What can a PET scan detect

Positron Emission Tomography (PET)

Positron emission tomography (PET) is an imaging examination method in medicine. According to the definition, it is one of the nuclear medical examination procedures that a radiologist always carries out. PET allows doctors to do that Metabolic activity in the body visible on images close. Positron emission tomography provides very precise results, but is relatively complex and expensive compared to other imaging methods.

Positron Emission Tomography - How It Works

Patients undergoing positron emission tomography will get one radiolabelled substance enters the bloodstream injected. This is also called Tracer or radiopharmaceutical. Doctors use these substances in a concentration that is considered harmless to health. A commonly used tracer is the labeled glucose "Fluoro-deoxy-glucose" (FDG).

This substance accumulates in regions of the body that are particularly metabolically active. This is the case with cancer cells, among other things. They divide faster and therefore have a higher need for sugar than healthy cells - so they use more glucose. But brain and heart muscle cells or inflamed tissue also have a more active metabolism.

The radioactively marked substance breaks down in the body without any external influence. During this process, it emits radiation - and this can be measured using positron emission tomography. A computer calculates high-resolution, spatial slice images (3D) from the measurement data. The depicted region is therefore broken down into thin “slices” layer by layer.

On the images, radiologists can follow the path of the substance through the body and recognize abnormalities in the metabolism using the radiation emitted. Tissues with a fast metabolic rate and high sugar consumption appear as very dark spots on black-and-white PET images, while they glow particularly intensely on color images.

A PET is helpful in diagnosing cancer, among other things. Malignant tumors can be detected even in the early stages. Doctors can also check the success of a therapy using positron emission tomography. Modern devices can even combine several imaging procedures with one another. The methods complement each other and enable very precise analyzes. For example, PET / CT or PET / MRT examinations are now possible in nuclear medicine. The combined investigations capture the structure and the metabolism at the same time of an organ or part of the body.


The positron emission tomography (PET) procedure can be combined with computed tomography (CT). The computer-calculated images of the two examination methods are superimposed - a fusion image is created.

In this the information complement each other the PET and the CT and thus result in a more precise result. Doctors can thus determine the type and location of a tumor faster and more precisely. The doctor can also use a PET / CT examination to determine whether a drug is working in the right place and thus monitor the success of a cancer therapy.


Positron emission tomography (PET) can also be combined with magnetic resonance tomography (MRT). In particular, the contrast in the soft tissues can be better represented with this hybrid method (PET / MRT) than with a combination of PET / CT.