MAPPING CEREBRAL VASOREACTIVITY WITHOUT A VASOACTIVE STIMULUS: AN APPLICATION IN ALZHEIMER'S DISEASE

• Grant number: 22/12153-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2022
• Effective date (End): November 30, 2023
• Field of knowledge: Health Sciences - Medicine - Medical Radiology
• Principal Investigator: Renata Ferranti Leoni
• Grantee: Isadora Camargo Ferreira
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Alzheimer's Disease (AD) is a neurodegenerative disease that can lead to dementia. Although the etiology is still not well established, studies point to increasing support for the vascular hypothesis of Neurofibrillary Tangles, in contrast to the Senile Plaques theory. Therefore, changes in cerebral hemodynamics can be observed even before the clinical symptoms of the disease. An important hemodynamic aspect is the cerebral vasoreactivity (CVR), which is the characteristic of smooth muscle in cerebral blood vessels to dilate or contract in response to metabolic changes or vasoactive stimuli. There is evidence that AD patients have CVR alterations. Among the methods used to perform CVR assessments, there is the magnetic resonance imaging (MRI) technique based on the BOLD (Blood Oxygenation Level Dependent) contrast, associated with a vasoactive stimulus, which may be breathing holding, acetazolamide injection or inhalation of CO2, with the aim of changing the concentration of CO2 in the blood and then promoting vasodilation. Recent studies have shown that there is a correlation between a certain frequency band of the BOLD signal acquired in a resting state with the concentration of CO2 in the blood, making CVR mapping possible without the challenges of hypercapnia. However, there is still no consensus on what is the optimal frequency range. Thus, the aim of this study is to investigate CVR in patients with AD, using BOLD contrast magnetic resonance images acquired at rest. We will use the Open Access Series of Imaging Studies 3 (OASIS-3) database and methodology previously developed and implemented by researchers from the InBrain group, where the project will be carried out.