Preparation:
You must discontinue any thyroid-related medications you are taking as follows:
- T4 (levothyroxine): 3–4 weeks prior
- T3 (liothyronine): 2 weeks prior
- Antithyroid medications: 1 week prior
You should not have undergone a CT scan with intravenous contrast within the past 2 weeks (or used any iodine-containing substances in general).
Procedure:
The scan will be performed approximately 20 minutes after the radiopharmaceutical is administered.