Objective assessment of utility of intraoperative ultrasound in resection of central nervous system tumors: A cost-effective tool for intraoperative navigation in neurosurgery

The Landscape of Neurosurgical Oncology Adjunct Usage in Africa: A Scoping Review

BACKGROUND

Intraoperative neurosurgical adjuncts improve extent of resection whilst mitigating patient morbidity. The delivery of neurosurgical care via these adjuncts is the norm in high-income countries, but there is yet to be a study highlighting the usage of neurosurgical oncology adjuncts in Africa. This paper aims to provide awareness of the use of these adjuncts in Africa, reasons for limited procurement, and possible solutions to the problem.

METHODS

This scoping review was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis Extension for Scoping Reviews guidelines. Semantic derivatives of neurosurgical oncology, adjuncts, and Africa were applied to medical databases. Studies in Africa with outcomes relating to adjunct usage, morbidity, mortality, and quality of life were selected. Book chapters and reviews were excluded.

RESULTS

Thirteen studies with 287 patients (0.5 to 74 years) were included in the final analysis. Most studies were cohort observational (46.2%) and originated from South Africa (46.2%). Meningioma was the most prevalent tumor histology (39.4%), and neuronavigation was the most readily used adjunct for surgical resection (30.8%). Using adjuncts, gross total resection was achieved in close to half the patient cohort (49.8%). Limited technology, lack of experience, cost of equipment, and inconsistency in power supply were noted as factors contributing to lack of adjunct usage.

CONCLUSIONS

Neurosurgical adjuncts provide significant benefits in neurosurgical oncology. There is limited utilization of intraoperative adjuncts in most of Africa owing to limited resources and experienced professionals. Bilateral partnerships with a focus on donation and education will foster safe and sustainable adjunct incorporation in Africa.

Intraoperative MRI use in transsphenoidal surgery for pituitary tumors: Trends and healthcare utilization

BACKGROUND

Intraoperative magnetic resonance imaging (iMRI) use in transsphenoidal approach (TSA) for pituitary tumors (PTs) has been reported to improve the extent of resection (EOR). The aim of this study is to report the trends and the impact of iMRI on healthcare utilization in patients who underwent TSA for PTs.

MATERIALS AND METHODS

MarketScan database were queried using the ICD-9/10 and CPT-4, from 2004 to 2020. We included patients ≥ 18 years of age PTs with > 1 year follow-up. Outcomes were length of stay (LOS), discharge disposition, hospital/emergency room (ER) re-admissions, outpatient services, medication refills and corresponding payments.

RESULTS

A cohort of 10,192 patients were identified from the database, of these 141 patients (1.4%) had iMRI used during the procedure. Use of iMRI for PTs remained stable (2004-2007: 0.85%; 2008-2011: 1.6%; 2012-2015:1.4% and 2016-2019: 1.46%). No differences in LOS (median 3 days each), discharge to home (93% vs. 94%), complication rates (7% vs. 13%) and payments ($34604 vs. $33050) at index hospitalization were noted. Post-discharge payments were not significantly different without and with iMRI use at 6-months ($8315 vs. $ 7577, p = 0.7) and 1-year ($13,654 vs. $ 14,054, p = 0.70), following the index procedure.

CONCLUSION

iMRI use during TSA for PTs remained stable with no impact on LOS, complications, discharge disposition and index payments. Also, there was no difference in combined index payments at 6-months, and 1-year after the index procedure in patients with and without iMRI use for PTs.

Enhancing the Reliability of Intraoperative Ultrasound in Pediatric Space-Occupying Brain Lesions

INTRODUCTION

Intraoperative ultrasound (IOUS) may aid the resection of space-occupying brain lesions, though technical limits may hinder its reliability.

METHODS

IOUS (MyLabTwice^®, Esaote, Italy) with a microconvex probe was utilized in 45 consecutive cases of children with supratentorial space-occupying lesions aiming to localize the lesion (pre-IOUS) and evaluate the extent of resection (EOR, post-IOUS). Technical limits were carefully assessed, and strategies to enhance the reliability of real-time imaging were accordingly proposed.

RESULTS

Pre-IOUS allowed us to localize the lesion accurately in all of the cases (16 low-grade gliomas, 12 high-grade gliomas, eight gangliogliomas, seven dysembryoplastic neuroepithelial tumors, five cavernomas, and five other lesions, namely two focal cortical dysplasias, one meningioma, one subependymal giant cell astrocytoma, and one histiocytosis). In 10 deeply located lesions, IOUS with hyperechoic marker, eventually coupled with neuronavigation, was useful to plan the surgical route. In seven cases, the administration of contrast ensured a better definition of the vascular pattern of the tumor. Post-IOUS allowed the evaluation of EOR reliably in small lesions (<2 cm). In large lesions (>2 cm) assessing EOR is hindered by the collapsed surgical cavity, especially when the ventricular system is opened, and by artifacts that may simulate or hide residual tumors. The main strategies to overcome the former limit are inflation of the surgical cavity through pressure irrigation while insonating, and closure of the ventricular opening with Gelfoam before insonating. The strategies to overcome the latter are avoiding the use of hemostatic agents before IOUS and insonating through normal adjacent brain instead of corticotomy. These technical nuances enhanced the reliability of post-IOUS, with a total concordance to postoperative MRI. Indeed, the surgical plan was changed in about 30% of cases, as IOUS showed a residual tumor that was left behind.

CONCLUSION

IOUS ensures reliable real-time imaging in the surgery of space-occupying brain lesions. Limits may be overcome with technical nuances and proper training.

Choice of intraoperative ultrasound adjuncts for brain tumor surgery

Background

Gliomas are among the most typical brain tumors tackled by neurosurgeons. During navigation for surgery of glioma brain tumors, preoperatively acquired static images may not be accurate due to shifts. Surgeons use intraoperative imaging technologies (2-Dimensional and navigated 3-Dimensional ultrasound) to assess and guide resections. This paper aims to precisely capture the importance of preoperative parameters to decide which type of ultrasound to be used for a particular surgery.

