Abstract #3480

The Effects of Basal Vascular Tone on Hypercapnic and Hypocapnic Cerebrovascular Reactivity: Implications for Clinical Autoregulation Studies.

Molly Gallogly Bright¹, Daniel P. Bulte², Manus J. Donahue², Jeff H. Duyn¹, Peter Jezzard²

¹Advanced MRI Section, LFMI, NINDS, NIH, Bethesda, MD, United States; ²FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford

The cerebrovascular reactivity response to arterial gas tensions offers insight into vascular compliance and may be useful for experimentally simulating conditions of hemodynamic compromise. We utilize BOLD fMRI and CO2 inhalation in healthy volunteers to understand how an increase in basal vasodilation influences the response to both vasoconstrictive (Cued Deep Breathing) and vasodilatory (Breath Hold) challenges. Three repetitions of each challenge were performed at 0% and 4%CO2 inhalation, and voxelwise %BOLD/δetCO2 mmHg maps were averaged across gray matter. BH-reactivity responses were significantly greater during 4% CO2 inhalation while CDB-reactivity responses were not significantly affected, indicating these challenges may offer complementary diagnostic information.