Direct Non-Invasive MRI Measurement of the Absolute CBV-CBF Relationship During Visual Stimulation in Normal Humans

Pelin Aksit Ciris¹, Maolin Qiu¹, Robert Todd Constable¹

BOLD signal reflects changes in CBV, CBF, blood oxygenation and metabolism, the quantification and physiological interpretation of which typically assumes that CBV=0.88CBF0.38 based on PET monkey measurements by Grubb et al. In this study, the absolute CBV-CBF relationship was measured directly in MRI non-invasively on 12 volunteers during visual stimulation. Measurements were within physiologically expected ranges, consistent with prior PET and contrast enhanced results in cortical GM. Non-invasive characterization of the CBV-CBF relationship in humans under various metabolic or functional challenges can advance understanding of fMRI signal mechanisms, with further potential clinical utility in vascular state or treatment monitoring.