Three-dimensional tomosynthesis and cone-beam computed tomography: an experimental study for fast, low-dose intraoperative imaging technology for guidance of sinus and skull base surgery.

OBJECTIVES: To describe three-dimension (3-D) tomosynthesis and cone beam computed tomography (CBCT) as an intraoperative imaging system to guide both sinus and skull-base surgery in a cadaveric model.
METHODS: Five cadaveric heads underwent baseline CBCT imaging. Surgical targets were resected from each head (uncinectomy, ethmoidectomy, medial maxillectomy, pituitary gland resection, and clivus ablation). Intraoperative imaging was provided so that for a given task, the acquisition arc (theta(tot) = 20 degrees , 45 degrees , 60 degrees , 90 degrees , 178 degrees ) of the tomosynthesis scan was fixed. Different heads and tasks were allocated different acquisition angles. There was no limit to the number of scans that could be requested. Residual target was highlighted with 3-D visualization software.
RESULTS: The larger the image acquisition angle, the better the image. Only CBCT (theta(tot) approximately 178 degrees ) provided nearly isotropic 3-D spatial resolution and soft-tissue visibility in all three views. The volume of residual tissue remaining and the volume of adjacent-normal tissue that was resected were calculated as a function of tomosynthesis angle. For the easier surgical tasks (uncinectomy, ethmoidectomy) the residual tissue was not related to the tomosynthesis angle. However, for the difficult ablative tasks, the image quality became more important and tomosynthesis angle was related to the residual tissue.
CONCLUSIONS: We describe an intraoperative imaging platform that can deliver near-real-time images of the target and related structures with low radiation dose. Tomosynthesis scanning angles higher than 60 degrees provided quantifiable benefits to the surgeon and facilitated total target ablation while helping to spare surrounding structures.