Comparison of I-124 PET/CT for the Diagnosis of Thyroid Cancer

Persons diagnosed with thyroid cancer are often treated initially with a thyroidectomy, which is followed by ablation using Iodine-131, a therapy which has been shown to be effective and safe. Imaging of metastatic thyroid cancer has been performed with whole body I-131 and Iodine 123 (I-123) imaging for many decades and use I-123 for staging studies. Iodine 124 (I-124) is a radioisotope of iodine which emits a positron and is imaged using PET (positron emission tomography). This is a single arm prospective trial that evaluates the ability of Iodine-124 (I-124) to detect metastatic thyroid cancer compared to non-interventional, usual care I-123 and I-131 images.

PRIMARY OBJECTIVES: 1\) Agreement between 1-124 PET and 1-123/1-131 SPECT. SECONDARY OBJECTIVES: 1. Sensitivity and specificity of I-124 PET to detect metastatic thyroid cancer compared to composite standard. 2. Reclassification rate of I-124 PET compared to I-123 SPECT. 3. Inter-reader variability for I-124 PET and I-123 SPECT. 4. Safety of I-124 PET. 5. Participant level detection rate for I-124 in the overall population. 6. Participant level detection rate for I-124 in participants who have negative I-123 SPECT. 7. Comparison of lesion detection between I-124 PET and 24 hour I-123 SPECT. 8. Comparison of lesion detection between I-124 PET and post-treatment I-131 SPECT. EXPLORATORY OBJECTIVES: 1\. Ability to predict lesion absorbed dose using I-124 PET/CT. OUTLINE: All participants will have a single PET/CT scan after administration of I-124 and will be followed for up to 3-5 days by phone for evaluation of adverse events. A subset of participants being evaluated for dosimetry will be imaged up to two additional times over five days after administration. Data from other scans for comparison will be obtained from the participant's medical record.