Quantifying the Brain Metabolism Underlying Task-Based BOLD Imaging
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Healthy
- Sponsor
- Massachusetts General Hospital
- Enrollment
- 30
- Locations
- 1
- Primary Endpoint
- Brain positron emission tomography (PET) imaging signals
- Status
- Not yet recruiting
- Last Updated
- 3 years ago
Overview
Brief Summary
The investigators will be studying brain glucose and oxygen metabolism using hybrid PET/fMRI imaging to better understand how decoupling between brain glucose and oxygen metabolism relates to the processing of unpredictable sensory signals.
Detailed Description
The proposed research consists of one experiment, combining positron emission tomography (PET) and magnetic resonance imaging (MRI) techniques to simultaneously estimate the cerebral metabolic rates of glucose (CMRglc) and oxygen (CMRO2), and their ratio (oxygen:glucose index; OGI). These outcome measures will be collected in the context of a behavioral intervention presenting subjects with predictable and unpredictable stimuli, and attended and unattended stimuli. Functional PET uses a slow infusion of 2-\[18F\]-fluro-deoxyglucose (FDG) to estimate regional CMRglc, measuring relative changes in radiotracer uptake between blocks of task and rest. Dual-calibrated fMRI uses a sequence of hyperoxic (increased O2) and hypercapnic (increased CO2) challenges, along with a specialized sequence of MRI scans (estimating cerebral blood flow and blood-oxygen level-dependent signal) to estimate absolute CMRO2. All subjects will be scanned, and each will complete the same behavioral intervention. First, the investigators will aim to assess the reliability of this hybrid imaging technique by having subjects complete two identical scan sessions. Second, the investigators will deliver a behavioral intervention to test the relationship between stimuli predictability, CMRglc, CMRO2, and OGI. This experimental design is capable of producing effects observable in single subjects, and prior studies using fPET and dual-calibrated fMRI have produced effect sizes that our sample size is more than adequate to detect.
Investigators
Christin Y. Sander, PhD
Assistant Professor
Massachusetts General Hospital
Eligibility Criteria
Inclusion Criteria
- •Adults aged 21-
- •No contraindications to MRI or PET scanning.
- •Right-handed.
- •Fluent to speak, read, and understand English.
Exclusion Criteria
- •Adults unable to consent
- •Contraindications to fMRI scanning and PET scanning (including the presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia)
- •Inability to lie motionless in the scanner
- •Pregnancy, seeking or suspecting pregnancy, or breastfeeding
- •History of major head trauma
- •Intracranial lesion
- •Cardiovascular disorders, including heart disorders or high blood pressure \[\>155/95\]
- •Breathing problems such as severe asthma, emphysema, or pulmonary disease
- •Bleeding disorder, or use of anticoagulants
- •Bladder obstruction, urinary problems, or history of impaired elimination
Outcomes
Primary Outcomes
Brain positron emission tomography (PET) imaging signals
Time Frame: after PET image analysis and with study completion, an average of 1 year
Changes in glucose metabolism will be quantified from brain PET images
Functional magnetic resonance imaging (fMRI) signals
Time Frame: after fMRI image analysis and with study completion, an average of 1 year
Changes in oxygen metabolism will be quantified from dual-calibrated fMRI
Oxygen-glucose index
Time Frame: after PET/fMRI image analysis and with study completion, an average of 1 year
Ratio of cerebral metabolic rates of glucose and oxygen from PET and fMRI signals