LOW AND MEAN RADIATION DOSES IMPACT ON THE CEREBRAL TRACTS STRUCTURE OF THE CHERNOBYL ACCIDENT LIQUIDATORS IN THE REMOTE PERIOD (BASED ON ROUTINE AND DIFFUSION-TENSOR MAGNETIC RESONANCE IMAGING DATA)

To evaluate correlation between brain structural damages and radiation exposure level for the Chernobyl nuclear power plant accident liquidators, routine and diffusion tensor magnetic resonance imaging methods are efficient to visualize and evaluate those damages; it is also important to compare magnetic resonance imaging data of liquidators with results, received for people of the same age and the same stage of cerebral vascular disease (the discirculatory encephalopathy of I and II stage), but who did not participate in the Chernobyl accident liquidation and did not suffer from other liquidation factors and radiation catastrophe aftermaths. As a result, the Chernobyl accident liquidators group (49 subjects) and group of control (50 subjects) were examined with routine magnetic resonance imaging methods and standard protocols. In addition, the innovative method of diffusion tensor magnetic resonance imaging was applied to examine 11 cerebral tracts, bilaterally (22 tracts in both hemispheres) for every subject of the research. It was for the first time when diffusion tensor magnetic resonance imaging was applied to conduct visual analysis of polymorphic brain changes for the Chernobyl accident liquidators and special research conducted to find correlation between fractional anisotropy coefficient and radiation exposure for these patients. The results of diffusion tensor magnetic resonance imaging indicated no statistically significant (p > 0,05) difference in the level of cerebral morphological changes and between average fraction anisotropy coefficient value in any cerebral tract for both sub-groups of liquidators with different level of irradiation: 28 subjects, who were exposed by low and very low radiation doses (0–100 micro-Sv, sub-group A) and 21 subjects, who were exposed by mean radiation doses (100–1000 micro-Sv, sub-group B). However, comparing diffusion tensor magnetic resonance imaging results of control group and liquidators group, statistically significant (p < 0,05) reduction of average fraction anisotropy coefficient was detected in frontal and temporal lobes. It proves significant micro-structural damages of mentioned brain areas caused by different factors of the Chernobyl accident liquidation.

Chernobyl nuclear power plant, accident liquidator, diffusion tensor magnetic resonance imaging, fraction anisotropy, low doses of radiation, mean doses of radiation

1. Aleksanin S.S., Astafyev, N.A. Bardysheva [et al.]. Ed. by prof. Aleksanin S.S. 30 years after Chernobyl: pathogenetic mechanisms of somatic pathologies, medical care experience for Chernobyl nuclear power plant liquidators: monograph. St.-Petersburg, Politechnica-Print, 2016, 506 p. (in Russian)

2. Hirmanov V.N, Tikhomirova O.V. Еd.: prof. Aleksanin S.S. Chernobyl nuclear power plant liquidators metabolic and hemodynamic mechanisms of cardio- and cerebral diseases in the remote period. St.-Petersburg, Politechnica-Service, 2010, 358 p. (in Russian).

3. Damulin I.V. Cognitive impairment in damage to small cerebral vessels. Соnsilium medicum, 2014, Vol.16. № 9, pp.10-16. (in Russian).

4. Fedorov V.P., Gundareva O.P., Sgibneva N.V. Radiation-Induced and Age-Related Changes in Cerebellar Neurons. Meditsinskaya radiologiya I radiatsionnaya bezopasnost = Medical radiology and radiation safety, Vol. 60, №4, pp. 12-18. (in Russian).

5. Nyagu A.I., Loganovsky K.N. Changes in the nervous system under chronic exposure to ionizing radiation. Zhurnal nevropatologii i psikhiatrii = Journal of neuropathology and psychiatry, 1997, N 2, pp. 62–69. (in Russian).

6. Zhavoronkova L.A., Kholodova N.B., Gogitidze N.V. Dynamic clinical-electroencephalographic and neuropsychological study of the condition of the central nervous system of the liquidators of the Chernobyl accident. Mezhdunarodnyy zhurnal radiatsionnoy meditsiny = International Journal of Radiation Medicine, 2001, Vol. 3, № 1–2, pp. 194–199. (in Russian).

7. Podsonnaya I.V., Efremushkin G.G., Zhelobetskaya E.D. The bioelectric activity of the brain in discirculatory encephalopathy and arterial hypertension developed in the Chernobyl nuclear disaster liquidators. Zhurnal nevrologii i psikhiatrii im. S.S. Korsakova = S.S. Korsakov Journal of Neurology and Psychiatry, 2012, N 10, pp. 33–38. (in Russian).

