Intraoperative ultrasound in brain tumor surgery: A review and implementation guide

Real-time brain tumor detection in intraoperative ultrasound: From model training to deployment in the operating room

Intraoperative ultrasound (ioUS) is a valuable tool in brain tumor surgery due to its versatility, affordability, and seamless integration into the surgical workflow. However, its adoption remains limited, primarily because of the challenges associated with image interpretation and the steep learning curve required for effective use. This study aimed to enhance the interpretability of ioUS images by developing a real-time brain tumor detection system deployable in the operating room. We collected 2D ioUS images from the BraTioUS and ReMIND datasets, annotated with expert-refined tumor labels. Using the YOLO11 architecture and its variants, we trained object detection models to identify brain tumors. The dataset included 1732 images from 192 patients, divided into training, validation, and test sets. Data augmentation expanded the training set to 11,570 images. In the test dataset, YOLO11s achieved the best balance of precision and computational efficiency, with a mAP@50 of 0.95, mAP@50-95 of 0.65, and a processing speed of 34.16 frames per second. The proposed solution was prospectively validated in a cohort of 20 consecutively operated patients diagnosed with brain tumors. Neurosurgeons confirmed its seamless integration into the surgical workflow, with real-time predictions accurately delineating tumor regions. These findings highlight the potential of real-time object detection algorithms to enhance ioUS-guided brain tumor surgery, addressing key challenges in interpretation and providing a foundation for future development of computer vision-based tools for neuro-oncological surgery.

Towards Optical Biopsy in Glioma Surgery

Currently, the focus of intraoperative imaging in brain tumor surgery is beginning to shift to optical methods such as optical coherence tomography (OCT), Raman spectroscopy, confocal laser endomicroscopy (CLE), and fluorescence lifetime imaging (FLIM). Optical imaging technologies provide in vivo and real-time high-resolution images of tissues. "Optical biopsy" can be considered as an alternative to traditional approaches for intraoperative histopathologic consultation. Intraoperative optical imaging can help to achieve precise intraoperative identification of tumor infiltrations within the surrounding brain parenchyma. Therefore, it can be considered as a complement to existing approaches based on wide-field imaging modalities such as MRI, US, or 5-ALA fluorescence. A promising future direction for intraoperative guidance during brain tumor surgery or stereotactic biopsy lies in the integration of optical imaging with machine learning techniques, enabling automated differentiation between tumor tissue and healthy brain parenchyma. We present this review to increase knowledge and form critical opinions in the field of using optical imaging in brain tumor surgery.

Intraoperative superb microvascular ultrasound imaging in glioma: novel quantitative analysis correlates with tumour grade

BACKGROUND

Accurate grading of gliomas is critical to guide therapy and predict prognosis. The presence of microvascular proliferation is a hallmark feature of high grade gliomas which to directly visualise traditionally requires targeted surgical biopsy of representative tissue. Superb microvascular imaging (SMI) is a novel high resolution Doppler ultrasound technique which can uniquely define the microvascular architecture of whole tumours.

METHODS

We examined both qualitative and quantitative vascular features of 32 gliomas captured with SMI, analysing flow signal density, vessel number, branching points, curvature, vessel angle deviation, fractal dimension, and entropy.

RESULTS

High-grade gliomas exhibit significantly greater vascular complexity and disorganisation, with increased fractal dimension and entropy, correlating with known histopathological markers of aggressive angiogenesis. The integrated ROC model achieved high accuracy (AUC = 0.95).

CONCLUSIONS

This study leveraged SMI to provide further insights into the microvascular architecture of gliomas which is not resolvable by magnetic resonance imaging. Applying novel quantitative analysis the study demonstrated that there are quantifiable differences in vascular morphology between high grade and low-grade gliomas. This unique in vivo imaging of glioma vascularity and quantification warrants further exploration as a potential new diagnostic and prognostic tool that may support glioma management, intraoperative decision-making and informing future prognosis.

Influence of Exposure Time and Driving Frequency on Cytotoxicity in In Vitro Ultrasound With Constant Mechanical Indices

Sonochemistry has become increasingly important in bioengineering research, and many in vitro and in vivo bioapplications have been developed. Cytotoxicity is always a concern in its implementation. For in vivo treatments and studies, mechanical index (MI) is known to ensure biocompatibility, and even in vitro MI has been used. Because cell characteristics and acoustic phenomena differ in vitro and in vivo, we questioned using MI in vitro. The in vitro cytotoxicity of ultrasound exposure should be investigated to support the development of cutting-edge sonochemistry. In this study, a system for irradiating cultured cells with 1-2 MHz-range ultrasound was developed to demonstrate the invalidity of employing MI alone in vitro. The results showed that cell damage is defined by the MI, ultrasound frequency, and exposure time, which are new indices for quantifying cell damage. Furthermore, cavitation and acoustic streaming are shown to be the main scientific factors that injure cells.

Advancing Glioma Management: The Pivotal Role of Surgical Neuro-Oncology in Driving Innovation and Translational Research

PURPOSE OF THE REVIEW

This study aims to assess the evolution of the role of surgery in advancing the treatment paradigm of primary central nervous system malignancies, gliomas.

RECENT FINDINGS

Diagnostic and therapeutic surgical intervention is the cornerstone for management of all gliomas. Current treatment guidelines for all gliomas include maximal safe resection, with concurrent and adjuvant chemo/radiotherapy, or other targeted molecular therapies, for high-grade gliomas and subsets of low-grade gliomas dependent on mutation profiling and IDH status. The extent of surgical resection affects overall survival across all grades of gliomas. Recently, several technological advances have augmented a surgeon's ability to push the boundaries of extent of resection, while also opening the door for novel intraoperative diagnostic and therapeutic interventions. Increasingly surgery is playing a pivotal role in the management of gliomas from diagnosis to therapeutic intervention, to drug delivery and progression monitoring. Novel technological advances such as advanced image guidance, fluorescence markers, intraoperative functional mapping, histological identification, and intraoperative radiation and drug delivery, provide a fertile ground for combining innovative modalities together to drive better treatment strategies and outcomes for patients.

Imaging adjuvants in pediatric surgical oncology

Surgery is a crucial component of pediatric cancer treatment, but conventional methods may lack precision. Image-guided surgery, including fluorescent and radioguided techniques, offers promise for enhancing tumor localization and facilitating precise resection. Intraoperative molecular imaging utilizes agents like indocyanine green to direct surgeons to occult deposits of tumor and to delineate tumor margins. Next-generation agents target tumors directly to improve specificity. Radioguided surgery, employing tracers like metaiodobenzylguanidine (MIBG), complements fluorescent techniques by allowing for detection of tumors at a greater depth. Dual-labeled agents combining both modalities are under development. Three-dimensional modeling and virtual/augmented reality aid in preoperative planning and intraoperative guidance. The above techniques show great promise to benefit patients with pediatric tumors, and their continued development will almost certainly improve surgical outcomes.

Ultrasound guided blood brain barrier opening using a diagnostic probe in a whole brain model

The blood-brain barrier (BBB) poses a significant challenge to drug delivery to the brain. A promising approach involves low-frequency, low-intensity pulsed ultrasound (US) waves combined with intravenously injected microbubbles (MB) to temporarily and non-invasively open the BBB. However, current technologies cannot easily integrate this procedure with US imaging. Passive cavitation detection, tracing the harmonic emissions of MB during sonication, has been the preferred method for real-time monitoring of US-mediated BBB opening. We used an ultrasound advanced open platform (ULA-OP) to simultaneously perform US-mediated BBB opening and US imaging with a single linear-array probe. In vitro guinea pig brains were perfused with MB and sonicated with different plane-wave transmission patterns. The most effective US pattern was interleaved with B-mode imaging pulses, enabling the direct assessment of the MB distribution during treatment. The extent of BBB permeabilization was assessed by quantifying FITC-albumin extravasation into the brain via confocal microscopy. US-treated hemispheres displayed BBB permeabilization, while control hemispheres did not. B-mode imaging allowed direct evaluation of MB distribution and interaction with the US beam. Therefore, we achieved effective BBB opening and simultaneous MB imaging using the same diagnostic probe, paving the way for US-guided therapeutic ultrasound application in the clinical context.

