Navigation-guided resection of maxillary tumours: The accuracy of computer-assisted surgery in terms of control of resection margins - A feasibility study

Oncological Outcomes Following Computer-Aided Reconstructive Jaw Surgery

The purpose of this study was to analyze computer-aided surgical planning (CAS) and margin status following oncological reconstructive surgery of the jaws. A retrospective study was conducted on patients who underwent microvascular reconstructive surgery from 2014 to 2021. The predictor variable was the use of CAS. The primary and secondary outcomes were histopathological bone margin status, local recurrence, and disease-free survival (DFS). Covariates included demographic, operative, pathological, and clinical outcomes. Thirty-five CAS and fifty-two non-CAS subjects were included for analysis. Demographic characteristics such as age, sex, and comorbidities were comparable between the study groups, with all p-values > 0.05. For operative variables, the osteocutaneous radial forearm flap was more commonly used in the non-CAS group (34.6%) compared to the CAS group (2.9%) (p < 0.01). The mean follow-up period was shorter in the CAS group (31.9 months) than in the non-CAS group (42.6 months) (p < 0.01). CAS was not associated with margin status (p = 0.65) or local recurrence (p = 0.08). DFS was comparable between the study groups (p = 0.74). Bone margin involvement was not associated with any covariates. The use of CAS in oncological reconstructive jaw surgery was not associated with increased bone margin involvement.

Intraoperative surgical navigation improves margin status in advanced malignancies of the anterior craniofacial area: A prospective observational study with systematic review of the literature and meta-analysis

The current scientific evidence suggests that surgical navigation (SN) can contribute to improve oncologic outcomes in sinonasal and craniofacial surgery. The present study investigated the feasibility of intraoperative SN and its role in improving the outcomes of surgically treated sinonasal and craniofacial tumors. This prospective study compared navigation-guided surgery for sinonasal or craniofacial malignancies with a pair-matched cohort (1:2 matching) of patients operated without SN. A systematic review of the literature was performed. Thirty-five patients who underwent navigation-guided surgery were included. The pair-matched control cohort included 70 patients operated without SN. The margin status analysis demonstrated a lower rate of positive margins (p = 0.013) in the SN group, especially in pT4 (p = 0.034), recurrent (p = 0.024), high-grade tumors (p = 0.043), and endoscopic-assisted open surgery (p = 0.035). The mean preoperative time did not show a significant difference between surgeries performed with or without SN (1.26 vs. 1.23 h, p = 0.445). However, surgeries utilizing SN had a significantly longer median duration compared to those without (8.10 vs. 6.00 h, p = 0.029). A total of 209 patients were included in the meta-analysis; 91 patients (43.5 %) underwent surgery with SN. The results of the meta-analysis showed an improvement in terms of negative margins rate with the use of SN (OR = 2.62; 95%-confidence interval: 1.33-5.17). In conclusion, intraoperative SN can contribute to achieve a clear margin resection, especially in locally advanced tumors, recurrences, highly aggressive histologies, and when endoscopic-assisted open surgery is employed.

Three-dimensional digital anatomical measurements of pterygoid plates and posterior maxillary region

BACKGROUND

The posterior maxilla and skull base is a region with a complex anatomy. Accurate resection of the pterygoid plate is critical during a maxillectomy procedure. However, there is a paucity of functional and anatomical studies on the pterygoid plate and skull base. This study aimed to investigate functional anatomy of the pterygoid plate and its surrounding structures in the posterior maxilla to provide a better understanding of surgical procedures in this region.

METHODS

3D software was used to measure 3D distances, angles, and areas of key anatomical landmarks on CT images of 100 hemifaces. Morphological classification of pterygoid plates was then performed.

RESULTS

Results of comparing right and left pterygoid plates revealed no significant differences in dimensions or angles. Comparisons between sexes revealed that a few parameters were significantly different (P < 0.01), including pterygoid height on the left side, distance from the zygomatico-maxillary buttress to the infraorbital fissure (Zy-IOF), and area of the left lateral pterygoid plate. The morphology of the lateral pterygoid plate was classified into four types based on the shape of the middle region: middle convex (42%), double concave (36%), flattened (10%), and middle concave (12%). The morphology of pterygoid plates was classified based on the divergence of medial and lateral pterygoid plates, with the narrow type (56%) being more common than the wide type in this study cohort.

CONCLUSIONS

This 3D digital anatomical study measured key landmarks for maxillary resection. Such measurement has never been reported. This anatomical study provides surgeons with information on the anatomy of the posterior maxilla and allows for safer and more accurate resection of the difficult-to-resect posterior maxilla.

Intraoperative surgical navigation as a precision medicine tool in sinonasal and craniofacial oncologic surgery

INTRODUCTION

Recent evidence supports the efficacy of surgical navigation (SN) in improving outcomes of sinonasal and craniofacial oncologic surgery. This study aims to demonstrate the utility of SN as a tool for integrating surgical, radiologic, and pathologic information. Additionally, a system for recording and mapping biopsy samples has been devised to facilitate sharing of spatial information.

MATERIALS AND METHODS

SN was utilized for biopsy mapping in 10 sinonasal/craniofacial oncologic procedures. Twenty-five raters with experience in anterior skull base oncology were interviewed to identify 15 anatomical structures in preoperative imaging, relying on topographical descriptions and surgical video clips. The difference in the localization of anatomical structures by raters was analyzed, using the SN-mapped coordinates as a reference (this difference was defined as spatial error).

RESULTS

The analysis revealed an average spatial error of 9.0 mm (95 % confidence interval: 8.3-9.6 mm), with significant differences between surgeons and radiation oncologists (7.9 mm vs 12.5 mm, respectively, p < 0.0001). The proposed model for transferring SN-mapped coordinates can serve as a tool for consultation in multidisciplinary discussions and radiotherapy planning.

