Quantification of the BOLD Response via Blood Gas Modulations

摘要: This thesis is intended to contribute a quantitative understanding of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal in order increase its clinical potential. Here, vascular, neuronal and physical processes which combine give resulting BOLD are investigated using respiratory challenges. The effect isocapnic hyperoxia on vascular responses at 7 Tesla. No significant change was found resting-state cerebral flow (CBF), volume (CBV) task-evoked CBF. challenges previously held idea that vasoconstrictive. The oscillations assessed with magnetoencephalography (MEG). Whilst reduction oscillatory power reported occipital lobe, significantly smaller than global measured hypercapnia. These findings suggest an ideal tool for calibrated fMRI. The relationship between transverse relaxation plays key role fMRI. However, previous measurements have been confounded by CBV. be sub-linear across 1.5, 3 Previous results supralinear 1.5/3 Tesla linear Tesla, attributed relative contribution intravascular/extravascular signals their dependence field strength, echo time. Finally, comparison single multiphase ASL made modified Look-locker EPI sequence presented allows simultaneous measurement CBF transit time, whilst increasing available signal. could important implications hypercapnia fMRI, where choice may affect estimated CMRO2. Furthermore, it provides framework future haemodynamic studies required.