Frequently Asked Questions

Positron emission tomography (PET) is an imaging technique, which can map functional processes of the brain. PET can investigate numerous processes in the brain using different 'radiotracers'. A radiotracer is a molecule that binds to a certain receptor of interest. It is labeled with a radioactive 'tag' which allows the PET camera to detect the signal. The amount of radiation you will receive is around the same dose you would receive from a CT scan. The government’s regulatory committee (FDA) has set a limit on the amount of exposure radiation exposure that is deemed safe and the dose you will receive is well below this limit.

After arriving at the PET center and having everything explained to you, a nurse will place an IV into your arm. The radiotracer will be injected through the IV and you will be asked to lie on the scanner bed with your head in the PET camera. The length of the scan varies depending on the study but will be between 30-90 minutes. Some studies require two scans in one day and some involve a drug challenge. This will be fully explained to you before you consent to taking part.

Magnetic Resonance Imaging (MRI) allows us to obtain images of internal structures of the body, including the brain. A strong magnetic field is used to make hydrogen atoms align according to the direction of the magnetic field. Radio waves emitted from the scanner cause these atoms to enter a higher energy state. The radio waves are then turned off causing the atoms to release energy, which is received as a signal by the scanner. Hydrogen atoms respond differently when in water and in different types of tissue - resulting in different signal strengths from different parts of the brain. This enables us to get images such as the one shown on the right

Because of the strong magnetic field you will be asked to remove any metal from your body, including things like belts, jewelry and piercings. You will then lie on the scanner bed and be moved into the scanner. You will be given ear protection as the scanner is noisy and a buzzer so that you can come out of the scanner at any time. For some of our scans you will just be asked to lie still, but for others you will be asked to carry out some simple tasks. For these you will be able to see instructions on a screen and will respond to pictures (e.g. of people’s faces) by pressing buttons.