PET3

**PET3** is not a distinct drug molecule, proprietary product, or sponsor development code. It is a clinical-trial intervention label for a regimen of **oral prednisolone 60 mg once daily for 3 days** used in treatment-naive patients with large-vessel giant cell arteritis before repeat fluorine-18-fluorodeoxyglucose PET/CT imaging. Prednisolone is a synthetic glucocorticoid that activates the glucocorticoid receptor, producing broad anti-inflammatory and immunosuppressive effects. The PET3 label specifically distinguishes the 3-day steroid-exposure group from the PET10 group, which received the same daily prednisolone dose for 10 days.