8. Lelyuk V.G, Lelyuk S.E. The Ultrasonic angiology. Realnoye vremya = Real Time, 2003, Мoscow, 324 p. (in Russian).

9. Guskova A.K. Medical Effects of the Chernobyl Nuclear Power Plant Accident: Major summaries and unsolved challenges. Meditsinskaya radiologiya I radiatsionnaya bezopasnost = Medical radiology and radiation safety, 2010, Vol. 55, № 3. pp. 17–28. (in Russian).

10. Aleksanin S.S., Mamatova N.T., Tikhomirova O.V. [et al.]. Functional State Peculiarities of Central Nervous System in Chernobyl Recovery Workers with Chronic Cerebrovascular Diseases. Meditsinskaya radiologiya i radiatsionnaya bezopasnost = Medical radiology and radiation safety, 2007, Vol. 52, N 5, pp. 5–11. (in Russian).

11. A.V. Pozdnyakov, A.I. Tazhilkin. Study of changes in children’s brain pathways using Diffusion-Tensor Tomography for different age groups. In: Sbornik naychnykh trudov po itogam mezhdunarodnoy nauchno-prakticheskoy konferentsii = Modern Medicine Perspectives, Voronezh, 2014, p. 69. (in Russian).

12. Mamedyarov A.M., Namazova-Baranova L.S. Assessment of Motor and Sensory Pathways of the Brain Using DiffusionTensor Tractography in Children with Cerebral Palsy. Vestnik Rossiyskoy Akademii meditsinskikh nauk = Annals of the Russian academy of medical sciences, 2014, № 9, pp.70-76. (in Russian).

13. Jia L. A diffusion tensor imaging study in essential tremor. J. Neuroimaging, 2011, Vol. 21, pp. 370-374.

14. Trufanov A.G. Role of fractional anisotropy in basal ganglia in Parkinson disease pathogenesis. Vestnik Rossiyskoy VoennoMeditsinskoy Akademii = Vestnik of Russian military medical Academy, 2012, № 2(38), pp.20-24. (in Russian).

15. Ublinsky M.V. Nuclear magnetic resonance as a research method for human brain biochemical and biophysical processes within the norm and in case of psychopathology, Thesis abstract Cand. Biol. Sciences, Moscow, 2016, 130 p. (in Russian).

16. Potapov A.A., Goryaynov S.A. The Long-associative pathways of the white matter: modern view from the perspective of neuroscience. Voprosy neyrokhirurgii im. N.N. Burdenko = Problems of Neurosurgery named after N.N. Burdenko, 2014, Vol. 78, pp. 66-77.(in Russian)

17. Ermolina Yu.V. Particularities of brain structural and functional changes for children with spastic form of cerebral palsy, Thesis abstract Cand. Med. Sciences, Moscow, 2016, 126 p. (in Russian).

18. Kitayev S.V., Popova T.A. Principles of diffusion tensor imaging and its application to neuroscience. Annaly klinicheskoy I eksperimentalnoy nevrologii = Annals of Clinical and Experimental Neurology, 2012, Vol.6, №1, pp.48–53. (in Russian).

19. Mazurenko E.V. Clinical and neuro-vizualisational aspects of cognitive disorders for Parkinson disease patients, Thesis abstract Cand. Med. Sciences, Minsk, 2017,107 p. (in Russian).

20. Panyushkina L.A. Clinical and morphological aspects of visual paths for glaucoma and Alzheimer disease, Thesis abstract Dr. Med. Sci., Moscow, 2015, 128 p. (in Russian).

21. Borroni B., Grassi M., Premi E., Gazzina S., Alberici A., Cosseddu M. [et al.] Neuroanatomical correlates of behavioural phenotypes in behavioural variant of frontotemporal dementia. Behav Brain Res., 2012, 235(2), pp. 124–129.

22. Khodzhaeva D.T., Khaydarova D.K. Lesions of pathways in different types of moderate cognitive disorders on the background of chronic ischemia of the brain. Zhurnal Evraziyskogo Soyuza uchenykh = Eurasion Union of Scientists, 2015, №10, pp.122–124. (in Russian).

23. Hodzhayeva D.T., Khaydarova D.K., Khaidarov N.K. Characteristic of lesions of conduction pathways with moderate cognitive impairment against a background of chronic cerebral ischemia Zhurnal Evraziyskogo Soyuza uchenykh = Eurasion Union of Scientists, 2015, №7(16), pp. 97-98. (in Russian).

24. Kiselev M.F., Azizova T.V., Akleev T.V. [et al.]. On the 59th Session of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (Vienna, 21-25 May 2012). Meditsinskaya radiologiya I radiatsionnaya bezopasnost = Medical radiology and radiation safety, 2012, N 5, pp.11-19. (in Russian).

25. Maksudov G.A. Vascular involvements of brain and spinal cord classification. Ed. Shmidt E.V., Moskva, 1975, pp. 12–17. (in Russian).