The capability of 17O MRI in a rat head was evaluated at the high magnetic field of 21.1 T (NHMFL, Tallahassee). The results demonstrated that 17O MR relaxation times are dependent on the magnetic field strength which correlates with experimental observations for sodium. Well separated MR peaks of 17O water and 6-17O glucose provided the time courses of water distribution and glucose consumption in vivo. 3D 17O MRI is possible with a resolution of 1 mm3 in normal rats. 17O MRI is a promising tool for future tumor detection and evaluation of tumor glucose consumption rates.