CONCLUSIONS

The current standard method to evaluate disease extension and margin status is associated with a spatial error approaching 1 cm, which could affect treatment precision and outcomes. The study emphasizes the potential of SN in increasing spatial precision and information sharing. Further research is needed to incorporate this method into a multidisciplinary workflow and measure its impact on outcomes.

Variation of resection margins in oral cancer in dependence of tumor stage and subsite - a retrospective cohort study

OBJECTIVES

Surgical resection is a key component of the treatment of head and neck cancer and the achievement of free surgical margins are essential for the patients' outcome in terms of survival. While there is a general recommendation for a free resection range of 5 mm, up to date, there is a lack of investigations on the quality of tumor resection in dependence of affected subsite and tumor stage. In the presented study, predictors for the achieved resection margins in surgically treated oral squamous cell carcinomas were analyzed.

MATERIALS AND METHODS

A cohort of 567 patients was included in a retrospective analysis and resection status with exact margin ranges were analysed. Tumor stage, affected subsite and the results of the intraoperative frozen section analysis were assessed. Primary endpoint was the achieved resection margin in mm, secondary endpoints were overall and progression-free survival.

RESULTS

The observed mean values of minimal resection margins differed significantly between the investigated subsites (p = 0.042),pathological tumor stages (p < 0.001) and in tumors which demonstrated perineural infiltration (Pn1, p = 0.002). Furthermore, there was a significant impact of the results of the intraoperative frozen section analysis on progression-free and overall survival (p < 0.001).

CONCLUSIONS

Our data clearly indicate that resection status differs between tumors of different subsites and tumor stages.

CLINICAL RELEVANCE

Clinical procedures should be adapted in order to achieve similar certainty in all resections, and, thus to improve patients' outcome.

Virtual tumor mapping and margin control with 3-D planning and navigation

Computer technology-based treatment approaches like intraoperative navigation and intensity-modulated radiation therapy have become important components of state of the art head and neck cancer treatment. Multidirectional exchange of virtual three-dimensional patient data via an interdisciplinary platform allows all medical specialists involved in the patients treatment to take full advantage of these technologies. This review article gives an overview of current technologies and future directions regarding treatment approaches that are based on a virtual, three-dimensional patient specific dataset: storage and exchange of spatial information acquired via intraoperative navigation allow for a highly precise frozen section procedure. In the postoperative setting, virtual reconstruction of the tumor resection surface provides the basis for improved radiation therapy planning and virtual reconstruction of the tumor with integration of molecular findings creates a valuable tool for postoperative treatment and follow-up. These refinements of established treatment components and novel approaches have the potential to make a major contribution to improving the outcome in head and neck cancer patients.

Custom CAD/CAM Peek Implants for Complex Orbitocranial Reconstruction: Our Experience with 15 Patients

Bone defects within the cranio-orbital complex present unique challenges in terms of surgical planning and reconstruction. This article presents a novel approach using PEEK material and advanced surgical technologies to address these challenges. A retrospective analysis of 15 patients who underwent craniofacial reconstruction using patient-specific polyetheretherketone (PEEK) implants between 2016 and 2021 was carried out. Comprehensive preoperative planning was performed, utilizing advanced imaging techniques and specialized software for virtual surgical planning. Patient-specific PEEK PSIs were designed and manufactured based on the preoperative plan. Intraoperative navigation was used to guide the surgical procedure, enabling precise osteotomy and optimal implant placement. This article describes the step-by-step process and the tools utilized in each phase. The etiologies were as follows: meningioma in seven cases, benign lesions in five cases, malignant tumors in two cases, and trauma sequelae in one case. In all cases, 3D-printed PEEK implants were utilized to achieve precise reconstruction. No major complications were described. In one case, an implant replacement was needed with successful outcomes. Our study demonstrates the feasibility and effectiveness of using PEEK patient-specific implants for personalized craniofacial reconstruction. The combination of advanced imaging, virtual planning, and CAD-CAM technology contributes to improved surgical outcomes in terms of oncologic margin control, functional restoration, and aesthetic results.

Clinical Experience with Autofluorescence Guided Oral Squamous Cell Carcinoma Surgery

In our study, the effect of the use of autofluorescence (Visually Enhanced Lesion Scope-VELscope) on increasing the success rate of surgical treatment in oral squamous carcinoma (OSCC) was investigated. Our hypothesis was tested on a group of 122 patients suffering from OSCC, randomized into a study and a control group enrolled in our study after meeting the inclusion criteria. The preoperative checkup via VELscope, accompanied by the marking of the range of a loss of fluorescence in the study group, was performed before the surgery. We developed a unique mucosal tattoo marking technique for this purpose. The histopathological results after surgical treatment, i.e., the margin status, were then compared. In the study group, we achieved pathological free margin (pFM) in 55 patients, pathological close margin (pCM) in 6 cases, and we encountered no cases of pathological positive margin (pPM) in the mucosal layer. In comparison, the control group results revealed pPM in 7 cases, pCM in 14 cases, and pFM in 40 of all cases in the mucosal layer. This study demonstrated that preoperative autofluorescence assessment of the mucosal surroundings of OSCC increased the ability to achieve pFM resection 4.8 times in terms of lateral margins.

Navigation-guided resection of locally advanced midface malignancies. Does it improve the safety of oncologic resection?

INTRODUCTION

Treatment of malignant midface tumors is a surgical challenge with an increased difficulty to obtain free surgical margins. The computer assisted surgery (CAS) and intraoperative navigation (ION) can be very helpful in complex midface resections. The main objective of this paper is to evaluate if the ION could improve the rate of free surgical margins in locally advanced midface malignancies.

MATERIALS AND METHODS

A retrospective cohort study was performed including 40 patients with a locally advanced malignant midface tumor (T4a/b) surgically treated from September 2016 to September 2022. Patients were divided in two groups, a control group included 20 patients operated on without ION and the study group included 20 patients treated with Navigation assisted surgery. A systematic analysis was performed comparing surgical margins in both groups.

