Identification of primary tumors and metastasis sites is an essential step in cancer diagnostics and the following treatment. Positron emission tomography-computed tomography (PET/CT) is one of the most reliable methods for scanning the whole organism for malignancies. In this work, we synthesized an 11 C-labeled oligonucleotide primer and hybridized it to an anti-cancer DNA aptamer. The 11 C-aptamer was applied for in vivo imaging of Ehrlich ascites carcinoma and its metastases in mice using PET/CT. The imaging experiments with the 11 C-aptamer determined very small primary and secondary tumors of 3 mm 2 and less. We also compared 11 C imaging with the standard radiotracer, 2-deoxy-2-[fluorine-18]fluoro-Dglucose ( 18 F-FDG), and found better selectivity of the 11 C-aptamer to metastatic lesions in the metabolically active organs than 18 F-FDG. 11 C radionuclide with an ultra-short (20.38 min) half-life is considered safest for PET/CT imaging and does not cause false-positive results in heart imaging. Its combination with aptamers gives us high-specificity and high-contrast imaging of cancer cells and can be applied for PET/CT-guided drug delivery in cancer therapies.
Timely and accurate diagnosis of focal lesions of the liver, despite the existing arsenal of of radiation examination modalities, still remains a challenge. Particular difficulty is caused by foci of small diameter, an atypical character of contrasting; a combination of multiple formations of different genesis; focus against the background of diffuse liver damage; liver damage, mimicking tumors. DECT method givesnew analysis algorithms that are different from traditional CT. The article presents a review of the literature on the use of qualitative and quantitative parameters of spectral scanning in different phases of contrast enhancement in the differential diagnosis of liver focal lesions. The use of low-energy monochromatic images and the quantitative analysis of iodine content contribute to a better detection of liver foci and greater confidence in differential diagnosis.
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