Abstract #0444

First demonstration of arterial spin labeling on a 1.5T MR-Linac for characterizing glioblastoma perfusion dynamics

Liam S. P. Lawrence¹, Brige Chugh^2,3, James Stewart², Mark Ruschin², Aimee Theriault², Jay Detksy², Sten Myrehaug², Pejman J. Maralani², Chia-Lin Tseng², Hany Soliman², Mary Jane Lim-Fat⁴, Sunit Das⁵, Arjun Sahgal², and Angus Z. Lau^1,6

¹Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ²Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, ³Department of Physics, Toronto Metropolitan University, Toronto, ON, Canada, ⁴Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, ⁵Department of Surgery, St. Michael's Hospital, Toronto, ON, Canada, ⁶Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON, Canada

Synopsis

Keywords: MR-Guided Radiotherapy, Tumor, MR-Linac, perfusion, glioblastoma

Motivation: Glioblastoma is a highly vascularized brain tumor. Changes in perfusion could guide treatment adaptation, but the dynamics of blood flow changes in glioblastoma during radiotherapy are poorly understood.

Goal(s): We sought to characterize changes in glioblastoma cerebral blood flow during radiotherapy.

Approach: We acquired twice-weekly arterial spin labeling (ASL) MRI in 22 glioblastoma patients during radiotherapy on a 1.5T MRI-linear accelerator (MR-Linac) and evaluated changes in cerebral blood flow.

Results: We provided the first demonstration of MR-Linac ASL. Tumor cerebral blood flow tended to decrease during radiotherapy. Highly-perfused tumor regions showed the greatest change.

Impact: We showed that frequent perfusion imaging on MRI-linear accelerators is feasible and that blood flow in highly-perfused regions of human glioblastoma tends to decrease during radiotherapy. Radiotherapy with dose escalation to highly perfused tumor regions likely requires target adaptation.

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