Statistical Shape Model of Costal Cartilage in the Human Body: Using Skeletonization, PCA and Regression to explore population variability

Sammanfattning

Human Body Models are digital representations of the human anatomy used forcrash test injury prediction. They provide an alternative to physical crash testdummies by providing more exact injury predictions while being cheaper to employ.Vehicle crashes are the most common cause of blunt thoracic injuries. The costalcartilage connects the ribs to the sternum and injuries to the costal cartilage isbelieved to cause ribcage instability, pain and prolonged disability. The geometry ofthe costal cartilage is sparsely studied. Not only does the shape and size of the costalcartilage vary, the topology differs between individuals. In this thesis, the topologyof the costal cartilage is studied using Skeletoinzation and graph search algorithms.Using the most common topology, a template mesh is cast to the subject geometriesusing Coherent Point Drift and Iterative Closest Point. The populational variance isstudied using Principal Component Analysis, resulting in a Statistical Shape Modelof the costal cartilage. Finally, Linear Regression is used to correlate the variationsto the demographic variables Age, Sex, Height and BMI. The resulting regressionmodel obtains an R2 of 0.23, which is similar to the values obtained when studyingequally complex geometries. The results indicate that the vertical spacing betweencartilages increase with height, and that the width of the costal cartilage increaseswith BMI.