Lesion detection at seven Tesla in multiple sclerosis using magnetisation prepared 3D-FLAIR and 3D-DIR

To examine the feasibility and value of 7 T 3D T2-weighted Fluid Attenuated Inversion Recovery (FLAIR) and Double Inversion Recovery (DIR) MR sequences for lesion detection in multiple sclerosis (MS).

High-resolution 3D-FLAIR and 3D-DIR MR sequences at 7 T were obtained using magnetisation preparation (MP), and compared with 2D-T2-weighted and 3D-T1-weighted sequences in 10 MS patients and five healthy controls. We determined contrast ratios and counted lesions according to anatomical location.

MR imaging at 7 T was safe and allowed multi-contrast imaging within clinically acceptable imaging times. Lesion to white matter (WM) and grey matter (GM) contrast ratios were higher in 3D-MP-FLAIR and 3D-MP-DIR compared with 2D-T2 and 3D-T1. Cortical (mixed+intra-cortical) and total lesion counts were 97/592 on 3D-MP-FLAIR and 100/558 on 3D-MP-DIR compared with 84/384 on 2D-T2 and 42/442 on 3D-T1. More juxta-cortical lesions were seen with 3D-MP-FLAIR (205) and 3D-MP-DIR (133) than with 2D-T2 (125) and 3D-T1 (70). Finally, higher numbers of lesions were found for deep WM lesions: 176 for 3D-MP-FLAIR and 196 for 3D-MP-DIR vs. 155 for 2D-T2 and 131 for 3D-T1.

Near isotropic 3D-MP-FLAIR and 3D-MP-DIR allows high quality T2-weighted MR imaging in MS at 7 T, improving (cortical) lesion detection.