Regional brain perfusion in 10 normal dogs measured using technetium-99m ethyl cysteinate dimer SPECT

Single photon emission computed tomography (SPECT) of the brain using perfu sion tracers allows estimation of regional brain perfusion. This allows in vivo examination of brain function in the setting or neuropsychologic and p athophysiologic changes. However functional imaging data on brain perfusion in dogs are limited. Hence, the aim of this study was to determine the sci ntigraphic regional perfusion pattern of the normal canine brain. Ten healt hy shepherd type dogs were injected with 925 MBq Technetium-99m ethyl cyste inate (ECD) 20 minutes before the examination. Acquisition was performed us ing a triple head gamma camera equipped with fanbeam collimators. Uniform a ttenuation correction and triple energy window correction were applied. Com puted tomographic images were obtained from the same dogs, reoriented along the orbito-meatal axis and SPECT perfusion data were coregistered to the C T-volume data. Based on morphological and suggested brain divisions, region s-of-interest (ROIs) were defined for the bilateral frontocerebral, temporo cerebral, parietocerebral, occipitocerebral, cerebellar, thalamic, and stri atal area. Regional count density was normalized on total counts. All dogs had the highest uptake in the thalamic/striatal area compared to a rather h omogeneous cerebral uptake. No significant left/right count differences wer e found, but a rostro-caudal gradient (+12-13%) was present. In this group, age and gender did not influence the perfusion pattern.