Dimensionality Reduction and Electrode Arrangement Optimization for an Electric Field Source Seeking Surgical Navigation Method

This study proposes a Dimensionality Reduction Electric Field Source Seeking (EFSS) method for real-time, high-precision navigation in intracranial puncture surgeries. The method integrates internal localization electrodes and external potential measurement electrodes to minimize surgical trauma while ensuring the accurate localization and guidance of surgical instruments. To optimize the electrode arrangement, two evaluation metrics-Mean Response Coefficient (MRC) and MRC-mean-were introduced. The simulation results demonstrated the effectiveness of these metrics, with the optimal arrangement achieving an average localization error below 2 mm and a 56% reduction in error after optimization. Experimental validation was conducted using a brain model with conductivity properties similar to those of human tissue. Localization experiments confirmed the robustness and accuracy of the EFSS method, with all results showing consistent repeatability and monotonic trends in performance across different electrode configurations. This study highlights the potential of the dimensionality reduction EFSS method as a novel and effective approach for navigation in minimally invasive intracranial surgeries.

Minimally-invasive common-path OCT system for neurosurgery applications

We present a minimally-invasive common-path optical coherence tomography (OCT) system operating at 1310 nm with a novel forward viewing monolithic endoscope designed specifically for neurosurgical applications with real-time 3D imaging capabilities. This system's real-time tissue identification capability could enhance the accuracy of stereotactic surgeries, including deep brain stimulation and biopsy, while its ability to detect blood flow could significantly reduce the risk of hemorrhage. The system was successfully tested in vivo in a rabbit cohort.

Navigated Intraoperative Ultrasound Offers Effective and Efficient Real-Time Analysis of Intracranial Tumor Resection and Brain Shift

BACKGROUND AND OBJECTIVES

Neuronavigation is a fundamental tool in the resection of intracranial tumors. However, it is limited by its calibration to preoperative neuroimaging, which loses accuracy intraoperatively after brain shift. Therefore, surgeons rely on anatomic landmarks or tools like intraoperative MRI to assess the extent of tumor resection (EOR) and update neuronavigation. Recent studies demonstrate that intraoperative ultrasound (iUS) provides point-of-care imaging without the cost or resource utilization of an intraoperative MRI, and advances in neuronavigation-guided iUS provide an opportunity for real-time imaging overlaid with neuronavigation to account for brain shift. We assessed the feasibility, efficacy, and benefits of navigated iUS to assess the EOR and restore stereotactic accuracy in neuronavigation after brain shift.

METHODS

This prospective single-center study included patients presenting with intracranial tumors (gliomas, metastasis) to an academic medical center. Navigated iUS images were acquired preresection, midresection, and postresection. The EOR was determined by the surgeon intraoperatively and compared with the postoperative MRI report by an independent neuroradiologist. Outcome measures included time to perform the iUS sweep, time to process ultrasound images, and EOR predicted by the surgeon intraoperatively compared with the postoperative MRI.

RESULTS

This study included 40 patients consisting of gliomas (n = 18 high-grade gliomas, n = 4 low-grade gliomas, n = 4 recurrent) and metastasis (n = 18). Navigated ultrasound sweeps were performed in all patients (n = 83) with a median time to perform of 5.5 seconds and a median image processing time of 29.9 seconds. There was 95% concordance between the surgeon's and neuroradiologist's determination of EOR using navigated iUS and postoperative MRI, respectively. The sensitivity was 100%, and the specificity was 94%.

CONCLUSION

Navigated iUS was successfully used for EOR determination in glioma and metastasis resection. Incorporating navigated iUS into the surgical workflow is safe and efficient and provides a real-time assessment of EOR while accounting for brain shift in intracranial tumor surgeries.

The importance of neurosurgical nursing in low- and middle-income countries - a critical review

Background

Neurosurgical nursing involves the provision of pre- and post-operative care to neurologic patients. Specialized nurses in the field of neurosurgery are vital for patient outcomes and wellbeing. Nevertheless, there is underestimation and limited access to neurosurgical nursing in low- and middle-income countries (LMICs). This review primarily aims to shed light on the significance of nursing in the neurosurgical department of LMICs. It provides insight into the healthcare systems, the collaborative approaches that emerged in this concern, and the issues pertaining to integrating neurosurgical nursing in these countries.

Methods

Literature search was conducted from March 2024, where the articles were retrieved from PubMed/Medline, EBSCOhost, Google Scholar, and Embase. The terms "neurosurgical nursing," "neurosurgery," "neurosurgical care," "neurosurgical nurses," and "low- and middle-income countries OR LMICs" were used to search relevant studies. Previous articles discussing neurosurgical care in LMICs were considered in this review.

Results

Nurses participate in 90% of interactions between healthcare providers and patients. They provide holistic care by considering the physical, cultural, and psychosociological needs pertaining to their patients. Furthermore, they possess ability to establish rapport via communication with patients which improves the standard of care delivered. To achieve results satisfactory to the wellbeing of affected populations, neurosurgical disciplines necessitate the aid of skilled nursing colleagues. However, there is a lack of relevant technology, innovations, and funding alongside human resources in LMICs.

Conclusion

Education, training, and dynamic collaboration are crucial factors for neurosurgical nurses to provide the best quality of care to patients. It is also pivotal to focus on research concerning the present issue, implement further policies which encourage dynamic cooperation between the neurosurgical multidisciplinary team, and collaborate on a global level to enhance neurosurgical nursing in LMICs.

Prognostic Modeling of Overall Survival in Glioblastoma Using Radiomic Features Derived from Intraoperative Ultrasound: A Multi-Institutional Study

BACKGROUND

Accurate prognostic models are essential for optimizing treatment strategies for glioblastoma, the most aggressive primary brain tumor. While other neuroimaging modalities have demonstrated utility in predicting overall survival (OS), intraoperative ultrasound (iUS) remains underexplored for this purpose. This study aimed to evaluate the prognostic potential of iUS radiomics in glioblastoma patients in a multi-institutional cohort.

METHODS

This retrospective study included patients diagnosed with glioblastoma from the multicenter Brain Tumor Intraoperative (BraTioUS) database. A single 2D iUS slice, showing the largest tumor diameter, was selected for each patient. Radiomic features were extracted and subjected to feature selection, and clinical data were collected. Using a fivefold cross-validation strategy, Cox proportional hazards models were built using radiomic features alone, clinical data alone, and their combination. Model performance was assessed via the concordance index (C-index).

RESULTS

A total of 114 patients met the inclusion criteria, with a mean age of 56.88 years, a median OS of 382 days, and a median preoperative tumor volume of 32.69 cm3. Complete tumor resection was achieved in 51.8% of the patients. In the testing cohort, the combined model achieved a mean C-index of 0.87 (95% CI: 0.76-0.98), outperforming the radiomic model (C-index: 0.72, 95% CI: 0.57-0.86) and the clinical model (C-index: 0.73, 95% CI: 0.60-0.87).

CONCLUSIONS

Intraoperative ultrasound relies on acoustic properties for tissue characterization, capturing unique features of glioblastomas. This study demonstrated that radiomic features derived from this imaging modality have the potential to support the development of survival models.

A method for mimicking tumour tissue in brain ex-vivo ultrasound for research application and clinical training

BACKGROUND

Intraoperative ultrasound is becoming a common tool in neurosurgery. However, effective simulation methods are limited. Current, commercial, and homemade phantoms lack replication of anatomical correctness and texture complexity of brain and tumour tissue in ultrasound images.

