PETCT (Positron Emission Tomography Computerised Tomography) is a detailed scan combining a normal Computed Tomography (CT) scan with a Positron Emission Tomography (PET) scan. It is performed on the same scanner all in one appointment.


What does it involve?

The CT scan uses x-ray technology to obtain an image of the body. The PET scan is a type of nuclear medicine imaging, using a small injection of radioactive tracer or dye which travels through the body and is detected by the scanner as the patient passes through it. Different tracers, called radiopharmaceuticals, will localise in different diseases or conditions and provide detailed information of the internal anatomy and function of the body such as blood flow, oxygen use and sugar (glucose) metabolism. Together the scan will create a 3D picture of the inside of the body enabling the consultant to plan a more accurate treatment plan, providing images that pinpoint the anatomic location of abnormal metabolic activity within the body.


PET/CT scan is an outpatient procedure and can be performed to:


  • Detect cancer
  • Determine whether a cancer has spread in the body
  • Assess the effectiveness of a treatment plan, such as cancer therapy
  • Determine if a cancer has returned after treatment
  • Determine blood flow to the heart muscle
  • Determine the effects of a heart attack, or myocardial infarction, on areas of the heart
  • Identify areas of the heart muscle that would benefit from a procedure such as angioplasty or coronary artery bypass surgery (in combination with a myocardial perfusion scan)
  • Evaluate brain abnormalities, such as tumors, memory disorders, seizures and other central nervous system disorders
  • Map normal human brain and heart function


On the day:

On the day of your PET/CT appointment, you will be given an injection (usually in the arm) of a low dose radioactive tracer. This will travel through the body and allows the physician to measure the activity of cells in different parts of the body. Typically, it will take approximately 60 minutes for the radiotracer to travel through the body and to be absorbed by the organ or tissue being studied so you will have an hour rest peiod enabling the tracer to circulate.

You will then be moved into the PET/CT scanner and the imaging will begin. The CT scan will be carried out first, followed by the PET scan. The scan itself usually takes 20-30 minutes and the whole process will take approximately 2 hours.


For more information on PECTCT and how to prepare for your appointment, please see the ‘Patient Information Leaflet’ in the right hand column