Comparison of I-124 and I-131 Radiopharmacokinetics in DTC Patients With Thyroid Hormone Withdrawal

Stopped early · Not applicable

Conditions studied: Thyroid Cancer

In brief

This research study is to compare the radiopharmacokinetics of I-124 to the radiopharmacokinetics of I-131 in patients who have well-differentiated thyroid cancer after thyroid hormone withdrawal. I-131 is routinely used for imaging and dosimetry for patients with well-differentiated thyroid cancer. In this study, I-124 is administered orally in capsular form, and the radiopharmacokinetics of I-124 is compared with I-131. I-124 is another isotope of iodine, which is cyclotron-produced. I-124 has multiple advantages: * Ideal Half-Life (4.2 days) for delayed imaging. * High resolution tomographic imaging. * Feasibility of quantitating lesion uptake. * Potential of dosimetry for the planning of radioiodine therapy. Voluntary patients will have I-124 dosimetry performed in addition to the I-131 dosimetry, which is planned as part of routine clinical care. I-124 dosimetry is composed of three parts: (1) the administration of I-124, (2) imaging, and (3) drawing blood samples. Patients will start 3-5 weeks of thyroid hormone withdrawal. This is similar to the procedure for I-131 dosimetry. Second, they will receive I-124. I-124 is similar to I-131 except I-124 decays in a different way to emit a positron so that the PET scanner can be used for imaging. I-124 is given in the form of one or several capsules, which are taken by mouth. This is also similar to I-131. Third, PET/CT imaging is done for approximately 30 minutes to one hour on five consecutive days. Radiation from PET/CT scan is far less than what they receive from a diagnostic CT scan. For the fourth part, a technologist will draw about 5 cc from the forearm on each of the five consecutive days. This is also similar to I-131. Initially, all patients will be randomized to one of two study groups. The first group will have the I-131 dosimetry performed first followed by the I-124 dosimetry, and the second group will have the I-124 dosimetry performed first followed by the I-131 dosimetry. The risk of this study is considered very low, and the potential benefits to the patient are considered very high.

Key facts

Study ID: NCT02947399
Run by: Medstar Health Research Institute
People needed: 16
Starts: 2008-11-01
Expected to finish: 2018-10-01
Last updated by the study team: 2018-11-01

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

18 years or older,
Well-differentiated thyroid carcinoma,
Referred for 131-I dosimetry,
Suspected of having metastases, which includes but is not limited to elevated TG without antibodies, clinical mass suggestive of metastases, radiographic finding on CT, MR, PET, and/or ultrasound, etc. suggestive of metastases, etc., and
Preparation for dosimetry and treatment planned with thyroid hormone withdrawal.

You may not qualify if…

< 18 years of age,
Pregnancy or breast feeding,
Inability to comply with instructions,
In ability to tolerate hypothyroidism as determined by the opinion of the referring endocrinologist,
Simultaneous participation or participation in any other research study within the last month,
A body weight greater than 350 lbs., and/or
A creatinine > 1.5 mg/ml for males and 1.4 mg/ml for females.

Where it is running

Washington Hospital Center — Washington D.C., District of Columbia, United States

Full record on ClinicalTrials.gov

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