Landmark-based 2D/3D registration of preoperative planning data to intraoperative photographs for mapping of functional areas in awake brain surgery

Accurate alignment of preoperative planning data with intraoperative conditions is critical for effective surgical navigation. In neurosurgery, this alignment is complicated by brainshift, which occurs when the brain shifts within the skull after the dura mater is opened and cerebrospinal fluid (CSF) is drained. We propose a novel method for intraoperative alignment of MRI-based planning data with photographs taken during awake brain surgery, using a landmark-driven 2D/3D registration technique. Landmarks are interactively selected on both the intraoperative photographs and 3D renderings of the brain’s structure and vasculature, derived from T1- weighted MR images with and without contrast enhancement. Registration is performed by minimizing the average distance between corresponding landmark pairs in the two modalities. The precision of this method is evaluated by comparing the positions of physically placed markers on the brain surface through multiple photographs taken from different angles. The landmark projections are reproducible with an average standard deviation of 0.925mm.