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Scheduled early postoperative computed tomography (EPOCT) after craniotomy for brain tumor resection is standard at many institutions. We analyzed utility of preplanned EPOCT after elective craniotomy for brain tumor resection.We retrospectively analyzed 755 brain tumor resections for which EPOCT was performed within 4 hours of surgery. Postoperative clinical neurologic examination results were classified into expected (baseline or predicted postoperative examination), changed (from baseline examination), and unreliable (sedated or baseline comatose patient). Scans were analyzed for unexpected and/or worrisome findings (e.g., hemorrhagic or ischemic stroke). In cases of unexpected findings, management changes were correlated to patient's neurologic examination. Demographic information, tumor histology, and tumor location were analyzed to determine risk factors for unexpected findings.Rate of unexpected EPOCT findings was 4.1%. Patients with expected postoperative examinations were at significantly lower risk of abnormal findings (odds ratio [OR] = 0.074, P0.001). Patients with intraventricular tumors (OR = 5.7, P = 0.001) were at higher risk compared with patients with metastatic tumors (OR = 0.24, P = 0.06). No unexpected EPOCT findings led to management changes in patients with expected postoperative neurologic examinations. All unexpected EPOCT findings in patients with changed postoperative neurologic examinations led to management changes. Patients with nonreliable neurologic examinations were at significantly higher risk for unexpected findings on EPOCT (OR = 6.33, P 0.001) and subsequent management changes.Routine EPOCT is not indicated for patients undergoing brain tumor resection if postoperative neurologic examination is unchanged, as imaging is unlikely to result in management changes. EPOCT should be obtained in all patients with worrisome changes in examination or nonreliable examinations, as both groups have high rates of unexpected findings on imaging that lead to management changes.

Surgery is a mainstay to treat malignant brain tumors. However, due to the infiltrative nature of these tumors, it is a great challenge for surgeons to accurately identify and excise all the tumor foci. EGFRvIII, a variant of epidermal growth factor receptor (EGFR), is found in 20% of glioblastoma cases, which is the brain tumor with the highest malignancy. In this study, we developed an EGFRvIII-targeted nanoprobe to guide glioblastoma surgery by pre-operatively defining the tumor boundary via magnetic resonance imaging (MRI) and intra-operatively guiding resection by surface-enhanced resonance Raman scattering (SERRS) imaging. In vivo MRI studies show that this nanoprobe delineates an orthotopic EGFRvIII+ U87MG glioblastoma xenograft with a higher target to background ratio than the control nanoprobe without targeting specificity. With the assistance of a handheld Raman scanner, this nanoprobe successfully guided EGFRvIII+ glioblastoma resection by tracking its characteristic SERRS signal peaks. Ex vivo Raman microscopy and histological images verified that this nanoprobe precisely demarcated the glioblastoma boundary and no residual neoplastic foci were observed in the tumor bed. This dual-modal nanoprobe not only precisely guided glioblastoma resection, but also overcame the brain shift induced false-positive signal by real-timely co-registering pre-operative and intra-operative images. This nanoprobe is promising for the improvement in diagnostic accuracy and surgical outcome of EGFRvIII+ glioblastoma.

The aim in brain tumor surgery is maximal tumor resection with minimal damage of normal neuronal tissue. Today diagnosis of tumor and definition of tumor borders intraoperatively is based on various visualization methods as well as on the histopathologic examination of a limited number of biopsy specimens via frozen sections. Unfortunately, intraoperative histopathology bears several shortcomings, and many biopsies are inconclusive. Therefore, the desirable treatment could be to have the ability to identify intraoperative cellular structures, and differentiate tumor from normal functional brain tissue on a cellular level. To achieve this goal new technological equipment integrated with new surgical concepts is needed.Confocal Laser Endomicroscopy (CLE) is an imaging technique which provides microscopic information of tissue in real-time. We are able to use these technique to perform intraoperative “optical biopsies” in bringing the microscope inside to the patients brain through miniaturized fiber-optic probes, and allow real-time histopathology. In our knowledge we are worldwide the only one neurosurgical group using CLE intraoperative for brain tumor surgery. We can detect and characterize intraoperative tumor cells, providing immediate online diagnosis without the need for frozen sections. It also provides delineation of borders between tumor and normal tissue on a cellular level, making surgical margins more accurate than ever before. The applications of CLE-assisted neurosurgery help to accurate the therapy by extending the resection borders and protecting the functionality of normal brain tissue in critical eloquent areas.

