Evaluation of the 18F-PSMA Positron Emission Tomography (PET)/CT in Patients With Medullary Thyroid Cancer

Rationale: In patients with medullary thyroid cancer (MTC), molecular imaging is used to assess the extent of disease in the primary diagnostic process and follow-up period to determine possible therapeutic options. The currently most used tracer in clinical practice, F-18 labelled fluorodeoxyglucose (18F-FDG), does not accurately detect MTC tumors with an indolent growth rate. A new, complimentary tracer is warranted to detect different subtypes. Objective: The primary objective is to assess the feasibility of using the F-18 labelled prostate specific membrane antigen (18F-PSMA) PET/CT for (re)staging patients with medullary thyroid cancer. The secondary objective is to compare the ability to detect MTC with the 18F-PSMA PET/CT to that of the 18F-FDG PET/CT. Study design: Prospective, single-centre, feasibility study. Study population: Patients (18 years of age or older) with biochemically and cytological/histological confirmed MTC, for whom the indication of an 18F-FDG PET/CT for tumor staging has already been determined on clinical grounds. Main study parameters/endpoints: The primary outcome of this study is the performance (lesion-based//patient-based sensitivity) of the 18F-PSMA PET to detect MTC lesions in patients with cytologically/histologically confirmed disease. Secondarily, the performance of the 18F-PSMA PET will be compared to the 18F-FDG PET/CT.