Regional Brain Perfusion in 12 Cats Measured with Technetium-99m-Ethyl Cysteinate Dimer Pinhole SPECT
T. Waelbers1; K. Peremans1; S. Vermeire1; A. Dobbeleir1; V.O. Boer2; H. de Leeuw2; M.A.D. Vente2; K. Piron1; M. Hesta1; I. Polis1
Introduction
With the use of Technetium-99m-Ethyl Cysteinate Dimer (99mTc-ECD), in vivo examination of the regional cerebral blood flow (rCBF), a measure for the regional brain activity, is possible using single photon emission computed tomography (SPECT). In dogs and humans rCBF changes have already been reported in association with behavioral disorders and epilepsy. To compare perfusion data in a clinical setting or for future research use, reliable perfusion data of normal, healthy cats are required.
Aim
The aim of this study was to determine the feasibility of 99mTc-ECD SPECT and to look at the regional cerebral perfusion pattern of the normal feline brain.
Methods
Twelve cats were used in this study. The brain perfusion tracer (99mTc-ECD) was injected intravenously and the acquisition, using a triple head gamma camera equipped with three multi-pinhole collimators (PH-SPECT), was started under general anaesthesia, 40 minutes after tracer administration. Nineteen regions of interest (ROIs) were defined using 7T MRI images of the feline brain and a topographical atlas and the SPECT data were coregistered to the MRI data. Two reference regions (the total brain and the cerebellum) were used for semi-quantification purposes. Semi-quantification was performed by normalizing the regional counts to the counts of these two reference regions resulting in the calculation of perfusion indices (PIT and PIC).
Results
The highest tracer uptake was noticed in the subcortical structures and in the gyrus cinguli and the lowest in the frontal cortex and the cerebellum. Left-right asymmetry in the temporal cortex and a rostrocaudal gradient of 5% were observed.
Conclusion
This study shows that 99mTc-ECD SPECT can be used to study the regional perfusion of the feline brain. Semi-quantification can be performed with the total brain or the cerebellum as a reference region and, like in humans and dogs, the uptake of 99mTc-ECD varies significantly between the different brain regions. This study provides a dataset of the rCBF in the adult, healthy cat, which can be used as a reference for future rCBF studies in cats.