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The number and contribution of high dose imaging modalities, computed tomography in particular, is rapidly increasing both in the 'Russian Federation and other developed countries. Maximal increase in the number of computed tomography examinations in Russia was observed in 2020 due to the full-scale application of this imaging modality for the diagnostics of the novel coronavirus infection COVID-19. The use of computed tomography for the examination of the chest for the pregnant women is associated with several issues. An internationally accepted approach for the provision of the radiation safety of the pregnant patients is the assessment of the absorbed dose in the fetus after each X-ray examination. However, there are no existingn approved methods for the assessment of the absorbed dose in the fetus in the Russian Federation. The aim of the current study was to assess the doses in the fetus for the pregnant women undergoing computed tomography of the chest due to the COVID-19 and to estimate the probability of the development of the deterministic effects for the fetus. The study was based on the collection of the parameter of Russian and international computed tomography protocols. Parameters of the international computed tomography protocols were collected viameta-analysis of the existing publications; Russian protocols — via data collection in computed tomography departments in St-Petersburg hospitals. Absorbed dose in the uterus of the female patient and effective dose for the fetus were calculated using NCICT 3.0 software for 8, 10, 15, 20, 25, 30, 35 and 38 weeks of pregnancy. The results of the calculations indicate the lack of significant differences between absorbed doses in the uterus and effective doses for the fetus for all stages of pregnancy. Maximal doses for the selected computed tomog­ raphy protocols were in the range of 0.5 mGy (mSv) for 8-25 weeks, 0.6 mGy (mSv) for 30 week, 1.4 mGy (mSv) for 35 week and 2.7 mGy (mSv) for 38 week. The threshold for the development of the deterministic effects equal to 100 mGy cannot be exceeded even for repeated (10-15) computed tomography chest scans. Hence, the use of computed tomography as the primary method of COVID-19 diagnostics and staging will not be associated with the development of deterministic effects in the fetus.

The article is devoted to the historical aspects of the emergence and development of methods of radiology diagnostics in perinatology — a science that studies the perinatal period and is at the junction of two disciplines: obstetrics and pediatrics. The official recognition of perinatal medicine as an independent direction took place in economically developed countries in 1976 (8 years after the first Congress on Perinatology), when the European Scientific Society of Perinatology was created. One of the most important tasks of perinatology is to assess the condition of the fetus and extrafetal structures, which include the placenta, umbilical cord, fetal membranes. As part of the development of perinatology, new areas of medical science have arisen and continue to actively develop, including radiology diagnostics in perinatology. Currently, during pregnancy, from radiology diagnostic methods, ultrasound and magnetic resonance imaging are safe and informative. The emergence and development of classical X-ray diagnostics is considered separately in the article. Attention is drawn to the current state of the methods of radiology diagnostics when used in perinatology, the order of appointment, indications and contraindications, advantages and disadvantages. The study of the history of the development of radiology imaging in perinatology makes it possible to trace the dynamics of the development of this industry, to analyze the stages of the formation of instrumental research methods during pregnancy. Thanks to the constant development of technology, a large amount of accumulated experience in radiology imaging during pregnancy, the creation of international communities for diagnostics in perinatology and the formation of interdisciplinary approaches for the management of pregnancy, it has become possible to quickly, safely and non-invasively receive information about the condition of a pregnant woman and a fetus.

BACKGROUND: Placental adhesive disorder is associated with a high risk of massive bleeding during pregnancy and caesarean delivery. Abnormal trophoblast invasion and pathological hypervascularization detected in these patients may be due to the imbalance of angiogenic factors such as PlGF and sFlt-1, which makes their study an important area of scientific and clinical practice. AIM: The aim of this study was to evaluate sFlt-1 and PlGF levels in women with placenta accrete spectrum and to compare the data with the results in women with normal pregnancy. MATERIALS AND METHODS: This case-control study included 71 pregnant women in the third trimester of pregnancy. The main group (n = 32) consisted of patients with prenatally diagnosed placenta previa and abnormally invasive placenta; the control group (n = 39) included patients with normal pregnancy. In the study groups, the levels of sFlt-1 and PlGF were determined, with ultrasound and MRI characteristics evaluated. Statistical analysis was performed using IBM SPSS Statistics 26.0. RESULTS: Serum sFlt-1 and PlGF levels in the study group differed as compared to controls. In women with placenta accreta spectrum, the median sFlt-1 level was 2886.0 [2175.04127.0] pg/ml vs. control: 1890.0 [1807.02205.0] pg/ml (р 0.001); the median PlGF level was 233.5 [171.4460.5] pg/ml vs. control: 880.9 [746.61210.0] pg/ml (p 0.001). A correlation was revealed between the angiogenic factor levels and the degree of pathological hypervascularization and collaterization according to MRI data. When comparing the probability of abnormally invasive placenta (PAS Grades 2 or 3) and the sFlt-1/PlGF ratio, an ROC curve was obtained with the AUC of 0.74 0.13 (95% CI: 0.481.0; p = 0.021). CONCLUSIONS: Patients with placental adhesive disorder had increased sFlt-1 levels and decreased PlGF levels compared to patients with normal pregnancy. The above levels correlated with the degree of pathological hypervascularization and collaterization detected by MRI. A prognostic model has been obtained, according to which the threshold value of the sFlt-1/PlGF ratio of 4.22 allows for distinguishing patients with deep placental invasion (PAS Grades 2 or 3).