Contrast optimization of fluid-attenuated inversion-recovery (FLAIR) MR imaging in patients with high CSF blood or protein content

After surgical resection of a brain tumor or infection of the cerebrospinal fluid (CSF), elevated levels of blood by-products or protein contaminations are seen in the patient's CSF spaces. In fast fluid-attenuated inversion-recovery (FLAIR) imaging CSF signal is nulled by an appropriate choice of the inversion recovery time TI to improve the contrast between tissue structures adjacent to CSF-filled volumes. With contaminated CSF, however, the longitudinal relaxation time T-1 may change significantly, which results in an incomplete suppression in the FLAIR images, if standard inversion times are used. In this work, a fast single-voxel T-1 measurement pulse sequence with integrated T-1 calculation that allows determination the optimal TI value in 15 sec is presented. The method was tested in five patients after surgical resection of a brain tumor, where FLAIR MRI with and without contrast agent was performed to identify remaining tumor fragments at the margin of the resection cavity, Magn Reson Med 43:764-767, 2000. (C) 2000 Wiley-Liss, Inc.