Sarcomas are cancers of the bones, muscles, nerves, and fat that require complete surgical removal for cure. The primary surgical goal therefore is to remove the tumor with a zone of normal, non-cancerous tissue surrounding the tumor, considered a ‘negative’ surgical margin. At present, surgeons rely on radiologic imaging and visual and tactile clues to gauge cancer depth and guide surgical excision. This can result in removal of too much or too little tissue, which can lead to unnecessary removal of vital structures or incomplete cancer removal, respectively. Both results can have negative effects on ultimate patient outcome, with positive margins reported in 23% of sarcoma surgeries. Near-infrared (NIR) fluorescence probes are molecules that when stimulated with specific, known frequencies of near-infrared light will emit light of another distinct frequency. NIR light penetrates human tissue reasonably well and therefore can be used to detect the presence and location of unseen structures labeled with NIR fluorescence probes through several centimeters of tissue. Intra-operative near-infrared (NIR) fluorescence probes have been effective for this purpose in brain tumor surgery and may be applicable to sarcoma surgery. Foundational research is needed to explore the potential of this affibody probe and perfusion probes to estimate margin thickness in sarcoma surgery. In this study we will determine if sarcoma labeling using NIR fluorescence probes is superior with perfusion probes or a novel affibody probe. We will also determine whether NIR fluorescence using perfusion probes or a novel affibody probe can be correlated accurately to margin thickness.

Introduction: Smart glasses became commercially available recently, and can overlay data onto the sight through the lenses. Its clinical application for surgical navigation has never been reported so far. Materials and Methods: Smart glasses Epson Moverio BT-200 were applied for newly developed augmented reality-based neuronavigation, which overlays 3D images onto the video image of patient’s head, in two phantom heads and four patients with brain tumors (2 gliomas, 1 meningioma, 1 hemangioblastoma). Two phantom heads were created from a 3D printer XYZ printer. Three-dimensional computer graphics of the scalp, the brain, the brain tumors, and surrounding vascular structures were created from preoperative imaging studies by using the visualization software Amira. They were visualized through the glasses after registration based on a set of four markers. After measurement of accuracy, this technique was applied to four patients. Results: Image overlay through the smart glasses was successful in all the two phantom heads and four patients. By using 100 target points from phantoms (5 targets in 5 measurements for 4 sides), a mean preparatory targeting error was 1.9 mm with a standard deviation of 1.1 mm. A targeting error during the intraoperative visualization was 3 to 7 mm. All the tumors were totally removed successively, and the patients suffered no postoperative complications. Conclusions: Overlay of the three-dimensional computer graphics through the smart glasses provided clear and accurate localization of the targeted brain tumors by relatively simple procedure during the operation. Further improvement of accuracy is also underway.

Confocal laser endomicroscopy (CLE), although capable of obtaining images at cellular resolution during surgery of brain tumors in real time, creates as many non-diagnostic as diagnostic images. Non-useful images are often distorted due to relative motion between probe and brain or blood artifacts. Many images, however, simply lack diagnostic features immediately informative to the physician. Examining all the hundreds or thousands of images from a single case to discriminate diagnostic images from nondiagnostic ones can be tedious. Providing a real-time diagnostic value assessment of images (fast enough to be used during the surgical acquisition process and accurate enough for the pathologist to rely on) to automatically detect diagnostic frames would streamline the analysis of images and filter useful images for the pathologist/surgeon. We sought to automatically classify images as diagnostic or non-diagnostic. AlexNet, a deep-learning architecture, was used in a 4-fold cross validation manner. Our dataset includes 16,795 images (8572 nondiagnostic and 8223 diagnostic) from 74 CLE-aided brain tumor surgery patients. The ground truth for all the images is provided by the pathologist. Average model accuracy on test data was 91% overall (90.79 % accuracy, 90.94 % sensitivity and 90.87 % specificity). To evaluate the model reliability we also performed receiver operating characteristic (ROC) analysis yielding 0.958 average for the area under ROC curve (AUC). These results demonstrate that a deeply trained AlexNet network can achieve a model that reliably and quickly recognizes diagnostic CLE images., SPIE Medical Imaging: Computer-Aided Diagnosis 2017

