The Use of 124-I-PET/CT Whole Body and Lesional Dosimetry in Differentiated Thyroid Cancer

• INCLUSION CRITERIA:

• Patients with established thyroid cancer diagnosis based on the pathology reportreviewed at the National Institutes of Health, who:

• underwent total thyroidectomy plus or minus neck lymph node dissection asclinically indicated,

• are presenting with known per structural imaging (US neck, CT or MRIneck/chest/abdomen/pelvis) persistent/recurrent disease either locally advancedor presenting with distant metastases; or

• are presenting with suspected persistent/recurrent locoregional or distantmetastases based on the high risk features such as advanced tumor per pathologyreport (tumor size >4 cm, exrathyroidal extension, higher risk pathology suchas tall cell, columnar cell, poorly differentiated variant, follicular thyroidcancer with gross vascular invasion, positive margins after the surgery, bulkylymphadenopathy in the central and/or lateral neck), detectable/increasingbaseline/suppressed thyroglobulin (Tg) level or detectable/increasing anti-Tgantibody titers if anti-Tg antibodies are present.

• are either RAI -naive or requiring repeated RAI therapy for locally advanceddisease or distant metastases or underwent therapy with BRAF inhibitor (dabrafenib or vemurafenib*) or selumetinib** for at least 4 weeks that mayre-induce RAI uptake.

• Underwent imaging with either a CT or MRI of the brain and spine withgadolinium contrast to screen for the brain/spine metastases.

• Age greater than or equal to 18 years of age.

• 24 hour urine iodine excretion of less than or equal to 150 micro grams/24hour.

• BRAF inhibitors are recommended by 2021 NCCN guidelines as one of themanagement options for BRAF mutant tumors(13,14)

• Selumetinib has an FDA orphan drug designation for adjuvanttreatment of metastatic thyroid cancer to re-induce RAI uptake

EXCLUSION CRITERIA:

-Patients with RAI-non avid disease documented by negative post-therapy whole body scans performed after previous RAI treatments and not subjected to re-differentiation therapy.

• Serious underlying medical conditions that restrict diagnostic testing or therapysuch as renal failure, congestive cardiac failure or active coexisting non-thyroidcarcinoma, severe depression which might be exacerbated by thyroid hormonewithdrawal.

• Patients with spinal or brain metastases as they are at risk of TSH-stimulationinduced swelling of metastatic lesions leading to potentially detrimental sideeffects. These patients will be evaluated per the standard of care protocol 77-DK-0096.

• Pregnant or lactating women per self report.

• Adults who are incapable of providing informed consent.