Pseudoprogression after radiation therapy for glioblastoma

Axial postcontrast T1 magnetic resonance images show a right parietal glioblastoma before subtotal resection (A), in the immediate postoperative period (B), and one month (C), three months (D), six months (E), and nine months (F) after completion of involved field radiation therapy. The reemergence of enhancement after radiation therapy (C, D) raised concern for tumor recurrence; however, these abnormalities spontaneously resolved over time (E, F), consistent with pseudoprogression related to radiation necrosis.