Figure 7.

Example of classification differences in the occipital cortex. As in those figures, the segmentation of the T1-weighted images alone is shown as a blue-green overlay, and the multimodal segmentation with the added FLAIR images in red-orange. In the left column the input MPRAGE and FLAIR image are shown. The yellow arrows show loss of contrast in the T1-weighted MPRAGE images, which was retained in the FLAIR images. The right column show the classification outcome in the MPRAGE alone segmentation (top, in green) and in the MPRAGE+FLAIR combination (in red-yellow). The yellow arrows pointing to loss of contrast show in the MPRAGE alone segmentation that these areas achieved a classification of about 0.1–0.2 as gray matter, but 0.9 or more in the combined MPRAGE+FLAIR combination. The images in the bottom right corner show the difference in the classification outcome. Note that the parts adjacent to the cortex where the MPRAGE alone segmentation attributed a higher classification probability than the MPRAGE+FLAIR combination (blue arrows) were not gray matter, but connective tissue. This is apparent from the inspection of the input MPRAGE image, where the dura is evident as a continuous sheet running over the left half of the figure, isointense to gray matter in the MPRAGE data but giving low signal in the FLAIR image.