Image-Guidance for Endoscopic Sinus Surgery

Development of a Machine Learning-Enabled Virtual Reality Tool for Preoperative Planning of Functional Endoscopic Sinus Surgery

Objectives  Virtual reality (VR) is an increasingly valuable teaching tool, but current simulators are not typically clinically scalable due to their reliance on inefficient manual segmentation. The objective of this project was to leverage a high-throughput and accurate machine learning method to automate data preparation for a patient-specific VR simulator used to explore preoperative sinus anatomy. Methods  An endoscopic VR simulator was designed in Unity to enable interactive exploration of sinus anatomy. The Saak transform, a data-efficient machine learning method, was adapted to accurately segment sinus computed tomography (CT) scans using minimal training data, and the resulting data were reconstructed into three-dimensional (3D) patient-specific models that could be explored in the simulator. Results  Using minimal training data, the Saak transform-based machine learning method offers accurate soft-tissue segmentation. When explored with an endoscope in the VR simulator, the anatomical models generated by the algorithm accurately capture key sinus structures and showcase patient-specific variability in anatomy. Conclusion  By offering an automatic means of preparing VR models from a patient's raw CT scans, this pipeline takes a key step toward clinical scalability. In addition to preoperative planning, this system also enables virtual endoscopy-a tool that is particularly useful in the COVID-19 era. As VR technology inevitably continues to develop, such a foundation will help ensure that future innovations remain clinically accessible.

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.

Role of Image Guided Navigation in Endoscopic Surgery of Paranasal Sinuses: A Comparative Study

The aim of the current study is to share our experience with surgical outcomes of Functional Endoscopic Sinus Surgery using an image-guidance system. The study was a randomised control trial with the comparison between two groups. Image guidance system (Electromagnetic) was used for endoscopic surgery on patients with disease of the paranasal sinuses (n = 30). Results were compared with those in control patients who underwent similar surgery without image guidance during the same period (n = 30). The operating room time (image-guidance group, 165.68 ± 6.55 min [mean ± SE]; control group, 163.33 ± 5.43 min), Intraoperative anatomical localization was accurate to within 2 mm. Intraoperative blood loss (image-guidance group, 566.67 ± 62.23 ml [mean ± SE]; control group, 636.33 ± 72.59 mL) and complication rates (image-guidance group, 3.3%; control group, 3.3%) did not differ significantly between groups. We find image guidance system a useful tool with accuracy of 2 mm. Actual intraoperative time, blood loss and complications do not differ significantly with or without the use of IGS.

The use and cost-effectiveness of intraoperative navigation in pediatric sinus surgery

OBJECTIVES/HYPOTHESIS

There are consensus statements about when to use intraoperative navigation (IN) in adult sinus surgery. However, no corresponding guidelines exist for pediatrics. Our objectives included: 1) assess the demographic and operative factors associated with IN use and 2) calculate the cost-effectiveness of IN use.

STUDY DESIGN

Retrospective chart review.

METHODS

One hundred nineteen pediatric patients undergoing sinus surgery between 2003 and 2016 were reviewed. Demographic and surgical factors were collected from medical records. Costs associated with use of IN were gathered from billing records.

RESULTS

Of the 119 patients, 60 underwent sinus surgery with navigation (wIN) and 59 underwent surgery without navigation (sIN). Children in the wIN group had more complex surgeries with more sinuses opened (P = .008). Individual attending surgeon and presence of trainee were associated with increased use of IN (P < .001 for both). IN resulted in a median of 31.5 minutes longer surgical time (P < .001). IN had an incremental cost/effectiveness ratio (ICER) of $22,378 for each year without revision surgery for patients with acute disease. However, for patients with chronic disease, the probability of undergoing a second surgery was the same between wIN and sIN groups, and navigation was not cost-effective (ICER of -$3,583).

CONCLUSIONS

IN use did not decrease complications or rates of revision surgery. It was used primarily as an educational tool or to increase confidence in intraoperative identification of landmarks. However, the use of IN added surgical time and was not cost-effective. Further research must be completed to determine when IN is indicated in pediatric sinus surgery.

