Multi-Frequency Synthesis and Orientation Control in SFDI

SFDI 中的多频合成和定向控制

• 批准号: 8386487
• 负责人: Bruce J. Tromberg
• 金额: $ 20.79万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8386487
• 关键词: Algorithms; Beds; Biological; Biopsy; Bone Tissue; Brain; Caring; Collagen; Complex; Computer Simulation; Computer software; Custom; Data; Dependence; Diffusion; Disease; Effectiveness; Elements; Engineering; Equation; Fluorescence; Frequencies; Goals; Heterogeneity; Histocompatibility Testing; Image; Imaging technology; Iris; Lead; Length; Light; Maps; Measurement; Measures; Mechanics; Medical Imaging; Methods; Microscopic; Modeling; Monitor; Muscle; Operative Surgical Procedures; Optics; Pattern; Phase; Process; Property; Relative (related person); Resolution; Sampling; Shapes; Simulate; Skin; Solutions; Space Perception; Speed; Structure; Surface; Techniques; Technology; Testing; Thick; Time; Tissue Sample; Tissues; Validation; Writing; absorption; attenuation; base; bone; brain tissue; charge coupled device camera; cost effective; data acquisition; design and construction; imaging modality; innovation; instrument; response; tissue phantom; tomography; white matter

DESCRIPTION (provided by applicant): Spatial Frequency Domain Imaging (SFDI) is a model-based, wide-field, non-contact method for measuring the absorption, scattering, and fluorescence properties of biological tissue. Optical properties are determined in each pixel simultaneously, by measuring the attenuation (or fluorescence) of sinusoidal patterns of light projected onto the sample at varying spatial frequencies and phases. Images are demodulated by processing 3 phase-shifted views of the sample. The mean interrogation depth at a given wavelength is controlled by the spatial frequency of projection, and frequency-dependent differences in path length are used to calculate tissue optical properties using computational models. Because 3 specific phases are required for each projected frequency, care must be taken to perfectly sequence all projections and camera triggers. While each of these processes is fairly rapid, together they can slow the acquisition to a fraction of the camera frame rate. In order to overcome this limitation and facilitate real-time SFDI, we will develop new methods using "frequency synthesis" - multiple frequencies synthesized into customized projection patterns. These patterns will be optimized for speed and frequency-dependent information content in order to facilitate rapid and accurate optical property measurements, probe buried objects, and perform tomography. When properly selected, frequency synthesized projections can potentially decrease the minimum acquisition time to the frame rate of the camera, allowing real-time SFDI and SFD tomography. The ability to project custom patterns not only allows us to generate multi-frequency components, it also adds the ability to change their orientation. This allows us to explore a new mode of contrast based on probing tissue structures that are aligned with the direction of the projected pattern. This is due to the fact that many tissue types, including bone, muscle, skin, and white matter in the brain, have orientated internal structures such that the degree of optical scattering depends on the direction of light propagation. The scattering direction of these oriented tissues is determined by their microscopic structure and obeys a diffusion equation. We will derive accurate solutions to the anisotropic diffusion equation in the spatial frequency domain. In an ordered medium, the attenuation of sinusoidal patterns depends on the relative orientation of the spatial frequency pattern and scatterer direction. Thus, by projecting multiple spatial frequencies in different directions and measuring the attenuation, we will be able to image the spatially varying scattering orientation over a large field of view. We expect that the combination of spatial frequency synthesis and orientation control will lead to new methods for quantitative, real-time imaging and tomography in thick tissues, as well as the characterization of exciting new contrast mechanisms based on an optical diffusion tensor. PUBLIC HEALTH RELEVANCE: These studies will allow us to acquire sufficient data to develop and validate a new optical technology for real-time, quantitative imaging and depth sectioning of tissues based on relatively simple, cost-effective imaging cameras and patterned light projection techniques. The technology has potential to replace conventional camera-based imaging methods by allowing quantitative viewing of functional tissue attributes beneath the surface, where disease typically begins. Our approach is expected to lead to new, bedside medical imaging methods for detecting disease, monitoring therapy response, and guiding surgical procedures.

描述（由申请人提供）：空间频域成像（SFDI）是一种基于模型的、宽视场的、非接触的方法，用于测量生物组织的吸收、散射和荧光特性。通过测量在不同空间频率和相位下投射到样品上的正弦光的衰减（或荧光），同时确定每个像素的光学特性。通过处理样品的3个相移视图来解调图像。给定波长的平均探测深度由投影的空间频率控制，路径长度的频率相关差异用于使用计算模型计算组织光学特性。因为每个投影频率需要3个特定的阶段，所以必须注意所有投影和相机触发的完美顺序。虽然这些过程中的每一个都相当快，但它们加在一起会使采集速度降低到相机帧速率的一小部分。为了克服这一限制并促进实时SFDI，我们将开发使用“频率合成”的新方法-将多个频率合成为定制的投影模式。这些模式将针对速度和频率相关的信息内容进行优化，以促进快速准确的光学特性测量，探测埋藏物体并进行断层扫描。如果选择得当，频率合成投影可以潜在地减少相机帧率的最小采集时间，从而实现实时SFDI和SFD断层扫描。投影自定义模式的能力不仅允许我们生成多频率组件，还增加了改变其方向的能力。这使我们能够探索一种新的对比模式，基于探测与投影模式方向一致的组织结构。这是因为许多组织类型，包括骨骼、肌肉、皮肤和大脑中的白质，都有定向的内部结构，因此光散射的程度取决于光传播的方向。这些取向组织的散射方向由其微观结构决定，并服从扩散方程。我们将在空间频域导出各向异性扩散方程的精确解。在有序介质中，正弦模式的衰减取决于空间频率模式和散射方向的相对方向。因此，通过在不同方向上投射多个空间频率并测量衰减，我们将能够在大范围内成像空间变化的散射方向