CMR-assessed aortic arch stiffness is associated with brain tissue integrity assessed by diffusion tensor imaging in patients with hypertension
Journal of Cardiovascular Magnetic Resonance volume 17, Article number: P401 (2015)
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.
78 patients with hypertension (35 men, mean age 46 ± 1 years) were prospectively included. Aortic imaging was performed using 1.5T MRI. To assess PWV over the aortic arch, one-directional through-plane velocity-encoded MRI was performed, planned perpendicular to the ascending aorta and additionally transecting the proximal descending aorta (Figure 1). Brain MRI was performed on 3.0 T MRI. Linear regression analysis was performed to assess the association between aortic arch PWV and brain macrostructure (brain volume and white matter lesion volume) and microstructure (fractional anisotropy [FA], mean diffusivity [MD], axial diffusivity [AxD], and radial diffusivity [RD] (Pierpaoli et al. Neuroimage 2001)). Models were adjusted for several cardiovascular risk factors.
Aortic arch PWV was not associated with brain macrostructure. In contrast, aortic arch PWV was associated with changes in white matter (FA: β = -0.30, p = 0.011; MD: β = 0.31; p = 0.005; AxD: β = 0.24, p = 0.040; RD: β = 0.33; p = 0.002) and grey matter integrity (MD: β = 0.28, p = 0.006; AxD: β = 0.27, p = 0.012; RD: β = 0.29, p = 0.006) (Table 1). This effect was independent of age, gender, body mass index, smoking, mean arterial blood pressure, duration of hypertension and cerebrovascular disease.
Our data suggest that aortic arch stiffness is independently associated with changes in brain tissue integrity in patients with hypertension. Subtle changes in brain microstructure are related to increased stiffness of the aortic arch, even in absence of overt brain abnormalities.
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Sala, M., van den Berg - Huysmans, A., van der Grond, J. et al. CMR-assessed aortic arch stiffness is associated with brain tissue integrity assessed by diffusion tensor imaging in patients with hypertension. J Cardiovasc Magn Reson 17 (Suppl 1), P401 (2015). https://doi.org/10.1186/1532-429X-17-S1-P401