Visualization of lenticulostriate arteries during insular low-grade glioma surgeries by navigated 3D ultrasound power Doppler: technical note

Factors affecting the extent of resection and neurological outcomes following transopercular resection of insular gliomas

BACKGROUND

Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs.

METHODS

Retrospective analysis of 66 patients with IG who underwent TO resection was performed.

RESULTS

Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable.

CONCLUSION

Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM.

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.

Technical evolution of pediatric neurosurgery: the evolution of intraoperative imaging

Imaging has always been fundamental to neurosurgery, and its evolution over the last century has made a dramatic transformation in the ability of neurosurgeons to define pathology and preserve normal tissue during their operations. In the mid-70 s, the development of computerized cross-sectional imaging with CT scan and subsequently MRI have revolutionized the practice of neurosurgery. Later, further advances in computer technology and medical engineering have allowed the combination of many modalities to bring them into the operating theater. This evolution has allowed real-time intraoperative imaging, in the hope of helping neurosurgeons achieve accuracy, maximal safe resection, and the implementation of minimally invasive techniques in brain and spine pathologies. Augmented reality and robotic technologies are also being applied as useful intra-operative techniques that will improve surgical planning and outcomes in the future. In this article, we will review imaging modalities and provide our institutional perspective on how we have integrated them into our practice.

Anatomical information of the lenticulostriate arteries on high-resolution 3D-TOF MRA at 3 T: comparison with 3D-DSA

PURPOSE

As the lenticulostriate arteries (LSAs) perfuse neurologically important areas, it is necessary to accurately assess the origin and number of the LSAs before surgery. Although three-dimensional time-of-flight MR angiography (3D-TOF MRA) is a non-invasive procedure, it requires high-resolution (HR) images to depict the LSAs with a small diameter. Therefore, we performed 3D-TOF MRA with the maximum HR (HR-MRA) using a 3 T scanner to examine whether a good depiction of the LSAs, equivalent to that of digital subtraction angiography (DSA), could be obtained.

METHODS

Our study group comprised 16 consecutive patients who underwent HR-MRA and 3D-DSA. In both studies, we evaluated the localization of the origin from M1, M2, or A1 segments, their number of stems, and depiction.

RESULTS

There was no significant difference in the visualization of the LSAs between HR-MRA and 3D-DSA (P values; M1, M2, and A1 = 0.39, 0.69, and 0.69, respectively), and both the number of stems and the localization of the origin of the LSAs corresponded between the two examinations.

CONCLUSION

HR-MRA at 3 T can depict the LSA well. It reveals the number of the LSA stems and the LSA origin comparatively with DSA.

Insular glioblastoma: surgical challenges, survival outcomes and prognostic factors

BACKGROUND

Insular gliomas are unique, challenging and evoke a lot of interest amongst neurosurgeons. Publications on insular glioma generally focus on the surgical intricacies and extent of resection pertaining to the low-grade gliomas. Insular glioblastomas (iGBM) have not been analysed separately before.

METHODS

Histologically proven WHO grade IV gliomas involving the insula over a 9-year period were studied. Their clinical presentation, radiological features, surgical findings and survival outcomes were assessed. Statistical methods were used to determine the favourable predictors of survival.

RESULTS

Out of 27 patients (M:F = 2.9:1), 18 (66%) patients had a tumour extension beyond the insula, 10 (37%) of whom had basal ganglia involvement. Total, near total and subtotal excisions were performed in 7 (26%), 9 (33%) and 11 (40.7%) patients, respectively. Twenty-three patients had glioblastoma, while four had gliosarcoma. IDH mutation was negative in six of the seven patients where it was done. Median overall survival was 5 months. Multivariate analysis showed that a female gender (p = 0.013), seizures in the preoperative period (p = 0.048) and completion of adjuvant therapy (p = 0.003) were associated with a longer survival.

CONCLUSION

Insular glioblastomas have a poor prognosis. Insular location and certain tumour characteristics often limit the extent of resection of iGBMs. Moreover, postoperative complications sometimes negate the advantages of a radical resection. A female gender, presentation with seizures and completion of adjuvant chemoradiotherapy appear to be good prognostic factors.

The transfrontal isthmus approach for insular glioma surgery

OBJECTIVE

The classic transopercular or transsylvian approach to insular gliomas removes the tumor laterally through the insular cortex. This study describes a new anteroposterior approach through the frontal isthmus for insular glioma surgery.

