The Assessment Of Aortic Compliance And Brachial Endothelial Function In Type2Diabetes Mellitus By Using3.0T High-resolution Magnetic Resonance Imaging

Part IComprehensive assessment of aortic compliance and brachial endothelial function in healthy volunteers by3.0T high-resolution MRI-a Feasibility studyObjective:To investigate the feasibility of assessing aortic arch pulse wave velocity(PWV), aortic distensibility(AD) and brachial artery flow-mediated dilation(FMD) of healthy volunteers by means of high-resolution magnetic resonance (MR) imaging at3.0T.Materials and Methods:A total of32healthy volunteers (24-37year old) underwent repeated twice high-resolution MRI to assess aortic arch PWV, ascending aorta(AA) AD, proximal descending aorta(PDA) AD, distal descending aorta(DDA) AD and FMD of the brachial artery in1-2hours. PWV was evaluated by2D Phase contrast(PC) velocity-encoded MR imaging with a4.7-7.8msec temporal resolution. Fiesta-cine MR imaging was used to assess AD and FMD with a18.75-31.25msec temporal resolution. The image quality of repeated twice scan was evaluated with4grade and the agreement between twice scan was tested with Kappa analysis. The reproducibility of results between repeated measurement for PWV, AA-AD, PDA-AD, DDA-AD and FMD were assessed with the intraclass correlation coefficient(ICC) analysis. The method of Bland-Altman plot was used to assess the agreement between repeated estimates.Results:All scan including PWV、AD and FMD can be completed in about half an hour for each examination. The image quality between repeated twice scan had good agreement(Kappa value0.776) with the score3.53,3.41, respectively. Reproducibility between repeated measurement was high for aortic PWV(4.33±0.88vs4.36±0.88m/s; ICCPWV=0.95, P<0.01), AA-AD(8.60±3.11vs8.59±3.10×10-3mmHg-1; ICCAA-AD=0.97, P<0.01), PDA-AD(6.95±2.44vs6.95±2.42×10-1ICCPDA-AD=0.99, P<0.01), DDA-AD(10.54±2.91vs10.55±2.90×10ICCDDA-AD=0.98, P<0.01) and FMD(24.94±12.55vs24.92±12.38%; ICCFMD=0.94, P<0.01). Good agreement between repeated measurement was found for aortic PWV(confidence interval[CI] between-0.55and0.50), AA-AD(CI between-0.11and0.12), PDA-AD(CI between-0.08and0.08), DDA-AD(CI between-0.23and0.21) and FMD(CI between-1.46and1.51).Conclusion:Comprehensive assessment of aortic compliance and brachial endothelial function can be completed in a single examination by3.0T high-resolution MRI with good reproducibility and be feasible in clinical application. Part ⅡThe combined effect of hypertension and type-2diabetes mellitus on aortic compliance and brachial endothelial dysfunction:an integrated study with3.0T MRIObjective:The purpose of this study was to investigate the combined effect of hypertension and type-2diabetes mellitus (DM2) on aortic stiffness and endothelial dysfunction by using an integrated3.0T MRI approach.Materials and Methods:A total of31non-hypertensive DM2patients(mean age55.4±8.5years;19male,12female) and31hypertensive DM2patients (mean age58.3±6.1years;18male,13female) underwent noninvasive3.0T MRI. Aortic distensibility(AD), aortic arch pulse-wave velocity (PWV) and brachial artery flow-mediated dilation (FMD) were assessed. Independent-Samples t-test and the Mann-Whitney U test were used to compare variables between groups as appropriate, while the chi-squared test was used for categorical variables. Pearson correlation analysis was performed to determine the relationship between measured parameters and to analyse the association between measured parameters and blood pressure. Univariable and multiple linear regression was used to determine the independent predictors of the measured parameters.Results:Compared with the non-hypertensive patients, the hypertensive patient showed lower AD at multiple levels (ascending aorta(AA):2.07±0.98×I0-3mm Hg-1vs.3.21±1.70×10-3mm Hg-1, p<0.01; proximal thoracic descending aorta(PDA):2.58±0.72×10-3mm Hg-1vs.3.58±1.47×10"3mm Hg-1, p<0.01; and distal descending aorta (DDA):3.11±1.84×10-3mm Hg-1vs.4.27±1.75×10-3mm Hg-1, p<0.01); faster PWV (7.46±2.28m/s vs.5.82±1.12m/s, p<0.05) and lower FMD (12.67±6.49%vs.20.66Q9.7%; p<0.01). Systolic blood pressure was independent predictors of PWV, AA-AD, DDA-AD and FMD. FMD was statistically significantly associated with PWV(r=-0.37, p<0.01) and AD(p<0.01)Conclusions:Hypertension has a contributive effect on aortic stiffness and endothelial dysfunction in DM2patients. Direct quantification of both aortic stiffness and endothelial dysfunction using one-stop high-resolution MRI may help stratify cardiovascular risks in DM2patients. Part ⅢAssociation of aortic compliance and brachial endothelial function with cerebral small vessel disease in type2diabetes mellitus patients:assessment with3.0T MRIObjective:To assess the possible association between aortic compliance and cerebral small vessel disease and between endothelial function and cerebral small vessel disease in type2diabetes mellitus(DM2) patients by using3.0T high resolution magnetic resonance imaging.Materials and Methods:Sixty two DM2patients (25women and37men; mean age:56.84±7.46years) were prospectively enrolled for noninvasive MR examinations of the aorta, brachial artery, and brain. Aortic distensibility(AD), aortic arch pulse wave velocity (PWV), flow-mediated dilation(FMD) of brachial artery, lacunar brain infarcts, and periventricular and deep white matter hyperintensities (WMHs) were assessed. Pearson and Spearman correlation analysis were performed to analyze the association of aortic arch PWV, AD and FMD with clinical data and biochemical test results. Univariable logistic regression analyses were used to analyze the association of aortic arch PWV, AD and FMD with cerebral small vessel disease. Multiple logistic regression analyses were used to find out the independent predictive factors of cerebral small vessel disease.Results:Mean aortic arch PWV was6.73±2.00m/s, ascending aorta AD (AA-AD) was2.64±1.49×10-3mm Hg-1, proximal thoracic descending aorta AD (PDA-AD) was3.08±1.25×10-3mm Hg-1, distal descending aorta AD (DDA-AD) was3.69±1.87×10-3mm Hg-1, FMD was16.67±9.11%. After adjustment for age, sex, smoke situation, diabetes duration and hypertension, PWV was statistically significantly associated with lacunar brain infarcts (OR=2.00;95%CI:1.14-3.2; p<0.05) and FMD was statistically significantly associated with periventricular white matter hyperintensities(OR=0.82;95%CI:0.71-0.95; p<0.05).Conclusion:Quantitative evaluation of aortic compliance and endothelial function by using3.0T high-resolution MRI may contribute to stratify the cardiovascular risk factors of DM2patients with a potential risk of cerebral small vessel disease.