METHODS

We utilise ex-vivo brain tissue, as opposed to synthetic materials, to achieve realistic echogenic complexity and anatomical correctness. Agar, at 10-20% concentrate, is injected into brain tissue to simulate the tumour mass. A commercially available phantom was purchased for benchmarking.

RESULTS

Qualitative analysis is performed by experienced professionals, measuring the impact of the addition of agar and comparing it to the commercial phantom. Overall, the use of ex vivo tissue was deemed more accurate and representative, compared to the synthetic materials-based phantom, as it provided good visualisation of real brain anatomy and good contrast within tissue. The agar tumour correctly produced a region of higher echogenicity with slight diffusion along the margin and expected interaction with the neighbouring anatomy.

CONCLUSION

The proposed method for creating tumour-mimicking tissue in brain tissue is inexpensive, accurate, and simple. Beneficial for both the trainee clinician and the researcher. A total of 576 annotated images are made publicly available upon request.

The Glial Scar: To Penetrate or Not for Motor Pathway Restoration?

Although notable progress has been made, restoring motor function from the brain to the muscles continues to be a substantial clinical challenge in motor neuron diseases/disorders such as spinal cord injury (SCI). While cell transplantation has been widely explored as a potential therapeutic method for reconstructing functional motor pathways, there remains considerable opportunity for enhancing its therapeutic effectiveness. We reviewed studies on motor pathway regeneration to identify molecular and ultrastructural cues that could enhance the efficacy of cell transplantation. While the glial scar is often cited as an intractable barrier to axon regeneration, this mainly applies to axons trying to penetrate its "core" to reach the opposite side. However, the glial scar exhibits a "duality," with an anti-regenerative core and a pro-regenerative "surface." This surface permissiveness is attributed to pro-regenerative molecules, such as laminin in the basement membrane (BM). Transplanting donor cells onto the BM, which forms plastically after injury, may significantly enhance the efficacy of cell transplantation. Specifically, forming detour pathways between transplanted cells and endogenous propriospinal neurons on the pro-regenerative BM may efficiently bypass the intractable scar core and promote motor pathway regeneration. We believe harnessing the tissue's innate repair capacity is crucial, and targeting post-injury plasticity in astrocytes and Schwann cells, especially those associated with the BM that has predominantly been overlooked in the field of SCI research, can advance motor system restoration to a new stage. A shift in cell delivery routes-from the traditional intra-parenchymal (InP) route to the transplantation of donor cells onto the pro-regenerative BM via the extra-parenchymal (ExP) route-may signify a transformative step forward in neuro-regeneration research. Practically, however, the complementary use of both InP and ExP methods may offer the most substantial benefit for restoring motor pathways. We aim for this review to deepen the understanding of cell transplantation and provide a framework for evaluating the efficacy of this therapeutic modality in comparison to others.

Intraoperative Ultrasound in Brain Surgery

This study describes the essential components and the technique of intraoperative ultrasound (IOUS), including probe selection and techniques used to produce quality images. Case examples are given to illustrate the value and the accuracy of IOUS in intracranial surgery of companion animals. IOUS has proven an invaluable addition to intracranial surgery, especially in real-time localization of the mass, identifying borders between mass and normal cerebral tissue, and identifying vascular supply to the mass.

Unveiling the potential of ultrasound in brain imaging: Innovations, challenges, and prospects

Within medical imaging, ultrasound serves as a crucial tool, particularly in the realms of brain imaging and disease diagnosis. It offers superior safety, speed, and wider applicability compared to Magnetic Resonance Imaging (MRI) and X-ray Computed Tomography (CT). Nonetheless, conventional transcranial ultrasound applications in adult brain imaging face challenges stemming from the significant acoustic impedance contrast between the skull bone and soft tissues. Recent strides in ultrasound technology encompass a spectrum of advancements spanning tissue structural imaging, blood flow imaging, functional imaging, and image enhancement techniques. Structural imaging methods include traditional transcranial ultrasound techniques and ultrasound elastography. Transcranial ultrasound assesses the structure and function of the skull and brain, while ultrasound elastography evaluates the elasticity of brain tissue. Blood flow imaging includes traditional transcranial Doppler (TCD), ultrafast Doppler (UfD), contrast-enhanced ultrasound (CEUS), and ultrasound localization microscopy (ULM), which can be used to evaluate the velocity, direction, and perfusion of cerebral blood flow. Functional ultrasound imaging (fUS) detects changes in cerebral blood flow to create images of brain activity. Image enhancement techniques include full waveform inversion (FWI) and phase aberration correction techniques, focusing on more accurate localization and analysis of brain structures, achieving more precise and reliable brain imaging results. These methods have been extensively studied in clinical animal models, neonates, and adults, showing significant potential in brain tissue structural imaging, cerebral hemodynamics monitoring, and brain disease diagnosis. They represent current hotspots and focal points of ultrasound medical research. This review provides a comprehensive summary of recent developments in brain imaging technologies and methods, discussing their advantages, limitations, and future trends, offering insights into their prospects.

The Role of Transcranial Ultrasound Imaging in Intensive Care Treatment of Decompressive Hemicraniectomy Patients: A Retrospective Single-Center Analysis

Background: Post-hemicraniectomy patients often need extended intensive care treatment. While computed tomography (CT) is considered the gold standard for regular imaging, its frequent use could be linked to adverse clinical outcomes. This study aimed to assess bedside transcranial ultrasound (TUS) to capture intracranial anatomical structures and pathologies. Methods: We analyzed 19 patients treated in our neurosurgical ICU from 1 January 2023 to 1 February 2024. Six physicians from our unit (three residents and three attending physicians) conducted a retrospective evaluation. A total of 158 sessions, including multiple freeze frames and video footage, were analyzed, including 7 imaging categories, using a Likert scale. Subsequently, correlation between CT and TUS was evaluated for midline (ML) shift, subdural space, lateral ventricular width (LVW), and extent of intracerebral hematoma using the Pearson's correlation coefficient (r). Results: TUS was performed on average on 8.32/19.53 days (mean inpatient stay). It provided the lowest Likert scores for the imaging categories ventricular system, midline, subdural space, intraventricular catheter placement, and cortical gyration. Residents reported slightly inferior assessability, resulting in higher scores on the Likert scale (0.02-0.93 mean difference compared with attending physicians). A high correlation was shown in terms of ML shift, LVW, and intracerebral hematomas. No relevant correlation was shown in subdural space. Conclusions: TUS is a safe, cost-, and time-efficient method, potentially gaining relevance for imaging post-hemicraniectomy patients. In our setting, the method seemed effective in depicting intraventricular catheter placement, hydrocephalus, ML shift, and space-occupying lesions. Further improvement in image quality could potentially reduce the overall number of indicated CT scans.

Intraoperative superb microvascular ultrasound imaging in glioma: novel quantitative analysis correlates with tumour grade

Accurate grading of gliomas is critical to guide therapy and predict prognosis. The presence of microvascular proliferation is a hallmark feature of high grade gliomas which traditionally requires targeted surgical biopsy of representative tissue. Superb microvascular imaging (SMI) is a novel high resolution Doppler ultrasound technique which can uniquely define the microvascular architecture of whole tumours. We examined both qualitative and quantitative vascular features of gliomas captured with SMI, analysing flow signal density, vessel number, branching points, curvature, vessel angle deviation, fractal dimension, and entropy. Results indicate that high-grade gliomas exhibit significantly greater vascular complexity and disorganisation, with increased fractal dimension and entropy, correlating with known histopathological markers of aggressive angiogenesis. The integrated ROC model achieved high accuracy (AUC = 0.95), highlighting SMI's potential as a non-invasive diagnostic and prognostic tool. While further validation with larger datasets is required, this study opens avenues for SMI in glioma management, supporting intraoperative decision-making and informing future prognosis.

