Anne Brandts

Association of Aortic Arch Pulse Wave Velocity with Left Ventricular Mass and Lacunar Brain Infarcts in Hypertensive Patients: Assessment with MR Imaging

PURPOSE To assess the possible association between aortic arch stiffness, which may cause hypertensive cardiovascular disease, and cardiac and cerebral end-organ damage in patients with hypertension by using magnetic resonance (MR) imaging. MATERIALS AND METHODS Approval from the local institutional review board was obtained, and patients gave informed consent. Fifty patients with hypertension (31 women and 19 men; mean age +/- standard deviation, 49.2 years +/- 12.7; mean systolic blood pressure, 152.1 mm Hg +/- 22.3; mean diastolic blood pressure, 88.0 mm Hg +/- 13.1), compliant for treatment with antihypertensive medication, were prospectively enrolled for MR examinations of the aorta, heart, and brain with standard pulse sequences. Aortic arch pulse wave velocity (PWV), left ventricular (LV) mass, LV systolic and diastolic function, lacunar brain infarcts, and periventricular and deep white matter hyperintensities (WMHs) were assessed. Univariable and multiple linear and logistic regression analyses were used for statistical analyses. RESULTS Mean aortic arch PWV was 7.3 m/sec +/- 2.5. Aortic arch PWV was statistically significantly associated with LV mass (r = 0.30, P = .03, beta = 1.73); indexes of systolic function, including ejection fraction (r = -0.38, P = .01, beta = -1.12); indexes of diastolic function, including the ratio of early diastolic to atrial contraction peak filling rates (r = -0.44, P < .01, beta = -0.11); lacunar brain infarcts (odds ratio [OR] = 1.8, P < .01); and periventricular (OR = 1.5, P = .01) and deep (OR = 1.6, P = .01) WMHs. Aortic arch PWV was statistically significantly associated with LV mass (r = 0.37, P = .03, beta = 2.11) and lacunar brain infarcts (OR = 1.8, P = .04), independent of age, sex, and hypertension duration, but not with indexes of diastolic and systolic function and WMHs. CONCLUSION Aortic arch stiffness is associated with LV mass and lacunar brain infarcts in hypertensive patients, independent of age, sex, and hypertension duration; these manifestations of end-organ damage may help to risk stratify hypertensive patients.

Cerebral Perfusion and Aortic Stiffness Are Independent Predictors of White Matter Brain Atrophy in Type 1 Diabetic Patients Assessed With Magnetic Resonance Imaging

OBJECTIVE To identify vascular mechanisms of brain atrophy in type 1 diabetes mellitus (DM) patients by investigating the relationship between brain volumes and cerebral perfusion and aortic stiffness using magnetic resonance imaging (MRI). RESEARCH DESIGN AND METHODS Approval from the local institutional review board was obtained, and patients gave informed consent. Fifty-one type 1 DM patients (30 men; mean age 44 ± 11 years; mean DM duration 23 ± 12 years) and 34 age- and sex-matched healthy control subjects were prospectively enrolled. Exclusion criteria comprised hypertension, stroke, aortic disease, and standard MRI contraindications. White matter (WM) and gray matter (GM) brain volumes, total cerebral blood flow (tCBF), total brain perfusion, and aortic pulse wave velocity (PWV) were assessed using MRI. Multivariable linear regression analysis was used for statistics, with covariates age, sex, mean arterial pressure, BMI, smoking, heart rate, DM duration, and HbA1c. RESULTS Both WM and GM brain volumes were decreased in type 1 DM patients compared with control subjects (WM P = 0.04; respective GM P = 0.03). Total brain perfusion was increased in type 1 DM compared with control subjects (β = −0.219, P < 0.05). Total CBF and aortic PWV predicted WM brain volume (β = 0.352, P = 0.024 for tCBF; respective β = −0.458, P = 0.016 for aortic PWV) in type 1 DM. Age was the independent predictor of GM brain volume (β = −0.695, P < 0.001). CONCLUSIONS Type 1 DM patients without hypertension showed WM and GM volume loss compared with control subjects concomitant with a relative increased brain perfusion. Total CBF and stiffness of the aorta independently predicted WM brain atrophy in type 1 DM. Only age predicted GM brain atrophy.

Left ventricular diastolic function assessment from three‐dimensional three‐directional velocity‐encoded MRI with retrospective valve tracking

To compare parameters describing left ventricular (LV) diastolic function obtained with three‐dimensional (3D) three‐directional velocity‐encoded (VE) MRI with retrospective valve tracking and two‐dimensional (2D) one‐directional VE MRI in patients with ischemic heart failure. Second, to compare classification of LV diastolic function, and in particular for discriminating restrictive filling patterns, with both MRI techniques versus Doppler echocardiography.

Quantitative assessment of left ventricular function in humans at 7 T.

The purpose of this study was to determine the ability of 7 T cardiac magnetic resonance imaging (MRI) to quantitatively assess left ventricular volumes, mass, and function from cine short‐axis series and left ventricular diastolic filling from velocity‐encoded MRI in 10 healthy volunteers. As comparative “gold standard,” the corresponding measures obtained at 1.5 T were taken. Left ventricular volumes, function, and mass were obtained by manual image segmentation. Trans‐mitral flow graphs were obtained from 2D one‐directional through‐plane velocity‐encoded MRI planned at the mitral valve in end‐systole. Imaging at 7 T MRI was successful in 80% of the examinations. Assessment of left ventricular volumes, function, and mass at 7 T showed good agreement with 1.5 T (no significant differences between variables describing volumes, function, and mass with intraclass correlation coefficients ranging from 0.77 to 0.96). Trans‐mitral stroke volume and the ratio between early and atrial peak filling rate showed strong agreement at both field strengths (no significant differences between stroke volumes and filling ratios with intraclass correlation coefficients 0.92 for stroke volumes and 0.77 for peak filling ratios). In conclusion, this study shows that assessing left ventricular volumes, function, and flow is feasible at 7 T MRI and that standardized MRI protocols provide similar quantitative results when compared with 1.5 T MRI. Magn Reson Med, 2010.