LEVEL OF EVIDENCE

4 Laryngoscope, 2019.

Accuracy of a Modern Intraoperative Navigation System for Temporal Bone Surgery in a Cadaveric Model

Objectives

To determine the accuracy of a modern navigation system in temporal bone surgery. While routine in other specialties, navigation has had limited use in the temporal bone due to issues of accuracy, perceived impracticality, and value.

Study Design

Prospective observational study.

Setting

Temporal bone laboratory.

Subjects and Methods

Eighteen cadaveric specimens were dissected after rigid fiducials were implanted and computed tomography scans were obtained. Target registration and target localization errors were then measured at various points.

Results

The mean overall target registration error was 0.48 ± 0.29 mm. The mean target localization error was 0.54 mm at the sinodural angle, 0.48 mm at the lateral semicircular canal, 0.55 mm at the round window, 0.39 mm at the oval window, and 0.52 mm at the second genu of the facial nerve.

Conclusion

A modern navigation system demonstrated submillimeter accuracy for all points of interest. Its use in clinical as well as training settings has yet to be fully elucidated.

Smartphone-Based Endoscope System for Advanced Point-of-Care Diagnostics: Feasibility Study

Background

Endoscopic technique is often applied for the diagnosis of diseases affecting internal organs and image-guidance of surgical procedures. Although the endoscope has become an indispensable tool in the clinic, its utility has been limited to medical offices or operating rooms because of the large size of its ancillary devices. In addition, the basic design and imaging capability of the system have remained relatively unchanged for decades.

Objective

The objective of this study was to develop a smartphone-based endoscope system capable of advanced endoscopic functionalities in a compact size and at an affordable cost and to demonstrate its feasibility of point-of-care through human subject imaging.

Methods

We developed and designed to set up a smartphone-based endoscope system, incorporating a portable light source, relay-lens, custom adapter, and homebuilt Android app. We attached three different types of existing rigid or flexible endoscopic probes to our system and captured the endoscopic images using the homebuilt app. Both smartphone-based endoscope system and commercialized clinical endoscope system were utilized to compare the imaging quality and performance. Connecting the head-mounted display (HMD) wirelessly, the smartphone-based endoscope system could superimpose an endoscopic image to real-world view.

Results

A total of 15 volunteers who were accepted into our study were captured using our smartphone-based endoscope system, as well as the commercialized clinical endoscope system. It was found that the imaging performance of our device had acceptable quality compared with that of the conventional endoscope system in the clinical setting. In addition, images captured from the HMD used in the smartphone-based endoscope system improved eye-hand coordination between the manipulating site and the smartphone screen, which in turn reduced spatial disorientation.

Conclusions

The performance of our endoscope system was evaluated against a commercial system in routine otolaryngology examinations. We also demonstrated and evaluated the feasibility of conducting endoscopic procedures through a custom HMD.

Juvenile psammomatoid ossifying fibroma in paranasal sinus and skull base

CONCLUSION

The endoscopic transnasal approach with IGS is a safe and effective technique, allowing completely resection of JPOF, with minimal morbidity and recurrence.

OBJECTIVES

JPOF is a benign but locally aggressive fibro-osseous lesion. This study presents a series of JPOF cases, involving anterior skull base and orbit, treated by endoscopic transnasal approach with image guidance system (IGS) to resect the mass completely.

METHOD

This study retrospectively reviewed the clinical presentations, surgical procedures, and complications of 11 patients with JPOF who were treated by endoscopic approach from May 2009 to April 2014. All patients were followed by endoscopic and CT scan evaluations during follow-up.

RESULTS

All of the 11 cases were boys, with a mean age of 11.8 years (range = 6-17 years). The size of mass in the paranasal sinus ranged from 2.5-4.6 cm in greatest dimension (mean = 3.7 cm), and the medial orbital wall and cranial base were involved in all patients. All 11 patients received successful operation and were relieved from symptoms without mortality and major complications. During follow-up (range from 17-67 months; mean follow-up = 25.8 months), only one patient was recurrent in local position. The skull base partial resected during surgery was found to rebuild after 1 year.

