Fully Automatic Adaptive Meshing Based Segmentation of the Ventricular System for Augmented Reality Visualization and Navigation.

OBJECTIVE: Effective image segmentation of cerebral structures is fundamental to 3-dimensional techniques such as augmented reality. To be clinically viable, segmentation algorithms should be fully automatic and easily integrated in existing digital infrastructure. We created a fully automatic adaptive-meshing-based segmentation system for T1-weighted magnetic resonance images (MRI) to automatically segment the complete ventricular system, running in a cloud-based environment that can be accessed on an augmented reality device. This study aims to assess the accuracy and segmentation time of the system by comparing it to a manually segmented ground truth dataset. METHODS: A ground truth (GT) dataset of 46 contrast-enhanced and non-contrast-enhanced T1-weighted MRI scans was manually segmented. These scans also were uploaded to our system to create a machine-segmented (MS) dataset. The GT data were compared with the MS data using the Sørensen-Dice similarity coefficient and 95% Hausdorff distance to determine segmentation accuracy. Furthermore, segmentation times for all GT and MS segmentations were measured. RESULTS: Automatic segmentation was successful for 45 (98%) of 46 cases. Mean Sørensen-Dice similarity coefficient score was 0.83 (standard deviation [SD] = 0.08) and mean 95% Hausdorff distance was 19.06 mm (SD = 11.20). Segmentation time was significantly longer for the GT group (mean = 14405 seconds, SD = 7089) when compared with the MS group (mean = 1275 seconds, SD = 714) with a mean difference of 13,130 seconds (95% confidence interval 10,130-16,130). CONCLUSIONS: The described adaptive meshing-based segmentation algorithm provides accurate and time-efficient automatic segmentation of the ventricular system from T1 MRI scans and direct visualization of the rendered surface models in augmented reality.

Repetitive Transcranial Magnetic Stimulation as a Therapeutic and Probe in Schizophrenia: Examining the Role of Neuroimaging and Future Directions.

Schizophrenia is a complex condition associated with perceptual disturbances, decreased motivation and affect, and disrupted cognition. Individuals living with schizophrenia may experience myriad poor outcomes, including impairment in independent living and function as well as decreased life expectancy. Though existing treatments may offer benefit, many individuals still experience treatment resistant and disabling symptoms. In light of the negative outcomes associated with schizophrenia and the limitations in currently available treatments, there is a significant need for novel therapeutic interventions. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that can modulate the activity of discrete cortical regions, allowing direct manipulation of local brain activation and indirect manipulation of the target's associated neural networks. rTMS has been studied in schizophrenia for the treatment of auditory hallucinations, negative symptoms, and cognitive deficits, with mixed results. The field's inability to arrive at a consensus on the use rTMS in schizophrenia has stemmed from a variety of issues, perhaps most notably the significant heterogeneity amongst existing trials. In addition, it is likely that factors specific to schizophrenia, rather than the rTMS itself, have presented barriers to the interpretation of existing results. However, advances in approaches to rTMS as a biologic probe and therapeutic, many of which include the integration of neuroimaging with rTMS, offer hope that this technology may still play a role in improving the understanding and treatment of schizophrenia.

Incorporating New Technologies to Overcome the Limitations of Endoscopic Spine Surgery: Navigation, Robotics, and Visualization.

Recently, spine surgery has gradually evolved from conventional open surgery to minimally invasive surgery, and endoscopic spine surgery (ESS) has become an important procedure in minimally invasive spine surgery. With improvements in the optics, spine endoscope, endoscopic burr, and irrigation pump, the indications of ESS are gradually widening from lumbar to cervical and thoracic spine. ESS was not only used previously for disc herniations that were contained without migration but is also used currently for highly migrated disc herniations and spinal stenosis; thus, the indications of ESS will be further expanded. Although ESS has certain advantages such as less soft tissue dissection and muscle trauma, reduced blood loss, less damage to the epidural blood supply and consequent less epidural fibrosis and scarring, reduced hospital stay, early functional recovery, and improvement of quality of life as well as better cosmesis, several obstacles remain for ESS to be widespread because it has a steep learning curve and surgical outcome is strongly dependent on the surgeon's skillfulness. A solid surgical technique requires reproducibility and ensured safety in addition to surgical outcomes. In this review article, how to improve ESS was investigated by grafting novel technologies such as navigation, robotics, and 3-dimensional and ultraresolution visualization.

