Feasibility of photoacoustic image guidance for telerobotic endonasal transsphenoidal surgery

Injury to the internal carotid arteries during the minimally invasive procedure to remove pituitary tumors (i.e., endonasal transsphenoidal surgery) could have many severe complications, including patient death. While preoperative CT or MR images are available to assist with navigation, the location of these arteries may be uncertain during surgery due to registration errors and intraoperative changes. Ideally, the surgeon should be able to visualize these arteries in real-time, even though they are behind the bone being drilled. We are therefore exploring the feasibility of a novel photoacoustic image-guided telerobotic system to measure the location of the artery with respect to the drill tip and to accurately visualize the spatial relationship between the artery and drill tip with respect to the imaging system components (i.e., the optical fiber attached to the drill and the ultrasound transducer). The potential system accuracy was evaluated in a two-stage approach that includes gross localization of the vessel center, followed by refinement with an image-based algorithm. This method was tested with a research-based da Vinci Surgical System, simulated photoacoustic data, and experimental data, revealing mean absolute errors of 1.89±0.93 mm and 0.3±0.2 mm for gross and fine positioning, respectively. Results are promising for surgeons to visualize the internal carotid arteries and thereby avoid injury with a teleoperative robotic approach.