Understanding Permeability Changes in Vestibular Schwannomas as Part of the Dynamic Response to Radiosurgery Using...

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Vestibular schwannomas often show temporary loss of MRI enhancement post-stereotactic radiosurgery (SRS).
• This is thought to result from reduced tumor vascularity.

Purpose of the Study:

• To characterize vascular permeability changes after SRS using dynamic contrast-enhanced GRASP MRI.
• To correlate these changes with long-term tumor regression.

Main Methods:

• Retrospective analysis of 19 patients with vestibular schwannoma undergoing SRS.
• Longitudinal GRASP MRI studies at 6, 18, and 30 months post-SRS.
• Analysis of vascular parameters (peak, AUC, slope) using the GRAVIS pipeline.

Main Results:

• Significant reductions in peak, AUC, and wash-in slope observed at 6, 18, and 30 months post-SRS.
• Larger pre-SRS tumors showed greater reduction in peak and AUC at 6 months.
• Vascular parameter changes at 6 months correlated with long-term tumor volume reduction.

Conclusions:

• A persistent slow vascular permeability dynamic, likely due to fibrosis, is observed after SRS.
• GRASP MRI provides a quantitative assessment of the radiobiological effects on tumor vasculature.