Concealment of neonatal cerebral infarction on MRI by normal brain water.

Magnetic resonance imaging (MRI) is highly sensitive in detecting cerebral infarction in adults, both in the acute and chronic stages. Cytotoxic and vasogenic edema produce an increase in the water content of acutely ischemic brain, resulting in good tissue contrast from adjacent normal brain on spin density, T1 and T2 weighted MR images. Gliosis and other chronic brain changes are well seen in later stages. We recently encountered a case of remote cerebral infarction in an infant, however, which was not evident on the initial MR examination at 7 weeks of age but which was clearly seen on a follow-up scan at 9 1/2 months. Our contention is that the infarct was masked by the known increased water content of the neonatal brain, which results in lengthened spin density and relaxation times; edema and gliosis may thus be obscured. This age-related concealment of ischemic brain changes on MR has not to our knowledge been reported, and we present this case as a caveat in the detection of cerebral infarction in neonates.