Treatment Options for IDH-Mutant Malignant Gliomas

OPINION STATEMENT

As the peak incidence of isocitrate dehydrogenase (IDH)-mutant gliomas is amongst young adults, there is a need to balance tumor control with long term side effects of therapy. Following initial clinical presentation and acquisition of contrasted diagnostic imaging, tissue diagnosis is essential in suspected diffuse glioma. Depending on the location and extent of disease, maximal surgical resection is preferred both for histologic diagnosis and initial therapy. Partial resection or biopsy alone is considered when the tumor cannot be completely resected or if there are clinical reservations regarding a more significant operation. The classification of diffuse glioma has evolved over time, with histopathology and molecular marker status guiding discussions of prognosis and postoperative management. In patients with IDH-mutant grade 2 glioma and low-risk features, observation with active surveillance is generally recommended following a gross total resection. For those with high-risk features, which historically included age > 40 years or subtotal resection, adjuvant chemotherapy and radiation therapy are generally recommended, however decisions for adjuvant therapy pose challenges as many of the landmark historical trials guiding adjuvant therapy were performed prior to the molecularly defined era. This is an area where multiple clinical trials are ongoing and hold promise to inform treatment paradigms, including recent data on the use of IDH-mutant inhibitors in grade 2 tumors with recurrent or residual disease. For IDH-mutant grade 3 and 4 glioma, adjuvant chemotherapy and radiation are recommended for all patients after initial resection.

Neuronavigation Combined With Intraoperative Ultrasound and Intraoperative Magnetic Resonance Imaging Versus Neuronavigation Alone in Diffuse Glioma Surgery

OBJECTIVE

This study aimed to integrate intraoperative ultrasound and magnetic resonance imaging (IMRI) with neuronavigation (NN) to create a multimodal surgical protocol for diffuse gliomas. Clinical outcomes were compared to the standard NN-guided protocol.

METHODS

Adult patients with diffuse gliomas scheduled for gross total resection (GTR) were consecutively enrolled to undergo either NN-guided surgery (80 patients, July 2019-January 2022) or multimodal-integrated surgery (80 patients, February 2022-August 2023). The primary outcomes were the extent of resection (EOR) and GTR. Additional outcomes included operative time, blood loss, length of hospital stay, and patient survival.

RESULTS

GTR was achieved in 69% of patients who underwent multimodal-integrated surgery, compared to 43% of those who received NN-guided surgery (P = 0.002). Residual tumor was detected by IMRI in 53 patients (66%), and further GTR was achieved in 28 of these cases. The median EOR was 100% for the multimodal group and 95% for the NN-guided group (P = 0.001), while the median operative time was 8 hours versus 5 hours (P < 0.001). Neurological deficits, blood loss, and hospital stay durations were comparable between 2 groups. Multimodal-integrated surgery resulted in greater EOR and higher GTR rates in contrast-enhancing gliomas, gliomas in eloquent regions, and large gliomas (≥50 mm). GTR in glioblastomas and other contrast-enhancing gliomas contributed to improved overall survival.

CONCLUSIONS

Compared to standard NN-guided surgery, multimodal-integrated surgery using NN, IMRI, and intraoperative ultrasound significantly increased the EOR and GTR rates for diffuse gliomas.

Learning to Match 2D Keypoints Across Preoperative MR and Intraoperative Ultrasound

We propose in this paper a texture-invariant 2D keypoints descriptor specifically designed for matching preoperative Magnetic Resonance (MR) images with intraoperative Ultrasound (US) images. We introduce a matching-by-synthesis strategy, where intraoperative US images are synthesized from MR images accounting for multiple MR modalities and intraoperative US variability. We build our training set by enforcing keypoints localization over all images then train a patient-specific descriptor network that learns texture-invariant discriminant features in a supervised contrastive manner, leading to robust keypoints descriptors. Our experiments on real cases with ground truth show the effectiveness of the proposed approach, outperforming the state-of-the-art methods and achieving 80.35% matching precision on average.

Intraoperative glioblastoma surgery-current challenges and clinical trials: An update

Surgical excision is an important part of the multimodal therapy strategy for patients with glioblastoma, a very aggressive and invasive brain tumor. While major advances in surgical methods and technology have been accomplished, numerous hurdles remain in the field of glioblastoma surgery. The purpose of this literature review is to offer a thorough overview of the current challenges in glioblastoma surgery. We reviewed the difficulties associated with tumor identification and visualization, resection extent, neurological function preservation, tumor margin evaluation, and inclusion of sophisticated imaging and navigation technology. Understanding and resolving these challenges is critical in order to improve surgical results and, ultimately, patient survival.

3D ultrasound-augmented image guidance for surgery of high-grade gliomas - A quantitative analysis focused on the extent of resection

Background

We have retrospectively reviewed our series of brain tumor patients operated on using 3D IntraOperative UltraSound (IOUS) to report technical advantages and areas of improvement.

Methods

Clinical and radiological data of patients with a diagnosis of high-grade glioma IV operated with and without IOUS were retrieved and analyzed.

Results

We have found 391 patients operated using IOUS coupled with neuronavigation and 257 using neuronavigation standalone. We have selected a pool of 60 patients with a diagnosis of GlioBlastoma (GB), comparing two equally sized groups operated with and without IOUS, respectively. The average extent of resection (EOR) in the IOUS group was 93%, while in the control group, it was 80%. IOUS was significantly associated with improved EOR (P < 0.0004), even when accounting for other factors affecting EOR. The average overall survival (OS) was 13.4 months, and the average progression-free survival (PFS) was 7.4 months. The Cox proportional hazard model showed an advantage in OS on patients operated using the IOUS. No statistically significant effect was observed on PFS.

Conclusion

Intraoperative ultrasound coupled with image guidance is associated with an improved EOR and possibly an improved OS. While we are aware of several limitations related to the present analysis, these data support the routine use of IOUS as a safe and reliable technology. Larger, prospective series with updated IOUS technology are desirable to verify the accuracy of these results.

Intraoperative MRI: A Review of Applications Across Neurosurgical Specialties

Intraoperative MRI (iMRI) made its debut to great fanfare in the mid-1990s. However, the enthusiasm for this technology with seemingly obvious benefits for neurosurgeons has waned. We review the benefits and utility of iMRI across the field of neurosurgery and present an overview of the evidence for iMRI for multiple neurosurgical disciplines: tumor, skull base, vascular, pediatric, functional, and spine. Publications on iMRI have steadily increased since 1996, plateauing with approximately 52 publications per year since 2011. Tumor surgery, especially glioma surgery, has the most evidence for the use of iMRI contributing more than 50% of all iMRI publications, with increased rates of gross total resection in both adults and children, providing a potential survival benefit. Across multiple neurosurgical disciplines, the ability to use a multitude of unique sequences (diffusion tract imaging, diffusion-weighted imaging, magnetic resonance angiography, blood oxygenation level-dependent) allows for specialization of imaging for various types of surgery. Generally, iMRI allows for consideration of anatomic changes and real-time feedback on surgical outcomes such as extent of resection and instrument (screw, lead, electrode) placement. However, implementation of iMRI is limited by cost and feasibility, including the need for installation, shielding, and compatible tools. Evidence for iMRI use varies greatly by specialty, with the most evidence for tumor, vascular, and pediatric neurosurgery. The benefits of real-time anatomic imaging, a lack of radiation, and evaluation of surgical outcomes are limited by the cost and difficulty of iMRI integration. Nonetheless, the ability to ensure patients are provided by a maximal yet safe treatment that specifically accounts for their own anatomy and highlights why iMRI is a valuable and underutilized tool across multiple neurosurgical subspecialties.

Intraoperative ultrasound and magnetic resonance comparative analysis in brain tumor surgery: a valuable tool to flatten ultrasound's learning curve

BACKGROUND

Intraoperative ultrasound (IOUS) is a profitable tool for neurosurgical procedures' assistance, especially in neuro-oncology. It is a rapid, ergonomic and reproducible technique. However, its known handicap is a steep learning curve for neurosurgeons. Here, we describe an interesting postoperative analysis that provides extra feedback after surgery, accelerating the learning process.

