The goal of this study was to differentiate the parts of lamb brain according to elastic scattering spectroscopy and detect the optical alterations due to coagulation. Cells and tissues are not uniform and have complex structures and shapes. They can be referred to as scattering particles. The process of scattering depends on the light wavelength and on the scattering medium properties; especially on the size and the density of the medium. When elastic scattering spectroscopy (ESS) is employed, the morphological alterations of tissues can be detected using spectral measurements of the elastic scattered light over a wide range of wavelengths. In this study firstly, the slopes of ESS spectra were used to differentiate the parts of lamb brains (brainstem, cerebellum, gray matter, white matter) in vitro in the range of 450 - 750 nm. Secondly, tissues were coagulated at different temperatures (45, 60, and 80 °C) and ESS spectra were taken from native and coagulated tissues. It was observed that as the coagulation temperature increased, the slope of the elastic scattering spectra decreased. Thus, optical properties of tissues were changed with respect to the change in nuclear to cytoplasmic ratio due to the water loss. Results showed that the slopes of ESS spectra in the visible range revealed valuable information about the morphological changes caused by coagulation.
The aim of this study was to estimate optical properties (μa, μs, μt, μs', τ, α, g) of native and coagulated (at 45°C, 60°C, 80°C) lamb brain tissues in visible and near-infrared spectral range in vitro. Optical properties of cerebellum, brainstem, cortical (grey matter), and sub-cortical regions (white matter) of frontal lobe tissues of lamb brain were estimated during this study. Diffused transmittance (Td), diffused reflectance (Rd), total reflectance (Rt) and total transmittance (Tt) were measured with single integrating sphere method. Data were processed with software (CAL-g3) developed in Biophotonics Laboratory in the Institute of Biomedical Engineering, Bogazici University. As a result, it was stated that both μa and μs values of tissues increased as temperature increases. Also scattering coefficients decreased with the increasing wavelength for all tissue types due to increase in Mie scattering.
In this study, tissue welding with 980-nm laser system, which is first-time in the literature, was performed. Hence, a preliminary study was done to determine optimal parameters for further studies. 1 cm long incisions done on the Wistar rat's dorsal skin were welded. Tissue welding with 980-nm wavelength depends on the degree of photothermal interaction. Thus, different power levels and exposure schedule were investigated. Dorsal sides of all animals were photographed from the date of surgery until they were sacrificed. The clinical examination - opening of wound and presence of infection - was noted. The rats did not show any abnormality on their health, behavior and nutrition manner. As a result, 980-nm diode laser was concluded to be a good candidate for tissue welding applications.
The effects of 980-nm diode laser and electrolytic lesions in Wistar rat brain tissue were observed by immunohistochemical staining for CD68 marker and Hematoxylin-Eosin (H&E). Bilateral lesions; laser lesions (2W/2sec) in the right hemispheres, and electrolytic lesions (1.5mA/20sec) in the left hemispheres were done through in vivo stereotaxic neurosurgical procedure. Subjects were classified into three groups due to the recovery period. Subjects in Group I, II, and III were sacrificed after 0, 2 and 7 days of recovery period respectively. After saline perfusion their brains were dislocated, and paraffin embedded sections were taken. One section for H&E and one for CD68 were cut consecutively in 3μm thickness by examining the lesion in every 30-μm thickness. CD68 was found more efficient marker than H&E in observing the after-effects of both types of lesions. The total damage of laser was smaller than that of electrosurgical unit. The shape of the ablated area in laser induced lesions was more spherical than that of electrosurgical unit. The number of macrophages increased as the recovery period increased for all subjects. Group III showed the highest number of macrophages in three, and the number of macrophages around electrolytic lesion is nearly 1.5 times higher than that of laser lesion. The remarkable ablating ability, the damage zone created and the healing of nearby tissue clearly showed that the 980-nm diode laser is an effective and useful alternative to electrosurgical unit in neurosurgery.
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