Evaluation of regional cerebral blood flow in acute head injury by stable xenon-enhanced computerized tomography.

Measurement of regional cerebral blood flow (rCBF) in head-injured patients is considered useful for understanding the cerebral hemodynamics of brain trauma and for determining the optimal therapy. Most data thus far obtained with 133Xe clearance techniques have made only relative contribution, due to limitations of the 133Xe method. More recently, is has become possible to measure rCBF by xenon-enhanced computerized tomography (Xe-CT), which obviates most problems inherent to the 133Xe method. On the other hand, computational errors and concerns regarding the safety of xenon inhalation have thwarted the clinical use of Xe-CT. Recent advances in CT technology, however, have largely eliminated these problems. Xe-CT CBF measurements in severe head injury demonstrate a good correlation between CBF values obtained with 133Xe and Xe-CT. By consistently applying these studies in conjunction with conventional CT, information on very early flow derangements (within 1 to 2 hours after injury) can be obtained, in relation to anatomical lesions. Preliminary data reveal higher incidences of global and focal ischaemia than found previously. Local ischaemia tends to evolve to hyperemia in the ensuing days.