Methods

This paper proposes two bagging algorithms considering base classifier logistic regression and random forest. These algorithms are trained on different subsets of the original data set. The goodness of fit of Logistic regression-based bagging algorithms is established using hypothesis testing. Furthermore, the performance measures for random-forest-based bagging algorithms used are AUC under ROC and AUC under the precision-recall curve. We also present a composite model without compromising the explainability of the models.

Results

These models were trained on the data of 350 patients who have undergone brain surgery from 2015 to 2020. The hypothesis test shows that a single parameter is sufficient instead of all three dimensions related to the tumor ($$p < 0.05$$ p < 0.05 ). We observed that the choice of intraoperative ultrasound depends on the surgeon making a choice, and years of experience of the surgeon could be a surrogate for this dependence.

Conclusion

This study suggests that neurosurgeons may not need to focus on a large set of preoperative parameters in order to decide on ultrasound. Moreover, it personalizes the use of a particular ultrasound option in surgery. This approach could potentially lead to better resource management and help healthcare institutions improve their decisions to make the surgery more effective.

Is intraoperative ultrasound more efficient than magnetic resonance in neurosurgical oncology? An exploratory cost-effectiveness analysis

Objective

Intraoperative imaging is a chief asset in neurosurgical oncology, it improves the extent of resection and postoperative outcomes. Imaging devices have evolved considerably, in particular ultrasound (iUS) and magnetic resonance (iMR). Although iUS is regarded as a more economically convenient and yet effective asset, no formal comparison between the efficiency of iUS and iMR in neurosurgical oncology has been performed.

Methods

A cost-effectiveness analysis comparing two single-center prospectively collected surgical cohorts, classified according to the intraoperative imaging used. iMR (2013-2016) and iUS (2021-2022) groups comprised low- and high-grade gliomas, with a maximal safe resection intention. Units of health gain were gross total resection and equal or increased Karnofsky performance status. Surgical and health costs were considered for analysis. The incremental cost-effectiveness ratio (ICER) was calculated for the two intervention alternatives. The cost-utility graphic and the evolution of surgical duration with the gained experience were also analyzed.

Results

50 patients followed an iMR-assisted operation, while 17 underwent an iUS-guided surgery. Gross total resection was achieved in 70% with iMR and in 60% with iUS. Median postoperative Karnofsky was similar in both group (KPS 90). Health costs were € 3,220 higher with iMR, and so were surgical-related costs (€ 1,976 higher). The ICER was € 322 per complete resection obtained with iMR, and € 644 per KPS gained or maintained with iMR. When only surgical-related costs were analyzed, ICER was € 198 per complete resection with iMR and € 395 per KPS gained or maintained.

Conclusion

This is an unprecedented but preliminary cost-effectiveness analysis of the two most common intraoperative imaging devices in neurosurgical oncology. iMR, although being costlier and time-consuming, seems cost-effective in terms of complete resection rates and postoperative performance status. However, the differences between both techniques are small. Possibly, iMR and iUS are complementary aids during the resection: iUS real-time images assist while advancing towards the tumor limits, informing about the distance to relevant landmarks and correcting neuronavigation inaccuracy due to brain shift. Yet, at the end of resection, it is the iMR that reliably corroborates whether residual tumor remains.

Systematic Review: Applications of Intraoperative Ultrasound in Spinal Surgery

BACKGROUND

Due to increased practicality and decreased costs and radiation, interest has risen for intraoperative ultrasound (iUS) in spinal surgery applications; however, few studies have provided a robust overview of its use in spinal surgery. We synthesize findings of existing literature on usage of iUS in navigation, pedicle screw placement, and identification of anatomy during spinal interventions.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were utilized in this systematic review. Studies were identified through PubMed, Scopus, and Google Scholar databases using the search string. Abstracts mentioning iUS in spine applications were included. Upon full-text review, exclusion criteria were implemented, including outdated studies or those with weak topic relevance or statistical power. Upon elimination of duplicates, multi-reviewer screening for eligibility, and citation search, 44 manuscripts were analyzed.

RESULTS

Navigation using iUS is safe, effective, and economical. iUS registration accuracy and success is within clinically acceptable limits for image-guided navigation (Table 2). Pedicle screw instrumentation with iUS is precise with a favorable safety profile (Table 2). Anatomical landmarks are reliably identified with iUS, and surgeons are overwhelmingly successful in neural or vascular tissue identification with iUS modalities including standard B mode, doppler, and contrast-enhanced ultrasound (CE-US) (Table 3). iUS use in traumatic reduction of fractures properly identifies anatomical structures, intervertebral disc space, and vasculature (Table 3).

CONCLUSION

iUS eliminates radiation, decreases costs, and provides sufficient accuracy and reliability in identification of anatomical and neurovascular structures in various spinal surgery settings.

[Intraoperative ultrasound-assisted surgery of spinal tumors]

OBJECTIVE

To improve technique of intraoperative ultrasound-assisted microsurgery of spinal tumors.

MATERIAL AND METHODS

There were 68 patients with 70 spinal tumors who underwent intraoperative ultrasound-assisted resection between 2007 and 2018. Age of patients varied from 21 to 80 (mean 48.5±14.3). Intradural tumors were diagnosed in 54 (79.4%) patients (of them intramedullary in 16 (23.5%) and extramedullary in 38 (55.9%) cases). Fourteen patients (20.6%) had extradural tumors. Intraoperative ultrasound was used to determine localization, margins and structure of tumors, interrelations with neural structures, zones of dura opening and myelotomy. We also assessed quality of resection and spinal decompression.

