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

Transsphenoidal Surgery for Pituitary Tumors

Transsphenoidal surgery for the treatment of pituitary masses in cats and dogs has become a more established treatment over the last 2 decades. Although expert centers and surgeons that provide this service remain limited, the patient population presented for pituitary surgery increases with wider availability of advanced imaging, together with more challenging cases. In this review, the current state of hypophysectomy is described with future challenges and opportunities.

Fluorescence imaging-guided surgery: current status and future directions

Surgery is one of the most important paradigms for tumor therapy, while fluorescence imaging (FI) offers real-time intraoperative guidance, greatly boosting treatment prognosis. The imaging fidelity heavily relies on not only imaging facilities but also probes for imaging-guided surgery (IGS). So far, a great number of IGS probes with emission in visible (400-700 nm) and near-infrared (NIR 700-1700 nm) windows have been developed for pinpointing disease margins intraoperatively. Herein, the state-of-the-art fluorescent probes for IGS are timely updated, with a special focus on the fluorescent probes under clinical examination. For a better demonstration of the superiority of NIR FI over visible FI, both imaging modalities are critically compared regarding signal-to-background ratio, penetration depth, resolution, tissue autofluorescence, photostability, and biocompatibility. Various types of fluorescence IGS have been summarized to demonstrate its importance in the medical field. Furthermore, the most recent progress of fluorescent probes in NIR-I and NIR-II windows is summarized. Finally, an outlook on multimodal imaging, FI beyond NIR-II, efficient tumor targeting, automated IGS, the use of AI and machine learning for designing fluorescent probes, and the fluorescence-guided da Vinci surgical system is given. We hope this review will stimulate interest among researchers in different areas and expedite the translation of fluorescent probes from bench to bedside.

Enhancing Surgical Vision: Augmented Reality in Otolaryngology-Head and Neck Surgery

Augmented reality (AR) technology has become widely established in otolaryngology-head and neck surgery. Over the past 20 years, numerous AR systems have been investigated and validated across the subspecialties, both in cadaveric and in live surgical studies. AR displays projected through head-mounted devices, microscopes, and endoscopes, most commonly, have demonstrated utility in preoperative planning, intraoperative guidance, and improvement of surgical decision-making. Specifically, they have demonstrated feasibility in guiding tumor margin resections, identifying critical structures intraoperatively, and displaying patient-specific virtual models derived from preoperative imaging, with millimetric accuracy. This review summarizes both established and emerging AR technologies, detailing how their systems work, what features they offer, and their clinical impact across otolaryngology subspecialties. As AR technology continues to advance, its integration holds promise for enhancing surgical precision, simulation training, and ultimately, improving patient outcomes.

Surgical Navigation in the Anterior Skull Base Using 3-Dimensional Endoscopy and Surface Reconstruction

Importance

Image guidance is an important adjunct for endoscopic sinus and skull base surgery. However, current systems require bulky external tracking equipment, and their use can interrupt efficient surgical workflow.

Objective

To evaluate a trackerless surgical navigation system using 3-dimensional (3D) endoscopy and simultaneous localization and mapping (SLAM) algorithms in the anterior skull base.

Design, Setting, and Participants

This interventional deceased donor cohort study and retrospective clinical case study was conducted at a tertiary academic medical center with human deceased donor specimens and a patient with anterior skull base pathology.

Exposures

Participants underwent endoscopic endonasal transsphenoidal dissection and surface model reconstruction from stereoscopic video with registration to volumetric models segmented from computed tomography (CT) and magnetic resonance imaging.

Main Outcomes and Measures

To assess the fidelity of surface model reconstruction and accuracy of surgical navigation and surface-CT model coregistration, 3 metrics were calculated: reconstruction error, registration error, and localization error.

Results

In deceased donor models (n = 9), high-fidelity surface models of the posterior wall of the sphenoid sinus were reconstructed from stereoscopic video and coregistered to corresponding volumetric CT models. The mean (SD; range) reconstruction, registration, and localization errors were 0.60 (0.24; 0.36-0.93), 1.11 (0.49; 0.71-1.56) and 1.01 (0.17; 0.78-1.25) mm, respectively. In a clinical case study of a patient who underwent a 3D endoscopic endonasal transsphenoidal resection of a tubercular meningioma, a high-fidelity surface model of the posterior wall of the sphenoid was reconstructed from intraoperative stereoscopic video and coregistered to a volumetric preoperative fused CT magnetic resonance imaging model with a root-mean-square error of 1.38 mm.

