Ultrasound Perfusion Imaging of the Human Brain

Abstract

Background and Purpose —Color-coded perfusion maps can be calculated from ultrasound harmonic gray-scale imaging data to analyze brain tissue perfusion. Methods —In 13 healthy volunteers, 2 doses (0.5 and 1.5 mL) of Optison, a perfluoropropane-containing ultrasound contrast agent, were injected intravenously, and they produced a strong increase in echo enhancement in the brain parenchyma. The contrast agent was injected twice for ultrasound examination of both hemispheres. A total of 24 hemispheres per dose was available for further analysis. We used harmonic imaging for quantification of echo enhancement. Color-coded perfusion maps were calculated from the ultrasound data. In 1 subject, magnetic resonance images were obtained parallel to the orientation of the ultrasound scans. Results —After administration of both doses of Optison, it was possible to evaluate brain tissue perfusion in all 24 hemispheres. Subtraction of precontrast images and color coding enhanced the visualization of hemispheric perfusion. The epiphyseal gland, anterior interhemispheric fissure, third ventricle, and lateral fissure can be used as reliable anatomic landmarks. Artifacts caused by abrupt changes in thickness of the temporal bone are observed as signal-void streaks oriented from the ultrasound probe toward the cerebral midline. Conclusions —Harmonic gray-scale imaging with Optison shows strong echo enhancement in the brain parenchyma. By calculating color-coded perfusion maps, it is possible to visualize human brain tissue perfusion at the patient’s bedside.