Abstract
Objective: The aim of the present study was to evaluate parameters of early blood flow (EBF) including duration of EBF, perfusion index (PI), uptake indexes 1 and 2 (UI1 and UI2) derived from dynamic thyroid scintigraphy in patients with Graves’ disease (GD), and euthyroid (EI). Maximum instant uptake and maximum uptake of the thyroid gland were also assessed.Methods: A total of 50 patients with GD and EI were included in this study. Each patient underwent two dynamic scans of 1-minute (20 images at 3 seconds) and 20-minute (20 images at 1 minute) with 99mTcO4. The time-activity curve of a 1-minute scan was employed to derive EBF parameters; likewise, the time-activity curve of a 20-minute scan was used to determine maximum instant uptake, and the gradient of the curve from the 10th to 20th minute was used to assess maximum uptake.Results: Values of EBF duration, PI, UI1, UI2, and maximum instant uptake were significantly lower in patients with GD than in those with EI (p<0.05). The calculated gradient of the second half of the curves for all of the patients ranged from 0 to 0.88 and was significantly higher in patients with GD than in those with EI.Conclusion: Lower values of PI, UI1, UI2 and durations of EBF, along with faster maximum instant uptake in patients with GD in comparison to EI are indicators of a heightened desire for hyper-functioning thyroid glands of patients with GD to absorb 99mTcO4. Additionally, because of the uprising gradient at the end of the 20-minute time-activity curve, a maximum thyroid uptake of 99mTcO4 was achieved at more than 20 minutes after the radiopharmaceutical injection.
Highlights
Various types of thyroid disorders may affect normal function of the thyroid glands
Dynamic scintigraphy was performed in two steps: first, in order to study perfusion of the thyroid gland, each patient was scanned over 1 minute as 20 frames of 3 seconds; second, in order to assess thyroid uptake, each patient was scanned over 20 minutes as 20 frames of 1 minute
It was found by ultrasonography that thyroid vascularity-and thyroid blood flowincreased in patients with hyperthyroidism [5]
Summary
Various types of thyroid disorders may affect normal function of the thyroid glands. For instance, in Graves’ disease, thyroid stimulating hormone receptor antibodies (TSHR-Ab) bind thyroid stimulating hormone receptor (TSHR) and activate it, leading to hyper-secretion, hypertrophy, and hyperplasia of the thyroid follicles [1]. One of the features of this interruption may appear in thyroid blood flow [2,3,4,5,6] Evaluation of this parameter may be an indicator in assessment of thyroid gland function. A number of methods have been introduced and employed to assess thyroid blood flow including angiography, electromagnetic flowmetry, doppler ultrasonography, and nuclear medicine imaging. Because of problems associated with the invasiveness of angiography and electromagnetic flowmetry, these methods are not commonly utilized; application of ultrasonography for this purpose benefits from simplicity, noninvasiveness, and the potential for quick differentiation between diffuse and nodular thyroid disease [7,8,9,10]. Because of the similarity of the 99mTcO4 with iodine (with respect to the molecular size), thyroid uptake of 99mTc can be used to assess thyroid function [14]
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