Gender differences in estimating I-131 thyroid uptake from Tc-99m thyroid uptake for benign thyroid disease

Area of Science:

• Nuclear medicine
• Endocrinology
• Radiopharmacology

Background:

• Personalized dosimetry for radioactive Iodine-131 (131I) treatments of thyroid diseases can improve efficacy.
• Accurate measurement of 131I thyroid uptake (131IU) is crucial for personalized dosimetry.
• Investigating alternative uptake measurement methods can streamline treatment planning.

Purpose of the Study:

• To evaluate if 99mTc thyroid uptake (99mTcU) can be used as a substitute for 131IU in personalized thyroid disease treatments.
• To determine the correlation between 99mTcU and 131IU across different patient demographics and diagnoses.

Main Methods:

• A retrospective analysis of 152 benign thyroid disease 131I treatments conducted between 2012 and 2020.
• Data from 117 female and 35 male patients diagnosed with Graves' disease, multinodular goitre, or toxic nodules were analyzed.
• Statistical correlation and predictive modeling were employed to compare 99mTcU and 131IU.

Main Results:

• A significant correlation was observed between 131IU and 99mTcU (r = 0.71 for males, r = 0.38 for females; p < 0.001).
• Patient age and time between measurements impacted correlation in females, but not males.
• Thyroid diagnosis and hormone levels correlated with uptake in both genders.
• 99mTcU was predictive of 131IU in males (R2 = 91%) but not females (R2 = 16%).

Conclusions:

• Using 99mTc thyroid uptake to estimate 131I uptake is not recommended for female patients at this center.
• While a good correlation was found in males, a larger sample size is required for validation.
• Significant gender differences in thyroid uptake parameters suggest the need for gender-specific considerations in 131I treatment planning and reporting.