A 53 year old right-handed man sought
medical attention because of a grand mal seizure. Brain biopsy revealed grade
IV astrocytoma. The MR demonstrates an area of mixed signal intensity on proton
density(PD) and T2-weighted(T2) images in a right parietal-occipital region.
The central rounded core of the lesion is seen after contrast enhancement to
contain cystic elements. Glucose metabolism is very low on the first PET study,
but has increased three months later. This suggests tumor recurrence, and
effectively rules out radiation necrosis.
Like Thallium SPECT, the PET scan has
been very useful in differentiating tumor recurrence and radiation necrosis. It
also allows specific targeting of the area of recurrence, which may be
surrounded by radiation necrosis in those patients who have received radiation.
Case contributed by Drs. C. D. Sturm
and R. Bucholz, St. Louis University.
