Multimodal sapphire scalpel for intraoperative diagnosis and therapy.
The multimodal sapphire scalpel was developed using the edge-defined film-fed growth technique aided by the cutting edge mechanical sharpening. The sapphire properties are combined with the presence of as-grown hollow internal capillary channels for the optical fibers accommodation. Thanks to the features of the sapphire scalpel, multimodal optical diagnosis of tissues with their dissection became available. The attained results justified a strong potential of the sapphire scalpel to become an efficient tool for minimizing the volume of the normal tissue removal around the tumor by detecting the tumor margins.
Optical coherence tomography of the ex vivo human and rat brain tissue samples is performed. The analysis of attenuation coefficient, coefficient based on effective refractive index, and their standard deviations was obtained from OCT measurements.
The methods used for digital processing of optical coherence tomography (OCT) and crosspolarization (CP) OCT images are focused on improving the contrast ratio of native structural OCT images. Such advances are particularly important for the intraoperative detection of glioma margins where the visual assessment of OCT images can be difficult and lead to errors. The aim of the study was to investigate the application of optical coefficients obtained from CP OCT data for the differentiation of glial tumorous tissue from a normal brain. Pseudocolor en-face OCT maps based on two optical coefficients (the commonly used rate of attenuation in the cochannel, and in addition, the interchannel attenuation difference) were constructed for normal rat brain coronal cross sections and for brains with a 101.8 rat glioblastoma model. It was shown that the use of optical coefficients significantly increased the available information from the OCT data in comparison with unprocessed images. As a result, this allowed contrasting of the white matter from the gray matter and tumorous tissue ex vivo, and for this purpose, the interchannel attenuation difference worked better. The interchannel attenuation difference values of white matter were at least seven and two times higher than corresponding values of the cortex and tumorous tissue, whereas the same parameter for cochannel attenuation coefficient values of white matter are about 4 and 1.4. However, quantitative analysis shows that both coefficients are suitable for the purpose of glioblastoma detection from normal brain tissue regardless of whether a necrotic component was present (in all compared groups p < 0.001).
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