The patient was injected with 10 mCi of 18-FDG and after allowing 30 minutes for localization, emission and transmission data were acquired. 18-FDG images demonstrate hypometabolic areas in the right frontal and occipital lobes with smaller foci of increased metabolism near the cortex that have the same intensity as grey matter. Smaller foci of increased metabolism may represent residual normal cortex or tumor that have the same intensity as cortical grey matter. In combination, the studies suggested recurrent tumor in both foci. 18-FDG brain studies may be difficult to interpret when tumor foci are of the same intensity as grey matter and in a peripheral location as normal cortex.
Careful registration is crucial for proper interpretation.