Clinical Significance Of Positron Emission Tomography In Preterm, Term Newborn Infants And Neonatal Hypoxic-ischemic Encephalopathy

BackgroundPET (position emission tomography) is a noninvasive measurement of the levels of radiopharmaceuticals labeled with positron emitters, which can provide anatomically physiological and pathophysiological information on metabolism, function, blood supply, cell proliferation, and distribution of receptor of organs and tissues from molecular level. The most frequently used tracer for the assessment of tissue glucose metabolism is ¹⁸F-fluorodeoxyglucose(¹⁸F-FDG). PET has been widely used in a lot of cerebral diseases in adults. Only a few pediatric and even fewer neonatal PET studies have been presented so far. The measurement, however, of the cerebral glucose metabolism is important to study the physiology and pathophysiology of the developing brain in preterm, term infants, and in neonatal patients suffering from hypoxic-ischemic encephalopathy (HIE).ObjectiveTo study the clinical value of cerebral glucose metabolism measure by ¹⁸F-fluorodeoxyglucose ¹⁸F-FDG PET in preterm, term newborn infants and neonatal hypoxic-ischemic encephalopathy (HIE).Methods To measure the cerebral glucose metabolism by ¹⁸F-FDG PET imaging in 67 newborn infants. Seven neonates were excluded due to failure of data collection by PET, which caused by inadequate of administration of ¹⁸F-FDG, low dose of ¹⁸F-FDG , and crying or movement of the infants during PET course. Sixty infants were included in the study. Among them, 36 preterm and term infants without any sign of brain injury were divided into 4 groups, including?32wk (n=4), 33-34wk (n=5), 35-36wk (n=12), and?37wk group (n=15), and the other 24 newborn infants suffering from HIE were divided into 3 groups, including mild HIE (n=13), medium HIE (n=7), and severe HIE group (n=4).¹⁸F was obtained by RDS?Cyclotron, and then, ¹⁸F-FDG was produced by Chemistry Process Control Unit. The data was collected by PET instrument after administration of 0.1mCi /kg ¹⁸F-FDG in the newborns, and standardized uptake values (SUV) were calculated to estimate the cerebral glucose metabolism.ResultsThe cerebral glucose metabolism was found to have a trend to be increased, and the structure of brain ¹⁸F-FDG PET imaging to be clear with the increase of gestational age, especially when the gestational age was older than 37wk.The brain ¹⁸F-FDG PET imaging in different gestational age showed that the uptake of ¹⁸F-FDG was relatively higher in thalamus, cerebellum, sensorimotor cortex and basal ganglia, where as relatively lower in cerebral cortex. The uptakes of ¹⁸F-FDG in?37wk group were found to be significantly higher than those in?32wk group (p<0.01).The cerebral glucose metabolism was significantly changed in neonatal HIE as measured by ¹⁸F-FDG PET. The cerebral uptake of ¹⁸F-FDG was either unbalanced bilaterally or relatively low in all sites especially in subcortical alba, thalamus, basal ganglia in HIE patients. Moreover, The uptakes of ¹⁸F-FDG in severe HIE patients were found to be significantly lower than those in mild and medium HIE patients(p<0.05 respectively).Conclusions1. The uptakes of ¹⁸F-FDG in?37wk term infants were significantly higher than those in?32wk preterm infants.2. The cerebral uptake of ¹⁸F-FDG was either unbalanced bilaterally or relatively low in all regions or some places as compared with other areas of the brain in neonatal patients with HIE.3. Cerebral glucose metabolism measured by ¹⁸F-FDG PET might be a useful tool for estimating the brain development and injury in newborn infants, and its clinical values need further investigating.