A selected set of short-axis slices from the normal MCAT heart at a 0.634 cm voxel size. Starting at the top we have (a) the true source distribution, (b) AC+SC+RC+PC, (c) AC+SC+RC, (d) AC+SC, (e) NC, and (f) FBP. No thresholding of slices was employed and each row is displayed relative to its own maximum.