Object Navigated transcranial magnetic stimulation (nTMS) combined with diffusion tensor imaging (DTI) is used preoperatively in patients with eloquent-located brain lesions and allows analyzing non-invasively the spatial relationship between the tumor and functional areas (e.g. the motor cortex and the corticospinal tract [CST]). In this study, we examined the diffusion parameters FA (fractional anisotropy) and ADC (apparent diffusion coefficient) within the CST in different locations and analyzed their interrater reliability and usefulness for predicting the patients' motor outcome with a precise approach of specific region of interest (ROI) seeding based on the color-coded FA-map. Methods Prospectively collected data of 30 patients undergoing bihemispheric nTMS mapping followed by nTMS-based DTI fiber tracking prior to surgery of motor eloquent high-grade gliomas were analyzed by 2 experienced and 1 unexperienced examiner. The following data were scrutinized for both hemispheres after tractography based on nTMS-motor positive cortical seeds and a 2nd region of interest in one layer of the caudal pons defined by the color-coded FA-map: the pre- and postoperative motor status (day of discharge und 3 months), the closest distance between the tracts and the tumor (TTD), the fractional anisotropy (FA) and the apparent diffusion coefficient (ADC). The latter as an average within the CST as well as specific values in different locations (peritumoral, mesencephal, pontine). Results Lower average FA-values within the affected CST as well as higher average ADC-values are significantly associated with deteriorated postoperative motor function (p = 0.006 and p = 0.026 respectively). Segmental analysis within the CST revealed that the diffusion parameters are especially disturbed on a peritumoral level and that the degree of their impairment correlates with motor deficits (FA p = 0.065, ADC p = 0.007). No significant segmental variation was seen in the healthy hemisphere. The interrater reliability showed perfect agreement for almost all analyzed parameters. Conclusions Adding diffusion weighted imaging derived information on the structural integrity of the nTMS-based tractography results improves the predictive power for postoperative motor outcome. Utilizing a second subcortical ROI which is specifically seeded based on the color-coded FA map increases the tracking quality of the CST independently of the examiner's experience. Further prospective studies are needed to validate the nTMS-based prediction of the patient's outcome., Highlights • ROI seeding based on nTMS-data and FA-maps improves DTI tractography of the CST. • Perfect interrater reliability for DTI tractography of the CST was observed. • The pattern of diffusivity disturbance predicts the postoperative motor outcome.

This chapter reviews the diagnostic imaging findings of the brain during and after surgery, including intraoperative MRI, brain tumor surgery and treatment accessories, resection cavities, Ommaya reservoirs, chemotherapy wafers, brachytherapy, as well as neurodegenerative, neuropsychiatric, and epilepsy surgery

International audience; AbstractIntroductionAfter elective craniotomy for brain tumour surgery, patients are usually admitted to an intensive care unit (ICU) for monitoring. Our goal was to evaluate the incidence and timing of neurologic and non-neurologic postoperative complications after brain tumour surgery, to determine factors associated with neurologic events and to evaluate the timing and causes of ICU readmission.Patients and methodsThis prospective, observational and analytic study enrolled 188 patients admitted to the ICU after brain tumour surgery. All postoperative clinical events during the first 24 hours were noted and classified. Readmission causes and timing were also analysed.ResultsTwenty-one (11%) of the patients were kept sedated after surgery; the remaining 167 patients were studied. Thirty one percent of the patients presented at least one complication (25% with postoperative nausea and vomiting (PONV), 16% with neurologic complications). The occurrence of neurological complications was significantly associated with the absence of preoperative motor deficit and the presence of higher intraoperative bleeding. Seven patients (4%) were readmitted to the ICU after discharge; 43% (n = 3) of them had a posterior fossa surgery.ConclusionPostoperative complications, especially PONV, are frequent after brain tumour surgery. Moreover, 16% of patients presented a neurological complication, probably justifying the ICU postoperative stay for early detection. The absence of preoperative motor deficit and intraoperative bleeding seems to predict postoperative neurologic complications. Finally, patients may present complications after ICU discharge, especially patients with fossa posterior surgery, suggesting that ICU hospitalization may be longer in this type of surgery.

Diffusion tensor imaging (DTI) is a recent technique that utilizes diffusion of water molecules to make assumptions about white matter tract architecture of the brain. Early on, neurosurgeons recognized its potential value in neurosurgical planning, as it is the only technique that offers the possibility for in vivo visualization of white matter tracts. In this review we give an overview of the current advances made with this technique in neurosurgical practice. The effect of brain shift and the limitations of the technique are highlighted, followed by a comprehensive discussion on its objective value. Although there are many limitations and pitfalls associated with this technique, DTI can provide valuable additional diagnostic information to the neurosurgeon. We conclude that current evidence supports a role for DTI in the multimodal navigation during tumor surgery.

SUMMARY This article describes the evolution and state-of-the-art of navigated transcranial magnetic stimulation for evaluation of patients with brain tumors in presumed eloquent location. Alternative noninvasive technologies for functional brain mapping are described and assessed in the context of their usability and clinical needs. In addition to the description of the current validation level and clinical application of navigated transcranial magnetic stimulation for motor and language mapping, the manuscript highlights ongoing research efforts and provides an outlook on upcoming developments in the field of noninvasive brain mapping. Finally, the clinical rationale for presurgical noninvasive brain mapping is discussed in the light of current developments in neurosurgery.

