Image mapping of untracked free-hand endoscopic views to an ultrasound image-constructed 3D placenta model.

Background: This study presents a tracker-less image-mapping framework for surgical navigation motivated by the clinical need for intuitive visual guidance during minimally invasive fetoscopic surgery.

Methods: A navigation framework mapping 2D endoscopic vision to a 3D ultrasound image model is proposed. This maps an endoscopic image onto a 3D placenta model through a one-time ultrasound image-based localization method followed by a series of concurrent image alignments and texture mapping of the untracked endoscopic video stream.

Results: The mean absolute error of our ultrasound image-based localization method was (1.63 mm, 0.93°). The simulation analysis reveals an upper bound mapping performance with a mean error of 1.53 mm. In a phantom experiment, the overall mapping performance is close to this accuracy and achieves a mean absolute error of 2 mm, thereby supporting the feasibility of this method.

Conclusions: This novel integration of intraoperative visual guidance has potential contributions to innovative fusions of image guidance techniques for effective navigation in minimally invasive fetoscopic surgery.