Impact of initial midline shift in glioblastoma on survival.

The impact of midline shift (MLS) on long-term survival and progression in glioblastoma (GBM) is unknown. The objective of this study was to analyze the influence of mass effect on survival and progression with consideration of the patient demographics, tumor morphology, operative techniques, molecular pathology, and postoperative treatment. One hundred ninety-eight patients with GBM were analyzed retrospectively. Both MLS groups (< or ≥ 10 mm) were compared with regard to survival, progression-free survival (PFS), and postoperative course of Karnofsky Performance Status (KPS). A two-sided Fisher exact test showed no statistically significant differences in the confounders between the low- and high-MLS groups. The median survival was 18.0 months (95% confidence interval (CI) = 15.3-20.7) in the low-MLS group (n = 173) and 9.0 months (95% CI = 4.8-13.2) in the high-MLS group (n = 25) (p = 0.045). In the high-MLS group, 59.1% (13/22) with an initially high MLS had a KPS of less than 70% after 3 months, whereas 20.5% of the low-MLS group had a KPS of less than 70% (p < 0.001). Binary logistic regression analysis including the O-6-methylguanine-DNA methyltransferase (MGMT) status, extent of resection, baseline KPS, and MIB-I index showed low MLS as the only predictor for survival at 12 months (p = 0.046, odds ratio (OR) = 2.70, 95% CI = 1.0-7.2). Median PFS was 6.0 months in the high-MLS group and 9.0 months in the low-MLS group (log-rank test; p = 0.08). An initial midline shift of 10 mm or greater seems to be an imaging characteristic that independently predicts the survival in glioblastoma.

The Value of Preoperative Planning Based on Navigated Transcranical Magnetic Stimulation for Surgical Treatment of Brain Metastases Located in the Perisylvian Area.

BACKGROUND: Brain metastases are the most common neoplasms in adults. When brain metastases are located in eloquent areas, their treatment still seems controversial and not clearly defined. It is therefore essential to provide correct preoperative planning to better define extension and characterization of brain metastasis. METHODS: We retrospectively looked for the tumor database of our institution, patients with single brain metastasis, located in the sylvian area, who underwent resection with the support of intraoperative neurophysiologic monitoring between 2008 and 2018. RESULTS: We retrieved data for 30 adults, each with a single brain metastasis that was located in the sylvian area, including the insula and the lower portion of the motor cortex. Neuronavigation and the intraoperative visualization of the navigated transcranial magnetic stimulation-based reconstruction of functional networks were used to delineate the ideal trajectory toward the lesion. The Karnofsky Performance Status significantly improved in the postoperative period. CONCLUSIONS: The correct planning of brain metastasis allows more secure removal of the neoplastic lesion, avoiding and/or reducing the appearance of neurologic deficits. Navigated transcranial magnetic stimulation represents a new method that can promote a more complete and safer resection of the metastatic lesion in eloquent areas. An optimal surgical result, in the absence of postoperative neurologic deficits, allows the patient to undertake adjuvant therapy able to prolong survival.

Image Guidance for Ventricular Shunt Surgery: An Analysis of Hospital Charges.

BACKGROUND: Image guidance for shunt surgery results in more accurate proximal catheter placement. However, reduction in shunt failure remains unclear in the literature. There have been no prior studies evaluating the cost effectiveness of neuronavigation for shunt surgery. OBJECTIVE: To perform a cost analysis using available hospital charges of hypothetical shunt surgery performed with/without electromagnetic neuronavigation (EMN). METHODS: Hospital charges were collected for physician fees, radiology, operating room (OR) time and supplies, postanesthesia care unit, hospitalization days, laboratory, and medications. Index shunt surgery charges (de novo or revision) were totaled and the difference calculated. This difference was compared with hospital charges for shunt revision surgery performed under 2 clinical scenarios: (1) same hospital stay as the index surgery; and (2) readmission through the emergency department. RESULTS: Costs for freehand de novo and revision shunt surgery were $23 946.22 and $23 359.22, respectively. For stealth-guided de novo and revision surgery, the costs were $33 646.94 and $33 059.94, a difference of $9700.72. The largest charge increase was due to additional OR time (34 min; $4794), followed by disposable EMN equipment ($2672). Total effective charges to revise the shunt for scenarios 1 and 2 were $34 622.94 and $35 934.94, respectively. The cost ratios between the total revision charges for both scenarios and the difference in freehand vs EMN-assisted shunt surgery ($9700.72) were 3.57 and 3.70, respectively. CONCLUSION: From an economic standpoint and within the limitations of our models, the number needed to prevent must be 4 or less for the use of neuronavigation to be considered cost effective.