Current Trends in Sinonasal Imaging

As endoscopic sinus surgery (ESS) has evolved since its introduction to the United States, so has technology for imaging the sinonasal cavities. Although imaging is most frequently performed for evaluating chronic sinusitis refractory to medical therapy, its uses have expanded beyond inflammatory sinus disease. Multidetector Computed Tomography is the current workhorse for both diagnosis and preoperative planning in prospective ESS patients, while MR imaging remains a complementary tool for evaluating suspected tumors or intracranial and orbital complications of rhinosinusitis. In this article, the authors review current trends and potential future directions in the use of these modalities for sinus imaging.

Stereotactic anatomical localization in complex sinus surgery: A systematic review and meta-analysis

OBJECTIVE

It is recognized that stereotactic anatomical localization (SAL) is a useful tool in endoscopic sinus surgery (ESS), but it may be most beneficial for complex rather than routine sinus procedures. This review sought to determine the safety and efficacy of SAL in complex indications for ESS.

DATA SOURCES

PubMed, EMBASE, Centre for Reviews and Dissemination, and the Cochrane Library were searched from inception up to April 4, 2014.

REVIEW METHODS

English studies comparing ESS with and without SAL in complex cases were included. Complex surgery included revision surgery, inverted papilloma, extensive sinus disease, or biopsy of tumors that are not exophytic. Safety outcomes included total, major, minor, orbital, dural, and major hemorrhage complications. Efficacy outcomes included operation completion, revision surgery, and patient-reported outcomes. Meta-analysis generated fixed-effects Mantel-Haenszel odds ratios (OR) and confidence intervals (CI).

RESULTS

A total of 2,381 studies were identified, of which nine met the inclusion criteria. Meta-analyses indicated a reduction in the likelihood of total (OR = 0.58; 95% CI, 0.37-0.92), major (OR = 0.36; 95% CI, 0.18-0.75), and orbital complications (OR = 0.38; 95% CI, 0.17-0.83). There was no demonstrated benefit of SAL at reducing revision surgery (OR = 0.64; 95% CI, 0.38-1.08), major hemorrhage (OR = 0.77; 95% CI, 0.29-2.06), or minor complications (OR = 0.85; 95% CI, 0.48-1.50).

CONCLUSION

Due to the rare outcomes under investigation, the included primary studies largely lacked the power to identify a statistically meaningful effect of SAL in ESS. However, meta-analyses of primary studies demonstrated a decreased likelihood of total, major, and orbital complications in complex ESS with the use of SAL.

Image-guided sphenoidotomy in revision functional endoscopic sinus surgery

The application of image-guided systems to sinus surgery is gaining in popularity. This study tried to evaluate the efficacy of image-guided surgery (IGS) in the fenestration of the sphenoid sinus in patients with chronic rhinosinusitis (CRS) who received revision functional endoscopic sinus surgery (FESS). A total of 51 CRS patients who received revision FESS incorporating IGS between January 2010 and August 2011 by two surgeons were enrolled in this study. A group of 30 CRS patients who underwent revision FESS by the senior surgeon without incorporating IGS was chosen for comparison. The penetration rates for the sphenoid sinus were 91.2% when performed by the senior surgeon with IGS and 91.3% when done by the other surgeon with IGS. The penetration rate for the sphenoid sinus was 68.6% for revision FESS without IGS. The fenestration rate for the sphenoid sinus in revision FESS without IGS was significantly lower than that in revision FESS with IGS (p = .004). Our results showed that IGS was a beneficial procedure for opening the sphenoid sinus in the revision cases.

[Intraoperative navigation system in endoscopic sinus surgery]

Intraoperative navigation systems have been developed to increase the safety and efficiency of endoscopic sinus surgery. The objective of this study was to compare the application and utilization of optical and electromagnetical navigation systems in our own experience during the endoscopic surgery.