METHOD

We conducted a descriptive retrospective unicenter study including patients operated from intra-axial brain tumors using neuronavigation (Curve, Brainlab) and IOUS (BK-5000, BK medical) guidance. All patients had preoperative Magnetic Resonance Imaging (MRI) prior to tumor resection. During surgery, 3D neuronavigated IOUS studies (n3DUS) were obtained through craniotomy N13C5 transducer's integration to the neuronavigation system. At least two n3DUS studies were obtained: prior to tumor resection and at the resection conclusion. A postoperative MRI was performed within 48 h. MRI and n3DUS studies were posteriorly fused and analyzed with Elements (Brainlab) planning software, permitting two comparative analyses: preoperative MRI compared to pre-resection n3DUS and postoperative MRI to post-resection n3DUS. Cases with incomplete MRI or n3DUS studies were withdrawn from the study.

RESULTS

From April 2022 to March 2024, 73 patients were operated assisted by IOUS. From them, 39 were included in the study. Analyses comparing preoperative MRI and pre-resection n3DUS showed great concordance of tumor volume (p < 0,001) between both modalities. Analysis comparing postoperative MRI and post-resection n3DUS also showed good concordance in residual tumor volume (RTV) in cases where gross total resection (GTR) was not achieved (p < 0,001). In two cases, RTV detected on MRI that was not detected intra-operatively with IOUS could be reviewed in detail to recheck its appearance.

CONCLUSIONS

Post-operative comparative analyses between IOUS and MRI is a valuable tool for novel ultrasound users, as it enhances the amount of feedback provided by cases and could accelerate the learning process, flattening this technique's learning curve.

Quenched Zwitterionic Cyclic Arg-Gly-Asp-Containing Pentapeptide Probe for Real-Time Brain Tumor Imaging

The efficacy of glioblastoma treatment is closely associated with complete tumor resection. However, conventional surgical techniques often result in incomplete removal, leading to poor prognosis. A major challenge is the accurate delineation of tumor margins from healthy tissues. Imaging-guided surgery, particularly using fluorescent probes, is a promising solution for intraoperative guidance. The recently developed 'always-on' types of targeted fluorescence probes generate signals irrespective of their presence in tumor cells or in blood circulation, hampering their effectiveness. Here, we propose a novel activatable fluorescence imaging probe, Q-cRGD, that targets glioma cells via the specific binding of the cyclic Arg-Gly Asp-containing pentapeptide (cRGD) to integrins. The Q-cRGD probe was synthesized by conjugating a near-infrared (NIR) dye to a tryptophan quencher via a disulfide linkage, including a cRGD-targeting ligand. This activatable probe remained inactive until the redox-responsive cleavage of the disulfide linkage occurred within the target cell. The zwitterionic nature of NIR dyes minimizes nonspecific interactions with serum proteins, thereby enhancing the tumor-to-background signal ratio (TBR). An in vivo fluorescence imaging study demonstrated a TBR value of 2.65 within 3 h of the intravenous injection of Q-cRGD, confirming its potential utility in imaging-guided brain cancer surgery.

Challenges with segmenting intraoperative ultrasound for brain tumours

Objective - Addressing the challenges that come with identifying and delineating brain tumours in intraoperative ultrasound. Our goal is to both qualitatively and quantitatively assess the interobserver variation, amongst experienced neuro-oncological intraoperative ultrasound users (neurosurgeons and neuroradiologists), in detecting and segmenting brain tumours on ultrasound. We then propose that, due to the inherent challenges of this task, annotation by localisation of the entire tumour mass with a bounding box could serve as an ancillary solution to segmentation for clinical training, encompassing margin uncertainty and the curation of large datasets. Methods - 30 ultrasound images of brain lesions in 30 patients were annotated by 4 annotators - 1 neuroradiologist and 3 neurosurgeons. The annotation variation of the 3 neurosurgeons was first measured, and then the annotations of each neurosurgeon were individually compared to the neuroradiologist's, which served as a reference standard as their segmentations were further refined by cross-reference to the preoperative magnetic resonance imaging (MRI). The following statistical metrics were used: Intersection Over Union (IoU), Sørensen-Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD). These annotations were then converted into bounding boxes for the same evaluation. Results - There was a moderate level of interobserver variance between the neurosurgeons [ I o U : 0.789 , D S C : 0.876 , H D : 103.227 ] and a larger level of variance when compared against the MRI-informed reference standard annotations by the neuroradiologist, mean across annotators [ I o U : 0.723 , D S C : 0.813 , H D : 115.675 ] . After converting the segments to bounding boxes, all metrics improve, most significantly, the interquartile range drops by [ I o U : 37 % , D S C : 41 % , H D : 54 % ] . Conclusion - This study highlights the current challenges with detecting and defining tumour boundaries in neuro-oncological intraoperative brain ultrasound. We then show that bounding box annotation could serve as a useful complementary approach for both clinical and technical reasons.

Resection of supratentorial high-grade gliomas availing of neuronavigation matched intraoperative ultrasound and Fluorescein: How far is it safe to push the resection?

Background

High-Grade Gliomas are the most common primary brain malignancies and despite the multimodal treatment, and the increasing amount of adjuvant treatment options the overall prognosis remains dismal. The present investigation aims to analyze the safety profile of the use of intraoperative ultrasounds (Io-US) in a homogeneous and matched cohort of patients suffering from High-grade gliomas (HGG) operated on with or without the aid of Io-US and Fluorescein in specific relation to the incidence of neurological and functional status sequelae.

Methods and materials

A retrospective analysis was performed on 74 patients affected by HGG. 22 patients were treated with Io-US matched with neuronavigational system (Group A); 15 patients were treated both with the use of Io-US and Fluorescein matched with neuronavigational system (Group B); 37 patients were treated with the use of the neuronavigational system only (Group C). Primary endpoints were the extent of resection and functional outcome (measured with Karnofski Performance Status).

Results

Significative differences were observed in terms of a higher extent of resection in Group B. In a multivariate analysis, this data appears to be independent of the location (eloquent/non-eloquent) of the lesion and from its histology. Regarding functional outcomes, no differences were detected between the two groups.

Conclusions

The present study is the first that analyzes the simultaneous use of Io-US and Fluorescein, and the results demonstrate that these two instruments together could improve the extent of resection in HGG while ensuring good outcomes in terms of functional status.

Revolutionizing Brain Tumor Care: Emerging Technologies and Strategies

Glioblastoma multiforme (GBM) is one of the most aggressive forms of brain tumor, characterized by a daunting prognosis with a life expectancy hovering around 12-16 months. Despite a century of relentless research, only a select few drugs have received approval for brain tumor treatment, largely due to the formidable barrier posed by the blood-brain barrier. The current standard of care involves a multifaceted approach combining surgery, irradiation, and chemotherapy. However, recurrence often occurs within months despite these interventions. The formidable challenges of drug delivery to the brain and overcoming therapeutic resistance have become focal points in the treatment of brain tumors and are deemed essential to overcoming tumor recurrence. In recent years, a promising wave of advanced treatments has emerged, offering a glimpse of hope to overcome the limitations of existing therapies. This review aims to highlight cutting-edge technologies in the current and ongoing stages of development, providing patients with valuable insights to guide their choices in brain tumor treatment.

