Abstract Details

Title Multiparametric MRI Assessment of Proton Radiation Therapy Post-treatment Effects on Brain Tissue for CNS and Head-neck Cancers

Topic Neuro-oncology

Presentation(s) S14 - Neuro-oncology (2:36 PM-2:48 PM)

Poster/Presentation
Number 009

Objective

To characterize features of radiation necrosis, post-treatment gliosis, or active tumor following proton radiation therapy in the brain using multiparametric MRI as a diagnostic tool.

Background Proton-beam radiation therapy (PRT) is increasingly used for treatment of primary CNS tumors and head/neck malignancies infiltrating the skull base. Post-PRT treatment changes to brain parenchyma are inadequately understood due to different linear energy transfer (LET) dose at the distal edge of PRT fields compared to standard RT but has clinical significance in neuro-oncology for accurate diagnosis of tumor and radiation necrosis (RN).

Design/Methods This study is IRB-approved. We retrospectively reviewed medical records of 137 patients treated with PRT to the brain, skull base, face, and neck at our institution over a 3-year period (9/2016-present). Treatment plans, field paths, and dosimetry were retrieved for new/progressive sites of parenchymal brain T1 post-Gadolinium enhancement or T2/FLAIR changes that underwent multiparametric MRI evaluation following PRT. Choline:NAA index (CNI), rCBV, K-trans values, and SUV were indexed for features of RN, active tumor, or indeterminate.

Results There were 19 cases with multiparametric MR imaging performed after PRT including spectroscopy, DSC-perfusion, and/or 18-FDG-PET, of which 12 were glioma, 4 meningioma, and 3 extra-CNS malignancies. 4/19 underwent multimodal treatment with photon VMAT. Patients’ median maximum PRT dose used was 58.91-CGE (range: 17.94-74.91) and median fields were 5 (2-8). ROIs over new/progressive imaging changes demonstrated median rCBV ratios of 1.49 (0.09-4.74) and median K-trans values of 0.19 (0.02-1.61) on DSC-perfusion. Hypermetabolism was seen by FDG-PET-MR with average SUV of 4.9. Spectroscopic findings revealed elevated CNI of 5.5 (0.8-50.2) at these sites.

Conclusions

Multiparametric MRI aids in imaging interpretation of post-PRT changes to the brain. Advanced MRI techniques assessing tissue permeability and metabolism are applicable to expose treatment-related pathology following PRT, allowing neuro-oncologists to avoid discontinuing treatment prematurely and to more accurately diagnose progressive tumor and RN.

Authors/Disclosures
Robin A. Buerki, MD, PhD (University of California, San Francisco) PRESENTER	No disclosure on file
	No disclosure on file
Andrew Gross, MD (First in Flight Neurology)	Dr. Gross has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Lisa R. Rogers, DO, FAAN (Henry Ford Hospital)	Dr. Rogers has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Novocure .

��ɫ��

��ɫ��