Radiation Physics

PV QA 3 - Poster Viewing Q&A 3

TU_17_3278 - Functional MRI: A Window into the Effects of Tumors and Radiation Therapy on the Brain's Resting State Cortical Networks

Tuesday, October 23
1:00 PM - 2:30 PM
Location: Innovation Hub, Exhibit Hall 3

Functional MRI: A Window into the Effects of Tumors and Radiation Therapy on the Brain's Resting State Cortical Networks
T. Mitchell1, C. D. Hacker1, J. D. Breshears2, N. P. Szrama2, M. Sharma2, D. T. Bundy2, M. Pahwa2, A. Z. Snyder1, J. S. Shimony1, and E. C. Leuthardt1; 1Washington University in St. Louis, SAINT LOUIS, MO, 2Washington University in St. Louis, Saint Louis, MO

Purpose/Objective(s): functional MRI (fMRI) utilizes fluctuations in the ratio of oxyhemoglobin to deoxyhemoglobin to map the cortical networks of the brain. In particular, resting-state fMRI (rs-fMRI) can be used to map the cortical networks of the brain using endogenous brain activity, and thus can be acquired independent of patient participation. This independence is beneficial in patients with altered cognitive status, making it advantageous in patients with brain tumors. The purpose of this study is to investigate changes to cortical networks due to the presence of tumors, with the ultimate goal of studying the effects of radiation on these networks, and potentially tailoring radiation therapy treatment planning to minimize changes post-radiation treatment.

Materials/Methods: 7 patients undergoing surgical resection of brain tumors participated in this study, and an additional 21 patients have been identified as having rs-fMRI data acquired both pre and post-radiation therapy. rs-fMRI correlation maps were generated using an artificial neural network known as a multilayer perceptron, with the output representing an estimate of each voxel belonging to each of seven resting state networks: language network, somatomotor network, visual network, dorsal attention network, ventral attention network, frontoparietal control, and default mode network.

Results: The efficacy of the multilayer perceptron was confirmed through comparison with motor and language networks as identified with direct electrocortical stimulation performed during resection. rs-fMRI mapping of tumor subjects reveals network distortion in the presence of tumors, with significant anisotropy across the midline seen in networks present in areas near the tumor. Interestingly, there were areas within the tumor that continued to display network connectivity. Additional study is needed to determine the effects of radiation on the cortical networks.

Conclusion: rs-fMRI provides insight into the brain’s organizational structure through identification of cortical networks. Though distorted, these networks are preserved in the presence of tumors, and further study is required to determine the effect of radiation on them.

Author Disclosure: T. Mitchell: None. J.D. Breshears: None. M. Sharma: None. D.T. Bundy: None. M. Pahwa: None. J.S. Shimony: None. E.C. Leuthardt: Stock; Neurolutions, General Sensing, Osteovantage.

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