DECLINE IN GLUCOSE-METABOLISM IN THE BRAIN NEURONAL CEROID LIPOSFUSCINOSIS (NCL) IN ENGLISH-SETTER - EVIDENCE BY POSITRON EMISSION TOMOGRAPHY (PET)

Positron emission tomography scans were performed on brains of homozyg ous and heterozygous English setters with neuronal ceroid-lipofuscinos is (NCL) from 13 months of age to 24-25 months of age for homozygous d ogs and to 38 months for heterozygous dogs, respectively. After iv inj ection of F-18-fluorodeoxyglucose (FDG), 7 coronal brain scans as well as sequential arterial blood samplings were performed for 45 min unde r pentobarbital anesthesia. From these data, three different functiona l images (DAR (standardized uptake value), FDG uptake (fractional upta ke) and glucose uptake) were reconstructed and quantitatively analysed . In the age range from 13 to 15 months, glucose images were comparabl e for both homozygous and heterozygous dogs, so that no differentiatio n was possible between healthy and diseased dogs on the basis of PET f indings. Between 18 and 24 months of age, a drastic decline in glucose metabolism was observed in homozygous dogs, while the decline in gluc ose utilization was very mild in this period for heterozygous dogs. Fu rthermore, in PET scans, cerebral atrophy and ventricular enlargement were clearly shown in homozygous dogs. Consequently at the age from 20 to 24 months, a clear differential dignosis between healthy (heterozy gous) and diseased (homozygous) dogs became possible even if the clini cal symptoms were still not clear in the latter. We conclude that the biochemical alterations in the brain in canine NCL occurs and progress es very rapidly in the last quarter of their lives.