Heterogeneity of MR signal intensity mapped onto brain surface models

Heterogeneity of gray matter signal intensity can be demonstrated on some MR sequences, particularly FLAIR. Quantifying this heterogeneity is of interest as it may distinguish among different cortical areas. Gray matter segmentation fails on FLAIR data due to overlap of gray and white matter signal intensity. This overlap also compromises region of interest based approaches. Although volume rendering can visualize some of these differences, it is non quantitative and averaging gray and white matter cannot be avoided. To overcome these obstacles we obtained T1 weighted data in addition to FLAIR data. T1 weighted data provides strong gray/white contrast, allowing a cortical surface to be extracted. Volume based registration of the FLAIR data set to the T1 data allows FLAIR signal intensity data to be mapped onto the surface generated from the T1 dataset. This allows regional FLAIR signal intensity differences to be visualized and to be compared across subjects.