Conclusions and Relevance

The results of this study suggest that SLAM algorithm-based endoscopic endonasal surgery navigation is a novel, accurate, and trackerless approach to surgical navigation that uses 3D endoscopy and SLAM-based algorithms in lieu of conventional optical or electromagnetic tracking. While multiple challenges remain before clinical readiness, a SLAM algorithm-based endoscopic endonasal surgery navigation system has the potential to improve surgical efficiency, economy of motion, and safety.

Applications of Preoperative and Intraoperative Technologies for Complex Primary and Secondary Facial Trauma Reconstruction

This article provides a review of the current technologies available in the preoperative and intraoperative management of complex and secondary maxillofacial trauma reconstruction. These patients present a unique challenge for which the advancement of imaging technologies, patient-specific modeling and implants, and intraoperative imaging and navigation can play an important role to improve their post-treatment outcomes.

A Self-Configuring Deep Learning Network for Segmentation of Temporal Bone Anatomy in Cone-Beam CT Imaging

OBJECTIVE

Preoperative planning for otologic or neurotologic procedures often requires manual segmentation of relevant structures, which can be tedious and time-consuming. Automated methods for segmenting multiple geometrically complex structures can not only streamline preoperative planning but also augment minimally invasive and/or robot-assisted procedures in this space. This study evaluates a state-of-the-art deep learning pipeline for semantic segmentation of temporal bone anatomy.

STUDY DESIGN

A descriptive study of a segmentation network.

SETTING

Academic institution.

METHODS

A total of 15 high-resolution cone-beam temporal bone computed tomography (CT) data sets were included in this study. All images were co-registered, with relevant anatomical structures (eg, ossicles, inner ear, facial nerve, chorda tympani, bony labyrinth) manually segmented. Predicted segmentations from no new U-Net (nnU-Net), an open-source 3-dimensional semantic segmentation neural network, were compared against ground-truth segmentations using modified Hausdorff distances (mHD) and Dice scores.

RESULTS

Fivefold cross-validation with nnU-Net between predicted and ground-truth labels were as follows: malleus (mHD: 0.044 ± 0.024 mm, dice: 0.914 ± 0.035), incus (mHD: 0.051 ± 0.027 mm, dice: 0.916 ± 0.034), stapes (mHD: 0.147 ± 0.113 mm, dice: 0.560 ± 0.106), bony labyrinth (mHD: 0.038 ± 0.031 mm, dice: 0.952 ± 0.017), and facial nerve (mHD: 0.139 ± 0.072 mm, dice: 0.862 ± 0.039). Comparison against atlas-based segmentation propagation showed significantly higher Dice scores for all structures (p < .05).

CONCLUSION

Using an open-source deep learning pipeline, we demonstrate consistently submillimeter accuracy for semantic CT segmentation of temporal bone anatomy compared to hand-segmented labels. This pipeline has the potential to greatly improve preoperative planning workflows for a variety of otologic and neurotologic procedures and augment existing image guidance and robot-assisted systems for the temporal bone.

Endoscopic Endonasal Biopsy for Diagnosis of Undifferentiated Lesions of the Cavernous Sinus

BACKGROUND

Radiologically undifferentiated lesions of the cavernous sinus can pose a diagnostic challenge. Although radiotherapy is the mainstay for treatment of cavernous sinus lesions, histologic diagnosis allows access to a wide variety of alternative treatment modalities. The region is considered a high-risk area for open transcranial surgical access, and the endoscopic endonasal approach presents an alternative technique for biopsy.

METHODS

A retrospective case series was performed of all patients undergoing endoscopic endonasal biopsy of isolated cavernous sinus lesions at 2 tertiary institutions. The primary outcomes were the percentage of patients in whom a histologic diagnosis was achieved and the proportion of patients in whom therapy differed from radiotherapy alone. Secondary outcomes included preoperative and postoperative 22-item Sino-Nasal Outcome Test symptom scores, as well as perioperative adverse outcomes.

RESULTS

Eleven patients underwent endoscopic endonasal biopsy, with a diagnosis achieved in 10 patients. The most common diagnosis was perineural spread of squamous cell carcinoma, followed by perineuroma and single cases of metastatic melanoma, metastatic adenoid cystic carcinoma, mycobacterium lepri infection, neurofibroma, and lymphoma. Six patients had treatments other than radiotherapy, including immunotherapy, antibiotics, corticosteroids, chemotherapy, and observation alone. There was no significant difference in prebiopsy and postbiopsy 22-item Sino-Nasal Outcome Test scores. There was 1 case of epistaxis requiring return to theater for cautery of the sphenopalatine artery and there were no mortalities.

