What it means
A radiotracer is a substance chosen to travel to a certain organ or type of cell, joined to a tiny radioactive label. The label gives off energy that a special camera can detect. It is usually injected into a vein, though some are swallowed or breathed in. Different tracers go to different places. FDG, which the body treats like sugar, collects in busy cells. Bone tracers collect where bone is rebuilding itself.
When it matters
The tracer itself is not a finding. What matters is where it collects. For many tracers, the kidneys and bladder light up normally as the body clears it. Areas with more or less tracer than expected are reported as increased uptake or photopenic (a cold spot). The radiation dose is kept low, and for most scans the tracer fades or leaves the body within a day or so. Allergic reactions are very rare.
Questions to ask your doctor
- Which radiotracer was used for my scan, and why that one?
- Did the tracer collect anywhere it normally would not?
- Do I need any precautions after the scan, such as around young children?