A new set of eyes: development of a novel microangioscope for neurointerventional surgery.

BACKGROUND: Endovascular technological advances have revolutionized the field of neurovascular surgery and have become the mainstay of treatment for many cerebrovascular pathologies. Digital subtraction angiography (DSA) is the 'gold standard' for visualization of the vasculature and deployment of endovascular devices. Nonetheless, with recent technological advances in optics, angioscopy has emerged as a potentially important adjunct to DSA. Angioscopy can offer direct visualization of the intracranial vasculature, and direct observation and inspection of device deployment. However, previous iterations of this technology have not been sufficiently miniaturized or practical for modern neurointerventional practice. OBJECTIVE: To describe the evolution, development, and design of a microangioscope that offers both high-quality direct visualization and the miniaturization necessary to navigate in the small intracranial vessels and provide examples of its potential applications in the diagnosis and treatment of cerebrovascular pathologies using an in vivo porcine model. METHODS: In this proof-of-concept study we introduce a novel microangioscope, designed from coherent fiber bundle technology. The microangioscope is smaller than any previously described angioscope, at 1.7 F, while maintaining high-resolution images. A porcine model is used to demonstrate the resolution of the images in vivo. RESULTS: Video recordings of the microangioscope show the versatility of the camera mounted on different microcatheters and its ability to navigate external carotid artery branches. The microangioscope is also shown to be able to resolve the subtle differences between red and white thrombi in a porcine model. CONCLUSION: A new microangioscope, based on miniaturized fiber optic technology, offers a potentially revolutionary way to visualize the intracranial vascular space.

Revision Rate of Misplaced Pedicle Screws of the Thoracolumbar Spine-Comparison of Three-Dimensional Fluoroscopy Navigation with Freehand Placement: A Systematic Analysis and Review of the Literature.

BACKGROUND: Recent studies have shown higher accuracy rates of image-guided pedicle screw placement compared to freehand (FH) placement. However, data focusing on the impact of spinal navigation on the rate of revision surgeries caused by misplaced pedicle screws (PS) are scarce. OBJECTIVE: This study is aimed at identifying the rate of revision surgeries for misplaced PS comparing three-dimensional (3D) fluoroscopy navigation (3DFL) with FH PS placement. METHODS: A retrospective analysis was conducted of 2232 patients (mean age, 65.3 ± 13.5 years) with 13,703 implanted PS who underwent instrumentation of the thoracolumbar spine between 2007 and 2015. Group 1 received surgery with use of 3DFL (January 2011 to December 2015), group 2 received surgery in the FH technique (April 2007 to December 2015). Because the use of 3DFL was initiated in January 2011, the examined period for 3DFL-navigated surgeries is shorter. Patients routinely received postoperative computed tomography scans and/or intraoperative control 3D scans. RESULTS: There was an overall rate of revision surgeries for malpositioned PS of 2.9%. In the 3DFL group, the rate of secondary revision surgeries was significantly lower with 1.35% (15/1112 patients) compared to 4.38% (49/1120 patients) in the FH group, respectively (odds ratio, 3.35; P < 0.01). Of all PS in the 3DFL group (30/7548 PS), 0.40% needed revision surgery (P < 0.01) compared to 1.14% in the FH group (70/6155 PS). CONCLUSIONS: We were able to show that the use of 3DFL-navigated PS placement significantly reduces the rate of revision surgeries after posterior spinal instrumentation compared to freehand PS placement.

White Paper: Interventional MRI: Current Status and Potential for Development Considering Economic Perspectives, Part 1: General Application.

Background MRI is attractive for the guiding and monitoring of interventional procedures due to its high intrinsic soft tissue contrast and the possibility to measure physiologic parameters like flow and cardiac function. Method The current status of interventional MRI for the clinical routine was analyzed. Results The effort needed for the development of MR-safe monitoring systems and instruments initially resulted in the application of interventional MRI only for procedures that could not be performed by other means. Accordingly, biopsy of lesions in the breast, which are not detectable by other modalities, has been performed under MRI guidance for decades. Currently, biopsies of the prostate under MRI guidance are established in a similar fashion. At many sites blind biopsy has already been replaced by MR-guided biopsy or at least by the fusion of MR images with ultrasound. Cardiovascular interventions are performed at several centers for ablation as a treatment for atrial fibrillation. Conclusion Interventional MRI has been established in the clinical routine for a variety of indications. Broader application can be expected in the clinical routine in the future owing to the multiple advantages compared to other techniques. Key points · Due to the significant technical effort, MR-guided interventions are only recommended in the long term for regions in which MRI either facilitates or greatly improves the intervention.. · Breast biopsy of otherwise undetectable target lesions has long been established in the clinical routine. Prostate biopsy is currently being introduced in the clinical routine for similar reasons. Other methods such as MR-guided focused ultrasound for the treatment of uterine fibroids or tumor ablation of metastases represent alternative methods and are offered in many places.. · Endovascular MR-guided interventions offer advantages for a number of indications and have already been clinically established for the treatment of children with congenital heart defects and for atrial ablation at individual centers. Greater application can be expected in the future.. Citation format · Barkhausen J, Kahn T, Krombach GA et al. White Paper: Interventional MRI: Current Status and Potential for Development Considering Economic Perspectives, Part 1: General Application. Fortschr Röntgenstr 2017; 189: 611 - 623.

Recent technological advances in pediatric brain tumor surgery.

X-rays and ventriculograms were the first imaging modalities used to localize intracranial lesions including brain tumors as far back as the 1880s. Subsequent advances in preoperative radiological localization included computed tomography (CT; 1971) and MRI (1977). Since then, other imaging modalities have been developed for clinical application although none as pivotal as CT and MRI. Intraoperative technological advances include the microscope, which has allowed precise surgery under magnification and improved lighting, and the endoscope, which has improved the treatment of hydrocephalus and allowed biopsy and complete resection of intraventricular, pituitary and pineal region tumors through a minimally invasive approach. Neuronavigation, intraoperative MRI, CT and ultrasound have increased the ability of the neurosurgeon to perform safe and maximal tumor resection. This may be facilitated by the use of fluorescing agents, which help define the tumor margin, and intraoperative neurophysiological monitoring, which helps identify and protect eloquent brain.

Technological Advances in Deep Brain Stimulation.

Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease processes in movement disorders as well clinician and patient demands has resulted in new avenues of development for DBS technology. This review describes new advances both related to hardware and software for neuromodulation. New electrode designs with segmented contacts now enable sophisticated shaping and sculpting of the field of stimulation, potentially allowing multi-target stimulation and avoidance of side effects. To avoid lengthy programming sessions utilising multiple lead contacts, new user-friendly software allows for computational modelling and individualised directed programming. Therapy delivery is being improved with the next generation of smaller profile, longer-lasting, re-chargeable implantable pulse generators (IPGs). These include IPGs capable of delivering constant current stimulation or personalised closed-loop adaptive stimulation. Post-implantation Magnetic Resonance Imaging (MRI) has long been an issue which has been partially overcome with 'MRI conditional devices' and has enabled verification of DBS lead location. Surgical technique is considering a shift from frame-based to frameless stereotaxy or greater role for robot assisted implantation. The challenge for these contemporary techniques however, will be in demonstrating equivalent safety and accuracy to conventional methods. We also discuss potential future direction utilising wireless technology allowing for miniaturisation of hardware.

Computed tomography-based image-guided system in spinal surgery: state of the art through 10 years of experience.

