Positron emission tomography (pet) can visualize metabolic processes in the body. It is particularly important in cancer diagnostics. Read more!


The Positron Emission Tomography (short: PET) is an imaging examination method, with which metabolic processes in the body are made visible. For this purpose, important substances are radioactively marked for the metabolism. Particular importance is attached to positron emission tomography in cancer diagnostics. Read here everything about the principle, the process and the validity of the procedure and learn what you have to pay attention to as a patient!

Product Overview


  • What is a positron emission tomography?

  • When do you perform a positron emission tomography?

  • What do you do with positron emission tomography?

  • What are the risks of positron emission tomography?

  • What should I pay attention to after positron emission tomography?

What is a positron emission tomography?

Positron emission tomography is a so-called nuclear medicine imaging study. With their help, metabolic processes in different parts of the body can be visualized. This is done via radioactive markers, which are administered to the patient, for example via a syringe.

PET is not a screening or check-up. It is only used as a supplement, for example if other diagnostic methods are not informative enough.

When do you perform a positron emission tomography?

Tumor tissue usually has a different metabolism than healthy cells. This is exploited for PET: Because radiolabeled substances in different cells accumulate to different degrees, the doctor can use PET to differentiate between healthy tissue, benign changes (benign tumors, scars, adhesions) and cancers. In the following diseases, for example, PET is used for diagnostics, but also for follow-up:

  • Lung and bronchial carcinoma
  • Cancers of the gastrointestinal tract (for example, gastric carcinoma or esophageal carcinoma)
  • Cancers in gynecology (breast, ovarian, cervical and other)
  • thyroid carcinoma
  • lymphoma
  • skin cancer
  • prostate cancer
  • Brain tumors

Even if daughter tumors (metastases) of a previously unknown tumor are discovered, the doctor can use positron emission tomography to detect the original type of cancer and find the primary tumor.

Where is positron emission tomography still used?

In addition to the high priority of positron emission tomography in the diagnosis of tumor diseases, it is also used for the investigation of inflammations (for example, infection of prostheses or blood vessels). In addition, some neurological changes can be seen, such as dementia or epilepsy. In cardiology, the examination reveals poorly perfused areas of the heart muscle. For example, the doctor uses them to check the adequate perfusion of the heart after a bypass operation.

For these diseases, the examination is important

  • Alzheimer
  • colon cancer
  • dementia
  • Ovarian Cancer
  • brain tumor
  • lung cancer
  • stomach cancer
  • gastric polyps
  • Thyroid

What do you do with positron emission tomography?

Before positron emission tomography, the doctor injects the patient with a weakly radiating substance (called marker or tracer) into a vein, for example on the arm. The substance spreads within the next hour in the body. During this time, the patient should be calm and relaxed: Speech or larger movements increase the strain on the muscles and their metabolism is stimulated - this can lead to false results in the PET.

If the radioactive substance in the body has been sufficiently distributed, the actual investigation begins. To do this, the patient is moved on a mobile couch through a recording device that measures the radiation in the various parts of the body, similar to a computer tomography. Again, it is important that the patient keeps as quiet as possible. Only then can a sharp picture emerge, which the doctor can judge. Depending on the body region, the examination itself lasts one to two hours. The patient will continue to be cared for by a medical assistant or doctor during this time and will be able to contact him at any time if he feels unwell

Combination PET / CT: What is it?

The so-called PET / CT is an examination procedure in which the positron emission tomography is combined with a computed tomography. The patient does not have to go through two separate examinations as the recording device measures the radioactive markers of the PET and at the same time makes CT images of the body.

On the one hand, the doctor receives information about the metabolic activity of the examined body region and, on the other hand, precise pictures of the anatomical structures. The combined procedure follows the same procedure as positron emission tomography.The patient receives only for some questions, a contrast agent, which can also be injected via a vein.

More about the symptoms

  • blurred vision
  • Blood in the stool
  • stomach pain
  • echolalia
  • gait disturbance
  • incontinence
  • loss in weight
  • dizziness
  • ptosis
  • pleural effusion

What are the risks of positron emission tomography?

Positron emission tomography uses radioactive markers. Therefore, many patients are afraid of the radiation exposure to which they are exposed during the procedure. The radiation exposure in PET, however, is only about two to three times as high as that which humans absorb on average annually through natural radioactivity of the environment. In addition, as the radioactive markers are only administered in small amounts and excreted quickly, the risk of long-term damage caused by strasbic use is beneficial to the patient!

The combined PET / CT examinations involve a higher radiation exposure as the patient is exposed to both PET and computed tomography radiation. Therefore, this examination is only carried out after careful consideration.

Can positron emission tomography be performed during pregnancy?

So far, there is no evidence that the investigation harms the unborn child - but it could not completely rule out it so far. Therefore, the doctor only carries out a PET in pregnant women if there is no alternative to this examination.

The same applies to breastfeeding because the radioactive marker passes into breast milk. If a breastfeeding patient has to undergo positron emission tomography, the doctor will tell her at what time after the examination she may breastfeed again.

What should I pay attention to after positron emission tomography?

After the examination you should drink as much as possible, preferably water or tea. So you help your kidney, the radioactive marker substances excrete faster. Since the substances in the body are rapidly degraded, there is usually no radiation exposure for others.

An exception are pregnant women, infants or toddlers: Since it can not be ruled out that they are permanently damaged by exposure to radiation, you should keep at least half a day off (for example, do not take children on their laps). If you are pregnant or nursing in your immediate environment, ask your doctor how best to deal with this situation and how long after you have had it Positron Emission Tomography avoid close contact.

Like This? Share With Friends: