Spectroscopic OCT

Spectroscopic OCT (SOCT) is an extension of OCT technology where not only the structural information, but also the spectroscopic information is retrieved. It is based on the principle that the bandwidth of a light source used in OCT is broad; therefore by using appropriate time-frequency analysis, a depth-resolved spectroscopy study can be performed. Spectroscopic OCT has at least two imaging targets: imaging spectral absorption and spectral scattering. These can be used to detect either endogenous molecules or exogenous agents.

molecular imaging

molecular imaging

Spectroscopic OCT has many different contrast contributions, e.g., spectral absorption and spectral scattering. It is important to separate them so that more accurate tissue properties can be retrieved. This is possible because different contrast mechanisms often have different spectral or range properties. For example, a least-squares algorithm can separate the attenuation due to absorption and scattering based on spectral properties.

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Accuracy of retrieval of dye concentration from SOCT signal using different time-frequency analyses

Xu C, Kamalabadi F, Boppart SA. Comparative performance analysis of time-frequency distributions for spectroscopic optical coherence tomography. Applied Optics, 44:1813-1822, 2005. PubMed
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Wavelength-Dependent Spectral Scattering

The spectral-scattering information contained within the SOCT signal can be used diagnostically to assess scatterer size and spatial distribution in cells and tissues. Dominant scatterers include nuclei and mitochondria. This technique is similar to Light Scattering Spectroscopy, except SOCT can perform analysis in depth, and in three-dimensions.

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Spectral-scattering analysis of SOCT signals can differentiate scatterer size.

Xu C, Carney PS, Boppart SA.  Wavelength-dependent scattering in spectroscopic optical coherence tomography.  Optics Express, 13:5450-5462, 2005. n/a PDF

 

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Spectroscopic spectral-domain optical coherence microscopy of adipose and muscle tissue. Spectral analysis of scatterer size enhances contrast.

Xu C, Vinegoni C, Ralston TS, Luo W, Tan W, Boppart SA.  Spectroscopic spectral-domain optical coherence microscopy.  Opt. Lett., 31:1079-1081, 2006. PubMed Abstract PDF