Is early (<12 month) imaging necessary after gamma knife radiosurgery for intracranial meningioma? A single-center retrospective review.

Introduction: Gamma knife radiosurgery (GKRS) is a safe, effective treatment for intracranial meningioma. Follow-up routinely includes MRI imaging to monitor treatment response. Ideal follow-up timing would be able to identify significant radiographic changes as early as possible while not being a cost burden to the healthcare system. In this study, we retrospectively reviewed the value of early ( < 12mo) imaging after GKRS for meningioma to inform the development of a thorough, cost-effective follow-up schedule.

Methods: We conducted a retrospective review of all intracranial meningiomas treated with GKRS at a single institution between January 2015 and December 2022. Patients were included if they completed at least one follow-up appointment with an MRI within 12-months of treatment. Patients were excluded if they had multiple meningiomas treated at one sitting or within 1-year of the index treatment, for insufficient records, or if the patient presented prior to scheduled follow-up.

Results: A total of 114 patients with 115 meningiomas completed 164 follow-up appointments between 1-11 months after receiving treatment with GKRS. 7 (4%) visits resulted in a change in management. 4 (2%) of these changes were due to the discovery of new lesions outside of the radiation field, 1 was at 3-months while the other 3 were at 9-months. 2 (1%) were due to radiographic changes in treated lesion size or enhancement pattern, 1 at 3-months and 1 at 6-months. 1 ( < 1%) was for peri-lesional edema with associated headaches at 9 months.

Conclusion : MRI imaging inside of 12-months after GKRS for intracranial meningioma had a low yield for identifying radiographic changes that altered management. Clinicians could consider deferring imaging follow-up until at least 12-months post-treatment.