BACKGROUND: Image-guided navigation systems (IGS) grant excellent clinical and radiological results, minimizing risks correlated with spinal instrumentation. However, there is some concern regarding the real need for IGS and its indications. OBJECTIVE: To analyze the accuracy, technical aspect, and radiation exposure data of the principal IGS based on computed tomography (CT) imaging. METHODS: The data of all patients treated for spinal instrumentation with the aid of an IGS system from January 2003 to March 2013 were retrospectively analyzed. We defined 2 groups: group I with an IGS system based on a preoperative CT scan; group II relied on an intraoperative CT scan. Screw accuracy was assessed with a postoperative CT scan control. Radiation dosage for patients was defined by using the technical parameters and dose report data. Statistical analysis was performed using the Fisher exact test with a significance of 5% (P value < .05). RESULTS: Two thousand twenty patients and 11,144 screws were analyzed. Group I had 794 patients (4246 screws); the accuracy was 96.1%. Group II had 1226 patients (6898 screws) treated, with 98.5% accuracy (P = .001). The radiation dose analysis showed better results in group II, with significant reduction of the effective dose to the patient. CONCLUSION: The IGS based on an intraoperative CT scan grants excellent results, eliminating the rate of reoperation for misplaced instrumentations (screws, plate, and cage) or for inadequate bone decompression. However, this technology cannot replace the surgical skills, experience, and knowledge necessary for spine surgery.

Evidence-based clinical practice for the neurointerventionalist.

The field of neurointerventional (NI) surgery has developed in the context of technologic innovation. Many treatments readily provided in 2014 would have been hard to imagine as recently as 10 years ago. The reality of present day NI care is that, while providers, payors, policy makers and patients rely on evidence to guide NI decision-making, the available data are often less robust than participants might desire. In this paper we will explore the fundamentals of evidence-based clinical practice.

[The interdisciplinary hybrid operation theatre. Current experience and future]. / Der interdisziplinäre Hybridoperationssaal. Erfahrungen und Zukunft.

Since June 2013 a hybrid operation theatre is used interdisciplinary in the department for surgery of Ulm University. In this operation theatre a floor-based flat panel c-arm, which is mounted on a robotic arm that can be controlled by the surgeon in a sterile environment, is linked to the operating table. Furthermore for the first time it was possible to integrate a navigation system in this setting. The interdisciplinary utilization (trauma, neurosurgery, cardiac and vascular surgery) makes this hybrid operation theatre very time and cost effective. In the orthopedic trauma department this system is mainly used for traumatic and oncologic pelvic and spinal injuries. In these anatomical regions the excellent image quality and large field of view of the robotic flat panel detector based 3D imaging combined with an intraoperative navigation system is a huge advantage. The system can also be used for complex fractures of the extremities. In the future there will be an integration of further imaging modalities and referenced holding devices in this setting.

Navigation in surgery.

INTRODUCTION: "Navigation in surgery" spans a broad area, which, depending on the clinical challenge, can have different meanings. Over the past decade, navigation in surgery has evolved beyond imaging modalities and bulky systems into the rich networking of the cloud or devices that are pocket-sized. DISCUSSION: This article will review various aspects of navigation in the operating room and beyond. This includes a short history of navigation, the evolution of surgical navigation, as well as technical aspects and clinical benefits with examples from neurosurgery, spinal surgery, and orthopedics. CONCLUSION: With improved computer technology and a trend towards advanced information processing within hospitals, navigation is quickly becoming an integral part in the surgical routine of clinicians.

Spinal robotics: current applications and future perspectives.

Even though robotic technology holds great potential for performing spinal surgery and advancing neurosurgical techniques, it is of utmost importance to establish its practicality and to demonstrate better clinical outcomes compared with traditional techniques, especially in the current cost-effective era. Several systems have proved to be safe and reliable in the execution of tasks on a routine basis, are commercially available, and are used for specific indications in spine surgery. However, workflow, usability, interdisciplinary setups, efficacy, and cost-effectiveness have to be proven prospectively. This article includes a short description of robotic structures and workflow, followed by preliminary results of a randomized prospective study comparing conventional free-hand techniques with routine spine navigation and robotic-assisted procedures. Additionally, we present cases performed with a spinal robotic device, assessing not only the accuracy of the robotic-assisted procedure but also other factors (eg, minimal invasiveness, radiation dosage, and learning curves). Currently, the use of robotics in spinal surgery greatly enhances the application of minimally invasive procedures by increasing accuracy and reducing radiation exposure for patients and surgeons compared with standard procedures. Second-generation hardware and software upgrades of existing devices will enhance workflow and intraoperative setup. As more studies are published in this field, robot-assisted therapies will gain wider acceptance in the near future.

