Cerebral oxygen extraction fractionMRI: Techniques and applications

Abstract

The human brain constitutes 2% of the body's total mass but uses 20% of the oxygen. The rate of the brain's oxygen utilization can be derived from a knowledge of cerebral blood flow and the oxygen extraction fraction (OEF). Therefore, OEF is a key physiological parameter of the brain's function and metabolism.OEF has been suggested to be a useful biomarker in a number of brain diseases.With recent advances in MRI techniques, several MRI-based methods have been developed to measure OEF in the human brain. These MRI OEF techniques are based on the T 2 of blood, the blood signal phase, the magnetic susceptibility of blood-containing voxels, the effect of deoxyhemoglobin on signal behavior in extravascular tissue, and the calibration of the BOLD signal using gas inhalation.Compared to 15 O PET, which is considered the "gold standard" for OEF measurement, MRI-based techniques are non-invasive, radiation-free, and are more widely available. This article provides a review of these emerging MRI-based OEF techniques. We first briefly introduce the role of OEF in brain oxygen homeostasis. We then review the methodological aspects of different categories of MRI OEF techniques, including their signal mechanisms, acquisition methods, and data analyses. The strengths and limitations of the techniques are discussed.Finally, we review key applications of these techniques in physiological and pathological conditions.

Effects of Anesthesia on Cerebral Blood Flow and Functional Connectivity of Nonhuman Primates

“…Multi-echo EPI allows for utilizing the TE-domain information to enhance fMRI analysis compared to traditional EPI in rsfMRI studies [ 47 ]. Cerebral physiology, including CBF, cerebral blood volume, CMRO2, and oxygen extraction fraction, can be measured using perfusion MRI, BOLD fMRI, and cerebral oxygen extraction fraction MRI techniques in humans and animals [ 48 , 49 ]. Functional connectivity can be estimated quantitatively using rsfMRI, positron emission tomography (PET), near-infrared spectroscopy (NIRS), electroencephalography (EEG), and magnetoencephalography (MEG) [ 50 ].…”

Advances in differential diagnosis of cerebrovascular diseases in magnetic resonance imaging: a narrative review

“…Using MRI can detect flowing blood and puzzling vascular malformations as well as demyelination disease without beam-hardening artifacts and any ionizing radiation (8,9). Compared to PET, MRI completes one scan faster with a temporal resolution of ~3 seconds (9)(10)(11). These advantages make MRI tests the leading neuroimaging techniques in differential diagnosis of CVDs.…”

“…The strength of this technique is having good spatial resolution of 1 mm that is far beyond the resolution of other imaging techniques. Correspondingly, BOLD-based MRI is particularly useful in determining prior mini-strokes (11,12).…”

Vascular space occupancy asymmetric spin echo (VASO‐ASE) for non‐invasive quantification of cerebral oxygen extraction fraction

“…Quantitative measurements of cerebral oxygen extraction fraction (OEF), or the ratio of oxygen consumed by brain tissue to that which is delivered, provide valuable functional information regarding tissue health in patients with cerebrovascular and neurodegenerative diseases. [1][2][3][4] OEF can be quantified using 15 O-positron emission tomography (PET) 1,5,6 ; however, this technique requires ionizing radiation, arterial blood sampling, and an on-site cyclotron due to the short 122 s half-life of 15 O, rendering it impractical as a generalizable diagnostic tool. Alternative T 2 -relaxation-under-spin-tagging (TRUST) 7 and asymmetric spin echo (ASE) 8 methods have been proposed for measuring OEF non-invasively in vivo using MRI.…”

“…Quantitative measurements of cerebral oxygen extraction fraction (OEF), or the ratio of oxygen consumed by brain tissue to that which is delivered, provide valuable functional information regarding tissue health in patients with cerebrovascular and neurodegenerative diseases 1–4 …”