Image2SSM: Localization-aware Deep Learning Framework for Statistical Shape Modeling Directly from Images

Statistical Shape Modelling (SSM) is an effective tool for quantitatively analyzing anatom- ical populations. SSM has benefitted largely from advances in deep learning where statis- tical representations of anatomies (e.g., point distribution models or PDMs) are inferred directly from images, alleviating the need for a time-consuming and expensive workflow of anatomy segmentation, shape registration, and model optimization. Nonetheless, to date, existing deep learning methods do not consider the rigid pose transformation of shapes or anatomy of interest. They also require a tight bounding box to be defined over the image of anatomy-of-interest before feeding the image to the deep network for network training and inference. In this paper, we propose a deep learning framework that simultaneously detects and segments the anatomy of interest, estimate the rigid transformation with respect to the population mean (average) using a spatial transformer, and estimates the corresponding statistical representation of that anatomy, all directly from unsegmented 3D image without the need for any additional supervision. Furthermore, we leverage the segmentation task to provide an attention model for the sub-network that estimates shape representation, giving more accurate shape statistics for shape analysis.