Application of the fiber-optic system for intraoperative study of pelvic organs in laparoscopic surgery

Abstract

An increasing number of cases of diseases and disorders of the female reproductive system are revealed every year, entailing negative social and economic consequences. At the same time, there is often no consensus regarding the tactics of diagnosis and treatment, also some pathologies are still poorly understood. Currently, minimally invasive organ-preserving laparoscopic interventions are quite common in gynecological practice. Their advantages are short postoperative rehabilitation time and less blood loss, as well as a good cosmetic effect due to the absence of an abdominal incision. However, visual examination in white light cannot provide the surgeon with information about the metabolic and circulatory processes in the organs under study.
To assess the state of biological tissues in medicine, optical diagnostic methods are widely used. In particular, laser Doppler flowmetry (LDF) is used to assess the parameters of blood microcirculation. The method of fluorescence spectroscopy (FS) helps to characterize the intensity of metabolic processes due to the assessment of the content in biological tissues of special coenzymes involved in cell respiration.
Therefore, the aim of this work was to integrate optical methods into the standard laparoscopy procedure performed on organs of the female reproductive system.
A fiber-optic system implementing both LDF and FS methods was developed especially for performing experimental measurements from approximately one diagnostic volume of biotissue (1-3 mm3). The main units of device were designed in cooperation with SPE “LAZMA” Ltd. (Moscow, Russia). A laser with a wavelength of 1064 nm was used in the LDF channel, while radiation sources with wavelengths of 365 nm and 450 nm were used in the FS channels. Delivery and registration of optical radiation was carried out using a specially designed laparoscopic probe introduced into the pelvic cavity through an instrumental channel created during the operation. One patient took part in the experimental studies, measurements were carried out as an additional diagnostic procedure in the framework of the surgical intervention. The studies were approved by the ethics committee of the Research Institute of Obstetrics, Gynecology and Reproductology named after D.O. Ott (minutes of the meeting No 110, June 10, 2021).
The study protocol included measuring the perfusion of ovarian tissues (1 study point) and myometrium (3 points) and recording the resulting LDF signals for about 1 minute. Simultaneously, two autofluorescence spectra of biological tissues excited by UV (365 nm) and blue (450 nm) radiation were registered, respectively. The obtained information shows that the LDF and FS methods are quite sensitive and have the potential to be used in this area of surgery.
Preprocessed data demonstrate the variability of the FS parameters. For example, for the myometrium, the maximum fluorescence intensity in UV light lies within the range of 241-486 units, while in blue light, the values ranged from 66 to 122 units. In this regard, a normalization method was applied to all the obtained raw fluorescence data, which allows to compensate for the spread of values in the observed spectra. In one of the measurements, a decrease in the fluorescence intensity at wavelengths of about 540 nm and 580 nm was noted, which can be explained by the presence of a large volume of blood in the tissue under study. Blood is known to be a good absorber of optical radiation in both visible and UV ranges, which leads to a registered signal weakening.
The variability of the perfusion values within one LDF signal is explained both by natural fluctuations in the blood flow in the diagnosed area and by artifacts of the surgeon's hand movements.
Accomplished experimental studies confirm the possibility of performing measurements using LDF and FS methods as additional diagnostics during the implementation of minimally invasive surgical interventions. The next step in conducting research is to design further experiments and collect data for statistical processing. It seems promising, as the expansion of standard laparoscopy capabilities using optical diagnostic technologies can allow the surgeon to obtain valuable information on the perfusion-metabolic characteristics of tissues of the organs of the female reproductive system.
The study was supported by the Russian Science Foundation under the project №21-15-00325.

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Nadezhda Golubova
Orel State University
Russia

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