CONCLUSIONS

In a limited case series, endoscopic endonasal biopsy was safe and effective in obtaining diagnosis for cavernous sinus lesions and had a significant impact on therapeutic decision making.

Skull-Base Surgery-A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon's capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

Essential equipment and services for otolaryngology care: a proposal by the Global Otolaryngology-Head and Neck Surgery Initiative

PURPOSE OF REVIEW

To highlight the need for comprehensive resource lists to provide baseline care of otolaryngologic conditions; to present a proposed list of essential equipment and services that may be applied toward surgical systems research, policymaking, and charitable efforts in global otolaryngology-head and neck surgery.

RECENT FINDINGS

To provide effective and high-quality surgical care across care settings, there must be a global standard for equipment and ancillary services necessary to provide baseline care. Though there have been efforts to devise resource standards via equipment lists and appraisal tools, these have been limited in scope to general surgery, emergency care, and a few other subspecialty surgical contexts. Recent efforts have brought attention to the significant burden imposed by otolaryngologic conditions such as hearing loss, otitis media, head and neck cancer, head and neck trauma, and upper airway foreign bodies. Yet, there has not been a comprehensive list of resources necessary to provide baseline care for common otolaryngologic conditions.

SUMMARY

Through an internal survey of its members, the Global Otolaryngology-Head and Neck Surgery Initiative has compiled a list of essential equipment and services to provide baseline care of otolaryngologic conditions. Our efforts aimed to address common otolaryngologic conditions that have been previously identified as high-priority with respect to prevalence and burden of disease. This expert-driven list of essential resources functions as an initial framework to be adapted for internal quality assessment, implementation research, health policy development, and economic priority-setting.

Adverse Events Associated With Image-Guided Sinus Navigation in Endoscopic Sinus Surgery: A MAUDE Database Analysis

OBJECTIVE

The utilization of image-guided navigation during endoscopic sinus surgery (ESS) has increased significantly since its introduction. However, the most common associated complications are still unknown. This study describes and analyzes adverse events related to image-guided ESS.

STUDY DESIGN

Cross-sectional analysis.

SETTING

The Food and Drug Administration's 2018-2022 MAUDE database (Manufacturer and User Facility Device Experience).

METHODS

The MAUDE database was searched for all reports on adverse events involving sinus navigation systems used in ESS from 2018 to 2022. Reported events were reviewed and categorized.

RESULTS

During the study period, there were 1857 adverse events from 1565 reports, which were divided into device-related (n = 1834, 98.8%) and patient-related (n = 23, 1.2%) complications. The most common device-related complications were nonfunctionality of the system (n = 512, 27.9%), device imprecision (n = 427, 23.3%), and device sensing problems (n = 277, 15.1%). The most common patient-related complications were cerebrospinal fluid (CSF) leak (n = 14, 60.9%), intracranial injury (n = 4, 17.4%), and bleeding/hemorrhage (n = 3, 13.1%). Imprecision was associated with increased risk of navigation abortion by the surgeon (odds ratio, 1.50 [95% CI, 1.38-1.65]; P < .001) and increased risk of CSF leak (odds ratio, 16.5 [95% CI, 3.66-74.0]; P < .001) as compared with other device-related complications.

CONCLUSIONS

The most commonly reported device- and patient-related adverse events associated with image-guided sinus navigation systems were device nonfunction, imprecision, device sensing difficulties, and CSF leak. When imprecise navigation occurred, there was an increased likelihood of CSF leak and navigation abortion by the surgeon. Health care providers should be mindful of these possible complications when electing to use image-guided sinus navigation during ESS.

Using a Proximity-Detection Technology to Nudge for Physical Distancing in a Swedish Workplace During the COVID-19 Pandemic: Retrospective Case Study

BACKGROUND

The recent COVID-19 pandemic has contributed to the emergence of several technologies for infectious disease management. Although much focus has been placed on contact-tracing apps, another promising new tactic is proximity tracing, which focuses on health-related behavior and can be used for primary prevention. Underpinned by theories on behavioral design, a proximity-detection system can be devised that provides a user with immediate nudges to maintain physical distance from others. However, the practical feasibility of proximity detection during an infectious disease outbreak has not been sufficiently investigated.

