Molecular imaging of radiotherapy-induced cerebrovascular inflammation and neuroinflammation in a rat model of stereotactic radiosurgery.

Motivation: Despite the advances in radiotherapy of brain tumors adverse radiation effects in healthy brain tissue can occur. Their underlying mechanisms are not fully understood, though previous research proposes the contribution of cerebrovascular impairment and neuroinflammation. Goal(s): Evaluate the development of BBB impairment, cerebrovascular inflammation and neuroinflammation in the rat model of stereotactic radiosurgery. Approach: Multi-modality molecular imaging including DCE-MRI, T2*-weighted MRI with VCAM-1 MPIOs and PET with TSPO-specific radiotracer. Results: In the rat model of SRS increased BBB permeability, cerebrovascular inflammation and neuroinflammation can be detected as early as 6 weeks after irradiation and these changes evolve over time in dose-dependent manner. Impact: It is the first study to demonstrate by in vivo imaging the progression of neuroinflammatory and cerebrovascular alterations in the rat model of SRS which helps to understand the time and dose-dependent manner of development of adverse radiation effects.