Phan Thinh, Crouzet Christian, Kennedy Gordon T, Durkin Anthony J, Choi Bernard
University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States.
University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States.
Neurophotonics. 2023 Oct;10(4):045001. doi: 10.1117/1.NPh.10.4.045001. Epub 2023 Oct 3.
Studying cerebral hemodynamics may provide diagnostic information on neurological conditions. Wide-field imaging techniques, such as laser speckle imaging (LSI) and optical intrinsic signal imaging, are commonly used to study cerebral hemodynamics. However, they often do not account appropriately for the optical properties of the brain that can vary among subjects and even during a single measurement. Here, we describe the combination of LSI and spatial-frequency domain imaging (SFDI) into a wide-field quantitative hemodynamic imaging (QHI) system that can correct the effects of optical properties on LSI measurements to achieve a quantitative measurement of cerebral blood flow (CBF).
We describe the design, fabrication, and testing of QHI.
The QHI hardware combines LSI and SFDI with spatial and temporal synchronization. We characterized system sensitivity, accuracy, and precision with tissue-mimicking phantoms. With SFDI optical property measurements, we describe a method derived from dynamic light scattering to obtain absolute CBF values from LSI and SFDI measurements. We illustrate the potential benefits of absolute CBF measurements in resting-state and dynamic experiments.
QHI achieved a 50-Hz raw acquisition frame rate with a field of view and flow sensitivity up to . The extracted SFDI optical properties agreed well with a commercial system (). The system showed high stability with low coefficients of variations over multiple sessions within the same day () and over multiple days (). When optical properties were considered, the hypercapnia gas challenge showed a slight difference in CBF ( to 0.5% difference). The resting-state experiment showed a change in CBF ranking for nine out of 13 animals when the correction method was applied to LSI CBF measurements.
We developed a wide-field QHI system to account for the confounding effects of optical properties on CBF LSI measurements using the information obtained from SFDI.
研究脑血流动力学可为神经系统疾病提供诊断信息。宽场成像技术，如激光散斑成像（LSI）和光学内在信号成像，常用于研究脑血流动力学。然而，它们往往没有适当地考虑到大脑的光学特性，这些特性在不同个体之间甚至在单次测量过程中都可能有所不同。在此，我们描述了将LSI和空间频域成像（SFDI）结合到一个宽场定量血流动力学成像（QHI）系统中，该系统可以校正光学特性对LSI测量的影响，以实现脑血流量（CBF）的定量测量。
我们描述了QHI的设计、制造和测试。
QHI硬件将LSI和SFDI在空间和时间上进行同步。我们使用仿组织体模对系统的灵敏度、准确性和精密度进行了表征。通过SFDI光学特性测量，我们描述了一种从动态光散射推导而来的方法，用于从LSI和SFDI测量中获得绝对CBF值。我们阐述了在静息状态和动态实验中进行绝对CBF测量的潜在益处。
QHI实现了50赫兹的原始采集帧率，视野和血流灵敏度高达 。提取的SFDI光学特性与商业系统（ ）吻合良好。该系统在同一天内的多个会话（ ）以及多天内（ ）均显示出高稳定性，变异系数较低。当考虑光学特性时，高碳酸血症气体激发实验显示CBF有轻微差异（差异为 至0.5%）。在对13只动物中的9只进行静息状态实验时，当将校正方法应用于LSI CBF测量时，CBF排名发生了变化。
我们开发了一种宽场QHI系统，利用从SFDI获得的信息来解决光学特性对CBF LSI测量的混杂影响。
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