MRI Estimation of Global Brain Oxygen Consumption Rate

Abstract

Measuring the global cerebral metabolic rate of oxygen (CMRO(2)) is a valuable tool for assessing brain vitality and function. Measurement of blood oxygen saturation (HbO(2)) and flow in the major cerebral outflow and inflow vessels can provide a global estimate of CMRO(2). We demonstrate a rapid noninvasive method for quantifying CMRO(2) by simultaneously measuring venous oxygen saturation in the superior sagittal sinus with magnetic resonance susceptometry-based oximetry, a technique that exploits the intrinsic susceptibility of deoxygenated hemoglobin, and the average blood inflow rate with phase-contrast magnetic resonance imaging. The average venous HbO(2), cerebral blood flow, and global CMRO(2) values in eight healthy, normal study subjects were 64%+/-4%, 45.2+/-3.2 mL per 100 g per minute, and 127+/-7 micromol per 100 g per minute, respectively. These values are in good agreement with those reported in literature. The technique described is noninvasive, robust, and reproducible for in vivo applications, making it ideal for use in clinical settings for assessing the pathologies associated with dysregulation of cerebral metabolism. In addition, the short acquisition time (approximately 30 seconds) makes the technique suitable for studying the temporal variations in CMRO(2) in response to physiologic challenges.

A novel ex vivo method for measuring whole brain metabolism in model systems

“…It has been reported using magnetic resonance imaging (MRI) that the human brain accounts for ~20% of total body oxygen consumption (Jain, Langham, & Wehrli, 2010). While this has not been studied in Drosophila , we were interested to compare larval brain OCR levels with whole larva respiration levels.…”

Non-invasive assessment of neonatal brain oxygen metabolism: A review of newly available techniques

“…CBF is usually measured by phase-contrast MRI[20, 22–26] or arterial spin labeling (ASL) MRI[27–32]. Arterial oxygenation, Y a , is usually measured by pulse oximetry[20, 24, 32], or assigned an assumed value given the highly oxygen content and small variation in arterial blood[18, 19]. The main difference among these MRI-based CMRO2 techniques is the approach by which venous oxygenation, Y v , is determined.…”

“…The main difference among these MRI-based CMRO2 techniques is the approach by which venous oxygenation, Y v , is determined. Based on the Y v measurement methods, these techniques can be divided into four categories: susceptibility effect in extravascular tissue[17], phase angle in intravascular blood signal[18], gas-inhalation modulated fMRI signal[21], and transverse relaxation time (T2) of blood signal[20, 32]. Among these four categories, two blood T2-based CMRO2 method[24, 32] and a phase angle-based method[33] have been shown to be feasible to apply in the neonate, which will be discussed later.…”

“…MR susceptometry measurement of Y v relies on the relative magnetic susceptibility difference between intravascular blood and surrounding tissue[18]. This susceptibility difference affects the intravascular water protons, which results in a phase-shift of the MR signal that is correlated with the intravascular blood oxygenation (Fig.…”

A Model for Resolving Flow Parameters for MRI-Neuroimaging Application

“…The use of fundamental mathematical concepts based on the solutions of Bloch NMR equation for MRI is definitely a novel idea (Odoh and De, 2009;Awojoyogbe et al, 2009;Jain et al, 2010;Emetere et al, 2014) though there are still unanswered questions on the extent of its applicability. The Bloch NMR equations are basically about magnetizations of flowing spins under given radiofrequency excitations and are dependent on the flow velocity of spins for measuring blood flow rate-velocity and volume flow rates.…”