Review of structured light in diffuse optical imaging

Abstract

Diffuse optical imaging probes deep living tissue enabling structural, functional, metabolic, and molecular imaging. Recently, due to the availability of spatial light modulators, wide-field quantitative diffuse optical techniques have been implemented, which benefit greatly from structured light methodologies. Such implementations facilitate the quantification and characterization of depth-resolved optical and physiological properties of thick and deep tissue at fast acquisition speeds. We summarize the current state of work and applications in the three main techniques leveraging structured light: spatial frequency-domain imaging, optical tomography, and single-pixel imaging. The theory, measurement, and analysis of spatial frequency-domain imaging are described. Then, advanced theories, processing, and imaging systems are summarized. Preclinical and clinical applications on physiological measurements for guidance and diagnosis are summarized. General theory and method development of tomographic approaches as well as applications including fluorescence molecular tomography are introduced. Lastly, recent developments of single-pixel imaging methodologies and applications are reviewed.

Single snapshot imaging of optical properties using a single-pixel camera: a simulation study

“…The standard SFDI method requires to acquire several images of the scene sequentially at two different spatial frequencies (e.g., f x ¼ 0 and 0.2 mm −1 ) and three different phases (0 deg, 120 deg, and 240 deg) to obtain the modulation amplitude of each spatial frequency. 3 In comparison, the SSOP method requires the acquisition of a single image and relies on filtering in the Fourier domain to extract the amplitude modulation at two spatial frequencies: f x ¼ 0 mm −1 and the projected spatial frequency (e.g., f x ¼ 0.2 mm −1 ). From these measurements, diffuse reflectances at these spatial frequencies are obtained by calibration using a phantom with known optical properties.…”

“…Among the numerous approaches proposed in this direction, the most recent ones rely on the spatial modulation of the light and processing in the frequency domain. [1][2][3] Spatial frequency-domain imaging (SFDI) techniques allow the measurement of tissues absorption and reduced scattering optical properties over an entire image at once, which are used to retrieve physiological tissues parameters. [4][5][6][7][8][9][10] However, major limitations of such imaging system include the necessity to project several patterns of light and to illuminate sequentially at several wavelengths to extract physiological parameters, impeding the use of such technology for real-time imaging.…”

Accelerating Monte Carlo modeling of structured-light based diffuse optical imaging via “photon sharing”

“…The appeal of these model-based imaging methods is largely elicited by their non-ionizing nature, high sensitivity, functional imaging and multiplexing capabilities, in addition to relatively low cost. Recently, new DOT/FMT instrumental methodologies based on structured-light, including spatial-frequency domain imaging (SFDI), have been proposed to improve upon the traditional point-source illumination schemes [2,3]. Enabled by spatial light modulators (SLMs) such as digital micro-mirror devices (DMDs), the illumination/detected light can be spread/acquired over large surfaces.…”

Deep Learning Enhanced Hyperspectral Fluorescence Lifetime Imaging

“…Moreover, the emergence of the theoretical framework of compressive sensing has empowered the implementation of efficient computational imaging systems 3 . Among all technical approaches, structured light techniques have played a significant role in advancing this field 4,5 . For instance, the incorporation of spatial light modulators in the optical chain has led to improved resolution in microscopy 6 , enabled the reconstruction of 4D phase amplitude data 7,8 , facilitated hyperspectral microscopy 9,10 or enabled fast optical tomography of thick specimens 11,12 .…”