Measuring the human retinal oxygenation response to a hyperoxic challenge using MRI: Eliminating blinking artifacts and demonstrating proof of concept

The retinal oxygenation response to a hyperoxic challenge measured using MR I appears to be an early and accurate marker of retinopathy risk in experim ental models, with promising clinical potential. However, the application o f this technique in humans is limited by blinking artifacts that can confou nd detection of subtle signal intensity changes. We asked subjects to refra in from blinking during a 12-s fast low-angle shot (FLASH) image, and to bl ink if needed during the following 3-s rest period. This no-blink blink cyc le was repeated sequentially 20 times during either room-air or 100% oxygen breathing. Significant change (P < 0.05) was detected for the first time f rom the resultant blinking-artifact-free images in the preretinal vitreous oxygen tension (upper limit of about 13 mm Hg (1.8 KPa, N = 3)) following a 10-min hyperoxic inhalation challenge. These results provide the proof-of- concept data needed for future MRI evaluation of the retinal oxygenation re sponse and human retinopathy, such as diabetic retinopathy. (C) 2001 Wiley- Liss, Inc.