Evaluation of Quantitative Thyroid Scintigraphy for Diagnosis of Hyperthyroidism

This study compared the dimensions of the thyroid gland measured by the scintigraphic method with those measured by the ultrasonographic method. Additionally, the correlation between the technetium uptake level of the thyroid gland and the thyroid-stimulating hormone (TSH) values of the patient was investigated.

The aim of this study was to measure the uptake values and scintigraphic dimensions of the thyroid gland by using Technetium 99m pertechnetate and to investigate the relationship between these values in euthyroid and hyperthyroid states.

The data of patients referred to the Nuclear Medicine Clinic at the Health Sciences University Gulhane Training and Research Hospital for thyroid scintigraphy (TS) between January 2019 and December 2021 were examined. In total, 100 patients (67 female and 33 male) aged 18-77 (mean ± SD: 42.3 ± 15.6) years were examined. According to the thyroid scintigraphic appearances, the patients were classified into five groups: normal thyroid gland, hypoactive nodular thyroid gland, hyperactive nodular thyroid gland, diffuse hyperplastic thyroid gland, and mixed nodular thyroid gland. The region of interest (ROI) covering both thyroid lobes was drawn. The ROI covering both submandibular glands and background activity was also drawn, and count measurements from these two areas were compared.

Following the thyroid scintigraphic evaluation of patients in the five groups, the following results were obtained: 13/100 (13%) were within normal ranges, 7/100 (7%) were hypoactive nodular, 31/100 (31%) were hyperactive nodular, 20/100 (20%) were diffuse hyperplasia, and 29/100 (29%) were mixed nodular. The thyroid/background activity ratio of cases reported as having a normoactive thyroid gland, with TSH values within normal limits, was calculated to be between 2.08 and 2.2 based on the scintigraphic images included in the study.

Tc-99m pertechnetate TS is a reliable method that can be used for various nuclear medicine applications, such as evaluating thyroid gland morphology and calculating its size.