Human Brain Interferometers for Better Blood Flow Monitoring

摘要： 创伤性脑损伤(TBI)治疗的一个主要目标是优化脑血流量(CBF)。 受伤后几天到几周。然而，目前还没有成熟的、非侵入性的方法来持续 监测成人的脑血流量。基于动态的漫反射光流量法监测CBF 近红外(NIR)光的散射用于研究时，这些方法存在着根本的局限性。 首先，它们需要昂贵的光子计数，这严格限制了可实现的速度、大脑特异性和大脑 覆盖范围。其次，它们缺乏深度辨别力，导致浅表组织中的血液流动受到污染。 第三，它们需要对光学特性的假设，这可能会因个人或大脑而异 地区。第四，它们对环境光的噪音很敏感。 为了解决这些限制，我们将干涉测量学引入人体漫反射光学，创建了一类新的近红外 基于光的监测工具，称为干涉漫反射光谱(IDOS)。首先，我们通过以下方式展示这一点 干涉测量，一个cmos传感器可以取代光子计数，并并行测量微弱漫反射光 显示CBF的波动。这一改进将轻型吞吐量/成本比提高了约100倍。因此，我们可以采取 更多测量(提高大脑覆盖范围)和更大的源收集器分离(改善大脑 专一性)。然后，我们证明了通过快速调整光源波长，我们也实现了飞行时间 (TOF)决议。这种额外的TOF维度更好地区分了大脑和表层组织，并提供了 估计光学性质，改进量化。最后，干涉测量方法本质上是 不受环境光影响。 在我们在成人身上取得的可喜结果的基础上，我们将开发、优化和验证iDOS， 快速、可靠的脑血流量监测。我们将确定iDOS相对于以下各项的优点和缺点 传统的方法。最后，我们将对重型颅脑损伤患者进行观察性脑血流监测。 神经重症监护病房(Neuro-ICU)，测试我们的无创脑血流测量预测经期的能力 缺氧的症状。

Abstract: A major goal in the management of traumatic brain injury (TBI) is to optimize cerebral blood flow (CBF) over the days to weeks following injury. Yet, there is currently no well-established, non-invasive method to continuously monitor CBF in adults. Though diffuse optical flowmetry (DOF) methods for monitoring CBF based on dynamic scattering of near-infrared (NIR) light are used in research, these methods suffer from fundamental limitations. First, they require costly photon counting, which strictly constrains achievable speed, brain specificity, and brain coverage. Second, they lack depth discrimination, leading to contamination from blood flow in superficial tissues. Third, they require assumptions about optical properties, which can vary between individuals or across brain regions. Fourth, they are sensitive to noise from ambient light. To address these limitations, we introduce interferometry to human diffuse optics, creating a new class of NIR light-based monitoring tools, called interferometric Diffuse Optical Spectroscopy (iDOS). First, we show that with interferometry, a CMOS sensor can replace photon counting and parallelize measurements of weak diffuse light fluctuations that reveal CBF. This advance improves light throughput-to-cost ratio by ~100x. We can thus take more measurements (improving brain coverage) with larger source collector separations (improving brain specificity). Then, we show that by rapidly tuning the light source wavelength, we also achieve time-of-flight (TOF) resolution. This extra TOF dimension better distinguishes brain from superficial tissue, and also provides estimates of optical properties, improving quantification. Finally, interferometric methods are essentially unaffected by ambient light. Building on our promising results in adult humans, we will develop, optimize, and validate iDOS for quantitative, rapid, and robust CBF monitoring. We will identify the advantages and weaknesses of iDOS relative to conventional methods. Finally, we will perform observational CBF monitoring in severe TBI patients in the neurointensive care unit (neuro-ICU), testing the ability of our non-invasive CBF measurements to predict periods of hypoxia.