Baboon basal ganglia stereotaxy using internal MRI landmarks : Validation and application to PET imaging

We report the residual anatomic error after a nine parameter visually guided registration of MR images with a baboon brain atlas to validate a stereotactic method for use in PET studies. MPRAGE images of brain in six baboons and one nemestrina monkey were placed in atlas space using internal landmarks and proportional measurements. An expert noted the location of 23 subcortical test points in the transformed images and in the atlas. The average absolute error at the test points was 1.62 mm. At the extremes of the brain surface, there was more variability. PET images could be combined across animals in a common atlas space. There is minimal subcortical error attributable to anatomic variability after this method of transforming MR images of baboon to stereotactic space. This method provides a useful tool for intrasubject PET baboon studies as well as "bootstrapping" for more refined methods.