BACKGROUND: Current outcomes prediction tools are largely based on and limited by regression methods. Utilization of machine learning (ML) methods that can handle multiple diverse inputs could strengthen predictive abilities and improve patient outcomes. Inpatient length of stay (LOS) is one such outcome that serves as a surrogate for patient disease severity and resource utilization. OBJECTIVE: To develop a novel method to systematically rank, select, and combine ML algorithms to build a model that predicts LOS following craniotomy for brain tumor. METHODS: A training dataset of 41 222 patients who underwent craniotomy for brain tumor was created from the National Inpatient Sample. Twenty-nine ML algorithms were trained on 26 preoperative variables to predict LOS. Trained algorithms were ranked by calculating the root mean square logarithmic error (RMSLE) and top performing algorithms combined to form an ensemble. The ensemble was externally validated using a dataset of 4592 patients from the National Surgical Quality Improvement Program. Additional analyses identified variables that most strongly influence the ensemble model predictions. RESULTS: The ensemble model predicted LOS with RMSLE of .555 (95% confidence interval, .553-.557) on internal validation and .631 on external validation. Nonelective surgery, preoperative pneumonia, sodium abnormality, or weight loss, and non-White race were the strongest predictors of increased LOS. CONCLUSION: An ML ensemble model predicts LOS with good performance on internal and external validation, and yields clinical insights that may potentially improve patient outcomes. This systematic ML method can be applied to a broad range of clinical problems to improve patient care.

BACKGROUND In brain CT angiography (CTA) for assisting brain tumor surgery, delineation of the superficial cerebral venous system is critical for selecting the optimal surgical approach. This delineation is, however, limited using conventional CT scanners, including an area-detector CT (ADCT) scanner, due to their insufficient spatial resolution. Since March 2017, a state-of-the-art ultrahigh-resolution CT (UHRCT) scanner has been clinically available to improve in- and through-plane spatial resolution compared with conventional CT scanners, mainly due to smaller slice thickness from 0.5 mm to 0.25 mm, larger channel number from 896 to 1792, and smaller x-ray focus from 0.9 x 0.8 mm to 0.4 x 0.5 mm.PurposeWe assessed usefulness of UHRCT to improve delineation of the superficial cerebral venous system in brain CTA for assisting brain tumor surgery compared with conventional ADCT. METHODS We retrospectively enrolled patients with intra- and/or extra-axial brain tumors who underwent preoperative brain CTA for assisting brain tumor surgery by UHRCT or ADCT using our routine technique and generated the CTA to delineate the superficial cerebral venous system using the same technique. Two reviewers by consensus subjectively counted the number of the superficial sylvian veins and the cortical veins draining into these veins and the maximal bifurcation order of the cortical veins draining into the superior sagittal sinus. We compared these numbers and the maximal bifurcation order in the CTA between the UHRCT and ADCT groups using the intraoperative findings as the reference. RESULTS The numbers and the maximal bifurcation order in the UHRCT group were significantly greater and more accurate than those in the ADCT group. CONCLUSIONS Use of UHRCT can be clinically useful for better delineating the superficial cerebral venous system in brain CTA and assisting brain tumor surgery.

Implementation of intraoperative magnetic resonance imaging (iMRI) has been shown to optimize the extent of resection and safety of brain tumor surgery. In addition, iMRI can help account for the phenomenon of brain shift and can help to detect complications earlier than routine postoperative imaging, which can potentially improve patient outcome. The higher signal-to-noise ratio offered by 3 Tesla (T) iMRI compared with lower field strength systems is particularly advantageous. The purpose of this article is to review the imaging protocols, imaging findings, and technical considerations related to 3T iMRI. To maximize efficiency, iMRI sequences can be tailored to particular types of tumors and procedures, including nonenhancing brain tumor surgery, enhancing brain tumor surgery, transsphenoidal pituitary tumor surgery, and laser ablation. Unique imaging findings on iMRI include the presence of surgically induced enhancement, which can be a potential confounder for residual enhancing tumor, and hyperacute hemorrhage, which tends to have intermediate signal on T1-weighted sequences and high signal on T2-weighted sequences due to the presence of oxyhemoglobin. MR compatibility and radiofrequency shielding pose particularly stringent technical constraints at 3T and influence the design and usage of the surgical suite with iMRI.

Molecular analytical methods are increasingly needed for a quick and reliable analysis of tissue in an operating room to provide more information during operations. In this Trends article, we highlight the current state and the developments of optical spectroscopic methods as intra operative tools. The clinical problem and challenges are illustrated on the example of brain tumor surgery. While fluorescence microscopy is already used, vibrational spectroscopy techniques will complement the standard method for brain tissue diagnostics. New portable instruments are currently available and can be stationed in the operating room for quick evaluation of tissue. The promise and limitations of fluorescence and vibrational spectroscopy as intraoperative tools are surveyed in this report.

