Group-level Regional Cerebral Uptake Quantification in Micro PET-CT

The lack of soft tissue CT contrast is an impediment to accurate quantification of regional cerebral uptake on micro PET-CT. Co-registration to an atlas can aid with quantitative analysis, particularly when MRI is not available. Methods: : A subject CT is cropped to the skull, the brain void is then filled to create a “skull cavity mask”. An MRI mouse brain volumetric template is then co-registered to the skull cavity mask via affine transformation. Each subsequent subject CT is then skull cropped and co-registered to the first, these transformations are then applied to each corresponding PET for group level co-registration . Results: : The method was tested on eight mice with each possible registration permutation; resulting in small variations in regional cerebral PET counts. Conclusion: We present a semi-automated method that allows for quantification of regional cerebral PET uptake from micro PET-CT images without subject MRI data.