Ultrasound-Guided Resection of High-Grade Gliomas: A Single-Arm Meta-Analysis

BACKGROUND

High-grade gliomas (HGGs) present a challenge in neuro-oncology, often necessitating surgical resection for optimal management. Ultrasound holds promise in achieving better gross total resection (GTR) and improving outcomes. This meta-analysis systematically evaluates literature providing robust evidence on the use of intraoperative ultrasonography (iUSG) in HGG resection.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines a comprehensive search was made across PubMed, Embase, Cochrane, and Web of Science utilized terms related to iUSG for HGG resection. The meta-analysis examined randomized trials and observational cohort studies on iUSG-guided HGG resection. GTR, subtotal resection, and postresection complications were assessed. Statistical analysis, employing R software for a single proportion analysis with confidence intervals of 95%, I2 statistics for heterogeneity, and the instrumental variables method with restricted maximum likelihood for a random effects model.

RESULTS

A total of 178 patients were included in our study. The GTR overall rate in patients with iUSG-guided resection was found to be 64% (95% confidence interval: 46%-81%). Two-dimensional ultrasound remains dominant at 80% against other options of ultrasound. Complications were reported at a 15% rate (95% confidence interval: 7%-23%).

CONCLUSIONS

Our study provided robust data on the utilization of iUSG-guided resection regarding the attainment of GTR and the complications related to resection. However, challenges such as outcome heterogeneity and limited complication reporting highlight the need for further research to optimize iUSG in HGG treatment. Long-term follow-up studies on patient survival and postsurgery quality of life will complement existing literature, guiding clinical practices in managing HGG.

Enabling Navigation and Augmented Reality in the Sitting Position in Posterior Fossa Surgery Using Intraoperative Ultrasound

Despite its broad use in cranial and spinal surgery, navigation support and microscope-based augmented reality (AR) have not yet found their way into posterior fossa surgery in the sitting position. While this position offers surgical benefits, navigation accuracy and thereof the use of navigation itself seems limited. Intraoperative ultrasound (iUS) can be applied at any time during surgery, delivering real-time images that can be used for accuracy verification and navigation updates. Within this study, its applicability in the sitting position was assessed. Data from 15 patients with lesions within the posterior fossa who underwent magnetic resonance imaging (MRI)-based navigation-supported surgery in the sitting position were retrospectively analyzed using the standard reference array and new rigid image-based MRI-iUS co-registration. The navigation accuracy was evaluated based on the spatial overlap of the outlined lesions and the distance between the corresponding landmarks in both data sets, respectively. Image-based co-registration significantly improved (p < 0.001) the spatial overlap of the outlined lesion (0.42 ± 0.30 vs. 0.65 ± 0.23) and significantly reduced (p < 0.001) the distance between the corresponding landmarks (8.69 ± 6.23 mm vs. 3.19 ± 2.73 mm), allowing for the sufficient use of navigation and AR support. Navigated iUS can therefore serve as an easy-to-use tool to enable navigation support for posterior fossa surgery in the sitting position.

Optical Methods for Brain Tumor Detection: A Systematic Review

Background: In brain tumor surgery, maximal tumor resection is typically desired. This is complicated by infiltrative tumor cells which cannot be visually distinguished from healthy brain tissue. Optical methods are an emerging field that can potentially revolutionize brain tumor surgery through intraoperative differentiation between healthy and tumor tissues. Methods: This study aimed to systematically explore and summarize the existing literature on the use of Raman Spectroscopy (RS), Hyperspectral Imaging (HSI), Optical Coherence Tomography (OCT), and Diffuse Reflectance Spectroscopy (DRS) for brain tumor detection. MEDLINE, Embase, and Web of Science were searched for studies evaluating the accuracy of these systems for brain tumor detection. Outcome measures included accuracy, sensitivity, and specificity. Results: In total, 44 studies were included, covering a range of tumor types and technologies. Accuracy metrics in the studies ranged between 54 and 100% for RS, 69 and 99% for HSI, 82 and 99% for OCT, and 42 and 100% for DRS. Conclusions: This review provides insightful evidence on the use of optical methods in distinguishing tumor from healthy brain tissue.

Achieving Gross Total Resection in Neurosurgery: A Review of Intraoperative Techniques and Their Influence on Surgical Goals

The definition of complete resection in neurosurgery depends on tumor type, surgical aims, and postoperative investigations, directly guiding the choice of intraoperative tools. Most common tumor types present challenges in achieving complete resection due to their infiltrative nature and anatomical constraints. The development of adjuvant treatments has altered the balance between oncological aims and surgical risks. We review local recurrence associated with incomplete resection based on different definitions and emphasize the importance of achieving maximal safe resection in all tumor types. Intraoperative techniques that aid surgeons in identifying tumor boundaries are used in practice and in preclinical or clinical research settings. They encompass both conservative and invasive techniques. Among them, morphological tools include imaging modalities such as intraoperative magnetic resonance imaging, ultrasound, and optical coherence tomography. Fluorescence-guided surgery, mainly using 5-aminolevulinic acid, enhances gross total resection in glioblastomas. Nuclear methods, including positron emission tomography probes, provide tumor detection based on beta or gamma emission after a radiotracer injection. Mass spectrometry- and spectroscopy-based methods offer molecular insights. The adoption of these techniques depends on their relevance, effectiveness, and feasibility. With the emergence of positron emission tomography imaging for use in recurrence benchmarking, positron emission tomography probes raise particular interest among those tools. While all such tools provide valuable insights, their clinical benefits need further evaluation.

Advances in Intraoperative Imaging for Vascular Neurosurgery

Cerebrovascular surgery has many intraoperative imaging modalities available. Modern technologies include intraoperative digital subtraction angiogram, indocyanine green (ICG) angiography, relative fluorescent measurement with ICG, and ultrasound. Each of these can be used effectively in the treatment of open aneurysm and arteriovenous malformation surgeries, in addition to arteriovenous fistula surgery, and cerebral bypass surgery.

Multiple surgical resections for progressive IDH wildtype glioblastoma-is it beneficial?

PURPOSE

The role of repeat resection for recurrent glioblastoma (rGB) remains equivocal. This study aims to assess the overall survival and complications rates of single or repeat resection for rGB.

METHODS

A single-centre retrospective review of all patients with IDH-wildtype glioblastoma managed surgically, between January 2014 and January 2022, was carried out. Patient survival and factors influencing prognosis were analysed, using Kaplan-Meier and Cox regression methods.

RESULTS

Four hundred thirty-two patients were included, of whom 329 underwent single resection, 83 had two resections and 20 patients underwent three resections. Median OS (mOS) in the cohort who underwent a single operation was 13.7 months (95% CI: 12.7-14.7 months). The mOS was observed to be extended in patients who underwent second or third-time resection, at 22.9 months and 44.7 months respectively (p < 0.001). On second operation achieving > 95% resection or residual tumour volume of < 2.25 cc was significantly associated with prolonged survival. There was no significant difference in overall complication rates between primary versus second (p = 0.973) or third-time resections (p = 0.312). The use of diffusion tensor imaging (DTI) guided resection was associated with reduced post-operative neurological deficit (RR 0.37, p = 0.002), as was use of intraoperative ultrasound (iUSS) (RR 0.45, p = 0.04).

CONCLUSIONS

This study demonstrates potential prolongation of survival for rGB patients undergoing repeat resection, without significant increase in complication rates with repeat resections. Achieving a more complete repeat resection improved survival. Moreover, the use of intraoperative imaging adjuncts can maximise tumour resection, whilst minimising the risk of neurological deficit.

Shedding light on ultrasound in action: Optical and optoacoustic monitoring of ultrasound brain interventions

Monitoring brain responses to ultrasonic interventions is becoming an important pillar of a growing number of applications employing acoustic waves to actuate and cure the brain. Optical interrogation of living tissues provides a unique means for retrieving functional and molecular information related to brain activity and disease-specific biomarkers. The hybrid optoacoustic imaging methods have further enabled deep-tissue imaging with optical contrast at high spatial and temporal resolution. The marriage between light and sound thus brings together the highly complementary advantages of both modalities toward high precision interrogation, stimulation, and therapy of the brain with strong impact in the fields of ultrasound neuromodulation, gene and drug delivery, or noninvasive treatments of neurological and neurodegenerative disorders. In this review, we elaborate on current advances in optical and optoacoustic monitoring of ultrasound interventions. We describe the main principles and mechanisms underlying each method before diving into the corresponding biomedical applications. We identify areas of improvement as well as promising approaches with clinical translation potential.

