Single-pixel diffuse optical tomography scanner for dynamic functional imaging

点击翻译按钮获取中文摘要

Rational and Objective****Diffuse optical tomography (DOT) is a low-cost imaging modality that can provide three-dimensional (3D) images of tissue absorption, which, in the near-infrared range, is mainly due to hemoglobin and water. By measuring tissue absorption at multiple wavelengths, tomographic functional images can be generated and used to detect localized physiological abnormalities. It is this capacity to noninvasively image tissue physiological parameters (and to do so using safe, portable instruments) that makes DOT such an attractive technology. While DOT has numerous advantages, its widespread adoption as a functional imaging modality has been restricted by the current tradeoff between spatial and temporal resolution. That is, current methods can either acquire data at high speed with poor spatial resolution, or at millimeter resolution but with poor temporal resolution.****The objective of this research program is to address this critical limitation.****Research Plan****1) We will build a DOT scanner based on:**** i) Early-photons imaging: These photons travel along paths that are confined close to the line of sight between the source and detector (quasi-mimicking X-rays), which reduces image blurring and significantly improves spatial resolution.**** ii) Wide-field patterned illumination: A digital micro-mirror device (DMD), made of a 2D array of micro-mirrors that can be individually turned “ON” or “OFF”, will be used to generate wide-field patterned illumination on the surface of the tissue. We will leverage recent advances in DMDs technology that produced units that can generate light patterns at very high speed (up to 23 kHz) with high light output (up to 48%), to build a fast and efficient illumination system.*** iii) Compressive detection: Light transmitted through the tissue will be projected onto a 2nd DMD (to spatially encode the light intensity), then integrated by a single photodetector. Notice that we will be using a single-pixel camera to generate 3D images without scanning or multiplexing.****2) We will develop an image reconstruction software based on accurate Monte Carlo modeling of early-photons propagation in tissue.****3) The spatial resolution of the scanner will be quantified using tissue-mimicking phantoms with spatially-resolved features.****4) The dynamic imaging capability of the system will be tested in an animal model of localized ischemia.****Impact****The research program detailed in this proposal will lead to the development of a DOT scanner capable of fast 3D imaging of thick tissue (up to 60-mm thickness) with millimeter resolution. Such a scanner will enable dynamic imaging of molecular tracers to develop methods for i) small animal molecular imaging, ii) monitoring treatment response in inflammatory arthritis, and iii) predicting response to chemotherapy in breast cancer.***