METHODS

The authors detailed the surgical techniques for resection of insular gliomas through the transfrontal isthmus approach. Fifty-nine insular gliomas with at least Berger-Sanai zone I involvement were removed with the new approach, and extent of resection and postoperative neurological outcomes were assessed.

RESULTS

Fifty-nine patients were enrolled in the study, including 35 men and 24 women, with a mean (range) age 44.3 (19-75) years. According to the Berger-Sanai classification system, the most common tumor was a giant glioma (67.8%), followed by involvement of zones I and IV (18.6%). Twenty-two cases were Yaşargil type 3A/B, and 37 cases were Yaşargil type 5A/B. The average angle between the lateral plane of the putamen and sagittal line was 33.53°, and the average width of the isthmus near the anterior insular point was 33.33 mm. The average angle between the lateral plane of the putamen and the sagittal line was positively correlated with the width of the isthmus near the anterior insular point (r = 0.935, p < 0.0001). The median (interquartile range [IQR]) preoperative tumor volume was 67.82 (57.64-92.19) cm3. Of 39 low-grade gliomas, 26 (66.67%) were totally resected; of 20 high-grade gliomas, 19 (95%) were totally resected. The median (IQR) extent of resection of the whole group was 100% (73.7%-100%). Intraoperative diffusion-weighted imaging showed no cases of middle cerebral artery- or lenticulostriate artery-related stroke. Extent of insular tumor resection was positively correlated with the angle of the lateral plane of the putamen and sagittal line (r = -0.329, p = 0.011) and the width of the isthmus near the anterior insular point (r = -0.267, p = 0.041). At 3 months postoperatively, muscle strength grade exceeded 4 in all cases, and all patients exhibited essentially normal speech. The median (IQR) Karnofsky performance score at 3 months after surgery was 90 (80-90).

CONCLUSIONS

The transfrontal isthmus approach changes the working angle from lateral-medial to anterior-posterior, allowing for maximal safe removal of insular gliomas.

Incidence of ischemic complications and technical nuances of arteries preservation for insular gliomas resection

Introduction

Insular gliomas have complex anatomy and microvascular supply that make resection difficult. Furthermore, resection of insular glioma is associated with a significant risk of postoperative ischemic complications. Thus, this study aimed to assess the incidence of ischemic complications related to insular glioma resection, determine its risk factors, and describe a single surgeon's experience of artery-preserving tumor resection.

Methods

We enrolled 75 consecutive patients with insular gliomas who underwent transcortical tumor resection. Preoperative and postoperative demographic, clinical, radiological [including diffusion-weighted imaging (DWI)], intraoperative neurophysiological data, and functional outcomes were analyzed. Motor evoked potentials (MEPs) and radiological characteristics like the relationship between the proximal segment of the lateral lenticulostriate arteries (LLSAs) and the tumor, the flat inner edge sign (the inner edge of the insular glioma is well-defined) or obscure inner edge sign, the distance between the lesion and posterior limb of the internal capsule and the invasion of the superior limiting sulcus by the tumor were analyzed. Strategies such as "residual triangle," "basal ganglia outline reappearance," and "sculpting" technique were used to preserve the LLSAs and the main branches of M2 for maximal tumor resection according to the Berger-Sinai classification.

Results

Postoperative DWI showed acute ischemia in 44 patients (58.7%). Moreover, nine patients (12%) had developed new motor deficits, as determined by the treating neurosurgeons. The flat inner edge sign [odds ratio (OR), 0.144; 95% confidence interval (CI), 0.024-0.876) and MEPs (>50%) (OR, 18.182; 95% CI, 3.311-100.00) were significantly associated with postoperative core ischemia, which affected the posterior limb of the internal capsule or corona radiata.

Conclusions

Insular glioma resection was associated with a high incidence of ischemia, as detected by DWI, as well as new motor deficits that were determined by the treating neurosurgeons. Insular glioma patients with obscure inner edge signs and intraoperative MEPs decline >50% had a higher risk of developing core ischemia. With our strategies, maximal safe resection of insular gliomas may be achieved.

