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

Thomas Hope

Status and phase: Enrolling; Phase 2

Conditions: Thyroid Cancer

Treatments: Procedure: Positron Emission Tomography (PET)/Computerized tomography (CT); Drug: Iodine-124

Study type: Interventional

Funder types: Other; Other U.S. Federal agency

Identifiers

NCT06961084

NCI-2025-03041 (Registry Identifier)

249212

Details and patient eligibility

About

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.

Full description

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.

Enrollment: 62 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. Age >= 18 years.

2. Histopathologically confirmed differentiated thyroid cancer, with clinical concern for metastatic disease:

   1. Metastatic disease seen on I-123 SPECT, Fluorodeoxyglucose (FDG) PET, CT scan or ultrasound.
   2. Elevated thyroglobulin in participant after total thyroidectomy.

   i. Participants with an undetectable thyroglobulin will be allowed if thyroglobulin antibodies are present.

3. Meeting criteria for one of the following two populations:

   1. American Thyroid Association (ATA) intermediate or high-risk thyroid cancer and planning on treatment using I-131.
   2. Metastatic disease on imaging (CT, MRI, ultrasound or FDG PET), and considering localized therapy such as surgery and radiation therapy.

4. Undergone total thyroidectomy.

5. Planned I-123 imaging within 45 days after enrollment.

6. Ability to understand a written informed consent document, and the willingness to sign it.

Exclusion criteria

1. Unlikely to comply with study procedures, restrictions and requirements and judged by the Investigator to be unsuitable for participation.
2. Known pregnancy, per institutional policy.

Trial design

Primary purpose: Diagnostic

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

---

62 participants in 1 patient group

Intervention: I-124 PET/CT

Experimental group

Description:

All participants will be administered an oral dose of 60 to 85 megabecquerel (MBq) +/- 10% for I-124 (capsule) prior to the Positron Emission Tomography (PET) imaging. Scan coverage will extend from the vertex to the mid-thighs and in certain circumstances, coverage may be extended to the toes. Imaging will be acquired 20-28 hours after I-124 administered. Participants will be followed up for any adverse events for up to 5 days after the scan has been completed.

Treatment:

Drug: Iodine-124

Procedure: Positron Emission Tomography (PET)/Computerized tomography (CT)