LOCAL VASCULAR CO2 REACTIVITY IN THE INFANT BRAIN ASSESSED BY FUNCTIONAL MRT

The local cerebral vascular response to hyperventilation vas investiga ted in five distressed, intubated infants by means of a T2 sensitive gradient-echo MRI technique at 1.5 T. In one preterm infant, the MR si gnal change during hyperventilation was sparse. In four term infants, the mean MR signal of the brain slice investigated decreased by 1.2-2. 6 % per kPa change in PCO2 as a reflection of decreased cerebral blood flow during hyperventilation. Pixel-wise analysis revealed absence of vascular response in the basal ganglia, the thalamus or in the occipi tal re,oion. In two adult controls, who hyperventilated voluntarily, t he vascular reactivity was homogeneously distributed predominantly ove r the grey matter. The experiments demonstrate that local impairment o f vascular CO2 reactivity in the distressed infant brain can be detect ed by T2 sensitive gradient-echo MRI, which is also known as function al MRI.