An investigation into the role of the optical detection set-up in the recording of cardiac optical mapping signals: A Monte Carlo simulation study
An investigation into the role of the optical detection set-up in the recording of cardiac optical mapping signals: A Monte Carlo simulation study
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DOI：
10.1016/j.physd.2008.06.014
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发表时间：
2009-06-01
影响因子：
4
通讯作者：
Rodriguez, Blanca
中科院分区：
文献类型：
--
作者：
Bishop, Martin J.;Bub, Gil;Rodriguez, Blanca
已知光子散射使从光学映射的心脏组织记录的荧光信号失真。然而，尚未评估定义光学检测设置的参数的贡献。在这项研究中，心室组织内光子散射的蒙特卡罗（MC）模拟与串联透镜光学检测装置的详细模型相结合，以解释（i）在心电活动的电压敏感荧光测量中记录的光子发射的空间起源（使用荧光染料di-4-ANEPPS）以及这如何影响信号失真，以及（ii）探测器特性在均匀照明和来自组织深度的光子发射期间在调制信号失真中可能起的作用。结果表明，对于所考虑的特定激发/发射波长（分别为488 mm和669 nm），在均匀照明期间散射体积的尺寸在表面记录平面中比在深度中进一步延伸约3倍。因此，当跨膜电位水平主要在表面平面中而不是在深度中不同时，电传播期间的荧光记录更加失真。此外，MC模拟结果表明，由于光子散射，荧光信号的空间准确性受到显著限制，只有一小部分记录的信号强度来自像素下方的组织（对于0.25 x 0.25 mm像素，约为11%）。增加像素尺寸会增加该分数，然而，它也会导致散射体积尺寸的增加，从而降低光学系统的空间分辨率，并增加信号失真。MC模拟还表明，心脏组织中的光子散射限制了光学检测系统调谐准确定位来自深度的荧光发射的能力。具体来说，我们的研究结果证明，产生最大信号强度的焦平面深度提供了一个低估的发射深度。总之，我们的研究表明，光子散射的MC模拟在指导光学映射设置的设计，以优化在不同的实验条件下的性能的潜力。(C)2008 Elsevier B. V.保留所有权利。
Photon scattering is known to distort the fluorescence signals recorded from optically mapped cardiac tissue. However, the contribution of the parameters which define the optical detection set-up has not been assessed. In this study, Monte Carlo (MC) simulations of photon scattering within ventricular tissue are combined with a detailed model of a tandem-lens optical detection apparatus to characterise (i) the spatial origin upon emission of photons recorded in voltage-sensitive fluorescence measurements of cardiac electrical activity (using the fluorescent dye di-4-ANEPPS) and how this affects signal distortion, and (ii) the role the detector characteristics could play in modulating signal distortion during uniform illumination and photon emission from tissue depth. Results show that, for the particular excitation/emission wavelengths considered (488 mm and 669 mn, respectively), the dimensions of the scattering volume during uniform illumination extend around 3 times further in the surface recording plane than in depth. As a result, fluorescence recordings during electrical propagation are more distorted when transmembrane potential levels differ predominantly in the surface plane than in depth. In addition, MC simulation results show that the spatial accuracy of the fluorescence signal is significantly limited due to photon scattering, with only a small fraction of the recorded signal intensity originating from tissue beneath the pixel (approximately 11% for a 0.25 x 0.25 mm pixel). Increasing pixel size increases this fraction, however, it also results in an increase in the scattering volume dimensions, thus reducing the spatial resolution of the optical system, and increasing signal distortion. MC simulations also demonstrate that photon scattering in cardiac tissue limits the ability of optical detection system tuning in accurately locating fluorescent emission from depth. Specifically, our results prove that the focal plane depth that yields maximum signal intensity provides an underestimation of the emission depth. In conclusion, our study demonstrates the potential of MC simulations of photon scattering in guiding the design of optical mapping set-ups to optimise performance under diverse experimental conditions. (C) 2008 Elsevier B.V. All rights reserved.