Snapshot MR Technique to Measure OEF Using Rapid Frequency Mapping

Abstract

Magnetic resonance (MR)-based oxygen extraction fraction (OEF) measurement techniques that use blood oxygen level-dependent (BOLD)-based approaches require the measurement of the R 2 ' decay rate and deoxygenated blood volume to derive the local oxygen saturation in vivo. We describe here a novel approach to measure OEF using rapid local frequency mapping. By modeling the MR decay process in the static dephasing regime as two separate dissipative and oscillatory effects, we calculate the OEF from local frequencies measured across the brain by assuming that the biophysical mechanisms causing OEF-related frequency changes can be determined from the oscillatory effects. The Parameter Assessment by Retrieval from Signal Encoding (PARSE) technique was used to acquire the local frequency change maps. The PARSE images were taken on 11 normal volunteers, and 1 patient exhibiting hemodynamic stress. The mean MR-OEF in 11 normal subjects was 36.66 ± 7.82%, in agreement with positron emission tomography (PET) literature. In regions of hemodynamic stress induced by vascular steal, OEF exhibits the predicted focal increases. These preliminary results show that it is possible to measure OEF using a rapid frequency mapping technique. Such a technique has numerous advantages including speed of acquisition, is noninvasive, and has sufficient spatial and temporal resolution.

Determination of oxygen extraction fraction using magnetic resonance imaging in canine models with internal carotid artery occlusion

“…Our experiments revealed good repeatability of MRI-based OEF measurements among scans. Additionally, OEF is a sensitive surrogate to predict brain tissues at risk 16 26 . In our study, comparison of the OEF map and TTC staining slices showed good consistency between the brain regions with elevated OEF and ischaemic foci on the slices ( Fig.…”

Oxygen extraction fraction measurement using quantitative susceptibility mapping: Comparison with positron emission tomography

“…One of these approaches relies on the measurement of T2* or T2’ relaxation associated with the presence of paramagnetic deoxygenated hemoglobin (deoxy-Hb) in brain tissue (blood oxygen dependent level, BOLD) to measure tissue OEF. 5–8 An alternative method utilizing a spin tagging technique has been developed, allowing quantification of OEF based on the measurement of T2 relaxation in venous blood. 9,10 However, most applications in these techniques were only for normal subjects, and there were few patient’s studies.…”