Evaluation of 18F-TFB PET/CT Scan in Patients With Differentiated Thyroid Cancer

This study is comparing a newer PET/CT scan using a tracer called 18F-TFB against the standard imaging test (iodine scan) for detecting thyroid cancer. The goal is to see whether the newer scan provides better or more accurate information. **You may be eligible if...** - You are 18 or older - You have confirmed papillary or follicular thyroid cancer (diagnosed by biopsy) - Your doctor has already recommended a standard iodine (TBI) scan - You are willing to also undergo the 18F-TFB PET/CT scan - You are not pregnant and can lie still for about 65 minutes in a scanner **You may NOT be eligible if...** - You had a contrast CT scan in the past 4 weeks - You have taken amiodarone (a heart drug) in the past 4 months - You have recently taken iodine supplements or iodine-containing products - You are pregnant Talk to your doctor to see if this trial is right for you.