Quantitative evaluation of oxygenation in venous vessels using T2‐Relaxation‐Under‐Spin‐Tagging MRI

Abstract

Noninvasive measurement of cerebral venous oxygenation can serve as a tool for better understanding fMRI signals and for clinical evaluation of brain oxygen homeostasis. In this study a novel technique, T2-Relaxation-Under-Spin-Tagging (TRUST) MRI, is developed to estimate oxygenation in venous vessels. This method uses the spin labeling principle to automatically isolate pure blood signals from which T2 relaxation times are determined using flow-insensitive T2-preparation pulses. The blood T2 is then converted to blood oxygenation using a calibration plot. In vivo experiments gave a baseline venous oxygenation of 64.8 ؎ 6.3% in sagittal sinus in healthy volunteers (n ‫؍‬ 24). Reproducibility studies demonstrated that the standard deviation across trials was 2.0 ؎ 1.1%. The effects of repetition time and inversion time selections were investigated. The TRUST technique was further tested using various physiologic challenges. Hypercapnia induced an increase in venous oxygenation by 13.8 ؎

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

“…The regional voxel-based methods model the effect of deoxygenated Hb in the capillary/post capillary bed on MR-measured transverse relaxation T 2 to quantify the voxel-wise oxygen saturation, which can be combined with ASL CBF measurement to yield CMRO 2 . Among these are quantitative BOLD 9 and QUIXOTIC. 10 However, these methods involve complex models, are time intensive and numeric simulations and phantom experiments show that reliable estimates are achieved only in the presence of very high signal-to-noise ratio.…”

“…11,12,25 Although these methods provide global rather than spatially resolved measures, they are robust, and allow much higher temporal resolution and CMRO 2 quantification in clinically feasible scan times. Recently proposed methods such as phase- Cerebral oxygen metabolism in neonates with CHD V Jain et al based regional oxygen metabolism 14 and T 2 relaxation under spin tagging (TRUST) 9 fall under this category. Our observations in anesthetized infants suggest that both MRI and optics-based techniques could be effectively integrated into future standard-of-care monitoring and management of critically ill neonates.…”

Effect of Hypoxia and Hyperoxia on Cerebral Blood Flow, Blood Oxygenation, and Oxidative Metabolism

“…where (Lu and Ge, 2008;Lu et al, 2012). This technique was found to be highly reproducible and can be conducted within 4 minutes.…”

The Influence of Carbon Dioxide on Brain Activity and Metabolism in Conscious Humans

“…Measurement of CMRO 2 was performed on a 3 Tesla MRI system (Philips Medical Systems, Best, The Netherlands) using a noninvasive technique (Lu and Ge, 2008;Xu et al, 2009). Briefly, CMRO 2 in units of mmol/min was calculated using Fick principle:…”

“…The CBF was measured with phase-contrast MRI, Y a was determined by a pulse oximeter; Y v was estimated with a recently developed technique, T2-relaxation-under-spintagging MRI (Lu and Ge, 2008). The details of the imaging parameters are described in Supplementary Text.…”