Gold-containing nanoparticles are proven to be an effective radiosensitizer in the radiotherapy of tumors. Reliable imaging of nanoparticles in a tumor and surrounding normal tissues is crucial both for diagnostics and for nanoparticle application as radiosensitizers. The Fe₃O₄ core was introduced into gold nanoparticles to form a core/shell structure suitable for MRI imaging. The aim of this study was to assess the in vivo bimodal CT and MRI enhancement ability of novel core/shell Fe₃O₄@Au theranostic nanoparticles. Core/shell Fe₃O₄@Au nanoparticles were synthesized and coated with PEG and glucose. C57Bl/6 mice bearing Ca755 mammary adenocarcinoma tumors received intravenous injections of the nanoparticles. CT and MRI were performed at several timepoints between 5 and 102 min, and on day 17 post-injection. Core/shell Fe₃O₄@Au nanoparticles provided significant enhancement of the tumor and tumor blood vessels. Nanoparticles also accumulated in the liver and spleen and were retained in these organs for 17 days. Mice did not show any signs of toxicity over the study duration. These results indicate that theranostic bimodal Fe₃O₄@Au nanoparticles are non-toxic and serve as effective contrast agents both for CT and MRI diagnostics. These nanoparticles have potential for future biomedical applications in cancer diagnostics and beyond.

The object of the study was to analyze radionuclide detection techniques for in vivo animal imaging. Material and Methods. A total of 49 publications available from Scopus, Web of Science, Google Scholar eLIBRARY and Pubmed and published between 2013 and 2019 were reviewed. Results. The nuclear medicine techniques, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) are the most suitable imaging modalities for in vivo animal imaging. Besides traditional radiopharmaceuticals, such as [18F]-FDG and [⁹⁹mTc]-MDP, the new radiolabeled tracers, such as [⁹⁹mTc]-3PRGD2, [ ⁹⁹mTc]-HisoDGR targeted to integrin, [¹⁸F]- tetrafluoroborate, labeled antibodies and others have been used for the noninvasive detection of tumors and for monitoring their response to treatment in mice and rats. 111In and 89Zr –labeled monoclonal antibodies are used to evaluate the expression level of many receptors such as EGFR, HER-2 and others in different tumors. PET imaging has demonstrated a good efficacy in tumor hypoxia imaging with [⁶⁴Cu]-ATSM, [¹⁸F]-FMISO. PET and SPECT can also be used for early evaluation of anticancer therapy response. Nuclear imaging techniques may assist in the vivo assessment of DNA damage (doubleand single-strand brakes) as well as apoptosis intensity in tumor and normal tissues. [99mTc]- duramycin is the most commonly used tracer for imaging of apoptosis. Changes in tumor cell proliferation in response to anticancer therapy can be assessed by PET imaging with [¹⁸F]-FLT. Conclusion. Nuclear medicine offers a unique means to study cancer biology in vivo and to optimize cancer therapy.

Neutron Capture Therapy (NCT) — highly selective method of binary radiotherapy of malignancies, which is based on physical phenomenon of thermal neutron radiation capture by atoms’ nuclei. Currently only 10B mediated NCT, known as boron neutron capture therapy (BNCT), is used in clinical practice. Boronophenylalanine — a modified amino acid is most widely used as 10B carrier. Despite of more than 70-years history of BCNT clinical application and promising results of curing patients with different tumors, this method of treatment is still under research and development. The most urgent issue is studying and prediction of radiation effects of healthy and tumor tissues after BNCT application. This task can be solved in experiments involving animals. The review contains results of BNCT studies both in laboratory animals with different tumor models and veterinary practice. Induced and transplanted models of central nervous system, oral cavity as well as subcutaneous and metastatic models are considered in the review. Obtained results of the studies show possible high antitumor efficacy of BPA mediated BNCT and fundamentally different mechanisms of BNCT effect on tumor and healthy tissues comparing to other known types of radiotherapy. Many issues still require addition research with modern methods of studies, such as in vivo preclinical imaging.

