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

A new pulse sequence, dubbed FAIR exempting separate T-1 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 T-1 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 T-1 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 T-1 maps with the activation images on a pixel-by-pixel basis show that the mean T-1 value of the CBF activation pixels is close to the T-1 of gray matter while the mean T-1 value of the BOLD activation pixels is close to the T-1 range of blood and cerebrospinal fluid. Copyright (C) 2001 John Wiley & Sons, Ltd.