OBJECTIVE

We aimed to evaluate the feasibility of using a wearable device to nudge for distance and to gather important insights about how functionality and interaction are experienced by users. The results of this study can guide future research and design efforts in this emerging technology.

METHODS

In this retrospective case study, a wearable proximity-detection technology was used in a workplace for 6 weeks during the production of a music competition. The purpose of the technology was to nudge users to maintain their physical distance using auditory feedback. We used a mixed methods sequential approach, including interviews (n=8) and a survey (n=30), to compile the experiences of using wearable technology in a real-life setting.

RESULTS

We generated themes from qualitative analysis based on data from interviews and open-text survey responses. The quantitative data were subsequently integrated into these themes: feasibility (implementation and acceptance-establishing a shared problem; distance tags in context-strategy, environment, and activities; understanding and learning; and accomplishing the purpose) and design aspects (a purposefully annoying device; timing, tone, and proximity; and additional functions).

CONCLUSIONS

This empirical study reports on the feasibility of using wearable technology based on proximity detection to nudge individuals to maintain physical distance in the workplace. The technology supports attention to distance, but the usability of this approach is dependent on the context and situation. In certain situations, the audio signal is frustrating, but most users agree that it needs to be annoying to ensure sufficient behavioral adaption. We proposed a dual nudge that involves vibration followed by sound. There are indications that the technology also facilitates learning how to maintain a greater distance from others, and that this behavior can persist beyond the context of technology use. This study demonstrates that the key value of this technology is that it places the user in control and enables immediate action when the distance to others is not maintained. This study provides insights into the emerging field of personal and wearable technologies used for primary prevention during infectious disease outbreaks. Future research is needed to evaluate the preventive effect on transmission and investigate behavioral changes in detail and in relation to different forms of feedback.

The Selective Role of Open and Endoscopic Approaches for Sinonasal Malignant Tumours

Endoscopic endonasal surgery has been demonstrated to be effective in the treatment of selected cases of sinonasal cancers. However, in cases of locally advanced neoplasms, as well as recurrences, the most appropriate approach is still debated. The present review aims to summarize the current state of knowledge on the utility of open approaches to resect sinonasal malignant tumours. Published comparative studies and meta-analyses suggest comparable oncological results with lower morbidity for the endoscopic approaches, but selection biases cannot be excluded. After a critical analysis of the available literature, it can be concluded that endoscopic surgery for selected lesions allows for oncologically safe resections with decreased morbidity. However, when endoscopic endonasal surgery is contraindicated and definitive chemoradiotherapy is not appropriate, craniofacial and transfacial approaches remain the best therapeutic option.

Image guidance for endoscopic sinus surgery in patients with chronic rhinosinusitis: a systematic review and meta-analysis protocol

INTRODUCTION

Endoscopic sinus surgery (ESS) is a current procedure for treating patients with chronic rhinosinusitis (CRS). Image-guided surgery (IGS) for ESS may help reduce complications and improve precision. However, it is uncertain in which cases IGS is beneficial. This work aims to compare ESS with and without IGS in patients with CRS.

METHODS AND ANALYSIS

PubMed, Embase, Scopus, Web of Science, Scielo, Cochrane Central Register of Controlled Trials, CINAHL, LILACS and Clinicaltrials.gov will be searched for reported clinical trials comparing the quality of life and perioperative outcomes of ESS with and without navigation. The search is planned for 20 April 2022. Three independent authors will select eligible articles and extract their data. The risk of bias will be assessed using the Cochrane Handbook for Systematic Reviews of Interventions. The Grading of Recommendation Assessment, Development and Evaluation method will evaluate the strength of the evidence. Data synthesis will be performed using the Review Manager software V.5.4.1. To assess heterogeneity, I² statistics will be computed. Additionally, meta-analysis will be performed if the included studies are sufficiently homogenous.

ETHICS AND DISSEMINATION

This study reviews published data, and thus it is not necessary to obtain ethical approval. The findings of this systematic review will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020214791.