Advances in Neuro-Oncological Imaging: An Update on Diagnostic Approach to Brain Tumors

This study delineates the pivotal role of imaging within the field of neurology, emphasizing its significance in the diagnosis, prognostication, and evaluation of treatment responses for central nervous system (CNS) tumors. A comprehensive understanding of both the capabilities and limitations inherent in emerging imaging technologies is imperative for delivering a heightened level of personalized care to individuals with neuro-oncological conditions. Ongoing research in neuro-oncological imaging endeavors to rectify some limitations of radiological modalities, aiming to augment accuracy and efficacy in the management of brain tumors. This review is dedicated to the comparison and critical examination of the latest advancements in diverse imaging modalities employed in neuro-oncology. The objective is to investigate their respective impacts on diagnosis, cancer staging, prognosis, and post-treatment monitoring. By providing a comprehensive analysis of these modalities, this review aims to contribute to the collective knowledge in the field, fostering an informed approach to neuro-oncological care. In conclusion, the outlook for neuro-oncological imaging appears promising, and sustained exploration in this domain is anticipated to yield further breakthroughs, ultimately enhancing outcomes for individuals grappling with CNS tumors.

The Value of Intraoperative Ultrasound in Brain Surgery

Favorable clinical outcomes in adult and pediatric neurosurgical oncology generally depend on the extent of tumor resection (EOR). Maximum safe resection remains the main aim of surgery in most intracranial tumors. Despite the accuracy of intraoperative magnetic resonance imaging (iMRI) in the detection of residual intraoperatively, it is not widely implemented worldwide owing to enormous cost and technical difficulties. Over the past years, intraoperative ultrasound (IOUS) has imposed itself as a valuable and reliable intraoperative tool guiding neurosurgeons to achieve gross total resection (GTR) of intracranial tumors.Being less expensive, feasible, doesn't need a high level of training, doesn't need a special workspace, and being real time with outstanding temporal and spatial resolution; all the aforementioned advantages give a superiority for IOUS in comparison to iMRI during resection of brain tumors.In this chapter, we spot the light on the technical nuances, advanced techniques, outcomes of resection, pearls, and pitfalls of the use of IOUS during the resection of brain tumors.

From Microscopic to Exoscopic Microsurgery: Are We Facing a Change of Paradigm?

BACKGROUND

Neurosurgery is a medical branch characterized by small and deep surgical field with the need of manipulation and dissection of anatomical structures. High light and magnification are required in order to avoid injuries to important anatomical structures and to avoid permanent neurological deficits. Introduction of operative microscope made a change of paradigm in neurosurgery allowing to better see what could not be seen with common light. Nowadays, introduction of several technologies have increased the safety and efficacy of neurosurgery. Among new technologies, the 3D exoscope is emerging pretending to shift the paradigm of microneurosurgery. In this work, we aim to show our first experience with the use of the exoscope showing advantages and disadvantages.

MATERIALS AND METHODS

We reviewed our surgical database from the introduction of the exoscope in our department (in November 2020 temporarily; then from November 2021 definitively) searching for all the microsurgery interventions performed in the period.

RESULTS

From the introduction of the exoscope in our department, we operated 244 cases with the OM and 228 with the exoscope. We operated 175 lesions located in the supratentorial compartment, 29 in the infratentorial, and 24 in the spinal column. Regarding the OM, the ratios were as follows: 122 females and 122 males; 235 adults and 9 children; 66 supratentorial lesions, 14 infratentorial lesions, and 164 spine surgeries. Our team showed a progressive switch from the microscope to the exoscope. Only one member of our team preferred to continue to use the standard operative microscope.

CONCLUSIONS

Our experience showed no complications related to the use of the exoscope that proved to be safe and effective both for surgery and teaching.

Multimodality Structural and Functional Monitoring in Brain Tumor Surgery: The Role of IONM and IOUS

Brain tumor surgery represents the pinnacle of technical and technological advances in the neurosurgery. The goal remains optimized extent of resection with preservation of neurological function. The benefit of a multimodal structural and functional intra-operative monitoring approach is to improve the ability of the surgeon to achieve the goal of optimized surgical resection. Despite significant technological advances, challenges in defining tumor and functional neural tissue interface remain a significant barrier. The opportunity to address this challenge, however, presents us with an exciting path ahead.

The surgical management of diffuse gliomas: Current state of neurosurgical management and future directions

After recent updates to the World Health Organization pathological criteria for diagnosing and grading diffuse gliomas, all major North American and European neuro-oncology societies recommend a maximal safe resection as the initial management of a diffuse glioma. For neurosurgeons to achieve this goal, the surgical plan for both low- and high-grade gliomas should be to perform a supramaximal resection when feasible based on preoperative imaging and the patient's performance status, utilizing every intraoperative adjunct to minimize postoperative neurological deficits. While the surgical approach and technique can vary, every effort must be taken to identify and preserve functional cortical and subcortical regions. In this summary statement on the current state of the field, we describe the tools and technologies that facilitate the safe removal of diffuse gliomas and highlight intraoperative and postoperative management strategies to minimize complications for these patients. Moreover, we discuss how surgical resections can go beyond cytoreduction by facilitating biological discoveries and improving the local delivery of adjuvant chemo- and radiotherapies.

Intraoperative Navigated Three-Dimensional Ultrasound Guidance Improves Resection in Gliomas Compared with Standard Two-Dimensional Ultrasound-Results from a Comparative Cohort Study

OBJECTIVE

Intraoperative ultrasound is a promising tool for intraoperative tumor resection control. Navigated three-dimensional US (n3DUS) has many benefits over standard two-dimensional US (2DUS).

METHODS

Two cohorts (2DUS and n3DUS) of patients with histologically confirmed adult diffuse gliomas undergoing US-guided resection control were compared. The primary outcomes assessed were extent of resection and morbidity. Multivariate analysis was performed to account for tumor characteristics (delineation and eloquence) and surgeon experience, which could confound the results.

RESULTS

n3DUS was used more often (n = 252) than 2DUS (n = 86). Tumor delineation was similar in 2DUS and n3DUS cohorts, although the n3DUS cohort included more nonenhancing, histologically lower grade (2-3) gliomas and had more gliomas located in eloquent regions; also, n3DUS was more often used by senior surgeons. Gross total resection (GTR) rates were 47%, and major morbidity was 9.5%. On multivariate analysis, after controlling for all other variables between the 2 groups, patients with well-delineated tumors, patients with prior treatment, and patients who underwent n3DUS were more likely to have GTR (adjusted odds ratios 3.0, 1.8, and 2.2, respectively), whereas patients with tumors in eloquent locations were half as likely (adjusted odds ratio 0.5) to have GTR. Eloquent located tumors were likely to be associated with higher neurological morbidity, although major morbidity was not significantly different.

CONCLUSIONS

Good delineation, noneloquent location, and use of n3DUS was associated with a higher probability of GTR in glioma surgery. Surgeons' experience did not influence the extent of resection. Morbidity was predominantly associated with eloquent location, independent of all other factors.

