FIGURE 2. Serial pairings of sagittal MRI and SPECT images for 15-y-old boy with exophytic brain stem glioma. Third column is black-and-white version of original SPECT images. Baseline images (A) are compared with scans at 8 (B) and 12 (C) mo, both of which show increased signal on ^99mTc-MIBI SPECT but no change on MRI. Final panel (D) demonstrates increased tumor on MRI at 16 mo, accompanied by decreased signal from SPECT.