Background Leksell GammaPlan (LGP) and SurgiPlan (ELEKTA Instruments AB, Stockholm, Sweden) may be used effectively for the detailed evaluation of regional neuroanatomy before open neurosurgical procedures. We report our initial experience in the cases of cerebral gliomas. Methods LGP v.8.3 was used before the surgical resection of cerebral gliomas for (1) the delineation of subdural grid electrodes and a detailed evaluation of their position relatively to cortical structures, and (2) for the fusion of structural magnetic resonance imaging and diffusion tensor imaging (DTI) for a detailed visualization of the corticospinal tract (CST) and optic radiation. Results Delineation of the subdural grid within LGP in a patient with seizures caused by left parietal glioma permitted a detailed assessment of the location of electrodes relative to the cortical gyri and sulci and significantly facilitated interpretation of brain mapping before tumor resection. In another patient with parieto-occipital glioma, simultaneous three-dimensional visualization of the tumor, CST, and optic radiation with the use of LGP permitted us to perform tumor resection without postoperative neurologic complications. Finally, incorporation of DTI into SurgiPlan resulted in precise planning of stereotactic biopsy for bilateral thalamic glioma. Conclusion The possibility for detailed evaluation of regional neuroanatomy based on various images within LGP and SurgiPlan may facilitate effective and safe surgical management of intracranial gliomas.

Navigated repetitive transcranial magnetic stimulation (nrTMS) Q2 24 is a novel technology that, unlike the other non-invasive methods 25 used to map language, applies a methodology (“virtual lesions”) 26 that is identical to that of the gold standard direct electrical stimu27 lation (DES) during awake surgery [1]. 28 The induction of brain plasticity due to pathological conditions 29 is an established observation and has been studied extensively 30 in stroke [2]. In brain tumor surgery, a small number of reports 31 have demonstrated that brain plasticity can occur in slow-growing 32 lesions and may enable the resection of tumors that were pre33 viously deemed inoperable due to their infiltration of areas that 34 carry essential language or motor function [3]. This article reports 35 for the first time a subacute reshaping of the language network 36 within 7 months after surgery for a left fronto-opercular glioblas37 toma detected by nrTMS. 38

Awake craniotomy (AC) has seen an expanded role in brain tumor surgery over the past few decades. AC allows intraoperative cortical mapping and the continuous assessment of neurophysiological parameters, which are otherwise unattainable under general anesthesia (GA). The ability of AC to analyze eloquent brain areas makes it a powerful method for reducing the risks associated with tumor resection, especially in motor and language cortex. We present a review of the literature to examine the benefits and limits of using AC over GA.A literature search was performed using the Medline and PubMed databases from 1970 and 2012 that compared craniotomy for tumor resection under GA and AC. Data of interest included length of hospital stay, operating time, extent of resection, and neurological sequelae.A total of 8 studies with 951 patients (411 utilizing AC and 540 utilizing GA) were included in this review. Our interpretation of the literature suggests that AC (4 d, n=110) results in a shorter hospital stay than GA (9 d, n=116). Mean extent of resection was slightly less under awake conditions (41%, n=321) versus GA (44%, n=444), and postoperative deficits were less frequent under awake conditions (7%, n=411) versus GA (23%, n=520). Surgery time was slightly less in the AC group (165 min, n=324) versus GA (168 min, n=477).Given the effectiveness of AC for resection of eloquent tumors, the data suggests an expanded role for AC in brain tumor surgery regardless of tumor location.

Extensive resective surgery plays a major role in prolonging survival of glioma patients. However, patient’s will is not to survive as long as possible, but rather to enjoy the longest possible «normal» life. Because glioma infiltrates functional tissue, it is necessary to define resection boundaries by functional maps rather than by tumoral imaging. In this perspective, advances in brain mapping have deeply improved the surgical management of glioma patients. In this chapter, we summarize the preoperative and intraoperative methods that allows to map the brain and we review the cortical and axonal mapping of the main cognitive functions.

Objective: VP Reveal (Vesalius Perfectus, Eindhoven, The Netherlands) is a commercially available “virtual reality” system designed to generate and review stereoscopic 3D models of any DICOM based CT, MRI, MRA, PET-scan within seconds. The system uses polarized 3D glasses and a 3D monitor.[for full text, please go to the a.m. URL], 67. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 1. Joint Meeting mit der Koreanischen Gesellschaft für Neurochirurgie (KNS)

3D medical images are important components of modern medicine. Their usefulness for the physician depends on their quality, though. Only high-quality images allow accurate and reproducible diagnosis and appropriate support during treatment. We have analyzed 202 MRI images for brain tumor surgery in a retrospective study. Both an experienced neurosurgeon and an experienced neuroradiologist rated each available image with respect to its role in the clinical workflow, its suitability for this specific role, various image quality characteristics, and imaging artifacts. Our results show that MRI data acquired for brain tumor surgery does not always fulfill the required quality standards and that there is a significant disagreement between the surgeon and the radiologist, with the surgeon being more critical. Noise, resolution, as well as the coverage of anatomical structures were the most important criteria for the surgeon, while the radiologist was mainly disturbed by motion artifacts.

