In Vivo Relaxation Parameters of Oxygen-17 (17O)

Stefan H. Hoffmann¹, Armin M. Nagel¹, Florian M. Meise¹, Reiner Umathum¹, Michael Bock¹

Cellular energy production is closely connected to the metabolization of oxygen (O₂) to water. Direct ¹⁷O-MRI can assess the in vivo H₂¹⁷O concentration metabolized from inhaled ¹⁷O gas. However, the MR-sensitivity of the ¹⁷O nucleus (I = 5/2) is poor. Information on the relaxation parameters is therefore crucial for optimizing the imaging process. In this study we measured the in vivo ¹⁷O relaxation times in the human brain (B₀ = 7T) to optimize imaging protocols for CMRO₂ measurements. Non-localized detection (T₁, T₂) was carried out in 10 healthy volunteers and 3D T₂^* determination and anatomical mapping to ¹H images was performed in one subject.