Avoiding vascular complications in insular glioma surgery – A microsurgical anatomy study and critical reflections regarding intraoperative findings

Introduction

Vascular lesions in insular glioma surgery can severely impact patients&amp;apos; quality of life. This study aims to present the results of our dissections and authors’ reflections on the insular vascular anatomy.

Matherials and Methods

The insular vascularization was examined using ×3 to ×40 magnification in 20 cadaveric cerebral hemispheres in which the arteries and veins had been perfused with colored silicone.

Results

In insular gliomas, this individualization of the anatomical structures is rarely possible, as the gyri are swollen by the tumor and lose their individuality. In the transsylvian approaches, the anatomical parameters for delimiting the insula in tumors are best provided by the superior and inferior circular sulci. The branches of the MCA are easily identified in the transcortical approach, but only at the end of the surgery after the tumor is resected.). One of the factors under-discussed in the literature is the involvement of the lenticulostriate arteries by the medial part of the tumor. In our experience of 52 patients (article submitted to publishing), LSTa were founded to be involved by the tumor in 13 cases. In 39 patients, there was no involvement of the LSTa, which allowed a more aggressive resection. Early preoperative identification of the anterior perforated substance on the MRI and its proximity to the tumor may help determine the route of the LSTa over the medial tumor boundaries.

Discussion

Our reflections introduced our imaging and anatomical concept regarding LSTa in insular glioma surgery. Accurate identification of origin, route, and distribution of the LSTa is pivotal to surgical success, especially in the lateral group. The anatomical knowledge of their path directly impacts the extent of tumor resection and functional preservation.

Conclusion

Knowledge of microsurgical anatomy, brain mapping, and surgical experience counts a lot in this type of surgery, creating a reasonable procedure flowchart to be taken intraoperatively.

Multiparametric Intraoperative Ultrasound in Oncological Neurosurgery: A Pictorial Essay

Intraoperative ultrasound (ioUS) is increasingly used in current neurosurgical practice. This is mainly explained by its affordability, handiness, multimodal real-time nature, and overall by its image spatial and temporal resolution. Identification of lesion and potential residue, analysis of the vascularization pattern, and characterization of the nature of the mass are only some of the advantages that ioUS offers to guide safe and efficient tumor resection. Technological advances in ioUS allow to achieve both structural and functional imaging. B-mode provides high-resolution visualization of the lesion and of its boundaries and relationships. Pioneering modes, such as contrast-enhanced ultrasound (CEUS), ultrasensitive Doppler, and elastosonography, are tools with great potential in characterizing different functional aspects of the lesion in a qualitative and quantitative manner. As already happening for many organs and pathologies, the combined use of different US modalities offers new insights in a multiparametric fashion. In this study, we present the potential of our multiparametric approach for ioUS during neuro-oncological surgery. In this effort, we provide a pictorial essay focusing on the most frequent pathologies: low- and high-grade gliomas, meningiomas, and brain metastases.

Navigated 3D-ultrasound power Doppler and visualization of lenticulostriate arteries during resections of insular gliomas

•

Preservation of LSAs is extremely important during resections of insular gliomas.

•

Navigated 3D-US power Doppler may enable intraoperative visualization of LSAs.

•

Quality of ultrasound scanner is important when LSAs should be visualized.

•

Reliability of LSAs depiction by 3D-US power Doppler is still investigated.

Sensitivity of three-dimensional time-of-flight 3.0 ​T magnetic resonance angiography in visualizing the number and course of lenticulostriate arteries in patients with insular gliomas

Background

Neurosurgical resection of insular gliomas is complicated by the possibility of iatrogenic injury to the lenticulostriate arteries (LSAs) and is associated with devastating neurological complications, hence the need to accurately assess the number of LSAs and their relationship to the tumor preoperatively.

Methods

The study included 24 patients with insular gliomas who underwent preoperative 3D-TOF MRA to visualize LSAs. The agreement of preoperative magnetic resonance imaging with intraoperative data in terms of the number of LSAs and their invasion by the tumor was assessed using the Kendall rank correlation coefficient and Cohen's Kappa with linear weighting. Agreement between experts performing image analysis was estimated using Cohen's Kappa with linear weighting.