RESULTS

Squamous cell carcinoma was the most common histological type. Oral cavity was the most common primary location. Overall, considering each specimen as an hexahedrium, 240 surgical margins were analyzed. 15 out of 120 margins analyzed in the navigation group (12.5 %) were positive while 30 out of 120 margins analyzed in control group (25 %) were affected (p 0.013). Concerning margin location, the ION group showed less involvement of the upper surface of specimen than in control group (p 0.048).

CONCLUSION

Navigation Assisted Surgery seems to improve the rate of free surgical margins in patients with locally advanced midface malignancies, specially concerning involvement of the superior margin. Further studies are recommended to corroborate these results and its potential influence in survival rates.

Analysis of the approach angle to medial orbitotomy that avoids accidental neurotrauma in the mesaticephalic dog skull utilizing 3D computer models and virtual surgical planning

This study was conducted to determine an approach angle to medial orbitotomy that avoids accidental neurotrauma in mesaticephalic dogs. Medical records of dogs with mesaticephalic skulls that were presented to the veterinary medical teaching hospital for head computed tomography (CT) between September 2021 and February 2022 were reviewed. Descriptive data were queried, and CT findings were analyzed. Dogs greater than 20 kg and possessing a disease-free orbitozygomaticomaxillary complex (OZMC) on at least one side of the skull were included in this study. Digital imaging and communications in medicine (DICOM) files of head CT studies were imported into medical modeling software, and the safe approach angle for medial orbitotomy was determined using three-dimensional (3D) computer models and virtual surgical planning (VSP) principles. Angles were measured along the ventral orbital crest (VOC) from the rostral cranial fossa (RCF) to the rostral alar foramen (RAF). The safe approach angle at four points from rostral to caudal along the VOC was measured. The results at each location were reported as mean, median, 95% CI, interquartile ranges, and distribution. The results were statistically different at each location and generally increased from rostral to caudal. The variances between subjects and the differences between locations were large enough to suggest a standard safe approach angle in mesaticephalic dogs cannot be determined and should be measured for each patient. A standardized approach angle to medial orbitotomy is not possible in the mesaticephalic dog. Computer modeling and VSP principles should be implemented as part of the surgical planning process to accurately measure the safe approach angle along the VOC.

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.

Endoscopic-assisted total maxillectomy with precise surgical margins

In traditional open maxillectomy, identifying the posterior margin is difficult because of its deep location and bleeding from the pterygoid venous plexus. Here, we present our endoscope-assisted total en bloc maxillectomy technique and discuss its merits and demerits compared to previously reported methods. We developed an endoscope-assisted total en bloc maxillectomy procedure. We reviewed a series of total maxillectomies performed with and without endoscopic assistance to verify the advantages of endoscopic assistance over conventional total maxillectomy. We analyzed (1) the precision using the distance of the remaining pterygoid process, (2) the operation time, and (3) blood loss. The length of the remnant pterygoid process was significantly shorter in the endoscopic assistance group. The operation time and blood loss were not significantly different between the two groups. Endoscopic assistance makes total maxillectomy more precise without requiring additional time and is a reasonable option for total maxillectomies.

Virtual surgical planning and 3D printing: Methodology and applications in veterinary oromaxillofacial surgery

Virtual surgical planning is the process of planning and rehearsing a surgical procedure completely within the virtual environment on computer models. Virtual surgical planning and 3D printing is gaining popularity in veterinary oromaxillofacial surgery and are viable tools for the most basic to the most complex cases. These techniques can provide the surgeon with improved visualization and, thus, understanding of the patients' 3D anatomy. Virtual surgical planning is feasible in a clinical setting and may decrease surgical time and increase surgical accuracy. For example, pre-operative implant contouring on a 3D-printed model can save time during surgery; 3D-printed patient-specific implants and surgical guides help maintain normocclusion after mandibular reconstruction; and the presence of a haptic model in the operating room can improve surgical precision and safety. However, significant time and financial resources may need to be allocated for planning and production of surgical guides and implants. The objectives of this manuscript are to provide a description of the methods involved in virtual surgical planning and 3D printing as they apply to veterinary oromaxillofacial surgery and to highlight these concepts with the strategic use of examples. In addition, the advantages and disadvantages of the methods as well as the required software and equipment will be discussed.

The state of virtual surgical planning in maxillary Reconstruction: A systematic review

Virtual surgical planning (VSP) and computer aided design utilization in head and neck reconstruction has become increasingly popular within the discipline. Advocates of the technology over traditional free hand surgery cite benefits including improved intraoperative efficiencies and postoperative outcomes that have been demonstrated during mandibular reconstruction. More recently, VSP for maxillary and mid facial reconstruction, generally considered more complex than their mandibular counterparts, have been applied with the hopes of similar benefits. However, our literature search revealed no large-scale randomized control trial substantiating these benefits. As such, the aim of this review was to synthesize the existing research on utilization of VSP in the context of maxillary reconstruction. Three databases were systematically searched for articles pertaining to maxillary reconstruction for oncologic, traumatic, or osteoradionecrosis indications. Four hundred and fourteen unique articles were reviewed by two independent reviewers ultimately revealing sixteen studies appropriate for qualitative synthesis including 142 patients. Results of our studies reveal the extreme heterogenicity of application of this technology under the label of virtual surgical planning. Outcome reporting methods were grossly inconsistent amongst all the articles resulting in inability to appropriately synthesize data quantitatively for a meta-analysis. Overall, there was no standard of reporting outcomes of maxillary reconstruction, and no randomized trials comparing virtual surgical planning versus freehand surgery and therefore there is insufficient data to objectively prove purported benefits. To facilitate future comparative studies, a minimal standard of reporting for maxillary VSP is presented and the need for a randomized control trial is highlighted.

