Morphological features of MS lesions on FLAIR* at 7 T and their relation to patient characteristics

Abstract

Recently, a new MRI technique was developed at 3 Tesla (T), called fluid attenuated inversion recovery* (FLAIR*). In this study, we implemented FLAIR* in an existing MS cohort at 7 T, to investigate whether we could corroborate results of previous 7 T studies that introduced specific MS lesion characteristics. Furthermore, we aimed to investigate the meaning of these lesion characteristics by relating them to clinical characteristics of the MS patient. Three-dimensional FLAIR and T2*-weighted images of 33 MS patients and 7 healthy controls were fused into FLAIR* images. Lesion type, signal intensity and morphology were analysed on FLAIR*, side-by-side with the original FLAIR and T2*, and correlated with clinical characteristics using Spearman's rho. Three morphological features of MS lesions were visualised: (1) central vessel (CV) within lesions, present in 78 % of total MS lesions; (2) hypointense rims around MS lesions, present in eight patients; (3) FLAIR* lesions that were hypointense at T2*, present in 13 patients. The presence of hypointense (rims around) lesions was not related to clinical characteristics. The simultaneous presence of rimlike lesions and hypointense lesions within MS patients was significantly correlated (ρ = 0.52, P < 0.01). We conclude that the implementation of the new MRI technique FLAIR* at ultra-high-field 7 T combines and corroborates the results of preceding 7 T research, by showing three morphological features of MS lesions. In addition, our study shows that these phenomena do not show a relation to patient's clinical characteristics and cannot be allocated to certain MS disease subtypes.