Endoscopography : Deriving a 3 D Textured Surface from Endoscopic Video , Then Registration with CT

Endoscopy [1] enables high-resolution visualization of tissue texture and is a critical step in many clinical workflows, including diagnosis and treatment planning for cancers in the nasopharynx. However, an endoscopic video does not provide its information in 3D space, making it difficult to use in tumor localization, and it is inefficient to review. We present a new imaging approach that we call endoscopography. Endoscopography reconstructs a full 3D textured surface, which we call an endoscopogram, from an endoscopic video. This endoscopogram opens the door for novel 3D visualizations of patient anatomy derived solely from endoscopic data. It also allows information contained in the tissue texture in the endoscopogram to be transferred to 3D image such as CT through a surface-to-surface registration. In particular, through an interactive tool, the physician can draw directly on the endoscopogram surface to specify a tumor, which then can be automatically transferred to CT slices to aid tumor localization. We describe the sequence of methods we have designed to achieve this goal. Through evaluations on synthethic, phantom, and patient data, we demonstrate that our surface reconstruction method can obtain accurate results within millimeters of ground-truth, and our registration approach can handle tissue deformations and reconstruction inconsistencies across endoscopic video frames.