Navigational Transmaxillary Endoscopic Approach for Inferomedial Tumors

Orbital tumors encompass a heterogeneous range of histopathology and usually variable in location. Traditionally, transconjunctival medial orbitotomy is used to access the medial orbital wall. However, it creates potential risk of soft tissue sequelae such as scarring, lid contracture, or entropion/ectropion. For the lesions close to the orbital apex, increased risk of optical nerve injury should be cautious during orbitotomy procedure. Transnasal endoscopic approach to the orbital walls has been applied since 1999. Although it provides good surgical visualization and prevents the soft tissue and neural complications, the narrow nasal corridor increases the surgical complexity. Extensive sphenoethmoidectomy is usually required to gaining access. Furthermore, the resultant medical orbital defect is difficult to repair. The maxillary sinus is the largest paranasal sinuses which is located beneath the orbital floor. It provides an ample working space for instrumentation. Meanwhile, repair of the orbital floor defect is feasible and with high degree of accuracy under navigation control. In this report, we propose a novel computer-assisted endoscopic protocol to excise the medial orbital tumors with immediate repair of the wall defect.

3D Printing and Virtual Surgical Planning in Oral and Maxillofacial Surgery

Compared to traditional manufacturing methods, additive manufacturing and 3D printing stand out in their ability to rapidly fabricate complex structures and precise geometries. The growing need for products with different designs, purposes and materials led to the development of 3D printing, serving as a driving force for the 4th industrial revolution and digitization of manufacturing. 3D printing has had a global impact on healthcare, with patient-customized implants now replacing generic implantable medical devices. This revolution has had a particularly significant impact on oral and maxillofacial surgery, where surgeons rely on precision medicine in everyday practice. Trauma, orthognathic surgery and total joint replacement therapy represent several examples of treatments improved by 3D technologies. The widespread and rapid implementation of 3D technologies in clinical settings has led to the development of point-of-care treatment facilities with in-house infrastructure, enabling surgical teams to participate in the 3D design and manufacturing of devices. 3D technologies have had a tremendous impact on clinical outcomes and on the way clinicians approach treatment planning. The current review offers our perspective on the implementation of 3D-based technologies in the field of oral and maxillofacial surgery, while indicating major clinical applications. Moreover, the current report outlines the 3D printing point-of-care concept in the field of oral and maxillofacial surgery.

Potential of Internet of Medical Things (IoMT) applications in building a smart healthcare system: A systematic review

Sudden spurting of Corona virus disease (COVID-19) has put the whole healthcare system on high alert. Internet of Medical Things (IoMT) has eased the situation to a great extent, also COVID-19 has motivated scientists to make new 'Smart' healthcare system focusing towards early diagnosis, prevention of spread, education and treatment and facilitate living in the new normal. This review aims to identify the role of IoMT applications in improving healthcare system and to analyze the status of research demonstrating effectiveness of IoMT benefits to the patient and healthcare system along with a brief insight into technologies supplementing IoMT and challenges faced in developing a smart healthcare system. An internet-based search in PUBMED, Google Scholar and IEEE Library for english language publications using relevant terms resulted in 987 articles. After screening title, abstract, and content related to IoMT in healthcare and excluding duplicate articles, 135 articles published in journal with impact factor ≥1 were eligible for inclusion. Also relevant articles from the references of the selected articles were considered. The habituation of IoMT and related technology has resolved several difficulties using remote monitoring, telemedicine, robotics, sensors etc. However mass adoption seems challenging due to factors like privacy and security of data, management of large amount of data, scalability and upgradation etc. Although ample knowledge has been compiled and exchanged, this structured systematic review will help the healthcare practitioners, policymakers/decision makers, scientists and researchers to gauge the applicability of IoMT in healthcare more efficiently.

Surgical Navigation, Augmented Reality, and 3D Printing for Hard Palate Adenoid Cystic Carcinoma En-Bloc Resection: Case Report and Literature Review

Adenoid Cystic Carcinoma is a rare and aggressive tumor representing less than 1% of head and neck cancers. This malignancy often arises from the minor salivary glands, being the palate its most common location. Surgical en-bloc resection with clear margins is the primary treatment. However, this location presents a limited line of sight and a high risk of injuries, making the surgical procedure challenging. In this context, technologies such as intraoperative navigation can become an effective tool, reducing morbidity and improving the safety and accuracy of the procedure. Although their use is extended in fields such as neurosurgery, their application in maxillofacial surgery has not been widely evidenced. One reason is the need to rigidly fixate a navigation reference to the patient, which often entails an invasive setup. In this work, we studied three alternative and less invasive setups using optical tracking, 3D printing and augmented reality. We evaluated their precision in a patient-specific phantom, obtaining errors below 1 mm. The optimum setup was finally applied in a clinical case, where the navigation software was used to guide the tumor resection. Points were collected along the surgical margins after resection and compared with the real ones identified in the postoperative CT. Distances of less than 2 mm were obtained in 90% of the samples. Moreover, the navigation provided confidence to the surgeons, who could then undertake a less invasive and more conservative approach. The postoperative CT scans showed adequate resection margins and confirmed that the patient is free of disease after two years of follow-up.

Development of a cadaveric head and neck cancer model and three-dimensional analysis of margins in surgical navigation-aided ablations

INTRODUCTION

The adequacy of the surgical resection is the main controllable variable that is in the hands of the surgical team. There exists an unmet need to increase the rate of negative margins, particularly in cancers invading the craniofacial area. The study aimed 1) at developing a gross tumor model to be utilized for research, educational, and training purposes and 2) establishing the 3-dimensional relationship between the outer surface of the surgical specimen and tumor surface and test the effect of guiding ablations on cadavers with surgical navigation (SN).

MATERIAL AND METHODS

Seven cadaver heads were employed to create 24 craniofacial tumor models. Simulation of tumor resections was performed by 8 surgeons. Fourteen and 10 resections were performed with and without SN-guidance, respectively. Gross specimens underwent computed tomography and 3-dimensional analysis through dedicated software. Task load was assessed through a validated questionnaire. Tumor model reliability was studied based on visual analogue scale rate by surgeons and radiologists.

