Image-guided surgery has recently been described in the literature as a useful technology for improved functional endoscopic sinus surgery localization. Image-guided surgery yields accurate knowledge of the surgical field boundaries, allowing safer and more thorough sinus surgery. We have previously reviewed our initial experience with The InstaTrak System. This article presents a multicenter clinical study (n=55) that assesses the system's capability for localizing structures in critical surgical sites. The purpose of this paper is to present quantitative data on accuracy and performance. We describe several new advances including an automated registration technique that eliminates the redundant computed tomography scan, compensation for head movement, and the ability to use interchangeable instruments.

A 53 year-old male gynecologist presented with human papillomavirus (HPV) 16 positive tonsillar squamous cell carcinoma. He had no identifiable risk factors with the exception of long term occupational exposure to laser plumes, having performed laser ablations and loop electrosurgical excision procedures (LEEP) on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice. The second patient is a 62 year old male gynecologist with a 30 year history of laser ablation and LEEP who subsequently developed HPV 16 positive base of tongue cancer. He also had very few other risk factors for oropharyngeal cancer or HPV infection. HPV is a probable causative agent for oropharyngeal squamous cell carcinoma and has been reported as being transmittable through laser plume. This paper suggests that HPV transmitted through laser plume can result in subsequent squamous cell carcinoma.

The patient populations in groups A and B were determined to have similar demographic profiles. Significantly more sinuses, specifically in the frontal location, were entered in group B compared with group A. Adjusted for the number of sinuses treated, the median operative times did not differ significantly between groups. Major and minor complication rates were similar in both groups and were consistent with the published literature. In a community hospital setting, once an electromagnetic guidance system became available, it was used in 92% of the cases performed by sev-eral otolaryngologists.

The patient populations in groups A and B were determined to have similar demographic profiles. Significantly more sinuses, specifically in the frontal location, were entered in group B compared with group A. Adjusted for the number of sinuses treated, the median operative times did not differ significantly between groups. Major and minor complication rates were similar in both groups and were consistent with the published literature. In a community hospital setting, once an electromagnetic guidance system became available, it was used in 92% of the cases performed by sev-eral otolaryngologists.