RESULTS

In surgery of spinal tumors, intraoperative ultrasound allows to localize the tumor with 95.3% sensitivity, determine the character of its growth, shape, size and internal structure. One can also differentiate the margins of neoplasm, control accuracy of approach, select the optimal zone for dura opening and myelotomy, objectively assess spinal cord and nerve roots decompression in real-time mode. Quality of intraoperative ultrasonography images is comparable to preoperative MRI, and even exceed resolution of MR scans in some cases.

CONCLUSION

In our study, intraoperative ultrasound has proven to be a method complementing preoperative CT and MRI. This approach provides additional data in real-time mode to form a complete picture of surgical area, increase accuracy of manipulations and reduce surgical trauma.

Pattern of use of intraoperative ultrasound in surgery for brain tumors influences outcomes in glial tumors

BACKGROUND

Intraoperative ultrasound (iUS) imaging has emerged as a promising adjunct in glioma surgery with both, 2-dimensional (2D) as well as navigated 3-dimensional (n3D), modes increasingly being used.

METHODS

We analyzed our decade-long experience of 1075 brain tumor (807, 75% gliomas) cases operated using iUS. A retrospective chart and electronic records review was performed. The primary aim was to understand the patterns of use of iUS mode and its purpose of application (as a localizing tool or as a resection control modality) as well as to evaluate its impact on the extent of resection.

RESULTS

The use of iUS increased over time, especially with the introduction of n3DUS though 2DUS remained the more commonly used mode (63%) overall during this period. For biopsies (156 cases), both 2D, as well as n3D iUS, were used as a localizing tool only. Lesion localization was the major purpose for use of iUS even for tumor resections (61%). Resection control was performed more often for gliomas (46.5% compared to 16.5% in non-glial tumors). n3DUS was the preferred modality as a resection control tool irrespective of histological class. GTR (gross total resection) was achieved in 53.1% cases overall, while in glial and non-glial tumors it was 44.7% and 80.7%, respectively. GTR was higher when iUS was used as a resection control modality. The US and MR defined EOR (extent of resection) showed substantial agreement (κ = 0.678) with high diagnostic accuracy of 84% for glial tumors. In glial tumors, iUS was used more often in eloquent tumors and GTR rates were slightly higher than when iUS was not used.

CONCLUSION

iUS is a versatile tool and is a useful surgical adjunct for glioma surgeons. Besides its proven benefit as a localizing tool, when used as a tool for resection control it improves the resection rates. n3DUS may offer benefits over 2DUS as a resection control modality, though the evidence is still evolving.

Enhanced Safety of Pedicle Subtraction Osteotomy Using Intraoperative Ultrasound

BACKGROUND

Pedicle subtraction osteotomy (PSO) can improve sagittal alignment but carries risks, including iatrogenic spinal cord and nerve root injury. Critically, during the reduction phase of the technique, medullary kinking or neural element compression can lead to neurologic deficits.

METHODS

We describe 3 cases of thoracic PSO and evaluate the feasibility, findings, and utility of intraoperative ultrasound in this setting.

RESULTS

Intraoperative ultrasound can provide a visual assessment of spinal cord morphology before and after PSO reduction and influences surgical decision making with regard to the final amount of sagittal plane correction. This modality is particularly useful for confirming ventral decompression of disc-osteophyte complex before reduction and also after reduction maneuvers when there is kinking of the thecal sac but uncertainty about the underlying status of the spinal cord. Intraoperative ultrasound is a reliable modality that fits well into the technical sequence of PSO, adds a minimal amount of operative time, and has few limitations.

CONCLUSIONS

We propose that intraoperative ultrasound is a useful supplement to standard neuromonitoring modalities for ensuring safe PSO reduction and decompression of neural elements.

Integrated multi-modality image-guided navigation for neurosurgery: open-source software platform using state-of-the-art clinical hardware

PURPOSE

Image-guided surgery (IGS) is an integral part of modern neuro-oncology surgery. Navigated ultrasound provides the surgeon with reconstructed views of ultrasound data, but no commercial system presently permits its integration with other essential non-imaging-based intraoperative monitoring modalities such as intraoperative neuromonitoring. Such a system would be particularly useful in skull base neurosurgery.

METHODS

We established functional and technical requirements of an integrated multi-modality IGS system tailored for skull base surgery with the ability to incorporate: (1) preoperative MRI data and associated 3D volume reconstructions, (2) real-time intraoperative neurophysiological data and (3) live reconstructed 3D ultrasound. We created an open-source software platform to integrate with readily available commercial hardware. We tested the accuracy of the system's ultrasound navigation and reconstruction using a polyvinyl alcohol phantom model and simulated the use of the complete navigation system in a clinical operating room using a patient-specific phantom model.

RESULTS

Experimental validation of the system's navigated ultrasound component demonstrated accuracy of [Formula: see text] and a frame rate of 25 frames per second. Clinical simulation confirmed that system assembly was straightforward, could be achieved in a clinically acceptable time of [Formula: see text] and performed with a clinically acceptable level of accuracy.

CONCLUSION

We present an integrated open-source research platform for multi-modality IGS. The present prototype system was tailored for neurosurgery and met all minimum design requirements focused on skull base surgery. Future work aims to optimise the system further by addressing the remaining target requirements.

Intraoperative contrast-enhanced ultrasound for intramedullary spinal neoplasms: patient series

BACKGROUND

Primary intramedullary spinal tumors cause significant morbidity and death. Intraoperative ultrasound as an adjunct for localization and monitoring the extent of resection has not been systematically evaluated in these patients; the effectiveness of intraoperative contrast-enhanced ultrasound (CEUS) remains almost completely unexplored.