MATERIAL AND METHODS

An optical-based image guidance systems (MatrixPolar Navigation System, Xion, Germany; Karl Storz Surgical Cockpit Navigation Panel Unit, Karl Storz, Germany; Stryker Navigation CartII ENT, Stryker, USA) and electromagnetic (Fusion ENT Navigation System, Medtronic, USA; Fiagon, fiagon GmbH, Germany) was used to performed 40 sinonasal and skull base surgeries. We compared the precision and accuracy of both types of systems and additional time necessary for setting up the system and real operating room time. We also analysed the convenience of navigation according to possibilities of easy instruments manipulation and fluency of navigation process.

RESULTS

The mean measured accurancy of anatomical localization at start of the surgery for optical systems was 1.62 ± 0.4mm and for electromagnetic respectively 1.79 ± 0.39 mm. The time to set up the optical system was longer than for electromagnetic one (12 vs 5 minutes). Operating room time was increased for both systems, for optical to 22 vs 8 minutes for electromagnetic one. Surgeon's working comfort during operation was better for electromagnetic systems and allowed for fluently movements with instruments.

CONCLUSIONS

Intraoperative navigation systems assist the surgeon with anatomical localization during endoscopic sinus surgery and improve its safety and efficacy. The choice of optical or electromagnetic system should be compared of effective costs and surgeon's preferences.

Anatomical variations of the sphenoid sinus and its adjacent structures: a review of existing literature

The sphenoid sinus, one of the posterior groups of sinuses, has long been regarded as a 'neglected sinus' due to the anatomical location, poor understanding and poor accessibility, till the advent of endoscopes and modern imaging techniques. Increasing knowledge and greater understanding of this sinus has permitted an evolution in surgical practices and boundaries. Various literatures of the past report a great variety of rates of pneumatization, rates of optic nerve protrusion and dehiscence, as well as internal carotid artery (ICA) protrusion and dehiscence. One similarity noted among these studies is that the rates vary according to the ethnicity of the patients. Recommendations have also been made along the way with regard to modified surgical techniques. This review aims to describe the pneumatization of sphenoid sinus and the topographical relation of the optic nerve and ICA in different populations.

Evaluation of a system for high-accuracy 3D image-based registration of endoscopic video to C-arm cone-beam CT for image-guided skull base surgery

The safety of endoscopic skull base surgery can be enhanced by accurate navigation in preoperative computed tomography (CT) or, more recently, intraoperative cone-beam CT (CBCT). The ability to register real-time endoscopic video with CBCT offers an additional advantage by rendering information directly within the visual scene to account for intraoperative anatomical change. However, tracker localization error (  ∼ 1-2 mm ) limits the accuracy with which video and tomographic images can be registered. This paper reports the first implementation of image-based video-CBCT registration, conducts a detailed quantitation of the dependence of registration accuracy on system parameters, and demonstrates improvement in registration accuracy achieved by the image-based approach. Performance was evaluated as a function of parameters intrinsic to the image-based approach, including system geometry, CBCT image quality, and computational runtime. Overall system performance was evaluated in a cadaver study simulating transsphenoidal skull base tumor excision. Results demonstrated significant improvement in registration accuracy with a mean reprojection distance error of 1.28 mm for the image-based approach versus 1.82 mm for the conventional tracker-based method. Image-based registration was highly robust against CBCT image quality factors of noise and resolution, permitting integration with low-dose intraoperative CBCT.

Displaying 3D radiation dose on endoscopic video for therapeutic assessment and surgical guidance

We have developed a method to register and display 3D parametric data, in particular radiation dose, on two-dimensional endoscopic images. This registration of radiation dose to endoscopic or optical imaging may be valuable in assessment of normal tissue response to radiation, and visualization of radiated tissues in patients receiving post-radiation surgery. Electromagnetic sensors embedded in a flexible endoscope were used to track the position and orientation of the endoscope allowing registration of 2D endoscopic images to CT volumetric images and radiation doses planned with respect to these images. A surface was rendered from the CT image based on the air/tissue threshold, creating a virtual endoscopic view analogous to the real endoscopic view. Radiation dose at the surface or at known depth below the surface was assigned to each segment of the virtual surface. Dose could be displayed as either a colorwash on this surface or surface isodose lines. By assigning transparency levels to each surface segment based on dose or isoline location, the virtual dose display was overlaid onto the real endoscope image. Spatial accuracy of the dose display was tested using a cylindrical phantom with a treatment plan created for the phantom that matched dose levels with grid lines on the phantom surface. The accuracy of the dose display in these phantoms was 0.8-0.99 mm. To demonstrate clinical feasibility of this approach, the dose display was also tested on clinical data of a patient with laryngeal cancer treated with radiation therapy, with estimated display accuracy of ∼2-3 mm. The utility of the dose display for registration of radiation dose information to the surgical field was further demonstrated in a mock sarcoma case using a leg phantom. With direct overlay of radiation dose on endoscopic imaging, tissue toxicities and tumor response in endoluminal organs can be directly correlated with the actual tissue dose, offering a more nuanced assessment of normal tissue toxicities following radiation therapy and accurate registration of radiation dose to the surgical field.

