Feasibility of near real-time image-guided sinus surgery using intraoperative fluoroscopic computed axial tomography

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

Image-Guided Surgery and Intraoperative Imaging in Rhinology: Clinical Update and Current State of the Art

INTRODUCTION

Image-guided surgery (IGS) has gained widespread acceptance in otorhinolaryngology for its applications in sinus and skull base surgery. Although the core concepts of IGS have not changed, advances in image guidance technology, including the incorporation of intraoperative imaging, have the potential to enhance surgical education, allow for more rigorous preoperative planning, and aid in more complete surgery with improved outcomes.

OBJECTIVES

Provide a clinical update regarding the use of image guidance and intraoperative imaging in the field of rhinology and endoscopic skull base surgery with a focus on current state of the art technologies.

METHODS

English-language studies published in PubMed, Cochrane, and Embase were searched for articles relating to image-guided sinus surgery, skull base surgery, and intraoperative imaging. Relevant studies were reviewed and critical appraisals were included in this clinical update, highlighting current state of the art advances.

CONCLUSIONS

As image guidance and intraoperative imaging systems have advanced, their applications in sinus and skull base surgery have expanded. Both technologies offer invaluable real-time feedback on the status and progress of surgery, and thus may help to improve the completeness of surgery and overall outcomes. Recent advances such as augmented and virtual reality offer a window into the future of IGS. Future advancements should aim to enhance the surgeon's operative experience by improving user satisfaction and ultimately lead to better surgical results.

Next-Generation Surgical Navigation Systems in Sinus and Skull Base Surgery

Over the past 25 years, rhinologists have adopted surgical navigation technology for endoscopic sinus and skull base procedures. Navigation systems often produce a wide target registration error (TRE). Ideally, next-generation systems will include a leap in target registration error reduce TRE through innovative hardware and software. Incorporation of microsensors will be another important innovation. Future systems are likely to include augmented reality, which can project overlays of critical anatomy on real-world endoscopic images. Recent trends in surgical navigation suggest a phase of rapid evolution.

Intraoperative 3D fluoroscopy in stereotactic surgery

BACKGROUND

Intraoperative localisation of a stereotactic probe remains challenging. Stereotactic X-ray, the "gold standard", as well as intraoperative magnetic resonance (MRI) and computed tomography (CT), require a dedicated operating room (OR). Fluoroscopy with crosshairs confirms only grossly the target position. An alternative would be a mobile three-dimensional (3D) fluoroscopy C-arm. To our knowledge, this is the first report on 3D C-arm fluoroscopy to verify stereotactical trajectories. The objective was to assess the feasibility of using a 3D C-arm to verify the intraoperative trajectory and target.

METHODS

A total of 12 stereotactic trajectories in 10 patients were analysed, comprising 8 biopsies and 4 electrode trajectories. The fluoroscopic scan was performed after implantation of the deep brain stimulation electrode or after advancing the biopsy needle to the tumour. An image set is acquired during a rotation of the 3D C-arm. The image set is reconstructed and merged to the preoperative CT scan. Calculating the vector error and the deviation assesses target and trajectory accuracy.

RESULTS

The mean trajectory deviation was 0.6 mm (±0.54 mm) and the mean vector error was 1.44 mm (±1.43 mm). There was no influence on the surgical time and the mean irradiation dosage was 401.9 cGycm(2).

CONCLUSIONS

This target and trajectory verification is feasible. Its accuracy seems comparable with MRI and CT. There is no additional time consumption. Irradiation is comparable with stereotactic X-ray.

Level of complete dissection of the ethmoid sinuses with a computed tomographic image guidance system

OBJECTIVES

We sought to determine the adequacy of endoscopic total ethmoidectomy with the use of a computed tomographic (CT) image guidance system.

METHODS

Endoscopic ethmoid sinus dissections were performed on cadavers by otolaryngologists. All cadavers were scanned before dissection. On each side of the cadaver, the ethmoid sinuses were examined independently. A complete endoscopic ethmoidectomy was performed with a CT image guidance system. After the endoscopic ethmoidectomy, the cadaver underwent a postdissection CT scan. The postdissection CT images were then evaluated for the level of complete dissection of the anterior and posterior ethmoid sinuses.

RESULTS

There were 18 ethmoid sinuses in the study. One specimen underwent a complete total ethmoidectomy with no residual cells. There were 4 complete anterior ethmoidectomies and 5 complete posterior ethmoidectomies. Overall, the average numbers of residual anterior ethmoid and posterior ethmoid air cells were 1.39 and 1.22, respectively. This difference was not statistically significant. The skull base was dissected more completely than the lamina papyracea, with a significant difference (p = 0.03). There was no difference in terms of residual cells between the left and right ethmoid sinuses (p > 0.05).

CONCLUSIONS

Even with the use of a CT image guidance system, a complete ethmoidectomy was still difficult to achieve. Residual ethmoid sinus cells were more commonly found along the lamina papyracea than along the skull base.