OBSERVATIONS

A retrospective case series of patients at a single institution who had consented to the off-label use of intraoperative CEUS was identified. Seven patients with a mean age of 52.8 ± 15.8 years underwent resection of intramedullary tumors assisted by CEUS performed by a single attending neurosurgeon. Histopathological evaluation revealed 3 cases of hemangioblastoma, 1 case of pilocytic astrocytoma, 2 cases of ependymoma, and 1 case of subependymoma. Contrast enhancement correlated with gadolinium enhancement on preoperative magnetic resonance imaging. Intraoperative CEUS facilitated precise lesion localization and myelotomy planning. Dynamic CEUS studies were useful in demonstrating the blood supply to lesions with a dominant vascular pedicle. Regardless of contrast uptake, the differential enhancement between spinal cord tissue and neoplasm assisted in determining interface boundaries.

LESSONS

Intraoperative CEUS constitutes a useful adjunct for the intraoperative delineation of contrast-enhancing intramedullary tumors and in vivo confirmation of gross-total resection. Systematic investigation is needed to establish the role of CEUS for resection of intramedullary spinal tumors of various pathologies.

Navigated ultrasound-based image guidance during resection of gliomas: practical utility in intraoperative decision-making and outcomes

OBJECTIVE

Intraoperative imaging is increasingly being used for resection control in diffuse gliomas, in which the extent of resection (EOR) is important. Intraoperative ultrasound (iUS) has emerged as a highly effective tool in this context. Navigated ultrasound (NUS) combines the benefits of real-time imaging with the benefits of navigation guidance. In this study, the authors investigated the use of NUS as an intraoperative adjunct for resection control in gliomas.

METHODS

The authors retrospectively analyzed 210 glioma patients who underwent surgery using NUS at their center. The analysis included intraoperative decision-making, diagnostic accuracy, and operative outcomes, particularly EOR and related factors influencing this.

RESULTS

US-defined gross-total resection (GTR) was achieved in 57.6% of patients. Intermediate resection control scans were evaluable in 115 instances. These prompted a change in the operative decision in 42.5% of cases (the majority being further resection of unanticipated residual tumor). Eventual MRI-defined GTR rates were similar (58.6%), although the concordance between US and MRI was 81% (170/210 cases). There were 21 false positives and 19 false negatives with NUS, resulting in a sensitivity of 78%, specificity of 83%, positive predictive value of 77%, and negative predictive value of 84%. A large proportion of patients (13/19 patients, 68%) with false-negative results eventually had near-total resections. Tumor resectability, delineation, enhancement pattern, eloquent location, and US image resolution significantly influenced the GTR rate, though only resectability and eloquent location were significant on multivariate analysis.

CONCLUSIONS

NUS is a useful intraoperative adjunct for resection control in gliomas, detecting unanticipated tumor residues and positively influencing the course of the resection, eventually leading to higher resection rates. Nevertheless, resection is determined by the innate resectability of the tumor and its relationship to eloquent location, reinforcing the need to combine iUS with functional mapping techniques to optimize resections.

Characteristics of Fluorescent Intraoperative Dyes Helpful in Gross Total Resection of High-Grade Gliomas-A Systematic Review

Background: A very important aspect in the treatment of high-grade glioma is gross total resection to reduce the risk of tumor recurrence. One of the methods to facilitate this task is intraoperative fluorescence navigation. The aim of the study was to compare the dyes used in this technique fluorescent intraoperative navigation in terms of the mechanism of action and influence on the treatment of patients. Methods: The review was carried out on the basis of articles found in PubMed, Google Scholar, and BMC search engines, as well as those identified by searched bibliographies and suggested by experts during the preparation of the article. The database analysis was performed for the following phrases: "glioma", "glioblastoma", "ALA", "5ALA", "5-ALA", "aminolevulinic acid", "levulinic acid", "fluorescein", "ICG", "indocyanine green", and "fluorescence navigation". Results: After analyzing 913 citations identified on the basis of the search criteria, we included 36 studies in the review. On the basis of the analyzed articles, we found that 5-aminolevulinic acid and fluorescein are highly effective in improving the percentage of gross total resection achieved in high-grade glioma surgery. At the same time, the limitations resulting from the use of these methods are marked-higher costs of the procedure and the need to have neurosurgical microscope in combination with a special light filter in the case of 5-aminolevulinic acid (5-ALA), and low specificity for neoplastic cells and the dependence on the degree of damage to the blood-brain barrier in the intensity of fluorescence in the case of fluorescein. The use of indocyanine green in the visualization of glioma cells is relatively unknown, but some researchers have suggested its utility and the benefits of using it simultaneously with other dyes. Conclusion: The use of intraoperative fluorescence navigation with the use of 5-aminolevulinic acid and fluorescein allows the range of high-grade glioma resection to be increased.

Intraoperative Imaging for High-Grade Glioma Surgery

This article discusses intraoperative imaging techniques used during high-grade glioma surgery. Gliomas can be difficult to differentiate from surrounding tissue during surgery. Intraoperative imaging helps to alleviate problems encountered during glioma surgery, such as brain shift and residual tumor. There are a variety of modalities available all of which aim to give the surgeon more information, address brain shift, identify residual tumor, and increase the extent of surgical resection. The article starts with a brief introduction followed by a review of with the latest advances in intraoperative ultrasound, intraoperative MRI, and intraoperative computed tomography.

