Improved sensitivity of proton MR to oxygen‐17 as a contrast agent using fast imaging: Detection in brain

The potential utility of H 2 17 O as a contrast agent has been demonstrated in biological solutions and isolated tissues but its use has been impaired by the need to run heavily T 2 ‐weighted spin‐echo images. By choosing an appropriate steady‐state free precession experiment sensitive to T 1 / T 2 , we have improved the available contrast‐to‐noise. per unit time by more than a factor of 5. This allows easy measurement of the proton effects for concentrations as low as 0.4% H 2 17 O in less than 1 min. Injection into small animals produces a marked reduction in the overall image intensity. Consecutive imaging at the rate of one every 52 s has been used to follow the rate of change in brain image intensity immediately after injection. © 1988 Academic Press, Inc.