FLAIR imaging using nonselective inversion pulses combined with slice excitation order cycling and k-space reordering to reduce flow artifacts

High-signal artifacts produced by cerebrospinal fluid (CSF) flow can advers ely affect fluid-attenuated inversion recovery (FLAIR) imaging of the brain and spinal cord. This study explores the use of a nonslice-selective inver sion pulse to eliminate CSF flow artifacts together with a technique called "K-space Reordered by Inversion-time for each Slice Position" (KRISP) to a chieve constant contrast in a multislice acquisition. Theory shows that wit h this method the CSF point spread function (PSF) has a minimum at the cent er and attenuated side lobes, providing CSF suppression, but residual edge signals remain. The PSF for brain is only mildly attenuated and signals for extended regions are not attenuated. KRISP FLAIR sequences were assessed i n 15 patients (10 brain and five spinal cord cases). The images showed redu ced CSF and blood flow artifacts and higher conspicuity of the cortex, meni nges, ventricular system, brainstem, and cerebellum when compared with conv entional FLAIR sequences. (C) 2001 Wiley-Liss, Inc.