RESULTS

SN reduced the rate of margin involvement, particularly by decreasing the percentage of the gross specimen outer surface involvement in areas uncovered by normal bony structures. The workload of SN-aided ablations was found to be medium-to-somewhat-high. Tumor model reliability was deemed satisfactory except for the extension to bony structures.

CONCLUSIONS

A gross tumor model for head and neck cancers involving the craniofacial area was developed and resulted satisfactorily reliable from both a surgical and radiologic standpoint. SN reduced the rate of margin involvement, particularly by improving delineation of bone-uncovered areas.

Navigation-Guided Transnasal Endoscopic Delineation of the Posterior Margin for Maxillary Sinus Cancers: A Preclinical Study

Background

The resection of advanced maxillary sinus cancers can be challenging due to the anatomical proximity to surrounding critical anatomical structures. Transnasal endoscopy can effectively aid the delineation of the posterior margin of resection. Implementation with 3D-rendered surgical navigation with virtual endoscopy (3D-SNVE) may represent a step forward. This study aimed to demonstrate and quantify the benefits of this technology.

Material and Method

Four maxillary tumor models with critical posterior extension were created in four artificial skulls (Sawbones^®). Images were acquired with cone-beam computed tomography and the tumor and carotid were contoured. Eight head and neck surgeons were recruited for the simulations. Surgeons delineated the posterior margin of resection through a transnasal approach and avoided the carotid while establishing an adequate resection margin with respect to tumor extirpation. Three simulations were performed: 1) unguided: based on a pre-simulation study of cross-sectional imaging; 2) tumor-guided: guided by real-time tool tracking with 3D tumor and carotid rendering; 3) carotid-guided: tumor-guided with a 2-mm alert cloud surrounding the carotid. Distances of the planes from the carotid and tumor were classified as follows and the points of the plane were classified accordingly: “red”: through the carotid artery; “orange”: <2 mm from the carotid; “yellow”: >2 mm from the carotid and within the tumor or <5 mm from the tumor; “green”: >2 mm from the carotid and 5–10 mm from the tumor; and “blue”: >2 mm from the carotid and >10 mm from the tumor. The three techniques (unguided, tumor-guided, and carotid-guided) were compared.

Results

3D-SNVE for the transnasal delineation of the posterior margin in maxillary tumor models significantly improved the rate of margin-negative clearance around the tumor and reduced damage to the carotid artery. “Green” cuts occurred in 52.4% in the unguided setting versus 62.1% and 64.9% in the tumor- and carotid-guided settings, respectively (p < 0.0001). “Red” cuts occurred 6.7% of the time in the unguided setting versus 0.9% and 1.0% in the tumor- and carotid-guided settings, respectively (p < 0.0001).

Conclusions

This preclinical study has demonstrated that 3D-SNVE provides a substantial improvement of the posterior margin delineation in terms of safety and oncological adequacy. Translation into the clinical setting, with a meticulous assessment of the oncological outcomes, will be the proposed next step.

Virtual Surgical Planning and 3D Printing in Veterinary Dentistry and Oromaxillofacial Surgery

Virtual surgical planning and three-dimensional (3D) printing are preoperative processes requiring the acquisition of high-quality imaging data. A surgical treatment plan is created and rehearsed virtually as the operator manipulates the 3D images of the patient within the software. When the operator is satisfied with the plan, including anticipated osteotomies, tumor excision margins, and reconstruction options, physical 3D prints can be produced. This article introduces the reader to the basic concepts involved in virtual surgical planning and 3D printing as well as their implementation in veterinary oromaxillofacial surgery.

Craniofacial Osteomas: From Diagnosis to Therapy

An osteoma is a benign bone lesion with no clear pathogenesis, almost exclusive to the craniofacial area. Osteomas show very slow continuous growth, even in adulthood, unlike other bony lesions. Since these lesions are frequently asymptomatic, the diagnosis is usually made by plain radiography or by a computed tomography (CT) scan performed for other reasons. Rarely, the extensive growth could determine aesthetic or functional problems that vary according to different locations. Radiographically, osteomas appear as radiopaque lesions similar to bone cortex, and may determine bone expansion. Cone beam CT is the optimal imaging modality for assessing the relationship between osteomas and adjacent structures, and for surgical planning. The differential diagnosis includes several inflammatory and tumoral pathologies, but the typical craniofacial location may aid in the diagnosis. Due to the benign nature of osteomas, surgical treatment is limited to symptomatic lesions. Radical surgical resection is the gold standard therapy; it is based on a minimally invasive surgical approach with the aim of achieving an optimal cosmetic result. Reconstructive surgery for an osteoma is quite infrequent and reserved for patients with large central osteomas, such as big mandibular or maxillary lesions. In this regard, computer-assisted surgery guarantees better outcomes, providing the possibility of preoperative simulation of demolitive and reconstructive surgery.

Augmented Reality and Intraoperative Navigation in Sinonasal Malignancies: A Preclinical Study

Objective

To report the first use of a novel projected augmented reality (AR) system in open sinonasal tumor resections in preclinical models and to compare the AR approach with an advanced intraoperative navigation (IN) system.

Methods

Four tumor models were created. Five head and neck surgeons participated in the study performing virtual osteotomies. Unguided, AR, IN, and AR + IN simulations were performed. Statistical comparisons between approaches were obtained. Intratumoral cut rate was the main outcome. The groups were also compared in terms of percentage of intratumoral, close, adequate, and excessive distances from the tumor. Information on a wearable gaze tracker headset and NASA Task Load Index questionnaire results were analyzed as well.