Intraoperative ultrasound has been used for brain tumor surgery since more than 30 years now. In glioma surgery, taking into account the latest advances in ultrasound technology and its integration in a neuronavigation system intraoperative ultrasound is absolutely competitive with more recent imaging or visualization tools like 5-aminolevulinic acid fluorescence and intraoperative MRI. Intraoperative ultrasound allows for precise tumor depiction and intraoperative orientation in various indications. The actual chapter provides information about typical indications for intraoperative ultrasound in brain tumor surgery. It provides a guide for typical transducers and describes the depiction of intracranial lesions in B-mode ultrasound. During the course of resection, intraoperative ultrasound is prone to artifacts. Thus, a description of the most typical artifacts in intracranial surgery and a practical guide how optimize image quality and to avoid artifacts is given in this chapter.

It is now taken for granted that for certain cranial neurosurgical procedures, such as brain tumor surgery or cerebral abscesses, the use of navigation is the norm. Furthermore, should a complication arise during surgery where navigation was not used, and navigation may have helped to avoid such a complication, one would find this difficult to defend. Yet this was not the situation up until recently, and even in the last 10 years, a process has been underway to convince the remaining few skeptics that the extra time required during initial setup/registration, and the limitations with respect to accuracy that accompany all of the current navigation systems on the market are more than compensated by the advantages cranial navigation offers once surgery is underway.

Contains fulltext : 171797.pdf (Publisher’s version ) (Open Access) In brain tumor surgery, recognition of tumor boundaries is key. However, intraoperative assessment of tumor boundaries by the neurosurgeon is difficult. Therefore, there is an urgent need for tools that provide the neurosurgeon with pathological information during the operation. We show that third harmonic generation (THG) microscopy provides label-free, real-time images of histopathological quality; increased cellularity, nuclear pleomorphism, and rarefaction of neuropil in fresh, unstained human brain tissue could be clearly recognized. We further demonstrate THG images taken with a GRIN objective, as a step toward in situ THG microendoscopy of tumor boundaries. THG imaging is thus a promising tool for optical biopsies.

Image guidance and visualization play an important role in modern surgery to help surgeons perform their surgical procedures. Here, the focus is on neurosurgery applications, in particular brain tumor surgery where a craniotomy (opening of the skull) is performed to access directly the brain region to be treated. In this type of surgery, once the skull is opened the brain can change its shape, and this deformation is known as brain shift. Moreover, the boundaries of many types of tumors are difficult to identify by the naked eye from healthy tissue. The main goal of this work was to study and develop image guidance and visualization methods for tumor surgery in order to overcome the problems faced in this type of surgery. Due to brain shift the magnetic resonance dataset acquired before the operation (preoperatively) no longer corresponds to the anatomy of the patient during the operation (intraoperatively). For this reason, in this work methods were studied and developed to compensate for this deformation. To guide the deformation methods, information of the superficial vessel centerlines of the brain was used. A method for accurate (approximately 1 mm) reconstruction of the vessel centerlines using a multiview camera system was developed. It uses geometrical constraints, relaxation labeling, thin plate spline filtering and finally mean shift to find the correct correspondences between the camera images. A complete non-rigid deformation pipeline was initially proposed and evaluated with an animal model. From these experiments it was observed that although the traditional non-rigid registration methods (in our case coherent point drift) were able to produce satisfactory vessel correspondences between preoperative and intraoperative vessels, in some specific areas the results were suboptimal. For this reason a new method was proposed that combined the coherent point drift and thin plate spline semilandmarks. This combination resulted in an accurate (below 1 mm) non-rigid registration method, evaluated with simulated data where artificial deformations were performed. Besides the non-rigid registration methods, a new rigid registration method to obtain the rigid transformation between the magnetic resonance dataset and the neuronavigation coordinate systems was also developed. Once the rigid transformation and the vessel correspondences are known, the thin plate spline can be used to perform the brain shift deformation. To do so, we have used two approaches: a direct and an indirect. With the direct approach, an image is created that represents the deformed data, and with the indirect approach, a new volume is first constructed and only after that can the deformed image be created. A comparison of these two approaches, implemented for the graphics processing units, in terms of performance and image quality, was performed. The indirect method was superior in terms of performance if the sampling along the ray is high, in comparison to the voxel grid, while the direct was superior otherwise. The image quality analysis seemed to indicate that the direct method is superior. Furthermore, visualization studies were performed to understand how different rendering methods and parameters influence the perception of the spatial position of enclosed objects (typical situation of a tumor enclosed in the brain). To test these methods a new single-monitor-mirror stereoscopic display was constructed. Using this display, stereo images simulating a tumor inside the brain were presented to the users with two rendering methods (illustrative rendering and simple alpha blending) and different levels of opacity. For the simple alpha blending method an optimal opacity level was found, while for the illustrative rendering method all the opacity levels used seemed to perform similarly. In conclusion, this work developed and evaluated 3D reconstruction, registration (rigid and non-rigid) and deformation methods with the purpose of minimizing the brain shift problem. Stereoscopic perception of the spatial position of enclosed objects was also studied using different rendering methods and parameter values.

