Objective To evaluate the feasibility and accuracy of mixed reality combined with surgical navigation in oral and maxillofacial tumor surgery. Methods Retrospective analysis of data of seven patients with oral and maxillofacial tumors who underwent surgery between January 2019 and January 2021 using a combination of mixed reality and surgical navigation. Virtual surgical planning and navigation plan were based on preoperative CT datasets. Through IGT-Link port, mixed reality workstation was synchronized with surgical navigation, and surgical planning data were transferred to the mixed reality workstation. Osteotomy lines were marked with the aid of both surgical navigation and mixed reality images visualized through HoloLens. Frozen section examination was used to ensure negative surgical margins. Postoperative CT datasets were obtained 1 week after the surgery, and chromatographic analysis of virtual osteotomies and actual osteotomies was carried out. Patients received standard oncological postoperative follow-up. Results Of the seven patients, four had maxillary tumors and three had mandibular tumors. There were total of 13 osteotomy planes. Mean deviation between the planned osteotomy plane and the actual osteotomy plane was 1.68 ± 0.92 mm; the maximum deviation was 3.46 mm. Chromatographic analysis showed error of ≤3 mm for 80.16% of the points. Mean deviations of maxillary and mandibular osteotomy lines were approximate (1.60 ± 0.93 mm vs. 1.86 ± 0.93 mm). While five patients had benign tumors, two had malignant tumors. Mean deviations of osteotomy lines was comparable between patients with benign and malignant tumors (1.48 ± 0.74 mm vs. 2.18 ± 0.77 mm). Intraoperative frozen pathology confirmed negative resection margins in all cases. No tumor recurrence or complications occurred during mean follow-up of 15.7 months (range, 6-26 months). Conclusion The combination of mixed reality technology and surgical navigation appears to be feasible, safe, and effective for tumor resection in the oral and maxillofacial region.

/pdf/accuracy-of-mixed-reality-combined-with-surgical-navigation-1tdpp01u.pdf

Accuracy of Mixed Reality Combined With Surgical Navigation Assisted Oral and Maxillofacial Tumor Resection

In the relevant global context, although virtual reality, augmented reality, and mixed reality have been emerging methodologies for several years, only now have technological and scientific advances made them suitable for revolutionizing clinical care and medical settings through the provision of advanced features and improved healthcare services. Over the past fifteen years, tools and applications using augmented reality (AR) have been designed and tested in the context of various surgical and medical disciplines, including maxillofacial surgery. The purpose of this paper is to show how a marker-less AR guidance system using the Microsoft® HoloLens 2 can be applied in mandible and maxillary demolition surgery to guide maxillary osteotomies. We describe three mandibular and maxillary oncologic resections performed during 2021 using AR support. In these three patients, we applied a marker-less tracking method based on recognition of the patient’s facial profile. The surgeon, using HoloLens 2 smart glasses, could see the virtual surgical planning superimposed on the patient’s anatomy. We showed that performing osteotomies under AR guidance is feasible and viable, as demonstrated by comparison with osteotomies performed using CAD-CAM cutting guides. This technology has advantages and disadvantages. However, further research is needed to improve the stability and robustness of the marker-less tracking method applied to patient face recognition.

/pdf/application-of-augmented-reality-to-maxillary-resections-a-1g7k6pz9.pdf

Application of Augmented Reality to Maxillary Resections: A Three-Dimensional Approach to Maxillofacial Oncologic Surgery

Background Mixed reality (MR) and its potential applications have gained increasing interest within the medical community over the recent years. The ability to integrate virtual objects into a real-world environment within a single video-see-through display is a topic that sparks imagination. Given these characteristics, MR could facilitate preoperative and preinterventional planning, provide intraoperative and intrainterventional guidance, and aid in education and training, thereby improving the skills and merits of surgeons and residents alike. Objective In this narrative review, we provide a broad overview of the different applications of MR within the entire spectrum of surgical and interventional practice and elucidate on potential future directions. Methods A targeted literature search within the PubMed, Embase, and Cochrane databases was performed regarding the application of MR within surgical and interventional practice. Studies were included if they met the criteria for technological readiness level 5, and as such, had to be validated in a relevant environment. Results A total of 57 studies were included and divided into studies regarding preoperative and interventional planning, intraoperative and interventional guidance, as well as training and education. Conclusions The overall experience with MR is positive. The main benefits of MR seem to be related to improved efficiency. Limitations primarily seem to be related to constraints associated with head-mounted display. Future directions should be aimed at improving head-mounted display technology as well as incorporation of MR within surgical microscopes, robots, and design of trials to prove superiority.

pdf/mixed-reality-in-modern-surgical-and-interventional-practice-3v9vf4pe.pdf

Mixed Reality in Modern Surgical and Interventional Practice: Narrative Review of the Literature

