Excitotoxin-induced cerebral hyperemia in newborn piglets: regional cerebral blood flow mapping with contrast-enhanced power Doppler US.

Abstract

To create regional cerebral blood flow maps with contrast material-enhanced power Doppler ultrasound (US). In six anesthetized newborn piglets, cerebral hyperemia was induced after intrastriatal injection of 5 mumol of N-methyl-D-aspartic acid. Coronal power Doppler US was performed with a microbubble-based contrast agent, and cerebral blood flow was determined before and at 15, 30, and 60 minutes after injection. Images were digitized and analyzed for changes in mean pixel intensity. A bolus injection curve was constructed by plotting mean pixel intensity versus time, and the area under this normalized curve was compared with cerebral blood flow. Hemispheric cerebral blood flow increased from 40 mL/min/100 g +/- 1 (mean +/- standard error) to 90 +/- 12, 86 +/- 8, and 85 +/- 12 at 15, 30, and 60 minutes after injection, respectively (P < .0001 [analysis of variance]). Hemispheric mean pixel intensity at peak contrast also increased from 69 units +/- 5 to 120 +/- 4, 112 +/- 6, and 98 +/- 13 at 15, 30, and 60 minutes after injection, respectively (P < .003). The area under the normalized curve correlated well with changes in hemispheric and striatal cerebral blood flow (r = .73, P = .0001; r = .62, P = .0001, respectively). In the newborn brain, regional blood flow maps can be created accurately with contrast-enhanced power Doppler US.