Purpose: The aim of this study was to establish the novel automatic method to quantify blood flow volumes of the major intracranial arteries by using SPECT.
Methods: We created the vascular templates to cover the territory supplied by the major intracranial arteries. Each blood flow volume was calculated as the regional cerebral blood flow on SPECT using this template × volume size of the template. In this study, we evaluated the volume flows in 22 cerebral hemispheres with normal perfusion and 28 hemispheres with severe stenosis in the internal cerebral artery (ICA) or middle cerebral artery (MCA) and that at acetazolamide test in 16 normal hemispheres and 20 hemispheres with stenosis.
Results: The mean blood flow volumes of the ICA and MCA in the normal hemispheres increased to more than 40% after acetazolamide test (161-228 mL/min for ICA and 111-157 mL/min for MCA), although those in the hemispheres with stenosis increased to less than 35% (158-192 mL/min for ICA and 107-127 mL/min for MCA). The receiver operating characteristic analyses revealed that the simple difference between the blood flow volume at acetazolamide test and that at rest using the new MCA template was superior to detecting reduction of cerebrovascular reactivity (CVR), compared with the conventional percent CVR using the original template.
Conclusions: Blood flow volumes of the intracranial arteries had been able to be quantified automatically on SPECT, and difference of CVR was available for predicting the blood demand-supply balance.