Hemodynamic Assessment of Carotid Artery Obstructive Lesions: Comparison of PET and SPECT

Abstract

Internal carotid artery (ICA) obstructive lesions (stenoses and occlusions) can cause brain ischemic disorders in two ways: by embolism of the proximal stump to a distal intracranial arterial branch, or by an acute decrease in cerebral perfusion pressure (CPP) downstream to the reduction in lumen size. There is no means by which the occurence of the former mechanism can be predicted. There is some evidence, gathered by previous studies, that the latter mechanism could occur only in patients in whom there was already a permanent (chronic) impairment of the CPP, even if it was previously asymptomatic. Over the past 10 years, several studies have tried to assess as accurately as possible the cerebral perfusion reserve (CPR) in such patients, with isotopic methods. The theoretical aims of such assessments are:

• Prediction of neurological outcome of patients with symptomatic or asymptomatic ICA lesions.

• Supply of helpful information for the perioperative management of patients with a decreased CPR, who are threatened both by low-flow ischemia [during systemic arterial pressure (SAP) lowering, or arterial clamping] and by reperfusion disaster (edema or hemorrhage).

• Assessment of the pyhsiological hemodynamic benefit of revascularization procedures, surgical or pharmacological.