PET Scans

A PET scan (Positron Emission Tomography) is a medical imaging technique that uses a small amount of radioactive material (tracer) to visualise the functional and metabolic activity of tissues and organs in the body. PET scans provide information about the cellular activity and metabolism, allowing healthcare professionals to detect and evaluate various medical conditions. Here’s some important information about PET scans:


PET scans are primarily used to detect and stage cancers, as well as monitor the response to cancer treatment. They can also be used to evaluate brain disorders, heart conditions and certain neurological conditions. PET scans provide information about the functioning of organs and tissues at a cellular level, helping to identify areas of abnormal activity.


Before a PET scan, a small amount of a radioactive tracer is injected into the patient’s body. The tracer is usually a substance that is similar to glucose, as cells actively use glucose for energy. The radioactive tracer emits positrons, which are detected by a PET scanner. The scanner consists of multiple rings of detectors that capture the emitted positrons and create a three-dimensional image of the distribution of the tracer in the body. The images can be analysed to evaluate the metabolic activity of various tissues and organs.

Hybrid PET/CT Scans

In many cases, PET scans are combined with CT scans to provide both functional and anatomical information. This combination, known as a PET/CT scan, allows for the precise localisation of abnormal metabolic activity detected by the PET scan within the corresponding anatomical structures provided by the CT scan. The fusion of PET and CT images provides more accurate and detailed information, aiding in diagnosis and treatment planning.


PET scans involve exposure to a small amount of radiation due to the use of the radioactive tracer. However, the radiation exposure is considered safe and within acceptable limits. The benefits of obtaining valuable diagnostic information from the PET scan outweigh the risks associated with the low radiation exposure. The radioactive tracer used in PET scans has a short half-life, meaning it quickly loses its radioactivity over time.


PET scans have certain limitations. They may not provide detailed anatomical information alone, which is why they are often combined with CT scans or other imaging modalities. Additionally, PET scans may produce false-positive or false-negative results and the interpretation of PET images requires expertise and experience. PET scans are usually performed in conjunction with other diagnostic tests and clinical information to provide a comprehensive evaluation.


PET scan technology continues to advance, with newer tracers and improved imaging systems. Various tracers have been developed to target specific biological processes or diseases, allowing for more accurate and targeted imaging. Additionally, PET/MRI scanners are being increasingly used, combining the functional information from PET scans with the superior soft tissue visualisation provided by MRI.

PET scans are powerful diagnostic tools that provide valuable information about the functional and metabolic activity of tissues and organs in the body. They play a crucial role in the detection, staging and monitoring of cancer, as well as in the evaluation of other medical conditions. The use of PET scans is typically determined based on the specific clinical question and in conjunction with other diagnostic tests and medical history.