Emeterio Nateras Oscar San, Harrison Joseph M, Muir Eric R, Zhang Yi, Peng Qi, Chalfin Steven, Gutierrez Juan E, Johnson Daniel A, Kiel Jeffrey W, Duong Timothy Q
Research Imaging Institute, University of Texas Health Science Center , San Antonio, TX , USA .
Curr Eye Res. 2014 Oct;39(10):1059-67. doi: 10.3109/02713683.2014.892997. Epub 2014 Mar 21.
To verify that a visual fixation protocol with cued eye blinks achieves sufficient stability for magnetic resonance imaging (MRI) blood-flow measurements and to determine if choroidal blood flow (ChBF) changes with age in humans.
The visual fixation stability achievable during an MRI scan was measured in five normal subjects using an eye-tracking camera outside the MRI scanner. Subjects were instructed to blink immediately after recorded MRI sound cues but to otherwise maintain stable visual fixation on a small target. Using this fixation protocol, ChBF was measured with MRI using a 3 Tesla clinical scanner in 17 normal subjects (24-68 years old). Arterial and intraocular pressures (IOP) were measured to calculate perfusion pressure in the same subjects.
The mean temporal fluctuations (standard deviation) of the horizontal and vertical displacements were 29 ± 9 μm and 38 ± 11 μm within individual fixation periods, and 50 ± 34 μm and 48 ± 19 μm across different fixation periods. The absolute displacements were 67 ± 31 μm and 81 ± 26 μm. ChBF was negatively correlated with age (R = -0.7, p = 0.003), declining 2.7 ml/100 ml/min per year. There were no significant correlations between ChBF versus perfusion pressure, arterial pressure, or IOP. There were also no significant correlations between age versus perfusion pressure, arterial pressure, or IOP. Multiple regression analysis indicated that age was the only measured independent variable that was significantly correlated with ChBF (p = 0.03).
The visual fixation protocol with cued eye blinks was effective in achieving sufficient stability for MRI measurements. ChBF had a significant negative correlation with age.
验证一种伴有提示性眨眼的视觉注视方案能否为磁共振成像（MRI）血流测量提供足够的稳定性，并确定人类脉络膜血流（ChBF）是否随年龄变化。
在五名正常受试者中，使用MRI扫描仪外部的眼动追踪相机测量MRI扫描期间可实现的视觉注视稳定性。受试者被指示在记录到MRI声音提示后立即眨眼，但在其他情况下要保持对一个小目标的稳定视觉注视。使用该注视方案，在17名正常受试者（24 - 68岁）中，使用3特斯拉临床扫描仪通过MRI测量ChBF。测量相同受试者的动脉压和眼内压（IOP）以计算灌注压。
在各个注视期内，水平和垂直位移的平均时间波动（标准差）分别为29±9μm和38±11μm，在不同注视期内分别为50±34μm和48±19μm。绝对位移为67±31μm和81±26μm。ChBF与年龄呈负相关（R = -0.7，p = 0.003），每年下降2.7 ml/100 ml/min。ChBF与灌注压、动脉压或IOP之间无显著相关性。年龄与灌注压、动脉压或IOP之间也无显著相关性。多元回归分析表明，年龄是唯一与ChBF显著相关的测量自变量（p = 0.03）。
伴有提示性眨眼的视觉注视方案对于MRI测量实现足够的稳定性是有效的。ChBF与年龄呈显著负相关。