Background. For preclinical studies of radiopharmaceuticals there is a high need for development new methods of in vivo metastasis diagnosis in mice after tumor cells transplantation. The study was carried out to assess feasibility of lung metastasis diagnosis with magnetic resonance imaging (MRI) visualization in mice C57Bl6.The aim of this study was to assess feasibility of MRI for verification of distant metastases of the solid B16-F10 melanoma with validation by anatomic dissection.Methods. Metastatic lesions were caused by injection of B16-F10 murine melanoma cells into cavum medullare of the tibia. Imaging studies were performed on the 21th day after transplantation using 7T magnetic resonance tomograph, coronal and axial images were acquired. Validation of metastasis was made by anatomic dissection and histological examination.Results. MRI method enables visualization of lung nodules with diameter at least 0.8 mm, because smaller nodules cannot be distinguished from heartbeat artifacts. Histological examination revealed that macroscopic anatomic dissection can precisely detect subpleural lung nodules.Conclusion. This study demonstrated feasibility of in vivo lung metastasis verification with MRI method in mice: metastases comparable in diameter to the size of large bronchi can be detected by MRI as well as by ex vivo dissection. For centrally located lung metastasis MRI method is preferable because macroscopic dissection enables to visualize only nodules which are located subpleurally.

The development of new drugs in nuclear medicine for diagnosis or treatment (chemotherapy) of brain tumors, in particular gliomas, is inextricably linked with the use of tumor models in animals (usually rats). Objective. To compare the widely used glioma cell model C6 and the new experimental tissue model of glioblastoma 101.8. Material and methods. A comparison was made of the diagnostic and morphological characteristics of the presented glioma models in two groups of animals with intracranially implanted tissue strain of experimental glioblastoma 101.8 (n=4) and the C6 glioma cell line (n=4) throughout the tumor development cycle within the rat brain. To monitor the progress of tumor growth and development, each animal underwent repeated diagnostic studies using PET-CT with 18F-FDG and 18F-FET to assess the metabolic activity and volume of the tumor. Also MRI images were collected. After the end of data acquisition, a histological examination of the tumor was carried out. Results. The tissue model of glioblastoma 101.8 demonstrated rapid growth and pronounced accumulation of the tracers in all animals during the tumor observation cycle. Formation of intratumoral necrosis and signs of disruption of the blood-brain barrier (BBB) were detected. In PET-CT studies of animals with a transplanted C6 tumor, no visible necrosis in the tumor structure was observed. Tumor growth was less rapid than in the case of model 101.8. The obtained morphological characteristics of 101.8 tumors transplanted into the rat brain demonstrated similar properties observed in real clinical conditions in patients with glioblastoma of the brain (necrosis, neovascularization, multiple pseudopalisade structures). Conclusions. Tumor model 101.8 can be recommended for scientific research as it most closely reproduces the diagnostic and morphological features of a human glioblastoma.

The occurrence of chronic diarrhea after cholecystectomy (CCY) has been described by many researchers. However, the main mechanisms of the development of this diarrhea are not fully understood. Supposed that dysregulation of the bile acids (ВA) absorption in the ileum is played a significant role in the development of diarrhea syndrome. Aim. To determine the role of the fibroblast growth factor 19 (FGF19) level in the serum and BA concentration in feces in pathogenesis of bile acid diarrhea (ВАD) in patients after CCY. Materials and methods. Sixty-one patients were examined at various times after CCY: 30 patients with chronic diarrhea that appeared after CCY (group 1) and 31 patients with normal stools (group 2). In all patients, the level of FGF19 in the blood serum, and the daily excretion of BA in the feces were studied. The control group consisted of 28 healthy individuals. Results. In the 1st group we found lower concentrations of FGF19 in the blood serum 86.2 ng/ml (67.8; 117.8) compared with concentrations in the 2nd group 259 ng/ml (170.6; 318.8), p0.001. The daily excretion of bile acids with feces in the 1st group was 657.4 mg/day (524.6; 830.1), which was twice more than in the 2nd group and the control group. It was established an inverse correlation between serum concentration of the FGF19 and the BA excretion in the feces in all examined patients. It indicates a possible relationship between the low concentration of FGF19 in blood serum and malabsorption of the BA. Conclusion. Low level of FGF19 in the blood serum and a high excretion of BA in the feces may be one of the causes of BAD in patients undergoing cholecystectomy. Our results indicate the important role of FGF19 in the development of chronic diarrhea, which can be considered as one of the variants of postcholecystectomy syndrome.