title: Calibration and validation of TRUST MRI for the estimation of cerebral blood oxygenation.
abstract: Recently, a T(2) -Relaxation-Under-Spin-Tagging (TRUST) MRI technique was developed to quantitatively estimate blood oxygen saturation fraction (Y) via the measurement of pure blood T(2) . This technique has shown promise for normalization of fMRI signals, for the assessment of oxygen metabolism, and in studies of cognitive aging and multiple sclerosis. However, a human validation study has not been conducted. In addition, the calibration curve used to convert blood T(2) to Y has not accounted for the effects of hematocrit (Hct). In this study, we first conducted experiments on blood samples under physiologic conditions, and the Carr-Purcell-Meiboom-Gill T(2) was determined for a range of Y and Hct values. The data were fitted to a two-compartment exchange model to allow the characterization of a three-dimensional plot that can serve to calibrate the in vivo data. Next, in a validation study in humans, we showed that arterial Y estimated using TRUST MRI was 0.837 ± 0.036 (N=7) during the inhalation of 14% O2, which was in excellent agreement with the gold-standard Y values of 0.840 ± 0.036 based on Pulse-Oximetry. These data suggest that the availability of this calibration plot should enhance the applicability of T(2) -Relaxation-Under-Spin-Tagging MRI for noninvasive assessment of cerebral blood oxygenation.
authors: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA. hanzhang.lu@utsouthwestern.edu
authors: Hanzhang
authors: H
authors: Lu
authors: Feng
authors: F
authors: Xu
authors: Ksenija
authors: K
authors: Grgac
authors: Peiying
authors: P
authors: Liu
authors: Qin
authors: Q
authors: Qin
authors: Peter
authors: P
authors: van Zijl
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