Fine tuning VBM for mouse brain analysis: model adjustment using atrophy simulation

D. BRAGGIO; J. BARBEITO; P. GONZALEZ; I. LARRABIDE

Simposio; 14th International Symposium on Medical Information Processing and Analysis; 2019

Voxel-based morphometry (VBM) is a technique used to detect and localize morphological differences in brain anatomy. Its design includes the adjustment of several parameters that influence final results, including the spatial normalization method used during preprocessing. VBM is widely applied in human studies, yet its usage for experimental animal models is scarce in the literature. Moreover, there is no a quantitative analysis nor validation of the method?s results when applied to small animal brain images. In this work we evaluated results of different VBM workflows by simulating tissue changes on the mouse brain. Using an automatic method we simulated atrophies on specific areas of the mouse brain cortex and cerebellum and created two experimental groups. We applied different VBM configurations to detect tissue changes between control group and each experimental group and compare its results with the location and extension of the atrophies simulated. Finally, we varied the size of the experimental group by randomly selecting sets of 9, 8 and 7 individuals and applied optimized VBM between control group and each experimental subset. Our results empirically demonstrated that optimized VBM was the most effective method to detect differences between groups. Detection was accurate on the brain cortex, while on the cerebellum the accuracy was reduced being the extension of findings smaller than expected and variable along different experimental group conformations. Our results suggested that a wider smoothing kernel is needed in this brain region, in order to minimize misalignments between individuals and obtain more consistent findings.