This paper presents the results of the experiments which were performed using the optical biopsy system specially developed for in vivo tissue classification during the percutaneous needle biopsy (PNB) of the liver. The proposed system includes an optical probe of small diameter acceptable for use in the PNB of the liver. The results of the feasibility studies and actual tests on laboratory mice with inoculated hepatocellular carcinoma and in clinical conditions on patients with liver tumors are presented and discussed. Monte Carlo simulations were carried out to assess the diagnostic volume and to trace the sensing depth. Fluorescence and diffuse reflectance spectroscopy measurements were used to monitor metabolic and morphological changes in tissues. The tissue oxygen saturation was evaluated using a recently developed approach to neural network fitting of diffuse reflectance spectra. The Support Vector Machine Classification was applied to identify intact liver and tumor tissues. Analysis of the obtained results shows the high sensitivity and specificity of the proposed multimodal method. This approach allows to obtain information before the tissue sample is taken, which makes it possible to significantly reduce the number of false-negative biopsies.
The impairments of cerebral blood flow microcirculation brought on by cardiac and respiratory arrest were assessed with multi‐modal diagnostic facilities, utilising laser speckle contrast imaging, fluorescence spectroscopy and diffuse reflectance spectroscopy. The results of laser speckle contrast imaging show a notable reduction of cerebral blood flow in small and medium size vessels during a few minutes of respiratory arrest, while the same effect was observed in large sinuses and their branches during the circulatory cessation. Concurrently, the redox ratio assessed with fluorescence spectroscopy indicates progressing hypoxia, NADH accumulation and increase of FAD consumption. The results of diffuse reflectance spectra measurements display a more rapid grow of the perfusion of deoxygenated blood in case of circulatory impairment. In addition, consequent histopathological analysis performed by using new tissue staining procedure developed in‐house. It shows notably higher reduction of size of the neurons due to their wrinkling within brain tissues influenced by circulation impair. Whereas, the brain tissues altered with the respiratory arrest demonstrate focal perivascular oedema and mild hypoxic changes of neuronal morphology. Thus, the study suggests that consequences of a cessation of cerebral blood flow become more dramatic and dangerous compare to respiratory arrest.
This work presents results of in vivo and in situ measurements of hepatocellular carcinoma by a developed optical biopsy system. Here, we describe the technical details of the implementation of fluorescence lifetime and diffuse reflectance measurements by the system, equipped with an original needle optical probe, compatible with the 17.5G biopsy needle standard. The fluorescence lifetime measurements observed by the setup were verified in fresh solutions of NADH and FAD++, and then applied in a murine model for the characterisation of inoculated hepatocellular carcinoma (HCC) and adjacent liver tissue. The technique, applied in vivo and in situ and supplemented by measurements of blood oxygen saturation, made it possible to reveal statistically significant transformation in the set of measured parameters linked with the cellular pools of NADH and NADPH. In the animal model, we demonstrate that the characteristic changes in registered fluorescent parameters can be used to reliably distinguish the HCC tissue, liver tissue in the control, and the metabolically changed liver tissues of animals with the developed HCC tumour. For further transition to clinical applications, the optical biopsy system was tested during the routing procedure of the PNB in humans with suspected HCC. The comparison of the data from murine and human HCC tissues suggests that the tested animal model is generally representative in the sense of the registered fluorescence lifetime parameters, while statistically significant differences between their absolute values can still be observed.
Liver cancer remains one of the most widespread cancer types worldwide. The time spent on the diagnosis is one of crucial factors ensuring the effectiveness of treatment. As percutaneous needle biopsy remains the gold standard for liver diagnosis, it is necessary to develop new methods for improving this procedure. One of the most promising directions is multimodal optical biopsy. The proposed protocol describes the methodology of real-time in vivo optical measurements of liver lesions during the percutaneous needle biopsy of the liver. The multimodal approach combines the methods of fluorescence and diffuse reflectance spectroscopy and conventional histological analysis.
Despite the fact that both acute cardiac cessation and respiratory arrest are the reasons of brain ischemia, its hemodynamics, oxygenation and structural pathology differs. This article represents blood re‐distribution and neuronal tissue degeneration during the first decade of minutes after the breathing and heart beating violation. The results show that cardiac cessation is much more life‐threatening statement that provokes blood circulation abnormalities and causes strong signs of cerebral ischemia in compare with the respiratory arrest.Further details can be found in the article by G. Piavchenko, I. Kozlov, V. Dremin, D. Stavtsev, E. Seryogina, K. Kandurova, V. Shupletsov, K. Lapin, A. Alekseyev, S. Kuznetsov, A. Bykov, A. Dunaev, and I. Meglinski (e202100216).image
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