Wilson Robert H, Crouzet Christian, Torabzadeh Mohammad, Bazrafkan Afsheen, Farahabadi Maryam H, Jamasian Babak, Donga Dishant, Alcocer Juan, Zaher Shuhab M, Choi Bernard, Akbari Yama, Tromberg Bruce J
University of California, Beckman Laser Institute, Irvine, California, United States.
University of California, Department of Biomedical Engineering, Irvine, California, United States.
Neurophotonics. 2017 Oct;4(4):045008. doi: 10.1117/1.NPh.4.4.045008. Epub 2017 Dec 26.
Quantifying rapidly varying perturbations in cerebral tissue absorption and scattering can potentially help to characterize changes in brain function caused by ischemic trauma. We have developed a platform for rapid intrinsic signal brain optical imaging using macroscopically structured light. The device performs fast, multispectral, spatial frequency domain imaging (SFDI), detecting backscattered light from three-phase binary square-wave projected patterns, which have a much higher refresh rate than sinusoidal patterns used in conventional SFDI. Although not as fast as "single-snapshot" spatial frequency methods that do not require three-phase projection, square-wave patterns allow accurate image demodulation in applications such as small animal imaging where the limited field of view does not allow single-phase demodulation. By using 655, 730, and 850 nm light-emitting diodes, two spatial frequencies ([Formula: see text] and [Formula: see text]), three spatial phases (120 deg, 240 deg, and 360 deg), and an overall camera acquisition rate of 167 Hz, we map changes in tissue absorption and reduced scattering parameters ([Formula: see text] and [Formula: see text]) and oxy- and deoxyhemoglobin concentration at [Formula: see text]. We apply this method to a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) to quantify hemodynamics and scattering on temporal scales ([Formula: see text]) ranging from tens of milliseconds to minutes. We observe rapid concurrent spatiotemporal changes in tissue oxygenation and scattering during CA and following CPR, even when the cerebral electrical signal is absent. We conclude that square-wave SFDI provides an effective technical strategy for assessing cortical optical and physiological properties by balancing competing performance demands for fast signal acquisition, small fields of view, and quantitative information content.
量化脑组织吸收和散射中快速变化的扰动可能有助于表征缺血性创伤引起的脑功能变化。我们开发了一个使用宏观结构化光进行快速固有信号脑光学成像的平台。该设备执行快速、多光谱、空间频域成像（SFDI），检测来自三相二进制方波投影图案的后向散射光，其刷新率比传统SFDI中使用的正弦图案高得多。尽管不如不需要三相投影的“单快照”空间频率方法快，但方波图案允许在诸如小动物成像等应用中进行精确的图像解调，在这些应用中有限的视野不允许单相解调。通过使用655、730和850纳米的发光二极管、两个空间频率（[公式：见正文]和[公式：见正文]）、三个空间相位（120度、240度和360度）以及167赫兹的整体相机采集速率，我们绘制了组织吸收和减少散射参数（[公式：见正文]和[公式：见正文]）以及[公式：见正文]处氧合血红蛋白和脱氧血红蛋白浓度的变化。我们将此方法应用于心脏骤停（CA）和心肺复苏（CPR）的大鼠模型，以量化从几十毫秒到几分钟的时间尺度（[公式：见正文]）上的血流动力学和散射。我们观察到在CA期间和CPR之后，即使在没有脑电信号的情况下，组织氧合和散射也会同时快速发生时空变化。我们得出结论，方波SFDI通过平衡对快速信号采集、小视野和定量信息内容的相互竞争的性能需求，为评估皮层光学和生理特性提供了一种有效的技术策略。
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