FAIR exempting separate T1 measurement (FAIREST): A novel technique for online quantitative perfusion imaging and multi-contrast fMRI

Abstract

A new pulse sequence, dubbed FAIR exempting separate T1 measurement (FAIREST) in which a slice-selective saturation recovery acquisition is added in addition to the standard FAIR (flow-sensitive alternating inversion recovery) scheme, was developed for quantitative perfusion imaging and multi-contrast fMRI. The technique allows for clean separation between and thus simultaneous assessment of BOLD and perfusion effects, whereas quantitative cerebral blood flow (CBF) and tissue T1 values are monitored online. Online CBF maps were obtained using the FAIREST technique and the measured CBF values were consistent with the off-line CBF maps obtained from using the FAIR technique in combination with a separate sequence for T1 measurement. Finger tapping activation studies were carried out to demonstrate the applicability of the FAIREST technique in a typical fMRI setting for multi-contrast fMRI. The relative CBF and BOLD changes induced by finger-tapping were 75.1 ± 18.3 and 1.8 ± 0.4%, respectively, and the relative oxygen consumption rate change was 2.5 ± 7.7%. The results from correlation of the T1 maps with the activation images on a pixel-by-pixel basis show that the mean T1 value of the CBF activation pixels is close to the T1 of gray matter while the mean T1 value of the BOLD activation pixels is close to the T1 range of blood and cerebrospinal fluid. Copyright © 2001 John Wiley & Sons, Ltd.