Neurosurgical intraoperative ultrasonography using contrast enhanced superb microvascular imaging -vessel density and appearance time of the contrast agent

Background: Ultrasonography (US) provides real-time information on structures within the skull during neurosurgical operations. Superb microvascular imaging (SMI) is the latest imaging technique for detecting very low-velocity flow with minimal motion artifacts, and we have reported on this technique for intraoperative US monitoring. We combined SMI with administration of contrast agent to obtain detailed information during neurosurgical operations.Materials and methods: Twenty patients diagnosed with brain tumor (10 meningiomas, 5 glioblastomas, 2 hemangioblastomas, 1 schwannoma, 1 malignant lymphoma, 1 brain abscess) underwent neurosurgery under US with SMI and contrast agent techniques. Vessel density and appearance time following contrast administration were analyzed.Results: Flow in numerous vessels was not visualized by SMI alone, but appeared following injection of contrast agent in all cases. Flow in tumors was drastically enhanced by contrast agent in schwannoma, hemangioblastoma and meningioma, compared to normal brain tissue. Flows in the dilated and bent vessels of glioblastoma were also enhanced, although flow in hypoechoic lymphoma remained inconspicuous. The characteristics of tumor vessels were clearly visualized and tumor borders were demonstrated by the difference between tumor flow and brain flow, by the increased tumor vessel density and decreased appearance time of contrast agent compared to normal brain vessels.Conclusions: The combination of SMI and contrast agent techniques for intraoperative US monitoring could provide innovative flow images of tumor and normal brain. The neurosurgeon obtains information about tumor flow and tumor borderline before tumor resection.

Navigated intraoperative ultrasonography for brain tumors: a pictorial essay on the technique, its utility, and its benefits in neuro-oncology

Intraoperative imaging has become one of the most important adjuncts in neurosurgery, especially in the surgical treatment of intra-axial tumors. Navigation and intraoperative magnetic resonance imaging have limitations, and intraoperative ultrasonography (IOUS) has emerged as a versatile and multifaceted alternative. With technological advances in ultrasound scanners and newer multifunctional probes, the potential of IOUS is increasingly being utilized in the resection of tumors. The addition of image guidance to IOUS has exponentially increased the power of this technique. Navigated ultrasonography (nUS) can now overcome many of the limitations of conventional standalone two-dimensional ultrasonography. In this pictorial essay, we outline our nUS technique (both two- and three-dimensional) for the resection of intra-axial tumors with illustrated examples highlighting the various steps and corresponding benefits of the technique.

Demonstrative study of brain anatomical landmarks by intraoperative ultrasound imaging

Objectives

Intraoperative use of ultrasound in brain surgery needs good understanding of the brain anatomy in ultrasound images. This study aims to compare ultrasound imaging of brain anatomical landmarks during surgery to perioperative computed tomography (CT), and perioperative magnetic resonance imaging (MRI) as demonstration for encouraging usage as low cost, available and hazardless device.

Methods

In total; 350 patients were subjected to brain surgeries under ultrasound guidance using 2.5–8 megahertz (MHZ) transducers, at neurosurgery department Zagazig university hospital from January 2012 to January 2019. Brain anatomical landmarks were compared between ultrasound images, and perioperative images for safe, and confident surgeries.

Results

Various intracranial anatomical landmarks could be well-demonstrated by ultrasound through the open fontanel, or once the skull was opened, and during surgical work in real time fashion, facilitating surgical procedures, and avoiding complications.

Conclusion

Real-time ultrasound is of great help during brain surgeries in delineating brain anatomical landmarks as well as MRI, and CT brain. The growing learning standard of intraoperative ultrasound (IOUS) use makes brain surgery more simple with avoiding brain shift problems, radiation exposure, and high cost of other intraoperative modalities.

New Hope in Brain Glioma Surgery: The Role of Intraoperative Ultrasound. A Review

Maximal safe resection represents the gold standard for surgery of malignant brain tumors. As regards gross-total resection, accurate localization and precise delineation of the tumor margins are required. Intraoperative diagnostic imaging (Intra-Operative Magnetic Resonance-IOMR, Intra-Operative Computed Tomography-IOCT, Intra-Operative Ultrasound-IOUS) and dyes (fluorescence) have become relevant in brain tumor surgery, allowing for a more radical and safer tumor resection. IOUS guidance for brain tumor surgery is accurate in distinguishing tumor from normal parenchyma, and it allows a real-time intraoperative visualization. We aim to evaluate the role of IOUS in gliomas surgery and to outline specific strategies to maximize its efficacy. We performed a literature research through the Pubmed database by selecting each article which was focused on the use of IOUS in brain tumor surgery, and in particular in glioma surgery, published in the last 15 years (from 2003 to 2018). We selected 39 papers concerning the use of IOUS in brain tumor surgery, including gliomas. IOUS exerts a notable attraction due to its low cost, minimal interruption of the operational flow, and lack of radiation exposure. Our literature review shows that increasing the use of ultrasound in brain tumors allows more radical resections, thus giving rise to increases in survival.

Chaperonology: The Third Eye on Brain Gliomas

The European Organization for Research and Treatment of Cancer/National Cancer Institute of Canada Phase III trial has validated as a current regimen for high-grade gliomas (HGG) a maximal safe surgical resection followed by radiotherapy with concurrent temozolamide. However, it is essential to balance maximal tumor resection with preservation of the patient&rsquo;s neurological functions. Important developments in the fields of pre-operative and intra-operative neuro-imaging and neuro-monitoring have ameliorated the survival rate and the quality of life for patients affected by HGG. Moreover, even though the natural history remains extremely poor, advancement in the molecular and genetic fields have opened up new potential frontiers in the management of this devastating brain disease. In this review, we aim to present a comprehensive account of the main current pre-operative, intra-operative and molecular approaches to HGG with particular attention to specific chaperones, also called heat shock proteins (Hsps), which represent potential novel biomarkers to detect and follow up HGG, and could also be therapeutic agents.

Intraoperative image-guided surgery in neuro-oncology with specific focus on high-grade gliomas

Surgery is paramount in glioma management and extent of resection is an independent significant prognostic factor. However, these tumors are often invisible intraoperatively. Hence imaging plays an important role in surgical guidance. A critical literature review, using MEDLINE/PubMed service was carried out. It demonstrated a gross total resection (GTR) with neuronavigation (NNS) of 31-36%, adding 5-aminolevulinic acid or fluorescein fluorescence, or intraoperative ultrasound or MRI improved GTR to 69.1, 84.4, 73.4 and 70% respectively. The differences between the four intraoperative technologies were not statistically significant. Therefore, NNS provided a platform for planning surgical approaches and localization of lesions, however significant brain shift rendered NNS useless without the addition of intraoperative imaging, of which 5-aminolevulinic acid, fluorescein, intraoperative ultrasound and intraoperative MRI significantly improved GTR and outcome of glioma surgery.

