The Role of Dynamic (۹۹m) Tc Pertechnetate Scintigraphy in Early Detection and Differentiation of Hyperthyroidism

Thyrotoxicosis is hypermetabolic states that is not always associated with hyperfunction of thyroid gland and can present a problem in diagnostic differentiation. We have tried to prove that performing thyroid scintigraphy with (۹۹m) Tc pertechnetate immediately after the first minute of intravenous injection enables the differentiation of Morbus Basedow and Plummer's disease from other diseases of thyroid gland. A total of ۱۲۰ patients were included in this prospective study, ۵۰ of them diagnosed with hyperthyroidism, while the other ۷۰ showed no signs of hyperthyroidism. Dynamic scintigraphy lasting ۲۰ minutes was performed in all patients. Static images of thyroid gland were taken immediately after the ۱st and the ۲۰th minute of the study. The dynamic study showed that thyroid blood flow index in patients with hyperthyroidism was approximately the same as that of patients without hyperthyroidism. The uptake capacity of (۹۹m) Tc pertechnetate at the end of the first minute was ۶ times higher for thyroid of patients with Basedow's disease and Plummer's disease compared to the other patients (p<۰.۰۵). The sensitivity and negative predictive value of scintigraphy in identifying Basedow and Plummer disease immediately after the first minute of the study were ۱۰۰%, while the specificity and positive predictive value were ۹۸.۵۷% and ۹۸.۰۴%, respectively. The results of our study have shown that in cases of hyperthyroidism, it is sufficient to perform only scintigraphic images of thyroid gland immediately after the ۱st minute of intravenous application of (۹۹m) Tc pertechnetate.