RADIOISOTOPE DIAGNOSTIC ALGORITHM FOR THE RELAPSE AND METASTASES DETECTION IN THE IODINE-NEGATIVE DIFFERENTIATED THYROID CANCER
Authors:   National Cancer Institute of the Ministry of Health of Ukraine, 33/43 Lomonosova St., Kyiv, 03022, Ukraine, Solodyannikova O. , Kmetyuk Y. ,   All-Ukrainian Center of Radiosurgery at the Feofania Hospital of the State Administrative Department, 21 Akademika Zabolotnoho St., Kyiv, 03143, Ukraine, Danilenko V. ,   National Cancer Institute of the Ministry of Health of Ukraine, 33/43 Lomonosova St., Kyiv, 03022, Ukraine, Sukach G. ,   National Cancer Institute of the Ministry of Health of Ukraine, 33/43 Lomonosova St., Kyiv, 03022, Ukraine
Published: December 2020

Objective. Developing of algorithm for the post-surgical management of patients with iodine-negative metastases of differentiated thyroid cancer (DTC). Materials and methods. The DTC patients with iodine-negative metastases (n = 115) were enrolled in the study. Of them the whole body scintigraphy (WBS) was performed with technetium-99m-hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) (n = 30), WBS with technetium-99m dimercaptosuccinic acid (99mTc-DMSA) (n = 30), 18FDG PET (n = 30), and computer tomography (CT-scan) (n = 25). Complex 99mTc-pertechnetate scans including the dynamic and static scintigraphy was performed supplementary to 99mTc-MIBI WBS in 10 patients to obtain the angiographic curves from DTC metastatic foci. The non-radioiodine radiopharmaceutical technologies, namely the labeled 99mTc-MIBI, 99mTc-DMSA, 99mTc-pertechnetate, and 18FDG were applied to detect the iodine-negative DTC metastases. Radioisotopic examinations were performed at the dual-head gamma camera (Mediso Medical Imaging Systems Ltd., Hungary) and single photonemission computed tomography (SPECT) scanner «E.CAM» (Siemens, Germany). PET/CT scans were performed on the «Biograph 64 TruePoint» imaging platform (Siemens, Germany) in accordance with the European Association of Nuclear Medicine (EANM) recommendations for the Siemens imaging devices with 3D-mode data acquisition. Results. The conducted research suggested that it is feasible to use the non-radioiodine (99mTc-MIBI and 99mTc-DMSA) radiopharmaceutical technologies to detect the iodine-negative DTC metastases. 18FDG PET is a highly informative technology for the detection of iodine-negative DTC metastases in case of lung involvement in the process. Compare of the non-radioiodine radiopharmaceuticals, CT scan and 18FDG-PET/CT indicated the highest sensitivity of 18FDG PET/CT (p < 0.05). WBS with 99mTc-MIBI and 99mTc-DMSA featured the highest specificity (100 %, p < 0.05). X-ray CT is marked by the significantly lower either sensitivity, specificity, and accuracy rate (p > 0.05). Developing and application of algorithm for the post-surgical management of patients with iodine-negative forms of DTC will allow for the betimes detection of relapses and metastases with administration of adequate surgical, radiation, and targeted treatment. Conclusions. Obtained results offer the opportunity to optimize the post-surgical management of patients with iodine-negative DTC forms using the options of radionuclide diagnostics with non-radioiodine radiopharmaceuticals. The latter are readily available providing the cost-cutting of diagnostic support in these patients. Place of morphological methods of diagnosis is determined and stage of monitoring of patients with the iodine-negative metastases is established. Possibility of the 18FDG-PET tests for the early diagnosis of iodine-negative metastases in DTC for the first time have been studied and substantiated in Ukraine. A comprehensive radiation algorithm for the long-term monitoring of this category of patients will allow the timely detection of recurrences and metastases of DTC and appropriate surgery, radiation and targeted therapy administration. Data obtained as a result of the study allowed to improve the overall and recurrence-free survival rates in the able-bodied DTC patients and reduce the costs of follow-up of patients with iodine-negative forms of DTC. Key words: differentiated thyroid cancer, radioiodine-negative metastases, non-radioiodine radiopharmaceuticals, 18FDG-PET/CT.