A brain perfusion single-photon emission computed tomography (SPECT) scan is a nuclear medicine imaging technique that is performed to investigate the regional blood flow in the brain. Blood flow in the brain is closely linked to neuronal activity and the distribution of activity reflects neuronal activity levels in different parts of the brain. A radiopharmaceutical called ^99mTc-hexamethylpropyleneamineoxime (HMPAO) is given as an injection into a vein in the arm. This radiopharmaceutical crosses into the brain and emits gamma rays. These gamma rays are detected by a gamma camera which creates a three-dimensional picture of the neuronal activity in the functioning brain.

Brain perfusion SPECT scans have many different clinical applications;

• Detection and evaluation of cerebrovascular disease
• Aid in the diagnosis and differential diagnoses of suspected dementia
• Detection of seizure focus in epilsepsy
• Assessment of brain death
• Evaluating suspected brain trauma
• Infection/inflammation