Direct navigated 3D ultrasound for resection of brain tumors: a useful tool for intraoperative image guidance

OBJECTIVE

Navigated 3D ultrasound is a novel intraoperative imaging adjunct permitting quick real-time updates to facilitate tumor resection. Image quality continues to improve and is currently sufficient to allow use of navigated ultrasound (NUS) as a stand-alone modality for intraoperative guidance without the need for preoperative MRI.

METHODS

The authors retrospectively analyzed cases involving operations performed at their institution in which a 3D ultrasound navigation system was used for control of resection of brain tumors in a "direct" 3D ultrasound mode, without preoperative MRI guidance. The usefulness of the ultrasound and its correlation with postoperative imaging were evaluated.

RESULTS

Ultrasound was used for resection control in 81 cases. In 53 of these 81 cases, at least 1 intermediate scan (range 1-3 intermediate scans) was obtained during the course of the resection, and in 50 of these 53 cases, the result prompted further resection. In the remaining 28 cases, intermediate scans were not performed either because the first ultrasound scan performed after resection was interpreted as showing no residual tumor (n = 18) and resection was terminated or because the surgeon intentionally terminated the resection prematurely due to the infiltrative nature of the tumor and extension of disease into eloquent areas (n = 10) and the final ultrasound scan was interpreted as showing residual disease. In an additional 20 cases, ultrasound navigation was used primarily for localization and not for resection control, making the total number of NUS cases where radical resection was planned 101. Gross-total resection (GTR) was planned in 68 of these 101 cases and cytoreduction in 33. Ultrasound-defined GTR was achieved in 51 (75%) of the cases in which GTR was planned. In the remaining 17, further resection had to be terminated (despite evidence of residual tumor on ultrasound) because of diffuse infiltration or proximity to eloquent areas. Of the 33 cases planned for cytoreduction, NUS guidance facilitated ultrasound-defined GTR in 4 cases. Overall, ultrasound-defined GTR was achieved in 50% of cases (55 of 111). Based on the postoperative imaging (MRI in most cases), GTR was achieved in 58 cases (53%). Final (postresection) ultrasonography was documented in 78 cases. The findings were compared with the postoperative imaging to ascertain concordance in detecting residual tumor. Overall concordance was seen in 64 cases (82.5%), positive concordance was seen in 33 (42.5%), and negative in 31 (40%). Discordance was seen in 14 cases-with ultrasound yielding false-positive results in 7 cases and false-negative results in 7 cases. Postoperative neurological worsening occurred in 15 cases (13.5%), and in most of these cases, it was reversible by the time of discharge.

CONCLUSIONS

The results of this study demonstrate that 3D ultrasound can be effectively used as a stand-alone navigation modality during the resection of brain tumors. The ability to provide repeated, high-quality intraoperative updates is useful for guiding resection. Attention to image acquisition technique and experience can significantly increase the quality of images, thereby improving the overall utility of this modality.

Identification of residual tumor with intraoperative contrast-enhanced ultrasound during glioblastoma resection

OBJECTIVE

The purpose of this study was to assess the capability of contrast-enhanced ultrasound (CEUS) to identify residual tumor mass during glioblastoma multiforme (GBM) surgery, to increase the extent of resection.

METHODS

The authors prospectively evaluated 10 patients who underwent surgery for GBM removal with navigated ultrasound guidance. Navigated B-mode and CEUS were performed prior to resection, during resection, and after complete tumor resection. Areas suspected for residual tumors on B-mode and CEUS studies were localized within the surgical field with navigated ultrasound and samples were sent separately for histopathological analysis to confirm tumor presence.

RESULTS

In all cases tumor remnants were visualized as hyperechoic areas on B-mode, highlighted as CEUS-positive areas, and confirmed as tumoral areas on histopathological analysis. In 1 case only, CEUS partially failed to demonstrate residual tumor because the residual hyperechoic area was devascularized prior to ultrasound contrast agent injection. In all cases CEUS enhanced B-mode findings.

CONCLUSIONS

As has already been shown in other neoplastic lesions in other organs, CEUS is extremely specific in the identification of residual tumor. The ability of CEUS to distinguish between tumor and artifacts or normal brain on B-mode is based on its capacity to show the vascularization degree and not the echogenicity of the tissues. Therefore, CEUS can play a decisive role in the process of maximizing GBM resection.

The effectiveness and cost-effectiveness of intraoperative imaging in high-grade glioma resection; a comparative review of intraoperative ALA, fluorescein, ultrasound and MRI

BACKGROUND

Surgical resection of high-grade gliomas (HGG) is standard therapy because it imparts significant progression free (PFS) and overall survival (OS). However, HGG-tumor margins are indistinguishable from normal brain during surgery. Hence intraoperative technology such as fluorescence (ALA, fluorescein) and intraoperative ultrasound (IoUS) and MRI (IoMRI) has been deployed. This study compares the effectiveness and cost-effectiveness of these technologies.

METHODS

Critical literature review and meta-analyses, using MEDLINE/PubMed service. The list of references in each article was double-checked for any missing references. We included all studies that reported the use of ALA, fluorescein (FLCN), IoUS or IoMRI to guide HGG-surgery. The meta-analyses were conducted according to statistical heterogeneity between studies. If there was no heterogeneity, fixed effects model was used; otherwise, a random effects model was used. Statistical heterogeneity was explored by χ² and inconsistency (I²) statistics. To assess cost-effectiveness, we calculated the incremental cost per quality-adjusted life-year (QALY).