Object Disturbance of the arcuate fasciculus in the dominant hemisphere is thought to be associated with language-processing disorders, including conduction aphasia. Although the arcuate fasciculus can be visualized in vivo with diffusion tensor imaging (DTI) tractography, its involvement in functional processes associated with language has not been shown dynamically using DTI tractography. In the present study, to clarify the participation of the arcuate fasciculus in language functions, postoperative changes in the arcuate fasciculus detected by DTI tractography were evaluated chronologically in relation to postoperative changes in language function after brain tumor surgery. Methods Preoperative and postoperative arcuate fasciculus area and language function were examined in 7 right-handed patients with a brain tumor in the left hemisphere located in proximity to part of the arcuate fasciculus. The arcuate fasciculus was depicted, and its area was calculated using DTI tractography. Language functions were measured using the Western Aphasia Battery (WAB). Results After tumor resection, visualization of the arcuate fasciculus was increased in 5 of the 7 patients, and the total WAB score improved in 6 of the 7 patients. The relative ratio of postoperative visualized area of the arcuate fasciculus to preoperative visualized area of the arcuate fasciculus was increased in association with an improvement in postoperative language function (p = 0.0039). Conclusions The role of the left arcuate fasciculus in language functions can be evaluated chronologically in vivo by DTI tractography after brain tumor surgery. Because increased postoperative visualization of the fasciculus was significantly associated with postoperative improvement in language functions, the arcuate fasciculus may play an important role in language function, as previously thought. In addition, postoperative changes in the arcuate fasciculus detected by DTI tractography could represent a predicting factor for postoperative language-dependent functional outcomes in patients with brain tumor.

Tractography: denition and application in brain tumor surgery Surgical treatment of brain tumors involves the maximum resection of the lesion, leading to a greater chance of tumor control and increase patient survival. On the other hand, surgical intervention should preserve eloquent areas and minimize the possible neurological de'cits resulting from the surgery. Currently, many tests are available to assist our surgical planning and strategy, aiming to achieve better results. In this article, we analyze the basic concepts of tractography and its applications in brain tumor surgeries.

Brain tumor surgery is one of the key factors in prolonging survival in patients with low- and high-grade gliomas. However, resections of these infiltrative lesions have historically been limited by the inability to accurately detect tumor margins. New methods in microscopy and dye injection have enabled more complete resections, but continue to lack biochemical specificity or high-resolution image acquisition. Stimulated Raman scattering microscopy represents an improvement over past techniques in the ability to differentiate intraparenchymal tissues on the basis of biochemical attributes, and is available for use in real-time, a feature that facilitates its translation to the surgical setting.

The advanced imaging techniques outlined in this article are only slowly establishing their place in surgical practice. Even a low risk of false information is unacceptable in neurosurgery, thus decision-making is necessarily conservative. As more validation studies and greater experience accrue, surgeons are becoming more comfortable weighing the quality of information from functional imaging studies. Advanced imaging information is highly complementary to established surgical "good practice" such as anatomic planning, awake craniotomy, and electrocortical stimulation; its greatest impact is perhaps on how neurosurgery is planned and discussed before the patient is ever brought to the operating room. Access to functional magnetic resonance (MR) imaging, diffusion tractography, and intraoperative MR imaging can influence neurosurgical decisions before, during, and after surgery. However, the widespread adoption of these techniques in neurosurgical practice remains limited by the lack of standardized methods, the need for validation across institutions, and the unclear cost-effectiveness particularly for intraoperative MR imaging. Before advanced imaging results can be used therapeutically, it is incumbent on the neurosurgeon and neuroradiologist to develop a working understanding of each technique's strengths and weaknesses, positive and negative predictive values, and modes of failure. This content presents several imaging methods that are increasingly used in neurosurgical planning. As these techniques are progressively applied to surgery, radiologists, medical physicists, neuroscientists, and engineers will be necessary partners with the treating neurosurgeon to bridge the gap between the experimental and the therapeutic.

