Estimation of Independent Non-Linear Deformation Modes for Analysis of Craniofacial Malformations in Crouzon Mice

Crouzon syndrome is a genetic disease resulting in pre- mature fusion of cranial sutures and synchondroses caus- ing craniosynostosis. A decade ago the Crouzon gene was discovered, and recently the first mouse model of the syn- drome was generated. In this study, a set of Micro CT scannings of the heads of wild-type (normal) mice and Crouzon mice were investigated. We present for what we believe is the first time, a sta- tistical deformation model based on independent compo- nent analysis (ICA). A set of deformation parameters for each mouse was calculated using a B-spline-based non- rigid registration. From the parameters controlling the deformations for each subject, the statistical model was estimated. ICA is demonstrated to provide localized deforma- tion components, many of which give a clear separation between Crouzon and wild-type mice. This is a clear improvement of a previous principal component-based model, which only provided one global deformation com- ponent describing the disease. The ICA components al- low interpretation of each deformation feature to be car- ried out independently of other features, and provides a basis for linking the observed craniofacial malformations to the fusing of sutures. ICA revealed an interesting new finding, not previously reported in the literature, namely asymmetries in the head in Crouzon mice. This phenomenon is probably caused by asymmetric closure of craniofacial sutures.