Comparison of gadolinium-enhanced fat-saturated T1-weighted FLAIR and fast spin-echo MRI of the spine at 3 T for evaluation of extradural lesions.

Abstract

Inversion recovery has been used to correct the loss of CSF and tissue contrast at 3 T versus 1.5 T but has not been formally investigated in the spine after IV administration of gadolinium-based contrast agent. The purpose of this study is to compare two sequences for gadolinium-enhanced spine imaging at 3 T--fat-saturated T1-weighted FLAIR and fat-saturated T1-weighted fast spin-echo (FSE)--for evaluation of extradural lesions and CSF-cord contrast. After IV administration of gadolinium-based contrast agent, fat-saturated T1-weighted FSE and FLAIR sequences were obtained in 156 MRI scans of 143 patients at 3 T. Three experienced radiologists compared these sequences for conspicuity differences in bone lesions, disk lesions, other epidural lesions, and cord-CSF contrast. A 7-point visual rating scale was used, with lower numbers indicating increased conspicuity on gadolinium-enhanced fat-saturated T1-weighted FLAIR and higher numbers indicating increased conspicuity on gadolinium-enhanced fat-saturated T1-weighted FSE. A slight increase in the conspicuity of gadolinium-enhancing bone lesions (mean score, 3.6; p < 0.0001), disk lesions (mean score, 3.5; p < 0.0001), and epidural lesions (mean score, 3.4; p < 0.0001) was seen on fat-saturated T1-weighted FLAIR compared with fat-saturated T1-weighted FSE. A higher degree of contrast between the spinal cord and CSF was seen on fat-saturated T1-weighted FLAIR, by a large margin (mean score, 1.8; p < 0.0001). All enhancing lesions seen on fat-saturated T1-weighted FSE images were also seen on fat-saturated T1-weighted FLAIR images. Decreased CSF-cord contrast at 3 T, as seen on T1-weighted FSE, can be regained by using T1-weighted FLAIR. Fat-saturated T1-weighted FLAIR may increase conspicuity of gadolinium-enhancing extradural lesions compared with fat-saturated T1-weighted FSE.