OBJECTIVE Transcranial magnetic stimulation (TMS) is a noninvasive method for analyzing cortical function. To utilize TMS for presurgical functional diagnostics, the magnetic impulse must be precisely targeted by stereotactically positioning the coil. The aim of this study was to evaluate the usefulness of TMS for operation planning when combined with a sensor-based electromagnetic navigation system (nTMS). METHODS Preoperative functional mapping with nTMS was performed in 10 patients with rolandic tumors. Intraoperative mapping was performed with the "gold standard" of direct cortical stimulation. Stimulation was performed in the same predefined 5-mm raster for both modalities, and the results were compared. RESULTS In regard to the 5-mm mapping raster, the centers of gravity of nTMS and direct cortical stimulation were located at the same spot in 4 cases and at neighboring spots in the remaining 6 cases. The mean distance between the tumor and the nearest motor response ("safety margin") was 7.9 mm (range, 5-15 mm; standard deviation, 3.2 mm) for nTMS and 6.6 mm (range, 0-12 mm; standard deviation, 3.4 mm) for direct cortical stimulation. CONCLUSION nTMS allowed for reliable, precise application of the magnetic impulse, and the peritumoral somatotopy corresponded well between the 2 modalities in all 10 cases. nTMS is a promising method for preoperative functional mapping in motor cortex tumor surgery.

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This paper addresses estimation of brain deformation during craniotomy using finite element modeling. Two mechanical models are optimized and compared for this purpose: linear solid-mechanic model and linear elastic model. Both models assume the realistic finite deformation of the brain after opening the skull. In this study, we use pre-operative and intra-operative magnetic resonance images (MRI) of five patients undergoing brain tumor surgery. Anatomical landmarks are identified by an expert radiologist on MRI and used for the method development and comparison studies. We use tetrahedral finite element meshes and optimize model parameters by minimizing the mean distance between the predicted locations of the anatomical landmarks using the pre-operative images and their actual locations on the intra-operative images. Evaluation of the objective function using a second set of landmarks not used in the optimization process suggests that accuracy of the solid mechanic model is higher than that of the elastic model for our application. Visual inspection of the results confirms this conclusion. The proposed method along with the location information of the surface landmarks measured in the operating room and marked on the pre-operative images can be used to estimate the brain deformations without needing intra-operative images. In this case, since the parameters of the brain tissue are not the same for different patients, the proposed optimization process is crucial for obtaining accurate results.

The goal of this study was to accomplish the cross-cultural adaptation of a quality of life instrument, specific for neurosurgical patients, called Innsbruck Health Dimensions Questionnaire for Neurosurgical Patients (IHD-NS). Thirty patients participated in this study, male and female, all having been submitted to brain tumor surgery more than twelve months before, and whose ages ranged from 26 to 66. After the process of translation/back translation and the elaboration of the Brazilian version of the instrument, the patients were assessed and reassessed within a one-month period. Statistical analyses evinced the preservation of the internal consistency, high agreement levels and highly significant intra-class correlation, allowing for the belief in the quality and reliability of the Portuguese version, named Questionário de Dimensões de Saúde para Pacientes Neurocirúrgicos de Innsbruck - DSI (NC).

International audience; OBJECTIVE:Awake craniotomy (AC) in brain lesions has allowed an improvement of both oncologic and functional results. However, intraoperative seizures (IOSs) were reported as a cause of failure of AC. Here, we analyze the incidence, risk factors, and consequences of IOSs in a prospective cohort of 374 ACs without electrocorticography (ECoG).METHODS:We performed a prospective study including all patients who underwent AC for an intra-axial supratentorial cerebral lesion from 2009-2014 in our department. Occurrence of IOS was analyzed with respect to medical and epilepsy history, tumor characteristics, operative technique, and postoperative outcomes.RESULTS:The study comprised 374 patients with a major incidence of low-grade glioma (86%). Most of the patients (83%) had epilepsy history before surgery (20% had intractable seizures). Preoperative mean Karnofsky performance scale (KPS) score was 91. IOSs occurred in 13 patients (3.4%). All IOSs were partial seizures, which quickly resolved by irrigation with cold Ringer lactate. No procedure failed because of IOS, and the rate of aborted AC whatever the cause was nil. Mean stimulation current intensity for cortical and subcortical mapping was 2.25 ± 0.6 mA. Presurgical refractory epilepsy was not associated with a higher incidence of IOS. Three months after surgery, no patients had severe or disabling permanent worsening, even within the IOS group (mean KPS score of 93.7).CONCLUSIONS:AC for intra-axial brain lesion can be safely and reproducibly achieved without ECoG, with a low rate of IOS and excellent functional results, even in patients with preoperative intractable epilepsy.

Some tumor-specific near-infrared (NIR) fluorescent dyes such as indocyanine green (ICG), IDRye800CW, and 5-aminolevulinic acid have been used clinically for detecting tumor margins or micro-cancer lesions. In this study, we evaluated the physicochemical properties of liposomally formulated phospholipid-conjugated ICG, denoted by LP-iDOPE, as a clinically translatable NIR imaging nanoparticle for brain tumors. We also confirmed its brain-tumor-specific biodistribution and its characteristics as the intra-operative NIR imaging nanoparticles for brain tumor surgery. These properties of LP-iDOPE may enable neurosurgeons to achieve more accurate identification and more complete resection of brain tumor.