RESULTS

Gross total resection (GTR) after ALA, FLCN, IoUS and IoMRI was 69.1%, 84.4%, 73.4% and 70% respectively. The differences were not statistically significant. All four techniques led to significant prolongation of PFS and tended to prolong OS. However none of these technologies led to significant prolongation of OS compared to controls. The cost/QALY was $16,218, $3181, $6049 and $32,954 for ALA, FLCN, IoUS and IoMRI respectively.

CONCLUSIONS

ALA, FLCN, IoUS and IoMRI significantly improve GTR and PFS of HGG. Their incremental cost was below the threshold for cost-effectiveness of HGG-therapy, denoting that each intraoperative technology was cost-effective on its own.

Intraoperative Ultrasound-Guided Resection of Gliomas: A Meta-Analysis and Review of the Literature

BACKGROUND

Image-guided surgery has become standard practice during surgical resection, using preoperative magnetic resonance imaging. Intraoperative ultrasound (IoUS) has attracted interest because of its perceived safety, portability, and real-time imaging. This report is a meta-analysis of intraoperative ultrasound in gliomas.

METHODS

Critical literature review and meta-analyses, using the MEDLINE/PubMed service. The list of references in each article was double-checked for any missing references. We included all studies that reported the use of ultrasound to guide glioma-surgery. The meta-analyses were conducted according to statistical heterogeneity between the studies using Open MetaAnalyst Software. If there was no heterogeneity, fixed effects model was used for meta-analysis; otherwise, a random effect model was used. Statistical heterogeneity was explored by χ(2) and inconsistency (I(2)) statistics; an I(2) value of 50% or more represented substantial heterogeneity.

RESULTS

A wide search yielded 19,109 studies that might be relevant, of which 4819 were ultrasound in neurosurgery; 756 studies used ultrasound in cranial surgery, of which 24 studies used intraoperative ultrasound to guide surgical resection and 74 studies used it to guide biopsy. Fifteen studies fulfilled our stringent inclusion criteria, giving a total of 739 patients. The estimated average gross total resection rate was 77%. Furthermore, the relationship between extent of surgical resection and study population was not linear. Gross total resection was more likely under IoUS when the lesion was solitary and subcortical, with no history of surgery or radiotherapy. IoUS image quality, sensitivity, specificity, and positive and negative predictive values deteriorated as surgical resection proceeded.

CONCLUSION

IoUS-guided surgical resection of gliomas is a useful tool for guiding the resection and for improving the extent of resection. IoUS can be used in conjunction with other complementary technologies that can improve anatomic orientation during surgery. Real-time imaging, improved image quality, small probe sizes, repeatability, portability, and relatively low cost make IoUS a realistic, cost-effective tool that complements any existing tools in any neurosurgical operating environment.

Intraoperative ultrasound in pediatric brain tumors: does the surgeon get it right?

PURPOSE

Intraoperative ultrasound (iUS) is a valuable tool-inexpensive, adds minimal surgical time, and involves minimal risk. The diagnostic predictive value of iUS is not fully characterized in Pediatric Neurosurgery. Our objective is to determine if surgeon-completed iUS has good concordance with post-operative MRI in estimating extent of surgical resection (EOR) of pediatric brain tumors.

METHODS

We reviewed charts of all pediatric brain tumor resections (single institution 2006-2013). Those with iUS and postoperative imaging (<1 week) were included. The surgeon's estimation of the EOR based on iUS and the post-operative neuroimaging results (gold standard) were collected, as well as information about the patients/tumors.

RESULTS

Two hundred two resections were reviewed and 58 cases were included. Twenty-six of the excluded cases utilized iUS but did not have EOR indicated. The concordance of interpretation between iUS and post-operative MRI was 98.3%. Of 43 cases where iUS suggested gross total resection, 42 were confirmed on MRI (negative predictive value (NPV), 98%). All 15 cases where iUS suggested subtotal resection were confirmed on MRI (positive predictive value (PPV), 100 %). Agreement between iUS and post-operative imaging had an overall Kappa score of 0.956, signifying almost perfect agreement.

CONCLUSION

The results from this study suggest that iUS is reliable with both residual tumor (PPV-100%) and when it suggests no residual (NPV-98%) in tumors that are easily identifiable on iUS. However, tumors that were difficult to visualize on iUS were potentially excluded, and therefore, these results should not be extrapolated for all brain tumor types.

From Grey Scale B-Mode to Elastosonography: Multimodal Ultrasound Imaging in Meningioma Surgery-Pictorial Essay and Literature Review

The main goal in meningioma surgery is to achieve complete tumor removal, when possible, while improving or preserving patient neurological functions. Intraoperative imaging guidance is one fundamental tool for such achievement. In this regard, intra-operative ultrasound (ioUS) is a reliable solution to obtain real-time information during surgery and it has been applied in many different aspect of neurosurgery. In the last years, different ioUS modalities have been described: B-mode, Fusion Imaging with pre-operative acquired MRI, Doppler, contrast enhanced ultrasound (CEUS), and elastosonography. In this paper, we present our US based multimodal approach in meningioma surgery. We describe all the most relevant ioUS modalities and their intraoperative application to obtain precise and specific information regarding the lesion for a tailored approach in meningioma surgery. For each modality, we perform a review of the literature accompanied by a pictorial essay based on our routinely use of ioUS for meningioma resection.

The status of contemporary image-guided modalities in oncologic surgery

OBJECTIVE

To review the current trends in optical imaging to guide oncologic surgery.

BACKGROUND

Surgical resection remains the cornerstone of therapy for patients with early stage solid malignancies and more than half of all patients with cancer undergo surgery each year. The technical ability of the surgeon to obtain clear surgical margins at the initial resection remains crucial to improve overall survival and long-term morbidity. Current resection techniques are largely based on subjective and subtle changes associated with tissue distortion by invasive cancer. As a result, positive surgical margins occur in a significant portion of tumor resections, which is directly correlated with a poor outcome.

