Height and maximum wall thickness was significantly correlated (p=0.001), weight and maximum wall thickness was significantly correlated (p=0.045). Hypertension and the prevalence of plaque in peripheral artery were significantly correlated (OR=4.64, p=0.023). The prevalence of plaque in seventy to eighty age group was higher than that in60-69age group. There was no significant correlation between Ankle-Brachial index and maximum wall thickness ().CONCLUSIONS:Hypertension is significantly associated with LEPAD. The prevalence of LEPAD increases with age. No significant correlation was found between ABI and MWT and most of plaques were observed in subjects with normal ABI value, suggesting that ABI will underestimate disease severity and the necessity of MR vessel wall imaging for assessment of LEPAD.