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Publicações

Publicações por CTM

2023

Measurement of tissue optical properties in a wide spectral range: a review [Invited]

Autores
Martins, IS; Silva, HF; Lazareva, EN; Chernomyrdin, NV; Zaytsev, KI; Oliveira, LM; Tuchin, VV;

Publicação
BIOMEDICAL OPTICS EXPRESS

Abstract
A distinctive feature of this review is a critical analysis of methods and results of measurements of the optical properties of tissues in a wide spectral range from deep UV to terahertz waves. Much attention is paid to measurements of the refractive index of biological tissues and liquids, the knowledge of which is necessary for the effective application of many methods of optical imaging and diagnostics. The optical parameters of healthy and pathological tissues are presented, and the reasons for their differences are discussed, which is important for the discrimination of pathologies and the demarcation of their boundaries. When considering the interaction of terahertz radiation with tissues, the concept of an effective medium is discussed, and relaxation models of the effective optical properties of tissues are presented. Attention is drawn to the manifestation of the scattering properties of tissues in the THz range and the problems of measuring the optical properties of tissues in this range are discussed. In conclusion, a method for the dynamic analysis of the optical properties of tissues under optical clearing using an application of immersion agents is presented. The main mechanisms and technologies of optical clearing, as well as examples of the successful application for differentiation of healthy and pathological tissues, are analyzed. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

2023

1st Spring Biophotonics Conference in Porto

Autores
Oliveira, LM; Meglinski, I; Tuchin, VV;

Publicação
JOURNAL OF BIOPHOTONICS

Abstract
[No abstract available]

2023

Fast calculation of spectral optical properties and pigment content detection in human normal and pathological kidney

Autores
Botelho, AR; Silva, HF; Martins, IS; Carneiro, IC; Carvalho, SD; Henrique, RM; Tuchin, VV; Oliveira, LM;

Publicação
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Abstract
A fast calculation method was used to obtain the spectral optical properties of human normal and pathological (chromophobe renal cell carcinoma) kidney tissues. Using total transmittance, total reflectance and collimated transmittance spectra acquired from ex vivo kidney samples, the spectral optical properties of both tissues, namely the absorption, the scattering and the reduced scattering coefficients, as well as the scattering anisotropy, dispersion and light penetration depth, were calculated between 200 and 1000 nm. Analysis of the mean absorption coefficient spectra of the kidney tissues showed that both contain melanin and lipofuscin, and that 83 % of the melanin in the normal kidney converts into lipofuscin in the pathological kidney.

2023

Broadband spectral verification of optical clearing reversibility in lung tissue

Autores
Oliveira, LR; Ferreira, RM; Pinheiro, MR; Silva, HF; Tuchin, VV; Oliveira, LM;

Publicação
JOURNAL OF BIOPHOTONICS

Abstract
The increase of tissue transparency through sequential optical immersion clearing treatments and treatment reversibility have high interest for clinical applications. To evaluate the clearing reversibility in a broad spectral range and the magnitude of the transparency created by a second treatment, the present study consisted on measuring the spectral collimated transmittance of lung tissues during a sequence of two treatments with electronic cigarette (e-cig) fluid, which was intercalated with an immersion in saline. The saline immersion clearly reverted the clearing effect in the lung tissue in the spectral range between 220 and 1000 nm. By a later application of a second treatment with the e-cig fluid, the magnitude of the optical clearing effect was observed to be about the double as the one observed in the first treatment, showing that the molecules of the optical clearing agent might have converted some bound water into mobile water during the first treatment.

2023

Characterization of optical clearing mechanisms in muscle during treatment with glycerol and gadobutrol solutions

Autores
Silva, HF; Martins, IS; Bogdanov, AA; Tuchin, VV; Oliveira, LM;

Publicação
JOURNAL OF BIOPHOTONICS

Abstract
The recent increasing interest in the application of radiology contrasting agents to create transparency in biological tissues implies that the diffusion properties of those agents need evaluation. The comparison of those properties with the ones obtained for other optical clearing agents allows to perform an optimized agent selection to create optimized transparency in clinical applications. In this study, the evaluation and comparison of the diffusion properties of gadobutrol and glycerol in skeletal muscle was made, showing that although gadobutrol has a higher molar mass than glycerol, its low viscosity allows for a faster diffusion in the muscle. The characterization of the tissue dehydration and refractive index matching mechanisms of optical clearing was made in skeletal muscle, namely by the estimation of the diffusion coefficients for water, glycerol and gadobutrol. The estimated tortuosity values of glycerol (2.2) and of gadobutrol (1.7) showed a longer path-length for glycerol in the muscle.

2023

Enhanced Ultraviolet Spectroscopy by Optical Clearing for Biomedical Applications (vol 27, 7200108, 2021)

Autores
Carneiro, I; Carvalho, S; Henrique, R; Selifonov, A; Oliveira, L; Tuchin, VV;

Publicação
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS

Abstract

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