Medical diagnosis using NIR and THz tissue imaging and machine learning methods

The problem of extracting useful information for medical diagnosis from 2D and 3D optical imaging experimental data is of great importance. We are discussing challenges and perspectives of medical diagnosis using machine learning analysis of NIR and THz tissue imaging. The peculiarities of tissue optical clearing for tissue imaging in NIR and THz spectral ranges aiming the improvement of content data analysis, methods of extracting of informative features from experimental data and creating of prognostic models for medical diagnosis using machine learning methods are discussed

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Terahertz solid immersion microscopy for sub-wavelength-resolution imaging of biological objects and tissues

We have developed a method of terahertz (THz) solid immersion microscopy for imaging of biological objects and tissues. It relies on the solid immersion lens (SIL) employing the THz beam focusing into the evanescent-field volume and allowing strong reduction in the dimensions of the THz beam caustic. By solving the problems of the sample handling at the focal plane and raster scanning of its surface with the focused THz beam, the THz SIL microscopy has been adapted for imaging of soft tissues. We have assembled an experimental setup based on a backward-wave oscillator, as a continuous-wave source operating at the wavelength of λ = 500 μm, and a Golay cell, as a detector of the THz wave intensity. By imaging of the razor blade, we have demonstrated advanced 0.2λ-resolution of the proposed THz SIL configuration. Using the experimental setup, we have performed THz imaging of a mint leaf revealing its sub-wavelength features. The observed results highlight a potential of the THz SIL microscopy in biomedical applications of THz science and technology

Light distribution in fat cell layers at physiological temperatures

Abstract Adipose tissue (AT) optical properties for physiological temperatures and in vivo conditions are still insufficiently studied. The AT is composed mainly of packed cells close to spherical shape. It is a possible reason that AT demonstrates a very complicated spatial structure of reflected or transmitted light. It was shown with a cellular tissue phantom, is split into a fan of narrow tracks, originating from the insertion point and representing filament-like light distribution. The development of suitable approaches for describing light propagation in a AT is urgently needed. A mathematical model of the propagation of light through the layers of fat cells is proposed. It has been shown that the sharp local focusing of optical radiation (light localized near the shadow surface of the cells) and its cleavage by coupling whispering gallery modes depends on the optical thickness of the cell layer. The optical coherence tomography numerical simulation and experimental studies results demonstrate the importance of sharp local focusing in AT for understanding its optical properties for physiological conditions and at AT heating

Continuously tunable middle-IR bandpass filters based on gradient metal-hole arrays for multispectral sensing and thermography

Continuously tunable middle-infrared bandpass filters have been developed based on gradient metal-hole arrays with two distinct geometries. The rotation filter relies on an array of metal holes with gradually changing periods and hole sizes in the azimuthal direction, while the translation filter exploits a metal-hole array with a linear gradient. The filters are fabricated in a Ti film on a ZnSe substrate using electron- beam nanolithography. They are characterized experimentally using Fourier-transform infrared spectroscopy, and the observed results are compared with numerical predictions of the finite element method. The developed filters offer wide spectral tunability when operating with a focused beam. Particularly, the central wavelength of the transmission band is tunable in the λc [ ð9, 15Þ μm range, for the rotation filter, and in the λc [ ð8, 13Þ μm range for the translation one, as a linear function of the filter angular or linear displacement. The filters feature relatively broad bandwidths of Δλ ≃ 0:2λc, while their spectral contrast and energy efficiency depend on the gradient type. The filter spectral response function shape and the extent of its spectra tunability can be further optimized by judicious design of the hole geometry and the metal-hole array gradient, respectively. The developed filters hold strong potential in the infrared multispectral sensing and imaging, thanks to their conceptual simplicity. Considering the linearity of Maxwell’s equations and availability of appropriate technologies for the fabrication of gradient arrays of sub-wavelength metal holes, the developed concept can be translated to other spectral ranges