Serial magnetic resonance diffusion and hemodynamic imaging in a neonatal rabbit model of hypoxic-ischemic encephalopathy

Dynamic changes in relative cerebral blood volume (rCBV) and apparent diffu sion coefficient (ADC) were investigated, using high speed magnetic resonan ce imaging (MRI) in an acute neonatal rabbit model of hypoxic-ischemic ence phalopathy (HIE). Serial rCBV imaging used a magnetic susceptibility blood pool contrast agent. Interleaved ADC and rCBV images were acquired with 9 s temporal resolution. Rabbits received unilateral common carotid artery (CC A) ligation followed by hypoxia, rCBV increased bilaterally within 1-2 min after the onset of hypoxia. A biphasic ADC decline was observed: a slowly d eclining phase (84 +/- 18% of baseline) followed by a rapid, focal drop to 55 +/- 8% of baseline in the ipsilateral cortex, which was paralleled by a rapid focal rCBV drop to 70 +/- 17% of baseline, ADC decline generally bega n in a small region of ipsilateral cortex and spread over the ipsilateral c ortex, ipsilateral subcortical tissue and contralateral cortex. The initial ADC drop usually preceded the initial rCBV drop by similar to 60 s, howeve r at later timepoints rCBV decline sometimes preceded ADC decline. Upon nor moxia, rCBV recovered to about baseline values while ADC recovered to basel ine or above. This method provides a sensitive means of non-invasively visu alizing acute hemodynamic- and metabolic-related changes in HIE with good t emporal and spatial resolution. Copyright (C) 1999 John Wiley & Sons, Ltd.