Investigation of leptomeningeal enhancement in MS: a postcontrast FLAIR MRI study.

Objective: To investigate possible leptomeningeal contrast enhancement using postcontrast fluid-attenuated inversion recovery (FLAIR) MRI as an additional marker of inflammation in patients with multiple sclerosis (MS).

Methods: A cohort of 112 patients (73 women) with clinically definitive MS or a clinically isolated syndrome suggestive of CNS demyelination were included. A pathologic control group of 5 stroke patients was also examined. MRI was performed on a 3T system including FLAIR, T2-weighted, T1-weighted-contrast injection, followed by T1-weighted and FLAIR.

Results: Of the 112 patients, 39 had an acute relapse at the time of MRI. In total, 96 contrast-enhancing lesions were identified on postcontrast T1-weighted images. The pathologic control group demonstrated the sensitivity of postcontrast FLAIR images demonstrating leptomeningeal enhancement in all cases. In contrast, only 1 out of 112 examined patients with MS showed a single area of abnormal leptomeningeal contrast enhancement.

Conclusions: In contrast to intraparenchymal blood-brain barrier (BBB) dysfunction that is frequently seen in patients with MS, BBB dysfunction of leptomeningeal vessels is usually not detectable in patients with early MS.