Field Shift Due to Paramagnetic Effect of Molecular Oxygen

Kejia Cai¹, Kalli Grasley¹, Anup Singh¹, David Pilkinton¹, Mohammad Haris¹, Hari Hariharan¹, Mark Elliott¹, Ravinder Reddy¹

Oxygen inhalation has been shown to be a simple and effective positive contrast agent in T2*-weighted images based on the BOLD effect. While paramagnetic effect of molecular oxygen could shift the static field, which is unrelated to blood oxygenation. In this study, we have characterized the static field shift due to oxygen inhalation at 9.4T by using SVS and B0 field maps. Proton Larmor frequency is shifted by ~1Hz per 1% of oxygen at 9.4T. One must be cautious on this confounding factor when conducting fMRI and field sensitive MRI studies with oxygen inhalation.