None listed
Conditions
Brief summary
The brain has a high metabolic rate and it is therefore important that local blood flow is closely matched to brain cell activation and metabolism (neurovascular coupling), and that brain blood flow increases to limit build up of metabolic waste products, such as carbon dioxide (cerebrovascular CO2 reactivity). The aim of this project is to conduct pilot studies to establish state-of-the-art methods for assessing neurovascular coupling and cerebrovascular CO2 reactivity within the Centre for Advanced Magnetic Resonance Imaging (CAMRI) at the University of Auckland. These studies will provide a foundation for future work investigating cerebrovascular dysfunction in clinical populations.
Interventions
MRI Safety Screening Form and Health Screening Questionnaire
Delivered by a trained investigator. Delivered face-to-face.
Delivered once. Takes 5-10 min to complete this paper form.
Measurement of cerebral blood flow and cerebral metabolic rate for oxygen using MRI
Assessed under baseline/resting conditions, and during neurovacular coupling and CO2 reactivity testing described below.
Delivered by a trained radiologist and investigator team. Delivered face-to-face.
Neurovascular coupling test i
MRI Safety Screening Form and Health Screening Questionnaire Delivered by a trained investigator. Delivered face-to-face. Delivered once. Takes 5-10 min to complete this paper form. Measurement of cerebral blood flow and cerebral metabolic rate for oxygen using MRI Assessed under baseline/resting conditions, and during neurovacular coupling and CO2 reactivity testing described below. Delivered by a trained radiologist and investigator team. Delivered face-to-face. Neurovascular coupling test in MRI scanner Participants will view a black/white flickering radial checkerboard visual stimulus alternated with a neutral grey screen baseline. Delivered by a trained radiologist and investigator team. Delivered face-to-face. Delivered as 5 x ~30s exposures, separated by ~30 s. Procedure conducted on a single occasion. Cerebrovascular CO2 reactivity Participants alternate between breathing room air and a premixed gas mixture with a mildly elevated partial pressure of CO2 (5% CO2, 21% O2, balance N2) via a Douglas bag (~2 min). Delivered by a trained radiologist and investigator team. Delivered face-to-face. Procedure conducted on a single occasion. Cardiac MRI Conventional ECG-gated retrospective cine cardiac MRI acquisitions will be acquired parallel and perpendicular to the cardiac long-axis. Delivered by a trained radiologist and investigator team. Delivered face-to-face. Delivered once. Takes ~15-20 min to complete.
Sponsors
University of Auckland
Study design
Allocation
Non-randomised trial
Primary purpose
Educational / counselling / training
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
• Healthy individuals • Not taking any prescription or over-the-counter medications (other than oral contraceptive pill) • Men and women • Aged over 18 years • Body mass index less than 30 kg/m2 (i.e. kilograms divided by height in metres squared)
Exclusion criteria
• Body mass index less than 18 kg/m2 (i.e. kilograms divided by height in metres squared) • Smokers • Alcohol intake > 28 units/week • Users of recreational drugs • Cardiovascular disease (e.g., coronary heart disease, hypertension) • Significant arrhythmias (e.g., atrial fibrillation, previous VT / significant ventricular ectopy) • Severe respiratory disease (e.g., chronic obstructive pulmonary disease) • Metabolic disease (e.g., type II diabetes) • Cancer • Connective tissue or inflammatory disease • Neurological or cerebrovascular disease • Infection or pyrexial illness • Thyroid disorders • Hepatic or renal impairment • Outside the stated age range • Current pregnancy • Underlying medical conditions, which in the opinion of the Investigator place the participant at unacceptably high risk for participating in the study • Inability to fully or appropriately provide consent (e.g., language issue, reading capability)
Outcome results
None listed