Diamox (Acetazolamide) Brain Stress Perfusion is a functional nuclear imaging technique performed to evaluate regional cerebral perfusion. 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.

source: Medscape.com