Augmented reality-assisted craniofacial reconstruction in skull base lesions - an innovative technique for single-step resection and cranioplasty in neurosurgery

Defects of the cranial vault often require cosmetic reconstruction with patient-specific implants, particularly in cases of craniofacial involvement. However, fabrication takes time and is expensive; therefore, efforts must be made to develop more rapidly available and more cost-effective alternatives. The current study investigated the feasibility of an augmented reality (AR)-assisted single-step procedure for repairing bony defects involving the facial skeleton and the skull base. In an experimental setting, nine neurosurgeons fabricated AR-assisted and conventionally shaped ("freehand") implants from polymethylmethacrylate (PMMA) on a skull model with a craniofacial bony defect. Deviations of the surface profile in comparison with the original model were quantified by means of volumetry, and the cosmetic results were evaluated using a multicomponent scoring system, each by two blinded neurosurgeons. Handling the AR equipment proved to be quite comfortable. The median volume deviating from the surface profile of the original model was low in the AR-assisted implants (6.40 cm³) and significantly reduced in comparison with the conventionally shaped implants (13.48 cm³). The cosmetic appearance of the AR-assisted implants was rated as very good (median 25.00 out of 30 points) and significantly improved in comparison with the conventionally shaped implants (median 14.75 out of 30 points). Our experiments showed outstanding results regarding the possibilities of AR-assisted procedures for single-step reconstruction of craniofacial defects. Although patient-specific implants still represent the gold standard in esthetic aspects, AR-assisted procedures hold high potential for an immediately and widely available, cost-effective alternative providing excellent cosmetic outcomes.

Navigation and non-navigation CT scan of the sinuses: comparison of the effective doses of radiation in children and adults

BACKGROUND

The advent of 3D navigation imaging has opened new borders to the endoscopic surgical approaches of naso-sinusal inflammatory and neoplastic disease. This technology has gained in popularity among otolaryngologists for endoscopic sinus and skull base surgeries in both adults and children. However, the increased tissue radiation required for data acquisition associated with 3D navigation protocols CT scans is a source of concern because of its potential health hazards. We aimed to compare the effective doses of radiation between 3D navigation protocols and standard protocols for sinus computed tomography (CT) scans for both the adult and pediatric population.

METHODS

We performed a retrospective cohort study through electronic chart review of patients undergoing sinus CT scans (standard and 3D navigation protocols) from May 2019 to December 2019 using a Siemens Drive (VA62A) CT scanner. The effective dose of radiation was calculated in mSv for all exams. Average irradiation doses were compared using a Student's T-Test or a Kruskall-Wallis test when appropriate.

RESULTS

A total of 115 CT scans were selected for analysis, of which 47 were standard protocols and 68 were 3D navigation protocols CT scans. Among these, 31 exams were performed on children and 84 exams on adults. For the total population, mean effective dose in the non-navigation CT scans was 0.37 mSv (SD: 0.16, N = 47) and mean effective dose in the 3D navigation sinus CT group was 2.33 mSv (SD: 0.45, N = 68). The mean difference between the two groups was statistically significant 1.97 mSv (CI 95% - 2.1 to - 1.83; P < 0.0001). There was a sixfold increase in radiation with utilization of 3D navigation protocols. The ratio was identical when the pediatric as well as the adult subset of patients were analyzed.

CONCLUSION

In our center, utilization of 3D navigation sinus CT protocols significantly increases radiation exposure. Otolaryngologists should be aware of this significant increase and should attempt to decrease the radiation exposure of their patients by limiting unnecessary scan orders and by evaluating 3D acquisition protocols locally with radiation physicists.

LEVEL OF EVIDENCE

Level IV.

In Silico Assessment of Safety and Efficacy of Screw Placement for Pediatric Image-Guided Otologic Surgery

Introduction: Current high-accuracy image-guided systems for otologic surgery use fiducial screws for patient-to-image registration. Thus far, these systems have only been used in adults, and the safety and efficacy of the fiducial screw placement has not yet been investigated in the pediatric population.

Materials and Methods: In a retrospective study, CT image data of the temporal region from 11 subjects meeting inclusion criteria (8–48 months at the time of surgery) were selected, resulting in n = 20 sides. These datasets were investigated with respect to screw stability efficacy in terms of the cortical layer thickness, and safety in terms of the distance of potential fiducial screws to the dura mater or venous sinuses. All of these results are presented as distributions, thickness color maps, and with descriptive statistics. Seven regions within the temporal bone were analyzed individually. In addition, four fiducial screws per case with 4 mm thread-length were placed in an additively manufactured model according to the guidelines for robotic cochlear implantation surgery. For all these screws, the minimal distance to the dura mater or venous sinuses was measured, or if applicable how much they penetrated these structures.