Background Mixed reality (MR) technology, which can fuse things in real and virtual space in real time, has been used mainly for simulation in neurosurgical training. Objective To develop MR technology into multimodal MR for intraoperative guidance during epilepsy surgery. Methods A 33-yr-old male patient suffered from intractable general tonic seizures due to left temporal meningoencephalocele. Preoperative scalp electroencephalograms localized interictal epileptic activity on the left temporal lobe. Iomazenil single photon emission tomography revealed temporal lobe lateralization. Magnetic resonance imaging (MRI) demonstrated left basal temporal meningoencephalocele extending into the pterygopalatine fossa through a bone defect at the base of the greater sphenoid wing. A 3-dimensional model was created for MR based on multimodal data including computed tomography, MRI tractography, and digital subtraction angiography, which enabled 3-dimensional visualization of abnormal subcortical fiber connections between the meningoencephalocele and the epileptic focus. Results By using intraoperative multimodal MR, we were able to safely remove the meningoencephalocele and perform epileptic focus resection. The patient was seizure-free postoperatively, and no adverse effects were noted. Conclusion Intraoperative multimodal MR was a feasible and effective technique, and it can be applied for a wide range of epilepsy surgeries.

Potential Efficacy of Multimodal Mixed Reality in Epilepsy Surgery.

Objective To explore the application of mixed reality technique for the surgery of oral and maxillofacial tumors. Methods In this study, patients with a diagnosis of an oral and maxillofacial tumor who were referred to Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from December 2018 to January 2020 were selected. The preoperative contrast-enhanced computed tomography data of the patients were imported into StarAtlas Holographic Medical Imaging System (Visual 3D Corp., Beijing, China). Three-dimensional (3D) model of tumor and key structures, such as skeleton and vessels were reconstructed to three-dimensionally present the spatial relationship between them, followed with the key structures delineation and preoperative virtual surgical planning. By using mixed reality technique, the real-time 3D model was displayed stereotactically in the surgical site. While keeping sterile during operation, the surgeon could use simple gestures to adjust the 3D model, and observed the location, range, and size of tumor and the key structures adjacent to the tumor. Mixed reality technique was used to assist the operation: 3D model registration was performed for guidance before tumor excision; intraoperative real-time verification was performed during tumor exposure and after excision of the tumor. The Likert scale was used to evaluate the application of mixed reality technique after the operation. Results Eight patients underwent mixed reality assisted tumor resection, and all of them successfully completed the operation. The average time of the 3D model registration was 12.0 minutes. In all the cases, the surgeon could intuitively and three-dimensionally observe the 3D model of the tumor and the surrounding anatomical structures, and could adjust the model during the operation. The results of the Likert scale showed that mixed reality technique got high scores in terms of perceptual accuracy, helping to locate the anatomical parts, the role of model guidance during surgery, and the potential for improving surgical safety (4.22, 4.19, 4.16, and 4.28 points respectively). Eight patients healed well without perioperative complications. Conclusion By providing real-time stereotactic visualization of anatomy of surgical site and guiding the operation process through 3D model, mixed reality technique could improve the accuracy and safety of the excision of oral and maxillofacial tumors.

Application of mixed reality technique for the surgery of oral and maxillofacial tumors

Pulmonary embolism (PE) is one of the fatal heart attacks, and lower limbs deep vein thrombosis (DVT) is the most common reason for PE. Inferior vena cava filter (IVCF) implantation is a most prevention for PE. But it may carry a high risk of injury because of the radiation and contrast agent. Patients with nephrotic syndrome (NS) or some other renal diseases may prone to thrombosis due to the excretion of protein C and protein S overmuch. So, it is necessary to develop a new therapy without contrast agent. Mixed-reality (MR) is a new technology as a guidance of inferior vena cava filter implantation exposed under no X-ray and required no contrast agent. We describe a case of old man with NS and PE who can’t tolerate traditional interventional surgery to prevent the embolus from falling off. We performed IVCF implantation guided by MR system which was totally suitable for this patient.  The patient was a 65-year-old man with NS treated with losartan and Haikun Shenxi Capsule regularly for one year. A month ago, he underwent ultrasound for his right leg swelling and thrombosis was found from right external iliac vein to femoral vein. Then he received treatment with thrombolysis and anticoagulation for lower limb DVT without IVCF implantation due to renal insufficiency in the local hospital. But recently, the patient had recurrence of chest distress and dyspnea with oxygen desaturation. Physical examination showed roughly normal. ECG and Echocardiography didn’t show a manifestation of PE or right-ventricular failure. Blood levels of D-dimer were severe elevated. As the patient suffered from NS for one year,

A first attempt of inferior vena cava filter successfully guided by a mixed-reality system: a case report.