METHODS

A comprehensive review of studies evaluating optical imaging techniques is performed.

RESULTS

A variety of cancer imaging techniques have been adapted or developed for intraoperative surgical guidance that have been shown to improve functional and oncologic outcomes in randomized clinical trials. There are also a large number of novel, cancer-specific contrast agents that are in early stage clinical trials and preclinical development that demonstrate significant promise to improve real-time detection of subclinical cancer in the operative setting.

CONCLUSIONS

There has been an explosion of intraoperative imaging techniques that will become more widespread in the next decade.

Relationship of intraoperative ultrasound characteristics with pathological grades and Ki-67 proliferation index in intracranial gliomas

OBJECTIVE

The purpose of the present study was to investigate the relationship between the intraoperative ultrasonographic appearances and the histopathological characteristics of glial tumors using the pathological grading system and the Ki-67 proliferation index.

MATERIALS AND METHODS

Patients with glial tumors who underwent surgery with the aid of intraoperative ultrasonography (IOUS) between September 2013 and August 2014 were included in the study. The lesions' IOUS characteristics were analyzed and compared with the results of surgical histopathological characteristics. Lesions were classified as low-grade gliomas (grade I-II, LGG) and high-grade gliomas (grade III-IV, HGG). The glioblastoma multiforme (grade IV, GBM) group was classified according to the Ki-67 values for further evaluation. The Chi square test (Fisher's exact test) was used for comparing the ultrasonographic characteristics of the low-grade and high-grade gliomas; HGG with different Ki-proliferation indexes. A value of P < 0.05 was considered statistically significant.

RESULTS

A total of 41 patients were included. The histopathological findings revealed 15 LGG and 26 HGG. Twenty of the 26 HGG were GBM. Differences were found between the intraoperative ultrasonographic characteristics of the low-grade and high-grade glial tumors. The majority of LGGs were mildly hyperechoic and homogeneous, with distinct margins and a regular contour. HGGs were mostly highly hyperechoic, with indistinct margins, irregular contours, and a heterogeneous internal texture. Surrounding edema was seen more often in HGGs. The differences in the echogenicity of the solid parts, the internal echo patterns, margins, contours, and peripheral edema (P < 0.05) were statistically significant, but the difference in the presence of cysts (P > 0.05) was not significant. In the GBM group, all of the lesions with distinct margins and regular contours had Ki-67 values ≤15 %. We compared the intraoperative ultrasonographic characteristics of the Ki-67 > 15 % group with those of the Ki-67 ≤ 15 % group for statistical significance. The difference between the echogenicity of the solid parts, margins, and contours was statistically significant between the groups (P < 0.05). The difference in the internal echo pattern, presence of cyst, and peripheral edema was insignificant (P > 0.05).

CONCLUSIONS

IOUS is a very useful imaging technique not only in defining the borders but also in characterizing the tumoral tissue. The IOUS characteristics of the glial tumors were a valuable tool in differentiating the grades of the glial tumors and might have a relationship with the Ki-67 proliferation index. We think this theory requires further investigation in more detailed comparative studies with larger numbers of patients.

Neurosurgical oncology: advances in operative technologies and adjuncts

Modern glioma surgery has evolved around the central tenet of safely maximizing resection. Recent surgical adjuncts have focused on increasing the maximum extent of resection while minimizing risk to functional brain. Technologies such as cortical and subcortical stimulation mapping, intraoperative magnetic resonance imaging, functional neuronavigation, navigable intraoperative ultrasound, neuroendoscopy, and fluorescence-guided resection have been developed to augment the identification of tumor while preserving brain anatomy and function. However, whether these technologies offer additional long-term benefits to glioma patients remains to be determined. Here we review advances over the past decade in operative technologies that have offered the most promising benefits for glioblastoma patients.

Usefulness of three-dimensional navigable intraoperative ultrasound in resection of brain tumors with a special emphasis on malignant gliomas

BACKGROUND

Intraoperative imaging is increasingly being used in resection of brain tumors. Navigable three-dimensional (3D)-ultrasound is a novel tool for planning and guiding such resections. We review our experience with this system and analyze our initial results, especially with respect to malignant gliomas.

METHODS

A prospective database for all patients undergoing sononavigation-guided surgery at our center since this surgery's introduction in June 2011 was queried to retrieve clinical data and technical parameters. Imaging was reviewed to categorize tumors based on enhancement and resectability. Extent of resection was also assessed.

RESULTS

Ninety cases were operated and included in this analysis, 75 % being gliomas. The 3D ultrasound mode was used in 87 % cases (alone in 40, and combined in 38 cases). Use of combined mode function [ultrasound (US) with magnetic resonance (MR) images] facilitated orientation of anatomical data. Intraoperative power Doppler angiography was used in one-third of the cases, and was extremely beneficial in delineating the vascular anatomy in real-time. Mean duration of surgery was 4.4 hours. Image resolution was good or moderate in about 88 % cases. The use of the intraoperative imaging prompted further resection in 59 % cases. In the malignant gliomas (51 cases), gross-total resection was achieved in 47 % cases, increasing to 88 % in the "resectable" subgroup.

CONCLUSIONS

Navigable 3D US is a versatile, useful and reliable intraoperative imaging tool in resection of brain tumors, especially in resource-constrained settings where Intraoperative MR (IOMR) is not available. It has multiple functionalities that can be tailored to suit the procedure and the experience of the surgeon.

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

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

Neuronavigation: principles, clinical applications and potential pitfalls

Localization of brain lesions and prevention of damage to vital structures are important in operation of brain pathologies. Despite development of many techniques including angiography, MRI, sonography, and frame base stereotaxy, a more accurate localizing technique is still needed (1, 2). A step forward to achieve this goal is to develop a navigation system. In this manuscript, we explained some clinical applications, advantages, and disadvantages of navigation system and tried to have a short glimpse on its future.