MRI Changes in Failed Radiosurgery for Vestibular Schwannomas

Area of Science:

• Neurosurgery
• Radiology
• Oncology

Background:

• Radiosurgery is a recognized treatment for vestibular schwannoma (VS).
• Long-term tumor control after radiosurgery can fail.
• Post-radiosurgery MRI changes may be misinterpreted in cases of treatment failure.

Purpose of the Study:

• To evaluate early MRI changes in patients with failed radiosurgery for vestibular schwannoma (VS).
• To identify specific MRI features that may indicate treatment failure despite initial apparent response.

Main Methods:

• Retrospective review of follow-up MRI data from a large series of VS patients treated with radiosurgery over 15 years.
• Analysis of a subgroup of VS cases with confirmed treatment failure requiring retreatment.
• Assessment of tumor volume evolution and contrast enhancement patterns using T1-weighted, 3D-co-registered MRI.

Main Results:

• 4% of patients (29/728) required retreatment for VS after a median of 3.14 years.
• Tumor volume increased in 48.3% of retreated patients.
• While 86.2% showed central contrast enhancement loss, 23 patients experienced full enhancement recovery, indicating complex post-treatment dynamics.

Conclusions:

• Tumor volume reduction and central contrast loss on MRI after radiosurgery for VS are common, even with treatment failure.
• These MRI changes should not be solely relied upon as indicators of successful long-term tumor control.
• Careful interpretation of serial MRIs is crucial for accurate assessment of radiosurgical outcomes in VS.