SPECT Brain Imaging

Updated: Mar 10, 2015
  • Author: Matthew Tam, MBBCh; Chief Editor: Gowthaman Gunabushanam, MD, FRCR  more...
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Brain perfusion single-photon emission computed tomography (SPECT) imaging is a functional nuclear imaging technique performed to evaluate regional cerebral perfusion.

Because cerebral blood flow is closely linked to neuronal activity, the activity distribution is presumed to reflect neuronal activity levels in different areas of the brain. A lipophilic, PH-neutral radiopharmaceutical (most commonly99m Tc-hexamethylpropyleneamine oxime [HMPAO] and99m Tc-ethylene cysteine diethylester [ECD], with a half-life of 6.02 hours) is injected into the patient, which crosses the blood-brain barrier and continues to emit gamma rays. [1, 2] A 3-dimensional representation of cerebral blood flow can be iterated using gamma detectors, allowing for interpretation.

Brain SPECT can be complemented with pharmaceutical agents that enhance regional cerebral blood flow, such as acetazolamide (carbonic anhydrase). Acetazolamide increases local pCO2 and causes arteriolar dilation, allowing for assessment of cerebrovascular reserve in transient ischemic attack, stroke, and vascular anomalies and distinguishing vascular from neuronal causes of dementia. [3]

Brain SPECT imaging has many different clinical applications.



Brain perfusion SPECT imaging can aid in the diagnosis and ongoing evaluation of many different medical conditions, as follows:

  • Detection and evaluation of cerebrovascular disease

  • Aid in the diagnosis and differential diagnoses of suspected dementia

  • Detection of seizure focus

  • Assessment of brain death

  • Evaluating suspected brain trauma

  • Neuropsychiatric disorders: Mood disorders, evaluating and subtyping attention-deficit disorder

  • Substance abuse

  • Infection/inflammation



Brain SPECT imaging is contraindicated in the following:

  • Pregnancy

  • Breastfeeding (this should be interrupted for 24 hours prior to imaging)

  • Lack of cooperation

Complication Prevention

Brain SPECT imaging is a safe procedure on the whole. However, care must be provided by the imaging technologist to reduce patient discomfort and minimize motion artifact. Care must also be provided to avoid tissue extravasation of radiopharmaceutical agents, as there is potential to induce tissue necrosis.