Intraoperative imaging for otorhinolaryngology-head and neck surgery

The applications of endoscopic techniques have expanded beyond the treatment of inflammatory sinus disease and toward the resection of anterior and middle skull base lesions. Image-guided surgery has emerged as an important tool that compensates for the limitations of surgical endoscopy. The disadvantage of image-guided surgery, however, is its dependence on preoperative imaging data. Intraoperative imaging provides near real-time imaging that has the potential to improve surgical outcomes and reduce operative morbidity. The role of intraoperative imaging in endoscopic sinus and skull base surgery has demonstrated great promise in recent literature. It has had an impact on surgical decision-making during functional endoscopic sinus surgery and the resection of anterior skull base neoplasia. Advances in portable MRI and volumetric CT technology have enhanced the efficiency and safety of intraoperative imaging. Although further studies are required to quantify the precise utility of this new technology, it appears that intraoperative imaging will be an important tool for rhinologic surgery.

Percutaneous laser discectomy guided with stereotactic computer-assisted surgical navigation

BACKGROUND AND OBJECTIVE

Percutaneous laser discectomy at various wavelengths has been used for minimally invasive surgery of herniated intervertebral discs. Using a high-intensity diode laser at 980-nm wavelength, we aimed to improve the safe insertion of the laser trocar with the aid of a stereotactic computer-assisted surgical navigation system.

STUDY DESIGN/MATERIALS AND METHODS

The experiments were performed on ex vivo porcine spines with intact soft tissue. Before laser irradiation, each specimen was imaged by computed tomography (CT) with fiduciary markers. The Digital Imaging and Communications in Medicine (DICOM standard) data sets were retrieved into the GE Healthcare Surgery InstaTRAK3500 Plus computer-assisted surgical navigation platform via the hospital Ethernet using a picture archiving and communication system. A special trocar with quartz waveguide connected to the navigation system was inserted into a total of 12 lumbar discs of two fresh intact porcine specimens. Various laser energies (200-700 J) with different exposure times were delivered. Pre- and post-irradiation magnetic resonance (MR) imaging and postoperative macroscopic and histologic studies were carried out.

RESULTS

A navigation system accuracy of better than 2 mm was achieved. Tracking of the instrument from pre-acquired formatted CT reconstructed images reduced overall radiation exposure by limiting the need for continuous intraoperative C-arm fluoroscopy. The use of surgical navigation by CT images enhanced the precision insertion of the laser trocar. Irradiation with the 980-nm wavelength diode laser resulted in tissue evaporation changes of the intervertebral disc material as demonstrated by comparing pre- and post-irradiation changes of MR images and macro- and microscopic changes of the dissected disc material.

CONCLUSION

This preclinical study demonstrates the clinical utility of a 980-nm diode laser delivered through a fiber-optic waveguide trocar in which precise insertion was enabled by the use of surgical navigation. This in turn decreases the exposure to ionizing radiation during the procedure.

Combined image guidance and intraoperative computed tomography in facilitating endoscopic orientation within and around the paranasal sinuses

BACKGROUND

The utility of image guidance (image-guided surgery [IGS]) and intraoperative computed tomography (CT) scanning as a tool for less experienced endoscopic surgeons to aid in localization of paranasal sinus and skull base anatomic structures was evaluated.

METHODS

Partial endoscopic dissection was performed on cadaver specimens by three fellowship trained rhinologists. Anatomic sites within and around the sinuses were tagged with radio-opaque markers. Otolaryngology residents identified tagged anatomic sites using four successive levels of technology: endoscopy alone (simulating outpatient clinic), endoscopy plus preoperative CT (simulating endoscopic sinus surgery [ESS] without IGS), endoscopy plus IGS registered to preoperative CT (simulating current ESS with IGS), and endoscopy plus IGS registered to real-time intraoperative CT. Responses were graded as follows: consensus rhinologist answer (4 points), close answer without clinically significant difference (3 points), within anatomic region but definite clinical difference (2 points), outside of anatomic region (1 point), no answer (0 points).

RESULTS

Eleven residents participated. Of 20 specific anatomic sites, IGS-intraoperative CT provided the most accurate anatomic identification at 16 sites. For 8 sites, IGS-intraoperative CT had a significantly higher score than endoscopy alone (p < 0.05; eta2 = 0.29-0.67). For 6 sites, IGS-preoperative CT scan had a significantly higher score than endoscopy alone (p < 0.05; eta2 = 0.30-0.67). All participants found that IGS-intraoperative CT scan made them most comfortable in identifying anatomy.

CONCLUSION

Combined IGS and intraoperative CT scan technology may be an instructional adjunct for less experienced paranasal sinus surgeons for dissection and evaluation of unfamiliar or distorted anatomy.

Clinical Utility of Intraoperative Volume Computed Tomography Scanner for Endoscopic Sinonasal and Skull Base Procedures

Background

Intraoperative surgical navigation has become widely accepted as an important tool for improvement of surgical outcomes and reduction of complication in endoscopic sinus surgery (ESS). The purpose of this study was to assess the clinical utility of intraoperative volume computed tomography (CT) scanning in endoscopic sinonasal and skull base procedures.

