Detection of misery perfusion with split-dose 123I-iodoamphetamine single-photon emission computed tomography in patients with carotid occlusive diseases

Background and Purpose-Patients with carotid occlusive disease and stage 2 cerebral hemodynamic failure characterized by an increased oxygen extraction fraction (OEF) as measured by positron emission tomography (PET) and otherwise known as misery perfusion have a high risk of cerebral ischemia and subsequent stroke In clinical practice the detection of patients with misery perfusion through the use of widely available noninvasive and cost effective modalities such as single photon emission computed tomography (SPECT) is extremely important Methods-We evaluated the relationships between the regional hemodynamic status of cerebral circulation measured with split dose [I-123] N isopropyl p iodoamphetarnine SPECT (I-123 IMP SPECT) and an acetazolamide challenge and hemodynamic parameters including OEF measured with PET in 27 patients with both unilateral and bilateral carotid occlusive diseases Results-A significant negative correlation was found between the SPECT measured cerebrovascular reserve after acetazolamide administration and both the PET measured OEF and cerebral blood volume Neither the cerebrovascular reserve nor the cerebral blood flow index when expressed as a SPECT measured cerebrum to cerebellum ratio was useful for detecting lesions with an elevated OEF However a combination of the cerebrovascular reserve and cerebral blood flow index showed high sensitivity specificity and positive predictive value for the detection of misery perfusion Conclusions-Our study suggests that split dose I-123 IMP SPECT with an acetazolamide challenge could be useful for screening patients with misery perfusion in carotid occlusive diseases.