CT AND MRI FINDINGS AFTER STEREOTAXIC RESECTION OF BRAIN-LESIONS

Objective: To describe postoperative CT and MRI findings and their tim e course in uncomplicated cases after stereotactic volumetric resectio ns of brain lesions. Materials and methods: One-hundred twenty-eight i maging studies (CT, 86; MRI, 42), performed 6 to 2 years after 52 ster eotactic operations, were retrospectively reviewed and analyzed in rel ation to time of surgery in cases without complications. Results: The extent of resection bed did not change during the first week after ope ration; reduction of size then began and continued up to 3-6 months. M ass effect and edema showed no change during the first 4 days, then la ter regressed gradually. Pneumocephalus was found in 58% of cases in t he first 3 weeks, but never later. Benign, surgically-induced enhancem ent appeared at the margins of encephalotomy and retractor trajectory at the end of the first postoperative week, became more prominent duri ng the following weeks, and lasted up to 3-5 months. In the majority o f cases enhancement prevented recognition of the residual tumor. Dural enhancement was observed at the craniotomy site very early after the operation and persisted up to 1 year. Meningeal enhancement over conve xities was found in 44% of MRI studies. Conclusion: Extent of the rese ction bed, mass effect, edema, and pneumocephalus show, in uncomplicat ed cases, a regular regression during the postoperative period. The ti me course of enhancement is complex and can be a source of diagnostic misinterpretation.