Results

A total of 335 cuts were simulated. Intratumoral cuts were observed in 20.7%, 9.4%, 1.2,% and 0% of the unguided, AR, IN, and AR + IN simulations, respectively (p < 0.0001). The AR was superior than the unguided approach in univariate and multivariate models. The percentage of time looking at the screen during the procedures was 55.5% for the unguided approaches and 0%, 78.5%, and 61.8% in AR, IN, and AR + IN, respectively (p < 0.001). The combined approach significantly reduced the screen time compared with the IN procedure alone.

Conclusion

We reported the use of a novel AR system for oncological resections in open sinonasal approaches, with improved margin delineation compared with unguided techniques. AR improved the gaze-toggling drawback of IN. Further refinements of the AR system are needed before translating our experience to clinical practice.

Advances in the Resection and Reconstruction of Midfacial Tumors Through Computer Assisted Surgery

Curatively intended oncologic surgery is based on a residual-free tumor excision. Since decades, the surgeon’s goal of R0-resection has led to radical resections in the anatomical region of the midface because of the three-dimensionally complex anatomy where aesthetically and functionally crucial structures are in close relation. In some cases, this implied aggressive overtreatment with loss of the eye globe. In contrast, undertreatment followed by repeated re-resections can also not be an option. Therefore, the evaluation of the true three-dimensional tumor extent and the intraoperative availability of this information seem critical for a precise, yet substance-sparing tumor removal. Computer assisted surgery (CAS) can provide the framework in this context. The present study evaluated the beneficial use of CAS in the treatment of midfacial tumors with special regard to tumor resection and reconstruction. Therefore, 60 patients diagnosed with a malignancy of the upper jaw has been treated, 31 with the use of CAS and 29 conventionally. Comparison of the two groups showed a higher rate of residual-free resections in cases of CAS application. Furthermore, we demonstrate the use of navigated specimen taking called tumor mapping. This procedure enables the transparent, yet precise documentation of three-dimensional tumor borders which paves the way to a more feasible interdisciplinary exchange leading e.g. to a much more focused radiation therapy. Moreover, we evaluated the possibilities of primary midface reconstructions seizing CAS, especially in cases of infiltrated orbital floors. These cases needed reduction of intra-orbital volume due to the tissue loss after resection which could be precisely achieved by CAS. These benefits of CAS in midface reconstruction found expression in positive changes in quality of life. The present work was able to demonstrate that the area of oncological surgery of the midface is a prime example of interface optimization based on the sensible use of computer assistance. The fact that the system makes the patient transparent for the surgeon and the procedure controllable facilitates a more precise and safer treatment oriented to a better outcome.

An integrated augmented reality surgical navigation platform using multi-modality imaging for guidance

An integrated augmented reality (AR) surgical navigation system that potentially improves intra-operative visualization of concealed anatomical structures. Integration of real-time tracking technology with a laser pico-projector allows the surgical surface to be augmented by projecting virtual images of lesions and critical structures created by multimodality imaging. We aim to quantitatively and qualitatively evaluate the performance of a prototype interactive AR surgical navigation system through a series of pre-clinical studies. Four pre-clinical animal studies using xenograft mouse models were conducted to investigate system performance. A combination of CT, PET, SPECT, and MRI images were used to augment the mouse body during image-guided procedures to assess feasibility. A phantom with machined features was employed to quantitatively estimate the system accuracy. All the image-guided procedures were successfully performed. The tracked pico-projector correctly and reliably depicted virtual images on the animal body, highlighting the location of tumour and anatomical structures. The phantom study demonstrates the system was accurate to 0.55 ± 0.33mm. This paper presents a prototype real-time tracking AR surgical navigation system that improves visualization of underlying critical structures by overlaying virtual images onto the surgical site. This proof-of-concept pre-clinical study demonstrated both the clinical applicability and high precision of the system which was noted to be accurate to <1mm.

The use of 3D virtual surgical planning and computer aided design in reconstruction of maxillary surgical defects

PURPOSE OF REVIEW

The present review describes the latest development of 3D virtual surgical planning (VSP) and computer aided design (CAD) for reconstruction of maxillary defects with an aim of fully prosthetic rehabilitation. The purpose is to give an overview of different methods that use CAD in maxillary reconstruction in patients with head and neck cancer.

RECENT FINDINGS

3D VSP enables preoperative planning of resection margins and osteotomies. The current 3D VSP workflow is expanded with multimodal imaging, merging decision supportive information. Development of more personalized implants is possible using CAD, individualized virtual muscle modelling and topology optimization. Meanwhile the translation of the 3D VSP towards surgery is improved by techniques like intraoperative imaging and augmented reality. Recent improvements of preoperative 3D VSP enables surgical reconstruction and/or prosthetic rehabilitation of the surgical defect in one combined procedure.

SUMMARY

With the use of 3D VSP and CAD, ablation surgery, reconstructive surgery, and prosthetic rehabilitation can be planned preoperatively. Many reconstruction possibilities exist and a choice depends on patient characteristics, tumour location and experience of the surgeon. The overall objective in patients with maxillary defects is to follow a prosthetic-driven reconstruction with the aim to restore facial form, oral function, and do so in accordance with the individual needs of the patient.

The Wearable VOSTARS System for Augmented Reality-Guided Surgery: Preclinical Phantom Evaluation for High-Precision Maxillofacial Tasks

BACKGROUND

In the context of guided surgery, augmented reality (AR) represents a groundbreaking improvement. The Video and Optical See-Through Augmented Reality Surgical System (VOSTARS) is a new AR wearable head-mounted display (HMD), recently developed as an advanced navigation tool for maxillofacial and plastic surgery and other non-endoscopic surgeries. In this study, we report results of phantom tests with VOSTARS aimed to evaluate its feasibility and accuracy in performing maxillofacial surgical tasks.

METHODS

An early prototype of VOSTARS was used. Le Fort 1 osteotomy was selected as the experimental task to be performed under VOSTARS guidance. A dedicated set-up was prepared, including the design of a maxillofacial phantom, an ad hoc tracker anchored to the occlusal splint, and cutting templates for accuracy assessment. Both qualitative and quantitative assessments were carried out.

