CLINICAL METHODS AND INTERPRETATION OF THE RESULTS OF LASER DIAGNOSTICS

     In accordance with the used general physical principles of optical noninvasive medical diagnostics, in the noninvasive medical spectrophotometry (NMS) the object of the medical investigation consists in evaluation of biochemical composition of human tissues including tissues' peripheral blood and lymph supply. The most easily "in vivo" detected biochemical components in tissues by the optical technique are: water, melanin, different fractions of hemoglobin (oxyhemoglobin, deoxyhemoglobin, etc.), lipids, porphyrins as well as collagen and some other organic molecules. A lot of dynamic fluctuations in peripheral blood microcirculation processes at a short scale of time allow a doctor to observe similar fluctuations in the registered concentration of one or another biochemical component, that makes it possible to diagnosis a functional specialties of tissues' and vessels' clinical status (conditions). The changes in the registered parameters at a long scale of time allow a doctor to quantitatively study the efficacy of applied treatment procedures and tendencies in a patient's health. 
 
     Basing on that it is possible today to determine a number of medical & biological parameters of the peripheral tissues’ blood microcirculation - blood flow and perfusion, low-frequency rhythms of vasomotions of the vessels, some parameters of oxygen utilization in the tissue, etc. This technology allows a doctor to have a powerful, simple and convenient tool for monitoring and identifying some different destructive-inflammatory, tumorous, erosive-ulcerative impairments and processes in tissues and organs, for estimating some functional parameters of vessels and, even, of a vegetative nervous system in a total. For example, the noninvasive spectrophotometric technique allows a doctor to identify quickly a type of blood microcirculation in skin with the use of conventional functional tests (the tests with functional loading on the microcirculatory bedside), for instance - the test with occlusion. With the use of our reflectance oximeter "Spectrotest" it was shown in 2003 (see here our paper Tchernyi V.V., Rogatkin D.A. et. al. "Complex noninvasive spectrophotometry in examination of patients with vibration disease" // Proc. SPIE, vol. 6078, 2006. - pp.363-370) that there are various physiological rhythms in the StO2 parameter like ones exist in the blood perfusion which are measured by Laser Doppler Flowmetry. So, the noninvasive spectrophotometry can be used in different areas of the modern medicine: surgery, oncology, urology, dermatology, radiology, gynecology, etc. for a purpose of better understanding of basic pathophysiological aspects of diseases. It gives for a doctor a lot of additional information about the patient without the use of any invasive, expensive and long-time laboratory tests.

     One of the most perspective area of applications of this diagnostic technique is the oncology. For oncology the overwhelming majority of the research and publications is concentrated now on a problem of the differential diagnosis of normal and malignant tissues for different localizations and clinical forms of young cancers. In our research we didn't obtain such promising results, but, meanwhile, in our opinion the noninvasive optical spectrophotometry can have high possibilities in monitoring an efficiency of different methods of tumors treatment, the radiotherapy and the chemo-radiotherapy, for instance. It is well known that different processes of blood microcirculation and tissues oxygenation in malignant tumors have a strong influence on a radiotherapy efficacy. But there are in the modern radiology only few methods to prognosticate a positive radiotherapy outcome. Noninvasive spectrophotometry can assist a doctor to produce a more objective and grounded prognosis by means of indicating a parameter of specific oxygen utilization in the malignant tissue, a parameter of blood perfusion in it, as well as different parameters of activity of cells' respiratory ferments in a tumorous area (see our paper in Photonics & Laser in Medicine here). In particular, in one of series of our experiments we found out a certain correlation between data of fluorescent diagnostics and the presence a chronic hypoxia state in tissues. It was done on the basis of  registration of endogenous porphyrins fluorescence (see here and here). As the hypoxia is one of principal causes of radio resistance of tumors, determination of the oxygen status of a tumor "in situ" allows one to build an additional objective forecast for results of ionizing radiation treatment and soundly to appoint application to the patient of various radiosensitizers raising the maintenance of oxygen in cells of the tumor. Similarly, various inflammatory processes in the tissues are frequently accompanied by hypoxia. It allows using the methods of fluorescent spectroscopy in vivo to monitor the development of local inflammation in tissues and organs, including intraoperative monitoring. But in interpreting the results of fluorescence spectroscopy in vivo, a doctor needs to be very careful. The recorded signal depends on many parameters and non-linear depends on the relative concentration of fluorophores in the medium. Fluorescent data interpretation in terms of biochemical tissue composition is not a trivial task for the existed level of science. To read more - see our paper in Journal of Fluorescence (here).
 

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