Application of intraoperative ultrasound in the resection of high-grade gliomas

The incidence of gliomas is approximately 3-5/100,000, with high-grade gliomas accounting for approximately 30-40% of these tumors. Surgery is a confirmed positive factor in prolonging the survival of these patients, and a larger resection range means a longer survival time. Therefore, surgery for high-grade glioma patients should aim to maximize the extent of resection while preserving neurological function to achieve a better quality of life. There is consensus regarding the need to lengthen progression-free survival (PFS) and overall survival (OS) times. In glioma surgery, methods such as intraoperative computed tomography (ICT), intraoperative magnetic resonance imaging (IMRI), navigation, 5-aminolevulinic acid (5-ALA), and intraoperative ultrasound (IOUS) are used to achieve an expanded resection during the surgical procedure. IOUS has been increasingly used in the surgery of high-grade gliomas and various tumors due to its convenient intraoperative use, its flexible repeatability, and the relatively low cost of operating room construction. With the continuous upgrading of ultrasound equipment, IOUS has been able to better assist surgeons in achieving an increased extent of resection. This review aims to summarize the application of ultrasound in the surgery of high-grade gliomas in the past decade, its improvement in patient prognosis, and its prospects.

Unified Brain MR-Ultrasound Synthesis using Multi-Modal Hierarchical Representations

We introduce MHVAE, a deep hierarchical variational autoencoder (VAE) that synthesizes missing images from various modalities. Extending multi-modal VAEs with a hierarchical latent structure, we introduce a probabilistic formulation for fusing multi-modal images in a common latent representation while having the flexibility to handle incomplete image sets as input. Moreover, adversarial learning is employed to generate sharper images. Extensive experiments are performed on the challenging problem of joint intra-operative ultrasound (iUS) and Magnetic Resonance (MR) synthesis. Our model outperformed multi-modal VAEs, conditional GANs, and the current state-of-the-art unified method (ResViT) for synthesizing missing images, demonstrating the advantage of using a hierarchical latent representation and a principled probabilistic fusion operation. Our code is publicly available.

Intraoperative Imaging and Optical Visualization Techniques for Brain Tumor Resection: A Narrative Review

Advancements in intraoperative visualization and imaging techniques are increasingly central to the success and safety of brain tumor surgery, leading to transformative improvements in patient outcomes. This comprehensive review intricately describes the evolution of conventional and emerging technologies for intraoperative imaging, encompassing the surgical microscope, exoscope, Raman spectroscopy, confocal microscopy, fluorescence-guided surgery, intraoperative ultrasound, magnetic resonance imaging, and computed tomography. We detail how each of these imaging modalities contributes uniquely to the precision, safety, and efficacy of neurosurgical procedures. Despite their substantial benefits, these technologies share common challenges, including difficulties in image interpretation and steep learning curves. Looking forward, innovations in this field are poised to incorporate artificial intelligence, integrated multimodal imaging approaches, and augmented and virtual reality technologies. This rapidly evolving landscape represents fertile ground for future research and technological development, aiming to further elevate surgical precision, safety, and, most critically, patient outcomes in the management of brain tumors.

Lightfield hyperspectral imaging in neuro-oncology surgery: an IDEAL 0 and 1 study

Introduction

Hyperspectral imaging (HSI) has shown promise in the field of intra-operative imaging and tissue differentiation as it carries the capability to provide real-time information invisible to the naked eye whilst remaining label free. Previous iterations of intra-operative HSI systems have shown limitations, either due to carrying a large footprint limiting ease of use within the confines of a neurosurgical theater environment, having a slow image acquisition time, or by compromising spatial/spectral resolution in favor of improvements to the surgical workflow. Lightfield hyperspectral imaging is a novel technique that has the potential to facilitate video rate image acquisition whilst maintaining a high spectral resolution. Our pre-clinical and first-in-human studies (IDEAL 0 and 1, respectively) demonstrate the necessary steps leading to the first in-vivo use of a real-time lightfield hyperspectral system in neuro-oncology surgery.

Methods

A lightfield hyperspectral camera (Cubert Ultris ×50) was integrated in a bespoke imaging system setup so that it could be safely adopted into the open neurosurgical workflow whilst maintaining sterility. Our system allowed the surgeon to capture in-vivo hyperspectral data (155 bands, 350-1,000 nm) at 1.5 Hz. Following successful implementation in a pre-clinical setup (IDEAL 0), our system was evaluated during brain tumor surgery in a single patient to remove a posterior fossa meningioma (IDEAL 1). Feedback from the theater team was analyzed and incorporated in a follow-up design aimed at implementing an IDEAL 2a study.

Results

Focusing on our IDEAL 1 study results, hyperspectral information was acquired from the cerebellum and associated meningioma with minimal disruption to the neurosurgical workflow. To the best of our knowledge, this is the first demonstration of HSI acquisition with 100+ spectral bands at a frame rate over 1Hz in surgery.

Discussion

This work demonstrated that a lightfield hyperspectral imaging system not only meets the design criteria and specifications outlined in an IDEAL-0 (pre-clinical) study, but also that it can translate into clinical practice as illustrated by a successful first in human study (IDEAL 1). This opens doors for further development and optimisation, given the increasing evidence that hyperspectral imaging can provide live, wide-field, and label-free intra-operative imaging and tissue differentiation.

The Big Bang of Deep Learning in Ultrasound-Guided Surgery: A Review

Ultrasound (US) imaging is a paramount modality in many image-guided surgeries and percutaneous interventions, thanks to its high portability, temporal resolution, and cost-efficiency. However, due to its imaging principles, the US is often noisy and difficult to interpret. Appropriate image processing can greatly enhance the applicability of the imaging modality in clinical practice. Compared with the classic iterative optimization and machine learning (ML) approach, deep learning (DL) algorithms have shown great performance in terms of accuracy and efficiency for US processing. In this work, we conduct a comprehensive review on deep-learning algorithms in the applications of US-guided interventions, summarize the current trends, and suggest future directions on the topic.

The Use of Contrast-Enhanced Ultrasound (CEUS) in the Evaluation of the Neonatal Brain

In recent years, advancements in technology have allowed the use of contrast-enhanced ultrasounds (CEUS) with high-frequency transducers, which in turn, led to new possibilities in diagnosing a variety of diseases and conditions in the field of radiology, including neonatal brain imaging. CEUSs overcome some of the limitations of conventional ultrasounds (US) and Doppler USs. It allows the visualization of dynamic perfusion even in the smallest vessels in the whole brain and allows the quantitative analysis of perfusion parameters. An increasing number of articles are published on the topic of the use of CEUSs on children each year. In the area of brain imaging, the CEUS has already proven to be useful in cases with clinical indications, such as hypoxic-ischemic injuries, stroke, intracranial hemorrhages, vascular anomalies, brain tumors, and infections. We present and discuss the basic principles of the CEUS and its safety considerations, the examination protocol for imaging the neonatal brain, and current and emerging clinical applications.

Discriminating Glioblastoma from Peritumoral Tissue by a Nanohole Array-Based Optical and Label-Free Biosensor

In glioblastoma (GBM) patients, maximal safe resection remains a challenge today due to its invasiveness and diffuse parenchymal infiltration. In this context, plasmonic biosensors could potentially help to discriminate tumor tissue from peritumoral parenchyma based on differences in their optical properties. A nanostructured gold biosensor was used ex vivo to identify tumor tissue in a prospective series of 35 GBM patients who underwent surgical treatment. For each patient, two paired samples, tumor and peritumoral tissue, were extracted. Then, the imprint left by each sample on the surface of the biosensor was individually analyzed, obtaining the difference between their refractive indices. The tumor and non-tumor origins of each tissue were assessed by histopathological analysis. The refractive index (RI) values obtained by analyzing the imprint of the tissue were significantly lower (p = 0.0047) in the peritumoral samples (1.341, Interquartile Range (IQR) 1.339-1.349) compared with the tumor samples (1.350, IQR 1.344-1.363). The ROC (receiver operating characteristic) curve showed the capacity of the biosensor to discriminate between both tissues (area under the curve, 0.8779, p < 0.0001). The Youden index provided an optimal RI cut-off point of 0.003. The sensitivity and specificity of the biosensor were 81% and 80%, respectively. Overall, the plasmonic-based nanostructured biosensor is a label-free system with the potential to be used for real-time intraoperative discrimination between tumor and peritumoral tissue in patients with GBM.