RESULTS

VOSTARS, used in combination with the designed maxilla tracker, showed excellent tracking robustness under operating room lighting. Accuracy tests showed that 100% of Le Fort 1 trajectories were traced with an accuracy of ±1.0 mm, and on average, 88% of the trajectory's length was within ±0.5 mm accuracy.

CONCLUSIONS

Our preliminary results suggest that the VOSTARS system can be a feasible and accurate solution for guiding maxillofacial surgical tasks, paving the way to its validation in clinical trials and for a wide spectrum of maxillofacial applications.

Prosthodontic rehabilitation of head and neck cancer patients-Challenges and new developments

Head and neck cancer treatment can severely alter oral function and aesthetics, and reduce quality of life. The role of maxillofacial prosthodontists in multidisciplinary treatment of head and neck cancer patients is essential when it comes to oral rehabilitation and its planning. This role should preferably start on the day of first intake. Maxillofacial prosthodontists should be involved in the care pathway to shape and outline the prosthetic and dental rehabilitation in line with the reconstructive surgical options. With the progress of three‐dimensional technology, the pretreatment insight in overall prognosis and possibilities of surgical and/or prosthetic rehabilitation has tremendously increased. This increased insight has helped to improve quality of cancer care. This expert review addresses the involvement of maxillofacial prosthodontists in treatment planning, highlighting prosthodontic rehabilitation of head and neck cancer patients from start to finish.

Surgical Outcomes of Intraconal Cavernous Venous Malformation According to Their Location in Four Right-Angled Sectors

The present study evaluated the surgical outcomes of intraconal cavernous venous malformation according to their location in 4 right-angled sectors. Data regarding the surgical method and approach, surgical outcome, and postoperative complications were retrospectively analyzed for 18 patients with intraconal cavernous venous malformations that were surgically treated at the authors' center between March 2006 and May 2017. The lesion location was defined using 2 perpendicular lines connecting the optic disc and the 4 surrounding rectus muscles in the coronal plane, which resulted in the formation of 4 right-angled sectors (upper-outer quadrant, upper-inner quadrant, lower-inner quadrant, and lower-outer quadrant). Accordingly, there were 3, 3, 8, and 4 lesions in the upper-outer, upper-inner, lower-outer, and lower-inner quadrants, respectively. Ten patients received anterior orbitotomy and 8 received lateral orbitotomy. There were no recurrences during the follow-up period. All patients exhibited reduced proptosis after surgery. Vision improved in 4 patients and remained unchanged in 14. Five patients experienced ocular movement limitation (1 permanent and 4 temporary), 1 developed an inferomedial blowout fracture, 2 developed a temporary sensory deficit, and 1 developed temporary ptosis. The authors' findings suggest that intraconal cavernous venous malformations most frequently occur in the lower-outer quadrant. Although most lesions can be removed via anterior orbitotomy, large lesions located near the orbital apex or on the orbital wall require lateral orbitotomy. Ocular movement limitation is a common complication and can become permanent in rare cases, necessitating close monitoring. Lesion location and surgical approach do not seem to influence the postoperative complication rate.

Navigation-guided osteotomies improve margin delineation in tumors involving the sinonasal area: A preclinical study

OBJECTIVES

To demonstrate and quantify, in a preclinical setting, the benefit of three-dimensional (3D) navigation guidance for margin delineation during ablative open surgery for advanced sinonasal cancer.

MATERIALS AND METHODS

Seven tumor models were created. 3D images were acquired with cone beam computed tomography, and 3D tumor segmentations were contoured. Eight surgeons with variable experience were recruited for the simulation of osteotomies. Three simulations were performed: 1) Unguided, 2) Guided using real-time tool tracking with 3D tumor segmentation (tumor-guided), and 3) Guided by 3D visualization of both the tumor and 1-cm margin segmentations (margin-guided). Analysis of cutting planes was performed and distance from the tumor surface was classified as follows: "intratumoral" when 0 mm or negative, "close" when greater than 0 mm and less than or equal to 5 mm, "adequate" when greater than 5 mm and less than or equal to 15 mm, and "excessive" over 15 mm. The three techniques (unguided, tumor-guided, margin-guided) were statistically compared.

RESULTS

The use of 3D navigation for margin delineation significantly improved control of margins: unguided cuts had 18.1% intratumoral cuts compared to 0% intratumoral cuts with 3D navigation (p < 0.0001).

CONCLUSION

This preclinical study has demonstrated the significant benefit of navigation-guided osteotomies for sinonasal tumors. Translation into the clinical setting - with rigorous assessment of oncological outcomes - would be the proposed next step.

Endoscopic-assisted maxillectomy: Operative technique and control of surgical margins

BACKGROUND

When amenable to radical excision, cancer involving the maxilla is typically treated with maxillectomy followed by adjuvant therapy. Posterior tumor extension beyond the maxillary box leads to the invasion of complex areas, where achieving clear margins may be challenging.

METHODS

Patients undergoing endoscopic-assisted maxillectomy for nasoethmoidal, maxillary, or hard palate cancer between 2007 and 2017 were included in the study. Surgical technique, margin status, and recurrences were analyzed. Extension of posterior resection was classified in 3 types (type 1: resection of the pterygopalatine fossa; type 2: resection of the pterygoid plates and related muscles; type 3: resection of the upper parapharyngeal space). The analysis of putative risk factors for involvement of margins and local recurrence was performed with special focus on the posterior and medial margin.

RESULTS

The study included 79 patients (75 with available follow-up; mean: 20.6 months, range: 6-101 months), 37 (46.8%) of whom underwent type 1 resection, 34 (43.0%) type 2, and 8 (10.1%) type 3. According to pT category, 57 (72.2%) tumors were classified as T4a/T4b. Posterior and medial clear margins were achieved in 76/79 (96.2%) and 75/79 (94.9%) patients, respectively. T4b category, extension to the ethmoid, sphenoid sinus, pterygoid process, orbital cavity, and premaxillary tissues were significantly associated with a higher rate of margin involvement. None of the factors was significantly associated with medial margin involvement.

