University of TexasHealth Science Center, San Antonio, TX, USA.
Invest Ophthalmol Vis Sci. 2011 Jan 5;52(1):286-91. doi: 10.1167/iovs.10-6108. Print 2011 Jan.
To demonstrate blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) of vascular oxygenation changes in normal, unanesthetized human retinas associated with oxygen and carbogen challenge.
MRI was performed with a 3-T human scanner and a custom-made surface-coil detector on normal volunteers. BOLD MRI with inversion recovery was used to suppress the vitreous signal. During MRI measurements, volunteers underwent three episodes of air and 100% oxygen or carbogen (5% CO(2) and 95% O(2)) breathing. Eye movement was effectively managed with eye fixation, synchronized blinks, and postprocessing image coregistration. BOLD time-series images were analyzed using the cross-correlation method. Percent changes due to oxygen or carbogen inhalation versus air were tabulated for whole-retina and different regions of the retina.
Robust BOLD responses were detected. BOLD MRI percent change from a large region of interest at the posterior pole of the retina was 5.2 ± 1.5% (N = 9 trials from five subjects) for oxygen inhalation and 5.2 ± 1.3% (N = 11 trials from five subjects) for carbogen inhalation. Group-averaged BOLD percent changes were not significantly different between oxygen and carbogen challenges (P > 0.05). The foveal region had greater BOLD response compared with the optic nerve head region for both challenges.
BOLD retinal responses to oxygen and carbogen breathing in unanesthetized humans can be reliably imaged at high spatiotemporal resolution. BOLD MRI has the potential to provide a valuable tool to study retinal physiology and pathophysiology, such as how vascular oxygenation at the tissue level is regulated in the normal retina, and how retinal diseases may affect oxygen response.
演示正常、未麻醉的人类视网膜血管氧合变化的血氧水平依赖（BOLD）磁共振成像（MRI）与氧和碳氧合作用挑战相关。
使用 3-T 人体扫描仪和定制的表面线圈探测器对正常志愿者进行 MRI。使用反转恢复的 BOLD MRI 来抑制玻璃体信号。在 MRI 测量期间，志愿者经历了三次空气和 100%氧气或碳氧合（5%CO2 和 95%O2）呼吸。通过眼睛固定、同步眨眼和后处理图像配准有效地管理眼睛运动。使用互相关方法分析 BOLD 时间序列图像。记录了由于氧气或碳氧合吸入与空气相比的整个视网膜和视网膜不同区域的百分比变化。
检测到稳健的 BOLD 反应。来自视网膜后极的大感兴趣区域的 BOLD MRI 百分比变化在氧气吸入时为 5.2±1.5%（来自 5 名受试者的 9 次试验），在碳氧合吸入时为 5.2±1.3%（来自 5 名受试者的 11 次试验）。氧气和碳氧合挑战之间的组平均 BOLD 百分比变化没有显著差异（P>0.05）。对于这两种挑战，与视盘区域相比，中央凹区域的 BOLD 反应更大。
在未麻醉的人类中，可以可靠地以高时空分辨率对氧气和碳氧合呼吸的视网膜 BOLD 反应进行成像。BOLD MRI 有可能成为研究视网膜生理学和病理生理学的有价值工具，例如在正常视网膜中组织水平的血管氧合如何受到调节，以及视网膜疾病如何影响氧反应。