Methods

Retrospective review of patients who underwent intraoperative volume CT imaging (xCAT; XoranTechnologies, Ann Arbor, MI) during endoscopic sinonasal and skull base surgery during a 3-month period was performed. Intraoperative, computer-enabled triplanar review of reformatted 0.4-mm images was performed in all cases.

Results

Intraoperative volume CT scanning was completed in 25 patients. Surgical procedures included revision/primary ESS for chronic rhinosinusitis (CRS) with or without polyposis (12 cases) and mucoceles (6 cases) as well as endoscopic neoplasm resection (5 cases), endoscopic fibro-osseous lesion resection (1 case), and endoscopic meningoencephalocele repair (1 case). The indications for intraoperative CT scanning included assessment of surgical dissection (23 cases), extent of tumor resection (6 cases), and frontal stent placement (6 cases). Based on the intraoperative volume CT information, additional interventions, including additional tumor resection (2 cases), dissection of ethmoid partitions (2 cases), frontal bone drilling during Draf IIB (1 case), and repositioning of a frontal stent (1 case) were performed in 6 (24%) cases.

Conclusion

Intraoperative volume CT scanning was successfully performed in 25 patients undergoing ESS. Because additional surgical intervention was performed in 24% of cases, this technology may have an important role in endoscopic sinonasal and skull base procedures.

Safety in endoscopic sinus surgery

PURPOSE OF REVIEW

Endoscopic sinus surgery techniques and technologies have undergone rapid development over the past two decades. Recently, image guided systems have been implemented in endoscopic sinus surgery, carrying the promise of increased safety during surgery. This review compiles available data regarding the incidence of complications in endoscopic sinus surgery, the trends over time, and the impact of image guided surgery on complication rates.

RECENT FINDINGS

Reporting of complications in endoscopic sinus surgery is widely variable, confounding attempts to establish accurate data regarding complication rates. Few prospective, randomized trials exist comparing the safety of functional endoscopic sinus surgery with other surgical techniques. Major complications occur in 0-1.5% of cases and minor complications occur in 1.1-20.8% of functional endoscopic sinus surgery cases. Powered instrumentation does not appear to affect the incidence of complications, but may increase the severity of complications. It is unclear whether image guided surgery results in lower complication rates. Practical and ethical considerations make randomized trials to evaluate this issue problematic.

SUMMARY

In order to maximize safety, functional endoscopic sinus surgery surgeons must individually and collectively audit current practice, report complications in a systematic way, utilize available technology appropriately to support safe surgery, and diligently refine surgical technique as well as the systems supporting endoscopic surgical practice.

The use of portable intraoperative computed tomography scanning for real-time image guidance: a pilot cadaver study

BACKGROUND

This study was performed to assess the feasibility of using intraoperative computed tomography (CT) to provide real-time updates to image guidance systems (IGSs) during surgery.

METHODS

The xCAT ENT portable intraoperative CT scanner (Xoran Technologies, Ann Arbor, MI) was used to acquire scans before, midway, and at the end of six cadaver dissections during the Southern States Rhinology Course, Augusta, GA, in October 2006. These scans were used to recalibrate three different IGSs used during the dissection. Time measurements were recorded and dosimetry was obtained from the cornea, sphenoid sinus (near the optic chiasm), and from the operative field during acquisition of the images. IGS accuracy was determined at the skull base and lamina papyracea. Surgeons were interviewed on benefits of real-time updates to the IGS after completion of dissections.

RESULTS

The xCAT ENT scanner was compatible with all three IGS platforms. The average time to update the IGS was 13 minutes. Radiation doses to the cornea were 620 mrad per scan, and optic chiasm was 800 mrad/scan. The accuracy at the anterior skull base improved from 1.58 to 0.62 mm (p=0.026). The accuracy at the posterior skull base improved from 1.46 to 0.71 mm (p=0.014). The accuracy at the lamina was not significantly changed.

CONCLUSION

Intraoperative portable CT scanning with real-time IGS updates is feasible and likely would add little additional time. Accuracy is improved at the skull base. Prospective studies on actual patients are warranted.

[Computer-aided surgery of the paranasal sinuses and the anterior skull base]

Endoscopic or microscopic surgery for chronic rhinosinusitis with or without nasal polyps is a routine intervention in daily practice. It is often a delicate and difficult minimally invasive intervention in a narrow space, with a tunnel view of 4 mm in the case of endoscopy and frequent bleeding in chronically inflamed tissue. Therefore, orientation in such a "labyrinth" is often difficult. In the case of polyp recurrence or tumors, the normal anatomical landmarks are often missing, which renders orientation even more difficult. In such cases, computer-aided navigation together with images such as those from computed tomography or magnetic resonance imaging can support the surgeon to make the operation more accurate and, in some cases, faster. Computer-aided surgery also has great potential for education.