17O MRI is an attractive and promising goal utilizing ultra-high magnetic fields. The current study is devoted to the time changes of 17O MR signals detectable in a rat head at 21.1 T using bolus injection of 17O labeled water-17O and glucose-17O. The time course of 17O-water revealed a two stage process of distribution. During glucose injection the time course has the same stages as for water, and the third stage represents glucose metabolism. The shape of the high resolution glucose time course is important for the accurate determination of tissue glucose consumption.