Detection of 100% oxygen induced changes in retina using magnetic resonance imaging: a human study.

BACKGROUND Inner retinal oxygenation response (ΔPO(2)) is a worldwide study focus. However, the relevant reports on its radiological measurements are limited. In this study, magnetic resonance imaging (MRI), employing T1 weighted image (T1WI), was used to detect changes in ΔPO(2) following 100% oxygen inhalation in human subjects. METHODS MRI was performed on a 1.5-T GE scanner system. After obtaining ophthalmologic data, eleven healthy individuals were given room air and 100% oxygen inhalation in order with different intervals. The MRI T1WI data were collected for 50 minutes. Data were analyzed with NIH IMAGE software. RESULTS ΔPO(2) was not panretinally uniform, and changes in oxygenation response were spatially inhomogeneous. During the initial phase (before 5 minutes) of 100% oxygen inhalation, preretinal vitreous water signals in the region of papilla optica increased rapidly. On the contrary, in other regions signals declined. In a later period (35 minutes), ΔPO(2) was panretinally fluctuated and increased slowly and attained homeostasis. After hyperoxia (45 minutes), delayed-enhancement of preretinal vitreous water signals in regions other than the papilla optica occurred, and then dropped down. There was no significant difference (P > 0.05) at any consecutive time point during and after hyperoixa. CONCLUSIONS These results reveal that hyperoxia can induce region-specific signal changes in preretinal vitreous water. Regulatory activity of the retinal vessel network may be the mechanism during 100% oxygen inhalation. Moreover, MRI is a valuable tool for investigating ΔPO(2) and exploring the mechanism of retinal oxygenation response physiologically or pathologically in vivo.