Cerebral blood flow resistance mapping to identify amyloid-related imaging abnormality (ARIA) risk in Alzheimer's disease
openNIA - National Institute on Aging
ABSTRACT
The overall goal of this work is to refine a novel magnetic resonance imaging (MRI) protocol to assess a
cerebrovascular resistance index (CVRi), to apply this protocol in patients with Alzheimer’s disease (AD) to test
fundamental hypotheses regarding how CVRi is altered in the setting of elevated amyloid-beta () plaque
retention, and to assess how CVRi adjusts following pharmacological reduction of cerebral . Findings are
intended to serve as a necessary prerequisite for a larger, longitudinal study that will assess how CVRi may help
to triage patients for emerging anti-amyloid therapies based on personalized signatures of parenchymal health.
More specifically, accumulation of cerebral in the arterial vessel walls of patients with AD can reduce
vasoreactivity and increase cerebrovascular resistance, and this effect can be assessed using the CVRi defined
as the ratio of the mean arterial blood pressure (MAP; mmHg) and cerebral blood flow (CBF; ml blood/100g
tissue/min). CVRi has been reported to be directly related to accumulation in the setting of AD and partly
reflects vasotoxicity, vasoconstriction, and decreased response to changes in blood pressure. Furthermore,
heterogeneous distribution of can result in variable vascular resistance and capillary blood transit time
heterogeneity, which our lab has shown in other populations to alter oxygen extraction at the tissue level. I have
shown that it is possible to non-invasively measure altered capillary transit times by modeling arterial, tissue,
and venous blood arrival on non-invasive arterial spin labeling MRI. This method has primarily been applied in
patients with cerebrovascular diseases, however, in preliminary data provided here I provide evidence that
vascular transit dynamics are also altered in the setting of accumulation, elevated vascular resistance, and
neurodegeneration. This issue is fundamental, as recently approved anti-amyloid therapies alter vascular
dynamics and can lead to extravasation events, such as cerebral microbleeds. As such, it is becoming even
more relevant to develop an understanding of how alters vascular health and whether measures of vascular
health have relevance for portending cerebral microbleeds, which occur in a significant group of treated patients.
Here, I propose to refine methods for assessing the CVRi non-invasively in vivo with MRI, and to pair this
assessment with our established measures of vascular transit to better characterize these relationships in
patients with AD before and after pharmacological manipulation of cerebral
The study will also be overseen by mentors with complementary expertise in imaging science, cognitive
neurology, amyloid angiopathy, neuroradiology, and statistics with an ongoing collaboration, and will leverage
recruitment and resources available from an ongoing longitudinal neuroimaging study of anti-amyloid treatments.
Up to $76K
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