Electronic Thesis and Dissertation Repository


Master of Engineering Science


Electrical and Computer Engineering


Dr. R.Eagleson, Dr. S. DeRibaupierre


Craniosynostosis is a developmental abnormality in skull growth, due to the fusion of one or more sutures\cite{patho}. To accommodate the growing brain. the skull needs to grow quickly in the first few months of life, and most of the growth of the skull at that time occurs at the sutures. Craniosynostosis occurs when one or more sutures are fused in utero, resulting in an abnormal skull shape. Surgical intervention is usually required at a young age, and remodeling of the skull is done for cosmetic reasons as well as to avoid raised intracranial pressure. In order to study how the bone remodels after an operation, an accurate corregistration needs to be done. However, because of the rapid growth of the skull, in a non-symmetrical manner, a non-rigid registration is necessary; taking multiple point. The work done here looks at the best method to corregister images, the best fit mathematical model for a skull and the the overall skull shape transformations during development, on young rats CT data from a previous study was used. This project has four purposes. 1) segmenting the Rat skull to have a better view of the skull, with an analysis of the sutures and bones. 2) A 3D non-rigid affine registration based on landmarks identified overtime in each skull dataset was calculated. The registration accuracy is a function of the number of landmarks identified for tracking by a trained user. 3)Have a mathematical model using an ellipsoid to fit the points identified on the skull. This best-fit ellipsoid can then be tracked overtime to analyze the development of several rat skulls. We then compared the ellipsoid parameters to model the growth of the skull. The results show that the landmarks chosen for registration need to be chosen carefully, in a way that establishes a good ?Condition Number? for the transformation fitting stage. The proposed analysis can be used as a diagnostic tool for skull growth modeling and to quantify the proposed treatments. 3) The fitted model can also be used to estimate the growth rate in living rats. 4) Another purpose of this study is to measure craniometrics of the rats skull and compare it to the previous studies.