| Background and PurposeAtherosclerosis(AS)is a systemic disease and AS in two or more vascular beds is called polyvascular disease(polyVD).The predictive value of atherosclerosis in multiple vascular beds is higher than that in single vascular bed.Therefore,it is particularly important for stroke prevention to actively assess the polyVD and its distribution characteristics.White matter lesions(WML)are abnormal changes in the white matter of the lateral ventricle or subcortex.Some studies have found that WML is associated with cognitive impairment,depression,stroke,and etc.It is reported that AS in single vascular bed is an effective indicator for predicting the severity of WML.Magnetic resonance(MR)vessel wall imaging,which can clearly show the atherosclerotic plaque morphology and identify the plaque components,is often used to represent the polyVDThis study aimed to analyze the characteristics and distribution of AS in different vascular beds using high resolution three-dimensional(3D)multicontrast MR vessel wall imaging in asymptomatic elderly population.The main purposes of this study are as follows:1.To investigate the imaging characteristics and correlation of multiple vascular beds(carotid,thoracic and lower extremity arteries)AS in asymptomatic elderly subjects;2.To investigate the relationship between characteristics of AS in two vascular beds(lower extremity arteries and carotid arteries)and WML severityMaterials and MethodsAll asymptomatic elderly subjects(>60 years old)underwent MR imaging of the whole brain,thoracic aorta,bilateral carotid and lower extremity arteries.Brain was imaged on a 3.0T MR scanner by acquiring T2-FLAIR and T1W sequences.Thoracic aorta,carotid and lower extremity arteries were imaged by acquiring multicontrast sequences including 3D MERGE,3D TOF,3D VISTA,and 3D SNAP sequences.Two radiologists with more than 5 years of experience in vessel wall imaging used 3D-CASCADE software to quantitatively analyze the plaque morphological characteristics in three vascular beds.Qualitative analysis of plaque components included intraplaque hemorrhage(IPH),lipid nucleus(LRNC)and calcification(CA);WML score was 0-9 according to WML visual rating scale,and severe WMLs were defined as WML score greater than 3(WML>3).Experiment 1:A total of 55 asymptomatic elderly subjects were enrolled in this study.The incidence of plaque and plaque components in each vascular bed were measured.One-Way ANOVA method was used to compare between plaque characteristics among the three vascular beds.Logistic regression was used to predict the occurrence of AS involving more than 2 vascular beds.Spearman correlation analysis was used to investigate the correlation among three vascular bed plaque characteristics.Experiment 2:A total 112 elderly subjects were recruited.The plaque features of carotid and lower extremity arteries were evaluated and compared between subjects with WML?3 and those with WML>3.Logistic regression and receive-operating-characteristic-curve(ROC)analyses were used to determine the value of plaque features in discriminating severe WML.ResultsExperiment 1:The average age of the subjects was 71.5 ±6.2 years,of which 23 were males.Among the 55 subjects,the incidences of atherosclerosis in carotid,thoracic and lower extremity arteries were 54.55%,85.45%and 58.18%,respectively.The incidences of plaque components in carotid,thoracic and lower extremity arteries were:IPH:9.1%,20%,5.5%;LRNC:43.6%,74.5%,27.3%;CA:20%,12.7%,25.5%,respectively.Among all subjects,67.3%had multiple vascular beds atherosclerosis,3.6%had no lesions in three vascular beds,29.1%had one vascular bed lesion,34.5%had two vascular bed lesions and 32.7%had three vascular bed lesions.Our study showed that the morphology of the three vascular beds were related to each other.There was a correlation between IPH of thoracic aorta and lower extremity artery(r=0.480,p<0.001).Age was also found to be an independent risk factor for occurrence of AS in multiple vascular beds(OR,2.772;95%CI,1,275-6.029;p=0.010).Experiment 2:In total,112 subjects(mean age,72.0 ± 5.6 years;49 males)were included.Subjects with WML>3 showed significantly greater carotid WA and femoral artery stenosis and higher incidence of carotid CA(45.2%vs.22.2%)and femoral artery CA(48.8%vs.23.5%)and LRNC(54.8%vs.28.4%)compared to those with WML?3(all p<0.05).Carotid artery CA and femoral artery CA,LRNC and stenosis(with 10%increment)were found to be significantly associated with severe WML before and after adjusted for clinical factors(odds ratio ranged from 1.51 to 3.79,all p<0.05).ROC analysis showed,in discriminating severe WML,the area-under-the-curve increased from 0.615 to 0.754 after combining femoral artery LRNC and stenosis with carotid CA compared to the carotid CA alone.ConclusionsTo sum up,our results show that:(1)Asymptomatic elderly people generally have atheroscleosis in multiple vascular beds,especially the incidence of thoracic aortic plaque is high.Age is an effective indicator for predicting the occurrence of polyVD.There was a correlation between plaque morphology in each vascular bed.Therefore,it is necessary to screen multiple vessel beds in the elderly for prevention of ischemic stroke.(2)Characteristics of lower extremity arteries atherosclerosis determined by MR vessel wall imaging have added value for carotid atherosclerosis in determining severity of WML. |
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