Positron emission tomography
Positron emission tomography (PET) is, like CT or magnetic resonance tomography (MRT), a cross-sectional imaging technique. However, it does not visualize single organs but the metabolism of different body tissues.
In tumor diagnostics, a glucose analogue (fludeoxyglucose, FDG) tagged with a slightly radioactive fluorine is used as a tracer (FDG tracer). It is injected into a vein and metabolized almost like normal glucose. But because of its radioactive tagging it is possible to make the metabolization of the tracer visible by means of a special PET scanner. Cells with a high metabolic activity, such as tumor cells, usually metabolize an increased amount of glucose, so that the PET imaging scanner detects a strong signal in these areas.
With this method healthy tissue can be distinguished from tumor tissue. Depending on the treatment concept, PET examinations are used for initial staging, during chemotherapy (for treatment monitoring), after end of chemotherapy (for treatment control) or in case of a suspected relapse. Clinical trials have confirmed the prognostic value of PET imaging in treatment monitoring and treatment control.
One of the main objectives in hemato-oncology today is to individualize therapy. Therefore, the GHSG is investigating in its current trials whether a reduction or intensification of therapy based on treatment monitoring by means of PET is a reliable means for stratification of treatment.