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 MRI appears to be an early and accurate marker of retinopathy risk in experimental models, with promising clinical potential. However, the application of this technique in humans is limited by blinking artifacts that can confound detection of subtle signal intensity changes. We asked subjects to refrain from blinking during a 12-s fast low-angle shot (FLASH) image, and to blink if needed during the following 3-s rest period. This no-blink blink cycle was repeated sequentially 20 times during either room-air or 100% oxygen breathing. Significant change (P < 0.05) was detected for the first time from 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 response and human retinopathy, such as diabetic retinopathy.