Diffuse optical imaging

Diffuse optical imaging (DOI) is a method of imaging using near-infrared spectroscopy (NIRS)[1] or fluorescence-based methods.[2] When used to create 3D volumetric models of the imaged material DOI is referred to as diffuse optical tomography, whereas 2D imaging methods are classified as diffuse optical topography.

A fiber-optic array for breast cancer detection by way of diffuse optical tomography.

The technique has many applications to neuroscience, sports medicine, wound monitoring, and cancer detection. Typically DOI techniques monitor changes in concentrations of oxygenated and deoxygenated hemoglobin and may additionally measure redox states of cytochromes. The technique may also be referred to as diffuse optical tomography (DOT),[3] near infrared optical tomography (NIROT) or fluorescence diffuse optical tomography (FDOT), depending on the usage.

In neuroscience, functional measurements made using NIR wavelengths, DOI techniques may classify as functional near infrared spectroscopy fNIRS.

Physical mechanism

Biological tissues can be considered strongly diffusive media, since during light propagation the scattering phenomenon is dominant over absorption in the so-called "therapeutic window" spectral range. Photon migration in diffusive media is described by the heuristic model of the diffusion equation, which offers analytical solutions for some specific geometries. Starting from the measured absorption and scattering coefficients, it is possible to derive the concentrations of tissues' main chromophores.[4]

Diffuse optical imaging can be implemented in time domain, frequency domain or continuous wave, in reflectance or transmittance configuration.

See also

• Optical tomography
• Computed tomography laser mammography
• Diffuse optical mammography
• Diffusive optical imaging in neuroscience
• Near-infrared window in biological tissue
• Radiative transfer equation and diffusion theory for photon transport in biological tissue
• Time-domain diffuse optics

References

1. Durduran, T; et al. (2010). "Diffuse optics for tissue monitoring and tomography". Rep. Prog. Phys. 73: 076701. doi:10.1088/0034-4885/73/7/076701. PMC 4482362. PMID 26120204.
2. "Harvard.edu Diffuse Optical Imaging". Archived from the original on June 16, 2012. Retrieved August 20, 2012.
3. Jiang, Huabei (2018-09-03). Diffuse Optical Tomography. CRC Press. ISBN 978-1-315-21748-2.
4. Martelli, Fabrizio; Del Bianco, Samuele; Ismaelli, Andrea; Zaccanti, Giovanni (2009). Light Propagation through Biological Tissue and Other Diffusive Media: Theory, Solutions, and Software.