How to prepare for a brain scan to assess general brain function?
Patients should be informed that the test takes approximately one hour and typically involves the injection of the radiotracer followed approximately 30 minutes later by PET or SPECT imaging depending on the radiotracer. It is important to recognize that virtually everything affects brain function, and this should be considered when discussing the preparation with the patient.
Here are some of the issues related to scanning for general brain function.
Considerations for Patient Preparation Prior to Cerebral SPECT or PET Imaging
- • No caffeine or nicotine should be taken on the examination day.
- • The patient needs to be nil per os (NPO) (i.e., is not to ingest food or fluids per mouth) after midnight and undergoes assessment of serum blood glucose levels prior to FDG PET (typically, this should be <200 mg/dL).
- • Medications that alter the cerebral blood flow or metabolism, including psychotropic medications, should be temporarily discontinued if clinically possible. All medications have the potential to alter brain function.
- • Radiotracer injection is typically performed with open eyes and ears and with low ambient light and noise.
- • No movement or talking after radiotracer administration is recommended.
- • Sedation may be required and can be given in certain circumstances but only after radiotracer injection (i.e., after ≈30 minutes) to allow for radiotracer uptake in the brain.