Exendin PET/CT for Imaging of Paragangliomas

Study Overview
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Brief Summary
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Functional imaging of paragangliomas (PGLs) is not unequivocal. Existing functional imaging modalities show good but variable results in PGLs, warranting the search for additional molecular imaging targets. Investigators aim to evaluate the glucagon-like peptide 1 receptor (GLP-1R) as a novel target for molecular imaging of PGLs. For this purpose investigators will use the tracer 68Ga-NODAGA-exendin 4 for positron emission tomography/computed tomography (PET/CT) imaging.

Detailed Description
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Rationale: Functional imaging of paragangliomas (PGLs) is not unequivocal. Existing functional imaging modalities show good but variable results in PGLs, warranting the search for additional molecular imaging targets. Investigators aim to evaluate the glucagon-like peptide 1 receptor (GLP-1R) as a novel target for molecular imaging of PGLs. For this purpose investigators will use the tracer 68Ga-NODAGA-exendin 4 for positron emission tomography/computed tomography (PET/CT) imaging. Objective: The primary objective is to examine the feasibility of 68Ga-exendin-4 PET/CT for localization and functional characterization of PGLs. Study design: In this prospective pilot imaging study 68Ga-exendin-4 PET/CT will be performed in 10 patients with confirmed PGL who have undergone CT, somatostatin receptor (SSTR) PET/CT and 18F-FDG PET/CT (as standard diagnostic procedures) and are scheduled for surgery. 100 ± 10 MBq 68Ga-NODAGA-exendin-4 will be administered to 10 patients in total. In the first 5 patients PET/CT imaging will be performed 1, 2 and 4 hours after injection to determine the optimal imaging timepoint for the remainder of the patients, which will be applied in the remaining patients. The images will be reconstructed and evaluated by a nuclear medicine physician who is blinded to the results of the CT, SSTR PET/CT and 18F-FDG PET/CT to assess tumor detection. Additionally, quantitative analysis of 68Ga-exendin-4, SSTR PET and 18F-FDG PET/CT images will be performed. After the patients have undergone surgery, immunohistochemical analysis of surgical specimens will be performed to assess GLP-1R expression, which will be compared with in vivo tracer uptake.

Official Title
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Exendin PET/CT for Paragangliomas

Conditions
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Paraganglioma

Intervention / Treatment
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* Radiation: 68Ga-NODAGA-exendin-4 PET/CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Proven sympathetic PGL with a single tumor detected using standard diagnostic imaging No evidence of metastatic disease CT, SSTR PET/CT and 18F-FDG PET/CT performed (golden standard diagnostic imaging) Scheduled for surgery Able to sign informed consent Exclusion Criteria: Breast feeding Pregnancy or the wish to become pregnant within 1 month Calculated creatinine clearance below 40ml/min Evidence of other malignancy than PGL in conventional imaging (suspicious liver, bone and lung lesions) Age < 18 years Not able to sign informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients with confirmed paraganglioma<br>10 patients with confirmed PGL who have undergone CT, somatostatin receptor (SSTR) PET/CT and 18F-FDG PET/CT (as standard diagnostic procedures) and are scheduled for surgery. | Radiation: 68Ga-NODAGA-exendin-4 PET/CT<br>* PET/CT imaging 1 hour after injection of 100 MB 68Ga-NODAGA-exendin-4<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| detection rate of PGL's using 68Ga-exendin-4 PET/CT | Detection based on visual inspection of PET/CT images | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| optimal timepoint for imaging PGLs using 68Ga-exendin-4 PET/CT |  | After inclusion of the first 5 patients (up to 6 months) |