In Optical Coherence tomography (OCT), dispersion mismatches cause degradation of the image resolution and are, thus, compensated accordingly. However, dispersion is specific to the material that is causing the effect and can, therefore, carry useful information regarding the composition of the samples. In this summary, we propose a novel technique for estimating tissue dispersion by calculating the cross-correlation of images acquired at different center wavelengths to estimate the shift between their features, also known as walk-off, and use that to calculate the dispersion. Since a distinct reflector is not required, this method is applicable to any sample and can even be implemented in vivo and in situ in human tissues. The proposed technique was verified ex vivo resulting in Group Velocity Dispersion (GVD) values comparable to those obtained from estimating the walk-off from a mirror, as described in the literature. The applicability to cancer diagnosis was evaluated on a small set of gastrointestinal normal and cancer OCT images. Using the statistics of the GVD estimates, tissue classification resulted in 100% sensitivity and 81% specificity (92% correct classification rate). The success of these preliminary results indicates the potential of the proposed method, which should be further investigated to elucidate its advantages and limitations.
Dispersion mismatch between the two arms of an Optical Coherence Tomography (OCT) interferometer causes degradation of the image resolution. However, dispersion in tissue is specific to the chemical constituents of the cells and can therefore carry diagnostically useful information. Unfortunately, dispersion measurement techniques, presented so far in the literature, require the presence of strong distinct reflections in the OCT image which are rarely present when imaging tissues in vivo. The novel method presented here relies on the image speckle to calculate the PSF degradation and is therefore applicable to any tissue and can be implemented in vivo and in situ. The resolution degradation is estimated using a Wiener-type deconvolution and was verified ex vivo resulting in Group Velocity Dispersion (GVD) values comparable to the standard techniques. This technique has also been applied to normal and malignant samples of human colon to evaluate its applicability for cancer diagnosis. Using the statistics of the GVD estimate, the tissue classification resulted in 93% sensitivity and 100% specificity (96% correct classification rate). The success of these preliminary results indicates the potential of the proposed method which should be further.
In Optical Coherence tomography (OCT), dispersion mismatches cause degradation of the image resolution. However,
dispersion is specific to the material that is causing the effect and can therefore carry useful information regarding the
composition of the samples. In this summary, we propose a novel technique for estimating the dispersion in tissue which
uses the image speckle to calculate the PSF degradation and is therefore applicable to any tissue and can be implemented
in vivo and in situ. A Wiener-type deconvolution algorithm was used to estimate the image PSF degradation from the
speckle. The proposed method was verified ex vivo resulting in comparable values of the Group Velocity Dispersion
(GVD) as obtained by a standard estimation technique described in the literature. The applicability to cancer diagnosis
was evaluated on a small set of gastrointestinal normal and cancer OCT images. Using the statistics of the GVD
estimate, the tissue classification resulted in 93% sensitivity and 73% specificity (84% correct classification rate). The
success of these preliminary results indicates the potential of the proposed method which should be further investigated
to elucidate its advantages and limitations.
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