Methodology of Microcirculatory-Tissue Systems Multimodal Optical Diagnostics

Abstract

Violations of the microcirculatory-tissue systems (MTS) of the human body play a key role in the pathogenesis of various diseases complications, for example, rheumatological and endocrinological ones. Moreover, microcirculatory dysfunction plays a key role in the pathogenesis of gastrointestinal diseases, as well as ischemic organ damage in some acute abdominal surgical diseases. A modern trend in the development of optical non-invasive diagnostics (OND) is a multimodal approach combining several optical (less often – additional non-optical) methods in one diagnostic technology. This allows one to obtain highly efficient diagnostic tools for rheumatology, endocrinology, surgery, oncology, neurology, and other areas of medicine requiring determining the parameters of tissue perfusion-metabolic status. In order to ensure wider implementation of OND technologies into clinical practice, it is necessary to improve the multimodal approach methodology in the development of new methods and technical means for assessing the functional state of MTS in various fields of medicine. It is also necessary to resolve physical and technical issues, including substantiating medical and technical requirements for improving OND devices, carefully working out the issues of monitoring the technical condition to check their performance, identify hidden defects and failures, and compare the results obtained on various devices.
The aim of this work is to improve the quality of optical diagnostics of human body MTS and ensure the conditions for its widespread introduction into clinical practice through scientific substantiation and development of a general methodology of multimodal OND.
To solve the research problems, a systematic approach was used to develop algorithm for the synthesis of multimodal OND for assessing the functional state of MTS in various diseases. According to the developed scheme of interrelations between the main parameters and states of the MTS in various diseases, depending on research purposes, it is proposed to jointly apply the appropriate methods of OND. According to the biotechnical approach, a generalized biotechnical system (BTS) of multimodal optical diagnostics was synthesized to assess the functional state of the MTS of the human body. In addition to the decision rule, the developed BTS consists of hardware and software, including 4 main blocks: direct impact on the object, including, in addition on the biological tissue itself, test objects (optical phantoms); registration and processing of data. According to the proposed approach, the use of the decision rule (classifier) allows one to provide a diagnostic result to the doctor in the form of the presence/absence of microcirculatory-tissue disorders, as well as to determine the causes of the identified disorders and, thereby, brings the OND technology closer to the level of standard diagnostic methods.
Based on the BTS of multimodal OND a methods for assessing angiospastic and microcirculatory disorders in rheumatic diseases, and a method for assessing microcirculatory-metabolic disorders in MTS of lower limbs in diabetes mellitus were developed. Also in this work, algorithms were developed for assessing the state of the MTS of the human body under various conditions, such as sports and physiological stresses, during physiotherapeutic treatment and minimally invasive surgical procedures. The developed methods are based on the combined application of several widely used methods of OND, such as laser Doppler flowmetry (LDF), tissue reflectance oximetry, diffuse reflectance spectroscopy, fluorescence spectroscopy (FS) etc. It is important to emphasize that in these cases the results of multimodal diagnostics are not just a set of registered biomedical parameters, which are difficult to interpret by doctors due to both their complexity and high variability, but the information about the presence/absence of specific disorders in the MTS with the possibility of analyzing their causes.
In addition to the considering of the general issues of multimodal OND devices constructing, the substantiation of specialized medical and technical requirements was carried out. It allowed one to take into account the effect of blood circulation in biological tissue and pressure of the optical probe on the measurement results. To improve the metrological and technical support of multimodal OND, it is also necessary to develop new approaches and devices for monitoring their technical condition. Improved test objects (optical phantoms) for the most common optical methods in medical practice (LDF and FS) have been proposed, since they are the basic ones in modern multimodal OND.
The developed methodology of multimodal OND can be used to build medical decision support systems for the widest areas of medicine. The results of the work can be extended to other areas of medicine, for example, to improve optical biopsy methods in minimally invasive surgery, rheumatology, endocrinology, otolaryngology, dermatology, neurology, etc. The introduction of multimodal diagnostics into wearable devices (fitness bracelets, smartwatches) for long-term in vivo monitoring (daily or during sleep, tracking of circadian biorhythms; during treatment in a hospital or at home) also has great diagnostic potential.
The study was supported by the Russian Science Foundation under the project №21-15-00325.

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Speaker

Andrey Dunaev
Orel State University
Russia

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