Cerebral Blood Flow and Oxygen Metabolism Measurements Using Positron Emission Tomography on the First Day after Carotid Artery Stenting

Background: The aim of the present study is the characterization of hemodynamics to predict hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) with positron emission tomography (PET) obtained before and on the first day after the treatment. Methods: Cerebral perfusion and oxygen metabolism were evaluated by 15 O-gas PET in 18 patients with symptomatic internal carotid artery (ICA) stenosis before and on the first day after CAS. Regional cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMRO2), and cerebral blood volume (CBV) were measured in the ipsilateral and contralateral middle cerebral artery territories and compared between before and after CAS. Results: CBF increased in 16 of 18 patients on the first day after CAS and postoperative CBF was significantly higher than preoperative CBF bilaterally. OEF decreased in 15 of 18 patients on the first day after CAS and postoperative OEF was significantly lower than preoperative OEF in the ipsilateral hemisphere. CMRO2 and CBV did not change significantly. None of the patients showed HPS after CAS. All patients who had preoperative OEF of 53% or more (misery perfusion) in the ipsilateral hemisphere showed 50% or more increase in CBF postoperatively. The preoperative OEF value significantly correlated with the rate of postoperative increase in CBF bilaterally. Conclusions: CAS increases cerebral perfusion and improves hemodynamic compromise in patients with symptomatic ICA stenosis. Although we could not clarify the usefulness of PET before and on the first day after CAS in predicting HPS, a high preoperative OEF is related to postoperative marked CBF increase and might be used as a predictor of HPS. Patients with greater hemodynamic compromise with a high preoperative OEF should be managed carefully to prevent HPS, but they have a greater chance of CBF increase after CAS.