In vivo evaluation of a CT-compatible retractor for image guided trans-oral surgery

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PROJECT SUMMARY Cancers of the head and neck (oral cavity, pharynx, and larynx) are the 5th most common cancers worldwide. Trans-oral surgical approaches such as trans-oral robotic surgery (TORS) and trans-oral laser microsurgery (TLM) are effective, reducing complications and long-term treatment morbidity. One of the drawbacks of the trans-oral approach is the difficulty in intraoperatively assessing tumor extent and locating critical vascular structures, resulting in positive margins and risks of vascular complications. Image guidance and surgical navigation play a significant role in sinus, skull base, and neurosurgery, demonstrating improvement in the safety and efficacy of these procedures. There may be advantages to applying this technology to trans-oral surgery (TOS) for improved assessment of tumor depth and avoidance of vascular structures. Image guidance is currently not feasible for trans-oral surgery. The main reason is the significant intraoperative tissue deformation that occurs with the introduction of retractors needed to provide surgical access. This intraoperative deformation limits the ability to accurately register preoperative imaging to the intra-operative state. With the availability of intra-operative CT and MRI imaging at Dartmouth’s unique Center for Surgical Innovation, intra-operative imaging is feasible. However, current metallic instrumentation required for exposure and airway management during trans-oral surgery creates significant artifact on CT imaging. As part of an on-going NIH-funded R21 program (1R21CA246158-01A1), we have developed a novel 3D printed polymer retractor that enables us to acquire artifact free images of cadaver head during trans-oral surgery procedures and a surgical navigation framework to enable image-guided trans-oral robotic surgery. The work in this R21 is being performed on benchtop models and cadaver heads. Here in this R03, we are first proposing to prepare the retractor for in vivo deployment by evaluating the impact of sterilization on mechanical properties of the retractor and confirming system stability over the time-period of a typical TORS procedure. Secondly, we aim to deploy this retractor in a series of intraoperative trans-oral surgery procedures and compare the surgical working volume and function to that of standard metal retractor systems. The overarching goal of our efforts is to improve the safety and efficacy of trans-oral surgery and enable surgeons to perform surgery on more complex cases through the use of surgical navigation. Performing this in vivo evaluation in parallel with our R21 efforts to develop an image-guidance framework will accelerate our transition to in vivo evaluation of image-guided TORS. By the end of this program we expect to be prepared to evaluate a fully integrated surgical guidance system for use in trans-oral robotic surgery. Follow on in vivo human studies will be proposed to evaluate the efficacy of this framework in a clinical population of patients undergoing TORS.