Age-related changes in the cerebral distribution of Tc-99m-ECD from infancy to adulthood

Although cerebral blood flow in infants differs from that in older individu als, the distribution of Tc-99m-ethyl cysteinate dimer (ECD) in infants has not been well studied. This study compared Tc-99m-ECD distribution in infa nts and children with that in young adults. Methods: Tc-99m-ECD SPECT was p erformed on 37 patients suspected of having epilepsy, ranging in age from 3 mo to 26 y, The patients were divided into two age-matched groups, a drug- free group (n = 19) and a drug-taking group (n = 18), according to their an ticonvulsant medication status at the time of examination, Tc-99m-ECD (100- 740 MBq) was injected interictally, and SPECT data were acquired using a tr iple-head gamma camera. Mean whole-brain counts were obtained from 10 seque ntial SPECT images. Regions of interest were set bilaterally on five areas of the cerebral cortex and on the basal ganglia, thalamus and cerebellum. T he brain perfusion index (BPI) was obtained as a ratio of the mean counts i n each region of interest to the mean whole-brain counts. The relationship between BPI and age in each region in the drug-free and drug-taking groups was analyzed separately and together using linear regression. The relations hip between five patient age groups (<1 y, n = 4; 1-4 y, n = 9; 5-9 y, n = 8; 10-15 y, n = 7; >15 y, n = 9) and BPI in each region was also examined u sing multiple comparison analyses. Results: Significant positive correlatio ns between BPI and age in the frontal cortex and cerebellum were confirmed in the drug-free group. Anticonvulsant drugs did not affect the regression lines of BPI in the frontal cortex and cerebellum, Significant differences in BPI between age groups were seen in the parietal cortex, frontal cortex, occipital cortex, basal ganglia, thalamus and cerebellum in all patients. Conclusion: Age related changes in cerebral Tc-99m-ECD distribution were co nfirmed and found to be unaffected by the administration of anticonvulsant drugs. Tc-99m-ECD uptake in children and infants is different from cerebral blood flow glucose metabolism as previously reported, especially in the ce rebellum.