Feasibility of comprehensive heart‐brain MRI for investigating hemodynamic coupling in aging

Abstract

AbstractBackgroundCardiovascular risk factors have been linked with dementia risk in aging adults. However, mechanisms underlying heart‐brain hemodynamic coupling and effects on the brain remain unclear. 4D flow MRI is uniquely poised to systematically evaluate complex hemodynamics along the heart‐brain pathway. Owing to advancements yielding shorter scan times, 4D flow MRI can be acquired in approximately 7 minutes (heart) and 10 minutes (brain). This supports practical add‐on of 4D flow MRI to neuroimaging scans for comprehensive heart‐brain MRI evaluation in under an hour. We aimed to build a heart‐brain MRI acquisition and analysis framework to study relationships between hemodynamics and brain structure with age.Method17 healthy participants (age = 53.5±16.3[24‐76] years) underwent heart‐brain MRI at 3T (MAGNETOM Prisma, Siemens, Erlangen, Germany), including a free‐breathing whole‐chest 4D flow MRI research sequence, intracranial dual‐venc 4D flow MRI research sequence, and T1‐ and T2‐weighted structural neuroimaging. Participants were cognitively healthy and screened for history of cardiovascular and cerebrovascular problems that may influence blood flow. 4D flow MRI was used to evaluate blood flow velocities in the aorta and Circle of Willis (Figure 1: left). Mean velocity was determined on a voxel‐wise basis over the entire cardiac cycle. Volumetric and cortical thickness analysis was performed with FreeSurfer (v7.3; Figure 1: right). Left and right hippocampal and amygdala volumes were averaged and corrected for intracranial head size. We examined relationships between hemodynamics, volume and thickness measures, and age using Pearson correlations and multiple regression.ResultMean aortic velocity was associated with age (r = ‐0.59, p = 0.012), hippocampal volume (r = 0.68, p = 0.003), amygdala volume (r = 0.59, p = 0.012), and inferior temporal thickness (r = 0.49, p = 0.044). Figure 2. Mean velocity in the Circle of Willis (r = ‐0.49, p = 0.048), amygdala volume (r = ‐0.66, p = 0.004) and inferior temporal thickness (r = ‐0.60, p = 0.010) were also associated with age. Using multiple regression, mean aortic velocity was associated with hippocampal volume (p = 0.018) adjusting for age.ConclusionThis study demonstrates capture of comprehensive heart and brain data in a single imaging exam for assessment of age‐related relationships in hemodynamics and brain structure. Heart‐brain MRI is a promising tool for evaluation of hemodynamic coupling along the entire heart‐brain pathway. Grant support: NIH NIA P30AG059988, P30AG072977, K01AG080070; NINDS R21NS122511: