Current research on photonics and lasers in medicine in Russia

During the last 20 years, there has been significant increase all over the world in the applications of laser and photonics technology for clinical practice in hospitals. These biophotonic technologies are facilitating innovations and advancements in medical diagnostics and therapy. For many years, the application of medical lasers was a major priority in the Russian health care community, laser and fiber industry, and recently, based on the fundamental achievements of laser-tissue interactions, it has become one of the most active and important research fields in Russia [1–3].

This special issue, together with the next issue, on current laser and photonics medical research in Russia, has attracted many contributions from Russian scientific and clinical research groups. The current issue focuses on diagnostic applications and contains four original articles, one short report and one technical note from Russia academics, complemented by two contributions from Chinese scientific groups, who have a special collaboration with the Russian biophotonic community [4].

In the last 40 years, apart from endobronchial ultrasound, autofluorescence bronchoscopy (AFB) has been the one technology that has had the largest impact on diagnostic bronchoscopy. It is based on the fluorescence visualization of tissue inherent properties to identify preinvasive lesions of the central airways [5]. However, the method itself suffers from a poor specificity, which is about 56% (95% confidence interval, 0.45–0.66) according to a meta-analysis by Chen et al. [6]. Bulgakova et al. [7] take the approach that the number of false positive results can be reduced by a combination of autofluorescence (AF) imaging with quantitative spectroscopy. In their paper, they focus on the demonstration of additional spectral characteristics of AF emission which may have the potential to maximize the endogenous contrast between normal mucosa and bronchial malignancy in vivo. This article shows that real time measurements and estimation of all important spectral information, based on the probabilistic approach, is assumed to be useful for real time recommendations for biopsies and for minimizing the number of false positive results during the course of AFB [7].

Intracranial hemorrhage (ICH) is a common disease with an incidence ranging from 11 to 23 cases per 100,000 per year and being the most fatal stroke subtype with a mortality of up to 40% [8, 9]. The exact etiology and pathophysiology of ICH remains controversial, but it is possible that it is caused by the rupture of small arterioles [8, 10]. The mechanisms underlying the non-traumatic rupture of cerebral vessels are not fully clear, but there is strong evidence that stress, which is associated with an increase in arterial blood pressure, plays a crucial role in the development of acute ICH, and alterations in cerebral blood flow may also be a contributing factor to its pathogenesis. Semyachkina-Glushkovskaya et al. [11] investigated the particularities associated with alterations in arterial and venous cerebral circulation in hypertensive rats at different stages of stress-related development of ICH using three-dimensional Doppler optical coherence tomography (DOCT). It was shown that the evaluation of cerebral venous insufficiency using DOCT is an important diagnostic approach to assess the likelihood of developing cerebral hypotension and ICH [11].

Upconversion nanocomposites are photochemically highly stable nanoparticles, in which the upconversion luminescence can be excited [12]. This upconversion luminescence can be clearly distinguished from those of other organic luminophores and semiconductor nanoparticles, and is therefore applicable for biological studies and fluorescence diagnostics (FD). Furthermore, doping of such nanoparticles with paramagnetic ions, such as gadolinium could lead to FD being combined with magnetic resonance imaging, and thereby leading to a considerable improvement in the sensitivity of tumor diagnostics even in the early stages. In this context, Ryabova et al. [13] have concentrated their efforts on studies of upconversion characteristics of inorganic nanoparticles made of different materials doped with the rare-earth ion pairs Yb³⁺-Er³⁺ and Yb³⁺-Tm³⁺ as functions of the concentration and composition of a dopant at different excitation intensities.

During the past few years, Proskurin and Potlov [14] have devoted themselves to developing a method of diffuse optical tomography, which is one of the prospective tomographic methods for tissue and organ imaging and is based on light diffusion and the difference in light absorption between oxygenated and deoxygenated blood in the wavelength range of 700–1300 nm. In their paper, they report on a “model of the drop”, when an irradiation pulse with a fixed initial number of photons falls on the object near its surface and migrates, moving primarily to the center of it. This numerical model is considered as a possible way to describe the experimentally obtained data, both for homogeneous and inhomogeneous cases [14].

Methods of FD with 5-aminolevulinic acid (5-ALA) have frequently been used for the detection of different cancer diseases in clinical oncology [15]. Filonenko et al. [16] studied the effectiveness of FD using Alasens (5-ALA) for the detection of malignant lesions in the colon. In total, 78 patients with colonic polyps were examined with fluorescence colonoscopy in combination with local fluorescence spectroscopy. The combined approach resulted in an increase in the specificity of FD from 62.5% up to 93.7%.

Development of point-of-care diagnostic devices aims to diagnose diseases in a patient’s community outside of a hospital setting, which is of particular interest for resource-limited settings. They include both low-tech and high-tech methods and devices and are typically portable, fast, and relatively inexpensive [17]. Machihin et al. [18] describe a prototype of a spectral imaging module attachable to conventional rigid and flexible medical endoscopes, based on acousto-optic tunable filters (AOTF). According to the authors, the main advantage of the device is the minimization of the spatial and spectral image distortion by use of a specialized double AOTF monochromator that enables immediate and reliable detection of spectral features in any image pixel.

The first of the free contributions to this special issue from China is by Wu et al. [19]. It is about application of high-resolution label-free imaging methods to obtain tissue images for histological analysis. It involves a practical procedure of tissue preprocessing, serial sectioning, label-free imaging and image analysis which cost less time and give good contrast to obtain cellular structure and organization information of biological tissues. The second contribution is from He et al. [20] and is about the Mueller matrix transformation – a method for quantitatively characterizing the properties of anisotropic scattering media.

At this point, it should be mentioned that German- Russian cooperation in the field of clinical biophotonics has a long history and has been hugely successful. Through bilateral cooperation and collaboration between clinics, physicians and research labs, new methods of diagnostics and therapy have been established and translated for clinical use [21–24]. The German-Russian Cooperation Network on Biotechnology was founded as a result of the agreement between German and Russian Ministries of Education and Science. The objectives of the network are to initiate and establish cooperation between companies and scientific institutions in both countries, and to provide a systematic and sustainable basis for cooperation in traditional fields such as, for example, molecular biology or biochemistry, as well as in younger research areas such as biophotonics. The service offered by the cooperation network includes the organization of conferences, meetings, exhibitions, and exchange of students and scientists from Russia and Germany, as well as the allocation of specialized information, publication of trends and cooperation opportunities in a monthly newsletter and individual services for project teams. Especially the bilateral projects are intended to be result-oriented and give advice about funding, application and project management involving patents, marketing of products and setting-up businesses – all of this is of special importance for small and midsize enterprises interested in cooperation with institutions. One example of such cooperation is the project Light4LIFE that focuses on optical coherence tomography as a prospective novel medical instrumentation.

Additionally the network offers several hands-on training schemes to the particular clinical applications in Russia (for example Moscow, Nizhny Novgorod, Novosibirsk, Saratov). Recently, Dr. Herbert Stepp, from LIFE Center, University Hospital of Munich, gave an excellent internet plenary lecture, to an audience of more than 100 people. The lecture was about “Fluorescence detection and photosensitization of malignant brain tumors” and was given in the International School for Junior Scientists and Students of Optics, Laser Physics & Biophotonics (SFM-12), and organized by Saratov State University (25–28 September, 2012, Saratov) [25].

Even though this special issue only provides a small insight into the current research on the application of biophotonics and lasers for medical diagnostics in Russia, we hope that we have been able to show that medical use of lasers and biophotonics is one of the fastest growing fields in Russia today.