An Investigational Scan (I-124 PET/CT) for Diagnosing Metastasis in Patients with Thyroid Cancer
This phase II trial evaluates whether an investigational scan (I-124 positron emission tomography [PET]/computed tomography [CT]) is just as effective as the standard imaging technique (I-123 single photon emission computed tomography [SPECT]/CT) for determining whether thyroid cancer has spread from where it first started (primary site) to other places in the body (metastasized). I-124 is a radioactive isotope of iodine that selectively accumulates in thyroid tissue. I-124 emits positrons that can be detected by PET/CT, allowing visualization of thyroid tissue. A PET scan is a procedure in which a small amount of a radioactive agent is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the agent is taken up. Because the agent used in this study (I-124) is taken up selectively by thyroid tissue, the pictures can be used to find thyroid tumor tissue in the body. CT scan is a procedure that uses a computer linked to an x-ray machine to make a series of detailed pictures of areas inside the body. The pictures are taken from different angles and are used to create 3-dimensional views of tissues and organs. Combining a PET scan with a CT scan can help make the image easier to interpret. PET/CT scans are hybrid scanners that combine both modalities into a single scan during the same examination. The new I-124 PET/CT technique may be just as effective as the standard I-123 SPECT/CT technique for determining whether or not a patient's thyroid cancer has metastasized.