Increased Aortic Stiffness Measured by MRI in Patients With Type 1 Diabetes Mellitus and Relationship to Renal Function

OBJECTIVE Arterial stiffness is an important predictor of cardiovascular disease in type 1 diabetes mellitus (DM). The purpose of this study was to investigate whether type 1 DM is associated with increased aortic stiffness as measured by MRI, independently of renal dysfunction, and to evaluate the relationship between aortic stiffness and renal function within the normal range in patients with type 1 DM. MATERIALS AND METHODS We included 77 patients with type 1 DM (mean age, 46 ± 12 years) and 36 healthy control subjects matched for age and renal function in a cross-sectional study. Exclusion criteria consisted of microalbuminuria, renal impairment, aortic valve disease, and standard MRI contraindications. Aortic pulse wave velocity (PWV), a marker of aortic stiffness, was assessed by MRI. Renal function was expressed as the estimated glomerular filtration rate (GFR). Mann-Whitney U test and Spearmans correlation analysis were performed. Stepwise multivariable logarithmic regressions with forward entry analysis for estimated GFR were performed to study the relationship with aortic PWV using interaction terms for type 1 DM. RESULTS Patients with type 1 DM without microalbuminuria or renal impairment show increased aortic PWV compared with control subjects (p < 0.05). There was a statistically significant correlation between estimated GFR and aortic PWV in patients with type 1 DM (p < 0.001; r = -0.427) and control subjects (p = 0.002; r = -0.502), with aortic PWV being increased in patients with type 1 DM for each given estimated GFR within the normal range (p < 0.001). The decrease in estimated GFR per increase in aortic PWV was similar for patients with type 1 DM and control subjects (p, not significant). CONCLUSION Our data show that aortic stiffness, as measured by MRI, is increased and inversely related to renal function in patients with type 1 DM with normal albuminuria and normal estimated GFR.

Right coronary artery flow velocity and volume assessment with spiral K‐space sampled breathhold velocity‐encoded MRI at 3 tesla: Accuracy and reproducibility

To evaluate accuracy and reproducibility of flow velocity and volume measurements in a phantom and in human coronary arteries using breathhold velocity‐encoded (VE) MRI with spiral k‐space sampling at 3 Tesla.

Quantification of common carotid artery and descending aorta vessel wall thickness from MR vessel wall imaging using a fully automated processing pipeline

To develop and evaluate a method that can fully automatically identify the vessel wall boundaries and quantify the wall thickness for both common carotid artery (CCA) and descending aorta (DAO) from axial magnetic resonance (MR) images.

Aortic Arch Stiffness Is Associated With Incipient Brain Injury in Patients With Hypertension

BACKGROUND It has been shown that microstructural brain tissue damage can be detected in hypertension patients, while the underlying mechanisms are not fully understood. We aim to explore the association between diffusion tensor imaging (DTI) measures of brain injury and aortic arch pulse wave velocity (PWV) in hypertensive patients without clinically manifest cerebrovascular disease. METHODS Sixty-six hypertension patients (30 men, mean age 46±14 years) were prospectively included. Aortic arch PWV was assessed using velocity-encoded magnetic resonance imaging (VE-MRI). Brain tissue integrity was assessed by using DTI. Multivariable linear regression analysis was performed to assess the association between aortic arch PWV and fractional anisotropy (FA), axial diffusivity (AxD), and radial diffusivity (RD). RESULTS Increased aortic arch PWV was associated with decreased white matter FA (β = -0.30, P = 0.018), increased gray matter AxD (β = 0.28, P = 0.016), and increased gray and white matter RD (β = 0.30, P = 0.008 and β = 0.35, P = 0.003, respectively). These effects were independent of age, sex, body mass index, smoking, and white matter hyperintensity (WMH) volume. CONCLUSIONS Aortic arch stiffness relates to incipient brain injury before overt brain abnormalities may become apparent in patients with hypertension.

Associations between aortic pulse wave velocity and aortic and carotid vessel wall thickness in patients with hypertension: assessment with MRI

Hypertension puts continuous strain on arteries, resulting in arterial wall alterations such as vessel wall thickening and vessel wall stiffening. Due to the availability of suitable acoustic windows, vessel wall thickness (VWT) is studied traditionally by ultrasound from intima-media thickness in the carotid arteries. Arterial vessel wall stiffness can be expressed by Pulse Wave Velocity (PWV), the propagation speed of the systolic wave front through the aorta. For studying direct associations between PWV and VWT, it is desired to sample VWT in the aorta.

CMR-assessed aortic arch stiffness is associated with brain tissue integrity assessed by diffusion tensor imaging in patients with hypertension

Background Increased aortic stiffness may lead to insufficient flow wave dampening and subsequent transmission of excessive pulsatile energy towards end-organs such as the brain. It has been shown that CMR-assessed aortic stiffness may augment cerebral small vessel disease in patients with hypertension, as assessed by conventional structural magnetic resonance imaging (MRI). However, in addition to these overt brain abnormalities, currently it is unknown whether aortic stiffening relates to subtle changes in brain tissue integrity, which may be a precursor to overt brain abnormalities. Diffusion tensor imaging (DTI) in the brain has been used to evaluate such subtle changes in tissue integrity. The aim of this study was to assess the association between aortic arch pulse wave velocity (PWV) as a marker of arterial stiffness and brain changes assessed by conventional structural MRI as well as DTI in patients with hypertension.