Objective: The purpose of this study was to compare the contrast enhancement of lesions of the brain revealed by gadolinium-enhanced optimized fast fluid-attenuated inversion recovery (FLAIR) MR imaging with that of lesions on gadolinium-enhanced optimized T1-weighted spin-echo MR imaging.
Subjects and methods: Using computer simulations, we optimized the fast FLAIR parameters (TR, TEeff, and inversion time) and the T1-weighted spin-echo parameters (TR and TE) to provide maximum difference in signal intensity between enhancing lesions of the brain and white matter. Seventy-six consecutive patients referred for single-dose gadolinium-enhanced MR imaging of the brain underwent both optimized techniques, which were matched for spatial resolution, bandwidth, and number of excitations. The gadolinium-enhanced fast FLAIR and T -weighted spin-echo MR images were evaluated independently by two observers for number and size of enhancing lesions and for the degree of gray-white matter differentiation. Contrast-to-noise ratios were measured for enhancing lesions 1.0 cm or larger in diameter using 8 x 8 pixel regions of interest in the enhancing lesions and normal white matter.
Results: The most revealing parameters for fast FLAIR MR imaging proved to be a TR of 1500 msec, an inversion time of 683 msec, and a TEeff of 16 msec. For T1-weighted spin-echo MR imaging, the optimized parameters were a TR of 550 msec and a TE of 16 msec. In 28 patients, we saw enhancing lesions of the brain with at least one MR imaging technique. More lesions were seen on the T1-weighted spin-echo sequence (n = 141) than on the fast FLAIR sequence (n = 94) (p < .03). Gray-white matter differentiation was significantly better on the fast FLAIR sequence (p < .001). Contrast-to-noise ratios of enhancing lesions were greater on the T1-weighted spin-echo sequence (p < .001).
Conclusion: In this study, optimized gadolinium-enhanced conventional T1-weighted spin-echo MR imaging proved superior to gadolinium-enhanced fast FLAIR MR imaging in revealing lesions of the brain.