Figure 1.

Gadolinium-enhanced magnetic resonance images of a patient who was treated with 4500 cGy of radiation therapy for a residual pituitary adenoma (A, arrow) following incomplete surgical resection. Isodose curves of radiotherapy (shown in red, with percentages of maximal dose in white) demonstrate the isocenter of radiation therapy at the residual adenoma. Fifteen years after surgery and radiotherapy, the patient developed a glioblastoma multiforme involving the left and right hemispheres, crossing at the corpus callosum (B). The new lesion was radiographically distinct from the residual adenoma (B, arrow) and occurred within the port of previous radiation therapy.