Results: The cortical layer has been found to be mostly between 0.7–3.3 mm thick (from the 5^th to the 95^th percentile), while even thinner areas exist. The distance from the surface of the temporal bone to the dura mater or the venous sinuses varied considerably between the subjects and ranged mostly from 1.1–9.3 mm (from the 5^th to the 95^th percentile). From all 80 placed fiducial screws of 4 mm thread length in the pediatric subject younger than two years old, 22 touched or penetrated either the dura or the sigmoid sinus. The best regions for fiducial placement would be the mastoid area and along the petrous pyramid in terms of safety. In terms of efficacy, the parietal followed by the petrous pyramid, and retrosigmoid regions are most suited.

Conclusion: The current fiducial screws and the screw placement guidelines for adults are insufficiently safe or effective for pediatric patients.

Role of Navigation in Oral and Maxillofacial Surgery: A Surgeon's Perspectives

Surgeries related to the maxillofacial area deal with an intricate network of anatomical structures. With the complexity of the vital structures, it necessitates a surgical team to respect each anatomical boundary. In the past, there was an exceptionally high number of cases with surgical errors. These errors were not because of flaws in the surgeon’s skills or techniques but owing to lack of resources. Visualisation is one of the key factors that determines the precision of any surgical outcome. Advances in surgical planning have led to the introduction of a “Navigation” system that helps surgeons to see more, know more and ultimately do more for their patients. The usefulness of the navigation system in oral surgeries has been indicated by its surgical applications in craniomaxillofacial trauma, orthognathic surgeries, head and neck pathological resections, complex skull base surgeries and surgery involving temporomandibular joint. A vast majority of research literature has suggested remarkable improvement in surgical outcomes under the guidance of 3d planning and navigation. However, with such an inordinate advancement, financial expenses and a gradual learning curve are always a constraining factor in surgical navigation. This article overviews indication of navigation in craniofacial surgeries with a focus on applied aspect, planning and solution to the future problem.

Efficient Reject Options for Particle Filter Object Tracking in Medical Applications

Reliable object tracking that is based on video data constitutes an important challenge in diverse areas, including, among others, assisted surgery. Particle filtering offers a state-of-the-art technology for this challenge. Becaise a particle filter is based on a probabilistic model, it provides explicit likelihood values; in theory, the question of whether an object is reliably tracked can be addressed based on these values, provided that the estimates are correct. In this contribution, we investigate the question of whether these likelihood values are suitable for deciding whether the tracked object has been lost. An immediate strategy uses a simple threshold value to reject settings with a likelihood that is too small. We show in an application from the medical domain-object tracking in assisted surgery in the domain of Robotic Osteotomies-that this simple threshold strategy does not provide a reliable reject option for object tracking, in particular if different settings are considered. However, it is possible to develop reliable and flexible machine learning models that predict a reject based on diverse quantities that are computed by the particle filter. Modeling the task in the form of a regression enables a flexible handling of different demands on the tracking accuracy; modeling the challenge as an ensemble of classification tasks yet surpasses the results, while offering the same flexibility.

Updates in techniques for improved visualization in sinus surgery

PURPOSE OF REVIEW

Adequate visualization during endoscopic sinus surgery (ESS) is one of the most critical aspects of performing well tolerated and successful surgery. The topic of visualization encompasses a broad spectrum of preoperative and intraoperative manoeuvres the surgeon can perform that aid in the understanding of the patient's anatomy and in the delivery of efficient surgical care.

RECENT FINDINGS

Preoperative considerations to improve visualization include optimization of haemostasis through management of comorbidities (e.g. hypertension, coagulopathies), medication management (e.g. blood thinners) and systemic versus topical corticosteroids. New technologies allow preoperative visual mapping of surgical plans. Advances in knowledge of intraoperative anaesthesia have encouraged a move toward noninhaled anaesthetics to reduce bleeding. High definition cameras, angled endoscopes, 3D endoscopes and more recently augmented reality, image-guided surgery, and robotic surgery, represent the state of the art for high-quality visualization. Topical interventions, such as epinephrine, tranexamic acid and warm isotonic saline, can help to reduce bleeding and improve the operative field. Surgical manoeuvres, such as polyp debulking, septoplasty, carefully controlled tissue manipulation and a consistent repeatable approach remain fundamental to appropriate intraoperative surgical visualization.

SUMMARY

This chapter delineates medical, technical and technological means - preoperatively and intraoperatively - to achieve optimized visualization of the surgical field in ESS.