Abstract #0269

Whole-brain BOLD Responses to Graded Hypoxic Challenges at 7T, 9.4T, and 15.2T: Implications for Ultrahigh-Field BOLD-DSC MRI

Thuy Thi Le^1,2,3, Sang Han Choi¹, Geun Ho Im¹, Chan Hee Lee¹, Dongkyu Lee^4,5, Jacob Schulman^6,7, HyungJoon Cho⁵, Kamil Uludağ^1,2,6,7,8, and Seong-Gi Kim^1,2,3

¹Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of, ⁴Brain Tech Center, Korea Brain Research Institute, Daegu, Korea, Republic of, ⁵Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Korea, Republic of, ⁶Krembil Brain Institute, University Health Network, Toronto, ON, Canada, ⁷Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ⁸Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada

Synopsis

Keywords: High-Field MRI, Perfusion, Field-dependence, Quantitative images

Motivation: To address quantification challenges in susceptibility-based CBV measurements using BOLD-DSC.

Goal(s): Examine blood and tissue ΔR₂^* responses to varying blood oxygen saturation changes and magnetic field strengths.

Approach: Whole-brain BOLD responses were evaluated using 5-second hypoxic challenges (0%, 5%, and 10% O₂) in anesthetized mice at ultrahigh field strengths of 7T, 9.4T and 15.2T.

Results: CBV values showed dependency on hypoxic stimulus doses and magnetic field strengths, with higher susceptibility yielding greater CBV values. Normalizing regional CBV to white matter values mitigated the variability from susceptibility contrasts within the same field strength.

Impact: We investigated hypoxia-induced blood and tissue ΔR₂^* responses across varying ΔY levels and field strengths, alongside CBV assessments. This study provides biophysical insights into field-dependent BOLD signals at ultrahigh fields and addresses challenges in quantification of susceptibility-based CBV measurements.

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