Backgrounds Dynamic CT myocardial perfusion imaging (CT-MPI) allows absolute quantification of myocardial blood flow (MBF). Although appealing, CT-MPI has not yet been widely applied in clinical practice, partly due to our relatively limited knowledge of CT-MPI. Knowledge of distribution and variability of MBF in healthy subjects helps in recognition of physiological and pathological states of coronary artery disease (CAD). Objectives To describe the distribution and normal range of hyperemic MBF in healthy subjects obtained by dynamic CT-MPI and validate whether it can accurately identify functional myocardial ischemia when the cut-off value of hyperemia MBF is set to the lower limit of the normal range. Materials and Methods Fifty-one healthy volunteers (age, 38 ± 12 years; 15 men) were prospectively recruited. Eighty patients (age, 58 ± 10 years; 55 men) with suspected or known CAD who underwent interventional coronary angiography (ICA) examinations were retrospectively recruited. Comprehensive CCTA + dynamic CT-MPI protocol was performed by the third – generation dual-source CT scanner. Invasive fractional flow reserve (FFR) measurements were performed in vessels with 30–90% diameter reduction. ICA/FFR was used as the reference standard for diagnosing functional ischemia. The normal range for the hyperemic MBF were defined as the mean ± 1.96 SD. The cut-off value of hyperemic MBF was set to the lower limit of the normal range. Results The global hyperemic MBF were 164 ± 24 ml/100 ml/min and 123 ± 26 ml/100 ml/min for healthy participants and patients. The normal range of the hyperemic MBF was 116–211 ml/100 ml/min. Of vessels with an ICA/FFR result (n = 198), 67 (34%) were functionally significant. In the per-vessel analysis, an MBF cutoff value of <116 ml/100 ml/min can identify myocardial ischemia with a diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 85.9% (170/198), 91.0% (61/67), 83.2 % (109/131), 73.5% (61/83), and 94.8% (109/115). CT-MPI showed good consistency with ICA/FFR in diagnosing functional ischemia, with a Cohen's kappa statistic of 0.7016 (95%CI, 0.6009 – 0.8023). Conclusion Recognizing hyperemic MBF in healthy subjects helps better understand myocardial ischemia in CAD patients.

https://www.frontiersin.org/articles/10.3389/fcvm.2022.817911/pdf

Knowledge of Hyperemic Myocardial Blood Flow in Healthy Subjects Helps Identify Myocardial Ischemia in Patients With Coronary Artery Disease

Background Coronary microvascular dysfunction (CMD) is associated with increased cardiovascular events in patients with angina with non-obstructive coronary (ANOCA), especially heart failure. Conventional echocardiography is difficult to identify early alterations in cardiac function due to CMD. Methods We recruited 78 ANOCA patients. All patients underwent conventional echocardiography examination, adenosine stress echocardiography and examination of coronary flow reserve (CFR) by transthoracic echocardiography. Based on the CFR results, patients were divided into the CMD group (CFR < 2.5) and the non-CMD group (CFVR ≥ 2.5). Demographic data, conventional echocardiographic parameters, two-dimensional speckle-tracking echocardiography (2D-STE) parameters and myocardial work (MW) were compared between the two groups at rest and at stress. Logistic regression was used to analyze the factors associated with CMD. Results There was no significant difference in conventional echocardiography parameters, 2D-STE related indices or MW at rest between the two groups. Global work index (GWI), global contractive work (GCW), and global work efficiency (GWE) were lower in the CMD group than in the non-CMD group at stress (p = 0.040, 0.044, <0.001, respectively), but global waste work (GWW) and peak strain dispersion (PSD) were higher (both p < 0.001). GWI and GCW were associated with systolic blood pressure, diastolic blood pressure, product of heart rate and blood pressure, GLS and coronary flow velocity. While GWW was mainly correlated with PSD, GWE was correlated with PSD and GLS. In the non-CMD group, the responses to adenosine was mainly manifested as an increase in GWI, GCW and GWE (p = 0.001, 0.001, 0.009, respectively) and a decrease in PSD and GWW (p = 0.001, 0.015, respectively). In the CMD group, the response to adenosine was mainly manifested as an increase in GWW and a decrease in GWE (p = 0.002, and 0.006, respectively). In the multivariate regression analysis, we found that ΔGWW (difference in GWW before vs. after adenosine stress) and ΔPSD (difference in PSD before vs. after adenosine stress) were independent factors associated with CMD. The ROC curves showed that the composite prediction model consisting of ΔGWW and ΔPSD had excellent diagnostic value for CMD (area under the curve = 0.913). Conclusion In the present study, we found that CMD caused deterioration of myocardial work in ANOCA patients under adenosine stress, and that increased cardiac contraction asynchrony and wasted work may be the main changes caused by CMD.

/pdf/the-value-of-myocardial-work-in-the-estimation-of-left-30lbns6i.pdf

The value of myocardial work in the estimation of left ventricular systolic function in patients with coronary microvascular disease: A study based on adenosine stress echocardiography

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A first attempt of inferior vena cava filter successfully guided by a mixed-reality system: a case report.

Knowledge of Hyperemic Myocardial Blood Flow in Healthy Subjects Helps Identify Myocardial Ischemia in Patients With Coronary Artery Disease

The value of myocardial work in the estimation of left ventricular systolic function in patients with coronary microvascular disease: A study based on adenosine stress echocardiography