Results

The number of LSAs arising from the M1 segment varied from 0 to 9 (mean 4.3 ​± ​0.37) as determined by 3D-TOF MRA and 2-6 (mean 4.25 ​± ​0.25) as determined intraoperatively, κ ​= ​0.51 (95% CI: 0.25-0.76) and τ ​= ​0.64 (p ​< ​0.001). LSAs were encased by the tumor in 11 patients (confirmed intraoperatively in 9 patients). LSAs were displaced medially in 8 patients (confirmed intraoperatively in 8 patients). The tumor partially involved the LSAs and displaced them in 5 patients (confirmed intraoperatively in 7 patients), κ ​= ​0.87 (95% CI: 0.70-1), τ ​= ​0.93 (p ​< ​0.001). 3D-TOF MRA demonstrated high sensitivity (100%, 95% CI: 0.63-1) and high specificity (86.67%, 95% CI: 0.58-0.98) in determining the LSA-tumor interface.

Conclusions

3D-TOF MRA at 3T demonstrated sensitivity in determining the LSA-tumor interface and the number of LSAs in patients with insular gliomas.

Utilizing Intraoperative Navigated 3D Color Doppler Ultrasound in Glioma Surgery

Background

In glioma surgery, the patient’s outcome is dramatically influenced by the extent of resection and residual tumor volume. To facilitate safe resection, neuronavigational systems are routinely used. However, due to brain shift, accuracy decreases with the course of the surgery. Intraoperative ultrasound has proved to provide excellent live imaging, which may be integrated into the navigational procedure. Here we describe the visualization of vascular landmarks and their shift during tumor resection using intraoperative navigated 3D color Doppler ultrasound (3D iUS color Doppler).

Methods

Six patients suffering from glial tumors located in the temporal lobe were included in this study. Intraoperative computed tomography was used for registration. Datasets of 3D iUS color Doppler were generated before dural opening and after tumor resection, and the vascular tree was segmented manually. In each dataset, one to four landmarks were identified, compared to the preoperative MRI, and the Euclidean distance was calculated.

Results

Pre-resectional mean Euclidean distance of the marked points was 4.1 ± 1.3 mm (mean ± SD), ranging from 2.6 to 6.0 mm. Post-resectional mean Euclidean distance was 4.7. ± 1.0 mm, ranging from 2.9 to 6.0 mm.

Conclusion

3D iUS color Doppler allows estimation of brain shift intraoperatively, thus increasing patient safety. Future implementation of the reconstructed vessel tree into the navigational setup might allow navigational updating with further consecutive increasement of accuracy.

Postcentral gyrus resection of opercular gliomas is a risk factor for motor deficits caused by damaging the radiologically invisible arteries supplying the descending motor pathway

BACKGROUND

Postoperative motor deficits are among the worst morbidities of glioma surgery. We aim to investigate factors associated with postoperative motor deficits in patients with frontoparietal opercular gliomas.

METHODS

Thirty-four patients with frontoparietal opercular gliomas were retrospectively investigated. We examined the postoperative ischemic changes and locations obtained from MRI.

RESULTS

Twenty-one patients (62%) presented postoperative ischemic changes. Postoperative MRI was featured with ischemic changes, all located at the subcortical area of the resection cavity. Six patients had postoperative motor deficits, whereas 28 patients did not. Compared to those without motor deficits, those with motor deficits were associated with old age, pre- and postcentral gyri resection, and postcentral gyrus resection (P = 0.023, 0,024, and 0.0060, respectively). A merged image of the resected cavity and T1-weighted brain atlas of the Montreal Neurological Institute showed that a critical area for postoperative motor deficits is the origin of the long insular arteries (LIAs) and the postcentral gyrus. Detail anatomical architecture created by the Human Connectome Project database and T2-weighted images showed that the subcortical area of the operculum of the postcentral gyrus is where the medullary arteries supply, and the motor pathways originated from the precentral gyrus run.

CONCLUSIONS

We verified that the origin of the LIAs could damage the descending motor pathways during the resection of frontoparietal opercular gliomas. Also, we identified that motor pathways run the subcortical area of the operculum of the postcentral gyrus, indicating that the postcentral gyrus is an unrecognized area of damaging the descending motor pathways.

