Ultraschall in der Medizin : Organ der Deutschen Gesellschaft für Ultraschall in der Medizin, [der] Österreichischen Gesellschaft für Ultraschall in der Medizin, [der] Schweizerischen Gesellschaft für Ultraschall in Medizin und Biologie
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Transcranial Doppler and color-coded duplex sonography provide reliable information on cross-flow through the circle of Willis, stenoses, occlusions and vasospasm of the major basal cerebral arteries. The CO2 and acetazolamide tests allow quantitative evaluation of the hemodynamic impact of obstructive cerebrovascular disease. Furthermore, transcranial Doppler sonography is used for detection of enhanced intracranial pressure, confirmation of brain death, detection of cerebral microemboli ("high intensity transient signals" = "HITS"), and patent foramen ovale. ⋯ Transcranial color-coded duplex sonography identifies intracranial hemorrhage, cerebrovascular malformations, and hydrocephalus, but is inferior to neuroradiological techniques. Transpulmonary contrast agents make the examination of patients with inadequate insonation windows feasible, and increase diagnostic confidence in transcranial ultrasonography. Transcranial power-based color-coded duplex sonography ("power Doppler") may further improve transcranial ultrasonography, and visualize flow in smaller vessels.