PMC7421811_01
The 99m-STS with a dose of 21.8 mCi showed intense initial uptake of the tracer activity within the thyroid parenchyma followed by a near complete washout in the 3-hour delayed images suggestive of AIT-1. In addition, there is diffuse enlargement of the thyroid gland (left more than right) and physiologic pattern of tracer distribution observed in the nasopharyngeal mucosa, salivary glands, and imaged parts of the liver and myocardium. A photopenic area in the left chest region correlates with the pacemaker. (a) 10 min postinjection; (b) 3 hr postinjection.
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fig1
The 99m-STS showed intense initial intense uptake of the tracer activity within the thyroid parenchyma followed by a near complete washout in the 3-hour delayed images suggestive of AIT-1 (Figure 1).
PMC7421811_02
The 99m-STS with a dose of 19.4 mCi showed intense initial intense uptake of the tracer activity within the thyroid parenchyma followed by bilateral symmetrical gradual washout of tracer activity in the 1-hour and 2-hour delayed images suggestive of AIT-1. (a) 15 min delay; (b) 1 hr delay; (c) 2 hr delay.
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fig2
The 99m-STS showed similar results to patient 1, suggesting AIT-1 (Figure 2).
PMC7421811_03
99m-STS with a dose of 19.43 mCi showed an intense initial intense uptake of the tracer activity within both thyroid lobes (a) followed by a complete washout in the 2-hour delayed images (b) suggestive of AIT-1.
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fig3
TSI <89%, and TRAb <1%. Thyroid US showed enlarged multinodular goiter with normal vascularity of the thyroid gland on CFDS. The 99m-STS showed intense initial intense uptake of the tracer activity within both thyroid lobes followed by a complete washout in the 2-hour delayed images suggestive of AIT-1 as observed in patients 1 and 2 (Figure 3).
PMC7421811_04
99m-STS showed failure of localization of the tracer within the thyroid gland, by imaging criteria suggesting destructive effect of amiodarone to the function of the gland and confirming AIT-2 (a, b) 15 minutes delay high- and low-resolution images. (c, d) 1 hour delayed anterior and posterior images.
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fig4
It showed no evidence of tracer labeling within the thyroid lobes at the initial 15 minutes' images and the 1-hour follow-up image confirming AIT-2 (Figure 4).
PMC7421811_05
99m-STS with a dose of 24.9 mCi demonstrating persistent activity in the right and left lobes of the slightly enlarged thyroid gland at 10 minutes, declining at 60 minutes' image confirming diagnosis of AIT-1.
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fig5
Given no improvement in the patient's clinical condition, repeated thyroid function tests were ordered, and it showed persistent hyperthyroid status with TSH <0.004, free T4 2.18, free T3 2.1, and 24 hours' urine iodine 2905 mug (100-460 ug/24 hours). 99m-STS showed persistent activity in the right and left lobes of the slightly enlarged thyroid gland at 10 minutes, unchanged from the 2-minute image and declining at 60 minutes' compatible with AIT-1 (Figure 5).