CONCLUSION

Endoscopic-assisted maxillectomy combines several refinements including the facilitated detachment of the maxilla from the skull base and precise delineation of the posterior and medial margins of resection.

Computer-assisted surgery for reconstruction of complex mandibular defects using osteomyocutaneous microvascular fibular free flaps: Use of a skin paddle-outlining guide for soft-tissue reconstruction. A technical report

INTRODUCTION

We present our pre-operative virtual planning of complex mandibular reconstruction with a microvascular fibular composite free flap and its harvesting using our novel cutaneous positioning guide based on the perforator vessels for our soft tissue reconstructive surgery.

TECHNICAL REPORT

We applied our protocol to 42 consecutive patients needing mandibular composite reconstruction. All patients were preoperatively studied with a CTA scan to evaluate the fibular pattern of vascularization and the perforator vessels three-dimensional path and position. Computer assisted surgery (CAS) was performed: a skin paddle outlining guide (SPOG) was designed to reproduce the shape and area of the planned soft tissue resection. CTA measurements and in vivo findings were compared. After performing the CTA, we classified the viable perforators in High Perforators, Medium Perforators and Low Perforators. The average diameter of the perforator vessels was 3 mm. The average difference between the measurements performed on the CTA and the intra-operative measures was 1, 4 mm. The SPOG was based on calf proximal and distal diameters. The anatomical fitting of the guide was obtained thanks to two customized flanges that embrace circumferentially the proximal and distal portions of the leg. The SPOG encompassed appropriate skin/leg regions, allowing the surgeon to localise the required perforator vessel.

CONCLUSIONS

CTA protocol appears to be a valuable approach to asses and virtually simulate composite mandibular reconstructions. The SPOG seems to be a valuable tool to reproduce intra-operatively the planned soft tissue area to be reconstructed.

Navigation-guided resection of maxillary tumors: Can a new volumetric virtual planning method improve outcomes in terms of control of resection margins?

INTRODUCTION

In the present study, our aim was to confirm the role of navigation-guided surgery in reducing the percentage of positive margins in advanced malignant pathologies of the mid-face, by introducing a new volumetric virtual planning method for resection.

MATERIALS AND METHODS

Twenty-eight patients were included in this study. Eighteen patients requiring surgery to treat malignant midface tumors were prospectively selected and stratified into two different study groups. Patients enrolled in the Reference Points Resection group (RPR - 10 patients) underwent resection planning using the anatomical landmarks on CT scan; patients enrolled in the Volume Resection group (VR - 8 patients) underwent resection using the new volumetric virtual planning method. The remaining 10 patients (Control group) were treated without the use of a navigation system.

RESULTS

In total, 127 margins were pathologically assessed in the RPR group, 75 in the VR group, and 85 in the control group. In the control group, 16% of the margins were positive, while in the RPR group the value was 9%, and in the VR group 1%.

CONCLUSIONS

The volumetric tumor resection planning associated to the navigation-guide resection appeared to be an improvement in terms of control of surgical margins in advanced tumors involving the mid-face.

Impact of 3D virtual planning on reconstruction of mandibular and maxillary surgical defects in head and neck oncology

PURPOSE OF REVIEW

This review describes the advances in 3D virtual planning for mandibular and maxillary reconstruction surgical defects with full prosthetic rehabilitation. The primary purpose is to provide an overview of various techniques that apply 3D technology safely in primary and secondary reconstructive cases of patients suffering from head and neck cancer.

RECENT FINDINGS

Methods have been developed to overcome the problem of control over the margin during surgery while the crucial decision with regard to resection margin and planning of osteotomies were predetermined by virtual planning. The unlimited possibilities of designing patient-specific implants can result in creative uniquely applied solutions for single cases but should be applied wisely with knowledge of biomechanical engineering principles.

SUMMARY

The high surgical accuracy of an executed 3D virtual plan provides tumor margin control during ablative surgery and the possibility of planned combined use of osseus free flaps and dental implants in the reconstruction in one surgical procedure. A thorough understanding of the effects of radiotherapy on the reconstruction, soft tissue management, and prosthetic rehabilitation is imperative in individual cases when deciding to use dental implants in patients who received radiotherapy.

Multi-modality 3D mandibular resection planning in head and neck cancer using CT and MRI data fusion: A clinical series

OBJECTIVES

3D virtual surgical planning (VSP) and guided surgery has been proven to be an effective tool for resection and reconstruction of the mandible. Currently, most widely used 3D VSP approaches to mandibular resection do not include detailed tumour information in the VSP. This manuscript presents a strategy where the aim was to incorporate tumour visualisation into the 3D virtual plan. Three-dimensional VSP of the mandibular resections was based on the fusion of CT and MRI data which was subsequently applied in clinical practice.

METHODS

All patients diagnosed with oral squamous cell carcinoma between 2014 and 2017 at the University Medical Centre Groningen were included. The tumour was delineated on the MRI data, after which this dataset was fused with the CT bone data in order to construct a 3D bone and tumour model for virtual resection planning. Guided resections were performed and post-operative evaluation quantified the accuracy of the resection. The histopathological findings and patient and tumour characteristics were compared to those of a historical cohort (2009-2014) of conventional mandibular continuity resections.

RESULTS

Twenty-four patients were included in the cohort. The average deviation from planned resection was found to be 2.2 mm. Histopathologic analysis confirmed all resection planes (bone) were tumour free, compared to 96.4% in the historic cohort.

CONCLUSION

MRI-CT base tumour visualisation and 3D resection planning is a safe and accurate method for oncologic resection of the mandible. It is an improvement on the current methods reported for 3D resection planning based solely on CT data.