Spectral-Encoding for Video-Rate Hemodynamic Tomography

用于视频速率血流动力学断层扫描的光谱编码

• 批准号: 7272328
• 负责人: Brian W. Pogue
• 金额: $ 39.63万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7272328
• 关键词: brain imaging /visualization /scanning; computer program /software; computer system hardware; green fluorescent proteins; hemodynamics; human tissue; image enhancement; infrared spectrometry; laboratory rat; magnetic resonance imaging; oxygen consumption; oxygen tension; phantom model; technology /technique development; time resolved data; tomography; video recording system

DESCRIPTION (provided by applicant): Near-Infrared (NIR) spectroscopic tomography has been emerging as a method to image blood-based contrast in tissue. A potential strength of this imaging approach which has not been fully exploited to date is that it can be very fast, essentially real-time, similar to ultrasound. A major limitation in the development of fast NIR tomography systems has been the need to sequentially scan the light source, such that even with parallel detection, the image acquisition time is limited to frame rates of a few Hertz. This work introduces a new concept for imaging in parallel with all source locations simultaneously activated. The technique uses an array of light sources that are separated by fractions of a nanometer spectrally, yet clustered within a narrow (4 to 5 nm) bandwidth. Since the spectral features of tissue do not vary significantly over such a narrow band, these different laser sources will sample the same attenuation and scattering processes in tissue, yet in the detection channel the response associated with each source wavelength can readily be separated by a spectrograph, and thereby detected in parallel. This approach avoids the problem of source saturation of the detectors, while allowing parallel detection of all sources and all detectors in a single measurement event. This type of spectral encoding of the position is at the heart of several imaging systems such as MRI, where it allows parallel readout of the location from different radio frequencies. The system will be implemented in a small animal imaging geometry, using CCD and photomultiplier tube detection. Feasibility will be demonstrated in hardware and software through both tissue phantom and animal experiments. The hemodynamic response in terms of pulsatile flow in the brain will be imaged in the rat brain, as well as indocyanine green kinetics. The data acquisition will be generated at video rate, thereby allowing real-time visualization of the dynamics. In the R33 phase of the project, the same system design will be extended to multiple parallel detectors, allowing quantitative spectroscopy of oxygen saturation and total hemoglobin. The system will be used in existing MRI-NIR imaging systems for both brain and tumor imaging studies. The combined MRI-NIR imaging system will be calibrated in phantoms and software refined for rapid dynamic quantitative hemoglobin imaging with region-based targeting of the reconstruction. We hypothesize that dynamic imaging of total hemoglobin and oxygen saturation changes will provide fundamentally new information about tissue function and metabolic response to stimulus. The contrasts to be examined in rodent brain will be functional activation studies, as well as imaging of tumors will include (i) intrinsic blood pulsatile flow (ii) pulsatile flow and kinetics of indocyanine green, (iii) dynamic changes in oxygen saturation in response to long term and transient changes of inspired oxygen concentration, and (iv) glucose induced metabolic changes in oxygen consumption from the Crabtree effect.

描述（由申请人提供）： 近红外（NIR）光谱断层扫描已成为一种方法，以图像的血液为基础的组织的对比。迄今为止尚未被充分利用的这种成像方法的潜在优势是，它可以非常快，基本上是实时的，类似于超声。快速NIR层析成像系统的发展中的主要限制是需要顺序扫描光源，使得即使利用并行检测，图像采集时间也限于几赫兹的帧速率。这项工作介绍了一个新的概念，成像在所有的源位置同时激活并行。该技术使用一系列光源，这些光源在光谱上相隔几分之一纳米，但聚集在一个狭窄的（4到5纳米）带宽内。由于组织的光谱特征在这样的窄带上没有显著变化，因此这些不同的激光源将对组织中的相同衰减和散射过程进行采样，而在检测通道中，与每个源波长相关联的响应可以容易地由光谱仪分离，从而并行检测。这种方法避免了检测器的源饱和问题，同时允许在单个测量事件中并行检测所有源和所有检测器。这种类型的位置频谱编码是几种成像系统（如MRI）的核心，它允许从不同的无线电频率并行读出位置。该系统将实现对小动物的几何成像，采用CCD和光电倍增管检测。将通过组织体模和动物实验证明硬件和软件的可行性。将在大鼠大脑中对大脑脉动流方面的血液动力学反应以及吲哚菁绿绿色动力学进行成像。数据采集将以视频速率生成，从而允许动态的实时可视化。 在该项目的R33阶段，相同的系统设计将扩展到多个并行检测器，允许氧饱和度和总血红蛋白的定量光谱。该系统将用于现有的MRI近红外成像系统，用于脑和肿瘤成像研究。将在体模中校准组合的MRI-NIR成像系统，并对软件进行优化，以进行快速动态定量血红蛋白成像，并进行基于区域的重建靶向。我们假设，动态成像的总血红蛋白和氧饱和度的变化将提供从根本上新的信息组织功能和代谢反应的刺激。在啮齿动物脑中检查的对比将是功能激活研究，以及肿瘤成像将包括（i）固有血液脉动流（ii）吲哚菁绿色的脉动流和动力学，（iii）响应于吸入氧浓度的长期和瞬时变化的氧饱和度的动态变化，以及（iv）来自Crabtree效应的葡萄糖诱导的氧消耗的代谢变化。