Neuronavigation in the surgical management of brain tumors: current and future trends.

Neuronavigation has become an ubiquitous tool in the surgical management of brain tumors. This review describes the use and limitations of current neuronavigational systems for brain tumor biopsy and resection. Methods for integrating intraoperative imaging into neuronavigational datasets developed to address the diminishing accuracy of positional information that occurs over the course of brain tumor resection are discussed. In addition, the process of integration of functional MRI and tractography into navigational models is reviewed. Finally, emerging concepts and future challenges relating to the development and implementation of experimental imaging technologies in the navigational environment are explored.

Quantum computing: a prime modality in neurosurgery's future.

OBJECTIVE: With each significant development in the field of neurosurgery, our dependence on computers, small and large, has continuously increased. From something as mundane as bipolar cautery to sophisticated intraoperative navigation with real-time magnetic resonance imaging-assisted surgical guidance, both technologies, however simple or complex, require computational processing power to function. The next frontier for neurosurgery involves developing a greater understanding of the brain and furthering our capabilities as surgeons to directly affect brain circuitry and function. METHODS: This has come in the form of implantable devices that can electronically and nondestructively influence the cortex and nuclei with the purpose of restoring neuronal function and improving quality of life. RESULTS: We are now transitioning from devices that are turned on and left alone, such as vagus nerve stimulators and deep brain stimulators, to "smart" devices that can listen and react to the body as the situation may dictate. CONCLUSION: The development of quantum computers and their potential to be thousands, if not millions, of times faster than current "classical" computers, will significantly affect the neurosciences, especially the field of neurorehabilitation and neuromodulation. Quantum computers may advance our understanding of the neural code and, in turn, better develop and program implantable neural devices. When quantum computers reach the point where we can actually implant such devices in patients, the possibilities of what can be done to interface and restore neural function will be limitless.

Brain shift compensation and neurosurgical image fusion using intraoperative MRI: current status and future challenges.

Navigation systems are commonly used in neurosurgical operating theaters. Generally, they either rely on the use of preoperative or intraoperative image data. Using preoperative image data, the phenomenon of brain shift contributes most to errors, in addition to various other sources of decreased reliability, such as image-related errors or registration inaccuracy. Updating navigation after intraoperative magnetic resonance imaging (iMRI) serves as immediate feedback on the surgical result and furthermore compensates for the effects of brain shift. Together with an integration of functional data in the navigation such as diffusion tensor imaging (DTI)-based fiber tracking or functional MRI, there is evidence that iMRI contributes to maximize extent of resection in glioma surgery with a preservation of neurological function. The following article summarizes the work flow and clinical impact of iMRI and functional navigation, as well as current problems and possible solutions.

Evolution in management of otogenic brain abscess.

OBJECTIVE: To present the therapeutic results related with treating 103 patients with cerebral abscesses of otogenic origin during 3 various time frames (1953-1977, 1978-1989, and 1990-2011). PATIENTS: A total of 103 patients with cerebral abscess of otogenic origin. INTERVENTIONS: Diagnostics and treatment. MAIN OUTCOME MEASURES: Analysis of mortality rates, abscess location and its basis, coexisting complications, neurological condition at admittance, bacteriological tests, and presentation of the results of abscess treatment with the use of neuronavigation. RESULTS: Mortality rates dropped systematically from the initial value of 35% observed between 1953 and 1977, to 14% between 1978 and 1989, and finally reached 3% between 1990 and 2011. Abscesses were mainly located within the temporal lobe. They predominantly resulted from chronic inflammation of the middle ear. A wide panel of complications was associated with them. Strong concurrence between results of cultures taken from the ear and the abscess was noted. CONCLUSION: Cerebral abscesses remain one of the most severe complications related with inflammation of the middle ear. Both the operative methods and the postoperative care evolved (introduction of surgical microscope, new generation of antibiotics), the preoperative diagnostics facilitating the diagnosis and localization of the abscess progressed; nonetheless, the principles underlying the operative treatment remained unchanged. Neuronavigation constitutes a very important and supportive element in the management of otogenic brain abscesses.