Changes in cerebral glucose metabolism in newborn infants with cerebral infarction

Changes of positron emission tomography in newborn infants at different gestational ages, and neonatal hypoxic-ischemic encephalopathy

Cerebral glucose metabolism was measured by (18)F-fluorodeoxyglucose position emission tomography in infants at different gestational ages and with neonatal hypoxic-ischemic encephalopathy. Thirty-six preterm and term infants at different gestational ages without brain injury were divided into four subgroups: ≤32 weeks (n = 4), 33-34 weeks (n = 5), 35-36 weeks (n = 12), and ≥37 weeks (n = 15). Twenty-four newborn infants with hypoxic-ischemic encephalopathy were divided into three subgroups: mild (n = 13), moderate (n = 7), and severe (n = 4). Cerebral glucose metabolism manifested a trend toward increase, and the structure of cranial (18)F-fluorodeoxyglucose positron emission tomography images became clear with increased gestational age, especially at ≥37 weeks. Uptakes of (18)F-fluorodeoxyglucose in the ≥37-week group were significantly higher than in the ≤32-week group (P < 0.01). Cerebral glucose metabolism changed significantly in neonatal hypoxic-ischemic encephalopathy, and was either unbalanced bilaterally or relatively low at all sites. Moreover, uptakes of (18)F-fluorodeoxyglucose were significantly lower in severe than in mild and medium hypoxic-ischemic encephalopathy (P < 0.05). Cerebral glucose metabolism, as measured by (18)F-fluorodeoxyglucose positron emission tomography, may prove useful for estimating brain development and injury in newborn infants, and its clinical values need further investigation.

Brain positron emission tomography in preterm and term newborn infants

OBJECTIVE

To study the clinical values of positron emission tomography (PET) in preterm and term newborn infants through observing brain glucose metabolism by (18)F-fluorodeoxyglucose ((18)F-FDG) PET.

METHOD

To observe the brain (18)F-FDG PET imaging in 9 term and 7 preterm newborn infants in the same condition after administration of 0.1 mCi/kg (18)F-FDG.

RESULT

The brain (18)F-FDG PET imaging showed that the uptake of (18)F-FDG was relatively more in the thalamus, and less in the cerebral cortex in preterm and term newborn infants. The uptake of (18)F-FDG of cerebral cortex in preterm infants was less than that in term infants, so the structure of brain (18)F-FDG PET imaging was a little fainter in preterm neonates as compared with that in term newborns.

CONCLUSION

(18)F-FDG PET imaging could show different glucose metabolisms of brain in preterm and term infants. Brain (18)F-FDG PET imaging might be a useful tool for estimating the brain function in newborn infants, and its clinical values need further investigation.

Functional MRI of the newborn

In order to provide accurate prognosis and developmental intervention to newborns, new methods of assessing cerebral functions are needed. The non-invasive technique of functional magnetic resonance imaging (fMRI) can be considered as the leading technique for functional exploration of the infant's brain. Several studies have previously applied fMRI in both healthy and diseased newborns with different sensory and cognitive tasks. In this chapter, the methodological issues that are proper to the use of fMRI in the newborn are detailed. In addition, an overview of the major findings of previous fMRI studies is provided, with a focus on notable differences from those in adult subjects. More specifically, the functional responses and the localization of cortical activations in healthy and diseased newborns are discussed. We expect a rapid expansion of this field and the establishment of fMRI as a valid clinical diagnostic tool in the newborn.

Functional imaging of dolphin brain metabolism and blood flow

This report documents the first use of magnetic resonance images (MRIs) of living dolphins to register functional brain scans, allowing for the exploration of potential mechanisms of unihemispheric sleep. Diazepam has been shown to induce unihemispheric slow waves (USW), therefore we used functional imaging of dolphins with and without diazepam to observe hemispheric differences in brain metabolism and blood flow. MRIs were used to register functional brain scans with single photon emission computed tomography (SPECT) and positron emission tomography (PET) in trained dolphins. Scans using SPECT revealed unihemispheric blood flow reduction following diazepam doses greater than 0.55 mg kg(-1) for these 180-200 kg animals. Scans using PET revealed hemispheric differences in brain glucose consumption when scans with and without diazepam were compared. The findings suggest that unihemispheric reduction in blood flow and glucose metabolism in the hemisphere showing USW are important features of unihemispheric sleep. Functional scans may also help to elucidate the degree of hemispheric laterality of sensory and motor systems as well as in neurotransmitter or molecular mechanisms of unihemispheric sleep in delphinoid cetaceans. The findings also demonstrate the potential value of functional scans to explore other aspects of dolphin brain physiology as well as pathology.