Intraoperative C-arm cone-beam computed tomography: quantitative analysis of surgical performance in skull base surgery

OBJECTIVES/HYPOTHESIS

To determine whether incorporation of intraoperative imaging via a new cone-beam computed tomography (CBCT) image-guidance system improves accuracy and facilitates resection in sinus and skull-base surgery through quantification of surgical performance.

STUDY DESIGN

Landmark identification and skull base ablation tasks were performed with a CBCT intraoperative image-guidance system in the experimental group and with image-guided surgery (IGS) alone based on preoperative computed tomography (CT) in the control group.

METHODS

Six cadaveric heads underwent preoperative CT imaging and surgical planning identifying surgical targets. Three types of surgical tasks were planned: landmark point identification, line contour identification, and volume drill-out. Key anatomic structures (carotid artery and optic nerve) were chosen for landmark identification and line contour tasks. Complete ethmoidectomy, vidian corridor drill-out, and clival resection were performed for volume ablation tasks. The CBCT guidance system was used in the experimental group and performance was assessed by metrics of target registration error, sensitivity, and specificity of excision.

RESULTS

Significant improvements were seen for point identification and line tracing tasks. Additional resection was performed in 67% of tasks in the CBCT group, and qualitative feedback indicated unequivocal improvement in confidence for all tasks. In review of tasks in the control group, additional resection would have been performed in 35% of tasks if an intraoperative image was available.

CONCLUSIONS

An experimental prototype C-arm CBCT guidance system was shown to improve surgical precision in the identification of skull base targets and increase accuracy in the ablation of surgical target volumes in comparison to using IGS alone.

Improving superficial target delineation in radiation therapy with endoscopic tracking and registration

PURPOSE

Target delineation within volumetric imaging is a critical step in the planning process of intensity modulated radiation therapy. In endoluminal cancers, endoscopy often reveals superficial areas of visible disease beyond what is seen on volumetric imaging. Quantitatively relating these findings to the volumetric imaging is prone to human error during the recall and contouring of the target. We have developed a method to improve target delineation in the radiation therapy planning process by quantitatively registering endoscopic findings contours traced on endoscopic images to volumetric imaging.

METHODS

Using electromagnetic sensors embedded in an endoscope, 2D endoscopic images were registered to computed tomography (CT) volumetric images by tracking the position and orientation of the endoscope relative to a CT image set. Regions-of-interest (ROI) in the 2D endoscopic view were delineated. A mesh created within the boundary of the ROI was projected onto the 3D image data, registering the ROI with the volumetric image. This 3D ROI was exported to clinical radiation treatment planning software. The precision and accuracy of the procedure was tested on two solid phantoms with superficial markings visible on both endoscopy and CT images. The first phantom was T-shaped tube with X-marks etched on the interior. The second phantom was an anatomically correct skull phantom with a phantom superficial lesion placed on the pharyngeal surface. Markings were contoured on the endoscope images and compared with contours delineated in the treatment planning system based on the CT images. Clinical feasibility was tested on three patients with early stage glottic cancer. Image-based rendering using manually identified landmarks was used to improve the registration.

