Pattern of Tc‑99m Thyroid Scintigraphy in Different Thyroid Diseases:(Our Experience)

Background: Thyrotoxicosis is a spectrum of disorders with a rather common clinical presentation with different aetiologies. It is essential to accurately diagnose the cause before starting treatment. Scintigraphy of thyroid helps in differentiating accurately the various causes. Aim: This study aimed to evaluate the scintigraphic profile of thyrotoxicosis patients and to evaluate lobar activity differences in Technetium-99m (Tc-99m) thyroid scans among Egyptian patients with thyroid diseases, focusing on the influence of demographic factors (age and gender). Patients and Methods: This was a retrospective cross-sectional study implemented at the Nuclear Medicine Unit at Sohag University in Egypt between January 2023 and June 2024 on 117 thyroid patients newly diagnosed for thyrotoxicosis. Results: Most of patients (64.1%) were females, with a mean age of 40.6±10.8 years. Thyroid stimulating hormone (TSH) levels were uniformly low (median (IQR: 0.01 (0.017)), supporting hyperthyroidism in the population. Thyroid uptake (TTU =Total Thyroid Uptake, LLU=Left lobe Uptake, RLU=Right lobe Uptake) peaked in the 36–45 age group and declined in individuals over 45. Males consistently showed higher TTU (13.6 ± 9.8%), LLU (6.4 ± 4.7%), and RLU (7.1 ± 5.1%) than females, with P-values <0.001. Lobar uptake patterns revealed a dominance of higher RLU across all TTU categories. Conclusion: Using Tc 99m scintigraphy is a useful technique to differentiate between different a etiologies of thyrotoxicosis, with estimation of thyroid uptake.