Application of Multiparametric Intraoperative Ultrasound in Glioma Surgery

Gliomas are the most invasive and fatal primary malignancy of the central nervous system that have poor prognosis, with maximal safe resection representing the gold standard for surgical treatment. To achieve gross total resection (GTR), neurosurgery relies heavily on generating continuous, real-time, intraoperative glioma descriptions based on image guidance. Given the limitations of currently available equipment, developing a real-time image-guided resection technique that provides reliable functional and anatomical information during intraoperative settings is imperative. Nowadays, the application of intraoperative ultrasound (IOUS) has been shown to improve resection rates and maximize brain function preservation. IOUS, which presents an attractive option due to its low cost, minimal operational flow interruptions, and lack of radiation exposure, is able to provide real-time localization and accurate tumor size and shape descriptions while helping distinguish residual tumors and addressing brain shift. Moreover, the application of new advancements in ultrasound technology, such as contrast-enhanced ultrasound, three-dimensional ultrasound, navigable ultrasound, ultrasound elastography, and functional ultrasound, could help to achieve GTR during glioma surgery. The current review describes current advancements in ultrasound technology and evaluates the role and limitation of IOUS in glioma surgery.

Current Limitations of Intraoperative Ultrasound in Brain Tumor Surgery

While benefits of intraoperative ultrasound (IOUS) have been frequently described, data on IOUS limitations are relatively sparse. Suboptimal ultrasound imaging of some pathologies, various types of ultrasound artifacts, challenging patient positioning during some IOUS-guided surgeries, and absence of an optimal IOUS probe depicting the entire sellar region during transsphenoidal pituitary surgery are some of the most important pitfalls. This review aims to summarize prominent limitations of current IOUS systems, and to present possibilities to reduce them by using ultrasound technology suitable for a specific procedure and by proper scanning techniques. In addition, future trends of IOUS imaging optimization are described in this article.

Brain Shift in Neuronavigation of Brain Tumors: An Updated Review of Intra-Operative Ultrasound Applications

Neuronavigation using pre-operative imaging data for neurosurgical guidance is a ubiquitous tool for the planning and resection of oncologic brain disease. These systems are rendered unreliable when brain shift invalidates the patient-image registration. Our previous review in 2015, Brain shift in neuronavigation of brain tumours: A review offered a new taxonomy, classification system, and a historical perspective on the causes, measurement, and pre- and intra-operative compensation of this phenomenon. Here we present an updated review using the same taxonomy and framework, focused on the developments of intra-operative ultrasound-based brain shift research from 2015 to the present (2020). The review was performed using PubMed to identify articles since 2015 with the specific words and phrases: “Brain shift” AND “Ultrasound”. Since 2015, the rate of publication of intra-operative ultrasound based articles in the context of brain shift has increased from 2–3 per year to 8–10 per year. This efficient and low-cost technology and increasing comfort among clinicians and researchers have allowed unique avenues of development. Since 2015, there has been a trend towards more mathematical advancements in the field which is often validated on publicly available datasets from early intra-operative ultrasound research, and may not give a just representation to the intra-operative imaging landscape in modern image-guided neurosurgery. Focus on vessel-based registration and virtual and augmented reality paradigms have seen traction, offering new perspectives to overcome some of the different pitfalls of ultrasound based technologies. Unfortunately, clinical adaptation and evaluation has not seen as significant of a publication boost. Brain shift continues to be a highly prevalent pitfall in maintaining accuracy throughout oncologic neurosurgical intervention and continues to be an area of active research. Intra-operative ultrasound continues to show promise as an effective, efficient, and low-cost solution for intra-operative accuracy management. A major drawback of the current research landscape is that mathematical tool validation based on retrospective data outpaces prospective clinical evaluations decreasing the strength of the evidence. The need for newer and more publicly available clinical datasets will be instrumental in more reliable validation of these methods that reflect the modern intra-operative imaging in these procedures.

3D ultrasound-guided resection of low-grade gliomas: principles and clinical examples

3D ultrasound (US) is a convenient tool for guiding the resection of low-grade gliomas, seemingly without deterioration in patients' quality of life. This article offers an update of the intraoperative workflow and the general principles behind the 3D US acquisition of high-quality images.The authors also provide case examples illustrating the technique in two small mesial temporal lobe lesions and in one insular glioma. Due to the ease of acquiring new images for navigation, the operations can be guided by updated image volumes throughout the entire course of surgery. The high accuracy offered by 3D US systems, based on nearly real-time images, allows for precise and safe resections. This is especially useful when an operation is performed through very narrow transcortical corridors.