RESULTS

Using the T-shaped phantom with X-markings, the 2D to 3D registration accuracy was 1.5-3.5 mm, depending on the endoscope position relative to the markings. Intraobserver standard variation was 0.5 mm. Rotational accuracy was within 2°. Using the skull phantom, registration accuracy was assessed by calculating the average surface minimum distance between the endoscopy and treatment planning contours. The average surface distance was 0.92 mm with 93% of all points in the 2D-endoscopy ROI within 1.5 mm of any point within the ROI contoured in the treatment planning software. This accuracy is limited by the CT imaging resolution and the electromagnetic (EM) sensor accuracy. The clinical testing demonstrated that endoscopic contouring is feasible. With registration based on em tracking only, accuracy was 5.6-8.4 mm. Image-based registration reduced this error to less than 3.5 mm and enabled endoscopic contouring in all cases.

CONCLUSIONS

Registration of contours generated on 2D endoscopic images to 3D planning space is feasible, with accuracy smaller than typical set-up margins. Used in addition to standard 3D contouring methods in radiation planning, the technology may improve gross tumour volume (GTV) delineation for superficial tumors in luminal sites that are only visible in endoscopy.

Image guidance systems for minimally invasive sinus and skull base surgery in children

OBJECTIVE

The use of image guidance for sinonasal and skull base surgery has been well-characterized in adults but there is limited information on the use of these systems in the pediatric population, despite their widespread use. The aim of this study is to evaluate the use of image guidance systems to facilitate an endoscopic minimally invasive approach to sinonasal and skull base surgery in a pediatric population.

METHODS

A retrospective cohort study was performed at a tertiary pediatric hospital. Thirty-three children presented with complications of sinusitis, tumors, traumatic, or congenital lesions of the skull base and underwent endoscopic surgery using image guidance from March 2000 to April 2007. Patient variables including diagnosis, extent of disease, and complications were extracted from paper and computer charts. Additional surgical variables including set-up time, accuracy, surgeon satisfaction index and number of uses per case were also reviewed.

RESULTS

Twenty-eight patients (85%) underwent sinonasal surgery and five (15%) underwent skull base surgery. Indications included infectious complications of acute sinusitis (N=15), neoplasms (N=12), choanal atresia (N=4), and cerebrospinal fluid leak (N=2). Thirty-one patients (94%) required only one procedure. No surgical complications were reported. Surgeon satisfaction, mean accuracy and number of uses per procedure increased over time (p<0.05).

CONCLUSIONS

Image guidance systems are safe and effective tools that facilitate a minimally invasive approach to sinonasal and skull base surgery in children. Consistent with adult literature, usage and surgeon comfort increased with experience. The additional anatomical information obtained by image guidance systems facilitates a minimally invasive endoscopic approach for sinonasal and skull base pathologies.

Surgical management of benign sinonasal masses

A diverse group of pathologic findings requires surgical excision from the sinonasal tract. Symptoms directly related to pathologic findings, pending complications and the possibility or suspicion of malignancy, should be the cornerstones of surgical decision making. The management of benign sinonasal masses should follow a balanced algorithm to weigh the need for resection against the adverse effects of surgical removal. Endoscopic approaches have become the primary modality by which most benign masses of the nasal cavity and sinuses are managed. This article describes an aggressive surgical approach to these lesions while maintaining respect for their benign nature and the importance of preserving natural barriers to growth (spread), such as the dura and periorbita.

Novel compact laptop-based image-guidance system: preliminary study

OBJECTIVES

To describe a novel portable laptop-based image-guidance system and its preliminary navigational results.

METHODS

An optic-based, specially developed navigational system and a life-size endoscopic sinus anatomic model were used. The model was submitted to computer tomography (CT), and predefined anatomic landmarks were used to test the image-guidance accuracy according to the real model.

RESULTS

All anatomic landmarks were identified by the image-guidance system and all matched with endoscopic or eye views.

CONCLUSIONS

This novel compact navigation device was shown to be fast and reliable. A larger series, involving more models, cadavers, and patients, with the evaluation of multiple anatomic points needs to be done before we can reliably determine the overall accuracy of this novel device. However, this new system is promising, and in the future it can be part of the armamentarium of otolaryngologists' personal equipment in order to perform low-cost image-guided surgeries in different places with the same equipment.