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FIGURE 1. Representative slice at the level of the centra semiovalia from a 30-y-old healthy volunteer. (A) Segmented MRI used for PET simulation. GM ROIs are color coded (medial and lateral sections are pooled; left and right frontal lobe GM is green and red; left and right parietal GM is yellow and blue; WM voxels used for definition of mean WM value for MG-PVEc are gray; remaining WM is white). (B) Corresponding simulated PET slice. Also represented are the largest errors introduced in registration (with simultaneous display of segmented MRI and simulated PET with 6-pixel misalignment along the x-axis) (C); segmentation (with GM volumes of -9.7% and 10.1%) (D and E, respectively); and resolution estimate (with virtual PET as provided for feedback by the program, 8.7- and 13.2-mm FWHM) (F and G, respectively). Note that for registration and resolution estimate errors, detection of the error is possible by simple visual assessment.
