Measuring optical properties of an eye lens using magnetic resonance imaging
Measuring optical properties of an eye lens using magnetic resonance imaging
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DOI：
10.1016/j.mri.2003.07.005
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发表时间：
2004-02-01
影响因子：
2.5
通讯作者：
Pope, JM
中科院分区：
文献类型：
--
作者：
Jones, CE;Pope, JM
我们比较了光学测量和使用一种新的MRI技术的猪晶状体的焦距。还测量和比较了透镜的几何特性。MRI技术利用了透镜折射率和弛豫速率对局部蛋白质浓度的依赖性。通过测量具有不同蛋白质浓度的透镜匀浆样品的折射率和R2（= 1/T2）的相应值，凭经验确定折射率对R2的依赖性。R2图，从单指数拟合到通过包含光轴的透镜的切片的多回波图像构建，使用该关系转换为折射率图。通过折射率图的模拟光线跟踪提供了对透镜焦距的估计，该估计与使用激光光线跟踪方法的焦距的直接光学测量进行比较。结果发现，从两种技术估计的平均焦距同意在实验的不确定性。发现沿光轴的折射率分布沿着由形式n = n（0）+ n（1）× r（α）的简单函数很好地描述，其中r是（归一化的）透镜半径。(C)2004年爱思唯尔公司All rights reserved.
We compare the focal lengths of porcine lenses measured optically and by using a novel MRI technique. The geometric properties of the lenses were also measured and compared. The MRI technique exploits the dependence of both the lens refractive index and relaxation rates on the local protein concentration. By measuring the refractive index and corresponding values of R2 (= 1/T2) for samples of lens homogenates with different protein concentrations, the dependence of refractive index on R2 was determined empirically. R2 maps, constructed from monoexponential fits to multiecho images of a slice through the lens containing the optical axis, were converted to refractive index maps using this relationship. A simulated ray trace through the refractive index map provided an estimate of lens focal length that was compared to a direct optical measurement of focal length using a laser ray-tracing method. It was found that the mean focal lengths estimated from the two techniques agreed within experimental uncertainty. The refractive index profile along the optical axis was found to be well described by a simple function of the form n = n(0) + n(1) x r(a) where r is the (normalized) lens radius. (C) 2004 Elsevier Inc. All rights reserved.