The radiotracer piflufolastat, also known as Pylarify, is safe and FDA-approved. Side effects are rare and temporary and may include headache and a change in taste. Piflufolastat is a radionuclide dye, so it contains a small amount of radiation. The amount is similar to the exposure you receive during a CT scan and the tracer’s radioactive element is entirely gone from your body within a few days.