Possibility analysis of thyroid imaging parameters for dose adjustment in 131I treatment of hyperthyroidism.

Background: To determine the thyroid uptake rate by correcting the background and analyze its clinical significance.

Methods: The study included 161 patients with hyperthyroidism. The thyroid uptake rate was calculated by drawing a 100 pixels ROI (region of interest) background, above and below the thyroid and correcting the thyroid ROI for background counting. At the same time, the clinical baseline characteristic parameters such as age and thyroid volume etc. of patients with hyperthyroidism were collected. The consistency of ^99mTcO4uptake rate before treatment and ¹³¹I-uptake rate after treatment, and the correlation between uptake rate of thyroid and baseline characteristic parameters were also analyzed.

Results: The uptake rate of ^99mTcO4 was found positively correlated with 3 h-radioactive iodine uptake (RAIU), 24 h-RAIU, 3 h/24 h conversion rate, thyroid volume, ¹³¹I activity free triiodothyronine (FT3) and free thyroxine (FT4), and showed negative correlation with age, effective half-life (P<0.05). The uptake rate of ¹³¹I was found positively correlated with 3 h-RAIU, 24 h-RAIU, 3 h/24 h conversion rate, thyroid volume, ¹³¹I activity, FT3, FT4 (P<0.05). In patients with positive thyrotrophin receptor antibody (TRAb), a significant positive correlation between uptake rate of ^99mTcO4 and ¹³¹I (P<0.05) was observed. There was a high consistency between pretreatment uptake rate of ^99mTcO4 and post-treatment uptake rate of ¹³¹I (P=0.009; W=0.7).

Conclusions: The corrected thyroid uptake rate is remarkably correlated with clinical characteristic parameters of patients, which can be used to comprehensively evaluate the comprehensive condition of patients with hyperthyroidism.