Water protons (Oxygen-17 labeled) (H2¹⁷O)

Water protons within H2¹⁷O molecules and bulk water function as a diagnostic imaging probe in magnetic resonance imaging (MRI) rather than a conventional therapeutic target. The ¹⁷O isotope is the only stable, non-radioactive isotope of oxygen that possesses a nuclear spin (I=5/2), which allows it to interact with the hydrogen nuclei (protons) of water molecules through scalar coupling and rapid chemical exchange (Zhu et al., 2005, NMR in Biomedicine). This interaction significantly alters the relaxation properties of the water protons, specifically shortening the T2, T2*, and T1ρ relaxation times, which can be detected indirectly using standard proton MRI (Meissner et al., 2013, Magnetic Resonance in Medicine). This phenomenon is leveraged to non-invasively quantify the cerebral metabolic rate of oxygen consumption (CMRO2) and regional blood flow by monitoring the metabolic conversion of inhaled ¹⁷O2 gas into H2¹⁷O (Atkinson & Thulborn, 2010, NeuroImage). While these protons do not serve as a binding site for pharmacological agents, they are critical for assessing metabolic activity and tissue viability in clinical research related to ischemic stroke, oncology, and neurodegenerative disorders (Hoffmann et al., 2011, Magnetic Resonance Materials in Physics, Biology and Medicine).

Other names

Oxygen-17 labeled water protonsH2(17)O17O-waterWater-17OBulk water protons in the presence of H2¹⁷O

Proton relaxation enhancement (T2, T2*, and T1rho) via scalar coupling and chemical exchange between the protons and the quadrupolar 17O nucleus.