RecruitingEarly Phase 1Drug trialIn Vivo PARP-1 Expression With 18F-FluorThanatrace PET/CT in Patients With Pheochromocytoma and ParagangliomaThis study will enroll up to 30 evaluable patients with pheochromocytoma or paraganglioma who are undergoing surgical or systemic treatment. A pre-treatment 18F-FluorThanatrace (\[18F\]FTT) positron emission tomography/computed tomography (PET/CT) scan will be done prior to surgery or systemic therapy. PET/CT imaging will be used to evaluate PARP-1 expression in sites of pheochromocytoma or paraganglioma using the investigational radiotracer \[18F\]FTT. This is an observational study in that \[18F\]FTT PET/CT will not be used to direct treatment decisions. While patients and referring physicians will not be blinded to the \[18F\]FTT PET/CT results, treatment decisions will be made by the treating physicians based upon clinical criteria.