Definition
Positron emission tomography (PET) is a special imaging examination procedure that can be used to visualize metabolic processes in the body. For this purpose, the patient is administered low-level radioactive glucose via the vein, made visible with a measuring unit and the information is processed into a spatial image. The sugar is distributed throughout the body and accumulates especially in tissue with increased metabolic turnover. In many cases, PET is combined with computed tomography (CT), which also enables spatial imaging. The combined procedure of PET and CT is used, for example, in the diagnosis of cancer, nerve and heart diseases.
When will the examination take place?
Positron emission tomography is most frequently used to clarify suspected cancer. The examination can also be helpful in determining whether a cancer that has already been diagnosed has already spread. A further indication arises in patients in whom a conspicuous structure has been detected by computer tomography (CT).
PET can be used to show whether this has increased metabolic activity (for example, in inflammation or cancer) or whether the activity is reduced (for example, in scar tissue). In addition, the PET examination is also suitable for monitoring therapy. If, for example, a diagnosed cancer is being treated with chemotherapy or radiation, PET can be used to determine whether the tumor focus(s) is/are becoming smaller or disappearing completely.
Even after a completed tumor treatment, PET can be used as part of aftercare to determine whether or not new cancerous tumors have formed. A decisive factor in determining whether a patient is indicated for PET examination is individual consideration in conjunction with the patient’s medical history and other findings. In consultation with the treating physicians, the benefits must be weighed against the burden and risks of the examination.
PET from the brain
The brain is the organ with the highest consumption of energy, including in the form of sugar. The metabolic activity of the individual areas of the brain can therefore be easily visualized using positron emission tomography. PET can therefore contribute to the diagnosis of brain tumors, for example.
These usually show a greatly increased accumulation of the radioactively labeled sugar. The PET examination can also contribute to the diagnosis of seizure-related epilepsy. In seizure-free phases, the activity in the affected areas of the brain is reduced.
Conspicuous PET findings are also possible in dementia diseases such as Alzheimer’s. The metabolic activity is also rather reduced here. However, PET examination is not part of the standard diagnostic procedure for these diseases. Therefore, health insurance companies do not usually cover the costs. Whether a positron emission tomography of the brain is appropriate must therefore be decided individually.
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