Preservation of the Lenticulostriate Arteries During Insular Glioma Resection

Insular gliomas represent 25% and 10% of low- and high-grade gliomas, respectively. Their resection proves challenging due to the intimate involvement of eloquent parenchyma and the lenticulostriate arteries (LSAs), limiting facility of achieving maximal safe resection. The majority of postoperative deficits following insular glioma resection is attributed to compromise of the LSAs. It is contemporaneously critical and challenging to preserve these vessels, given they are numerous and small, with an intraparenchymal course hidden from direct visualization during the operative intervention. A lesser degree of medially directed displacement of the LSAs predicts tumoral encasement of these vessels, which portends a decreased likelihood for achieving a gross total resection and increased probability of postoperative morbidity. Preservation of these vessels thus requires knowledge of their location during the entirety of the insular glioma resection and is facilitated by pre- and intra-operative imaging. Intraoperative real-time tracking, however, may prove rather challenging, especially with transcortical access. Conventional catheter digital subtraction angiography, computed tomographic angiography, magnetic resonance imaging and angiography, and three-dimensional ultrasound powered Doppler have proven effective modalities in assessing lenticulostriate position, and their use facilitates a greater extent of resection while minimizing the attendant morbidity consequent to LSA injury.

Visualization of Lenticulostriate Arteries on CT Angiography Using Ultra-High-Resolution CT Compared with Conventional-Detector CT

BACKGROUND AND PURPOSE

The newly developed ultra-high-resolution CT is equipped with a 0.25-mm detector, which has one-half the conventional section thickness, one-half the in-plane detector element width, and one-half the reconstructed pixel width compared with conventional-detector CT. Thus, the ultra-high-resolution CT scanner should provide better image quality for microvasculature than the conventional-detector CT scanners. This study aimed to determine whether ultra-high-resolution CT produces superior-quality images of the lenticulostriate arteries compared with conventional-detector CT.

MATERIALS AND METHODS

From February 2017 to June 2017, thirteen patients with aneurysms (4 men, 9 women; mean age, 61.2 years) who underwent head CTA with both ultra-high-resolution CT and conventional-detector CT were enrolled. Two board-certified radiologists determined the number of all lenticulostriate arteries on the CTA coronal images of the MCA M1 segment reconstructed from 512 matrixes on conventional-detector CT and 1024 matrixes on ultra-high-resolution CT.

RESULTS

There were statistically more lenticulostriate arteries identified on ultra-high-resolution CT (average, 2.85 ± 0.83; 95% CI, 2.509-3.183) than on conventional-detector CT (average, 2.17 ± 0.76; 95% CI, 1.866-2.480) (P = .009) in 16 of the total 26 MCA M1 segments.

CONCLUSIONS

Improvements in lenticulostriate artery visualization were the result of the combined package of the ultra-high-resolution CT scanner plus the ultra-high-resolution scanning protocol, which includes higher radiation doses with lower than the national diagnostic reference levels and stronger adaptive iterative dose-reduction processing. This package for ultra-high-resolution CT is a simple, noninvasive, and easily accessible method to evaluate microvasculature such as the lenticulostriate arteries.

Ischemic stroke following elective craniotomy in children

OBJECTIVE An ischemic stroke following an elective craniotomy in a child is perceived to be a rare event. However, to date there are few papers on this topic. The purpose of this study was to investigate the occurrence of stroke following elective intracranial surgery at a children’s hospital. METHODS The authors performed a retrospective review of all patients who developed a perioperative stroke following an elective craniotomy from 2010 through 2017. Data were collected using an institutional database that contained demographic, medical, radiological, and outcome variables. RESULTS A total of 1591 elective craniotomies were performed at the authors’ institution during the study period. Of these, 28 (1.8%) were followed by a perioperative stroke. Radiographic diagnosis of the infarction occurred at a median of 1.7 days (range 0–9 days) from the time of surgery, and neurological deficits were apparent within 24 hours of surgery in 18 patients (62.5%). Infarcts tended to occur adjacent to tumor resection sites (86% of cases), and in a unilateral (89%), unifocal (93%), and supratentorial (93%) location. Overall, 11 (39.3%) strokes were due to a perforating artery, 10 (35.7%) were due to a large vessel, 4 (14.3%) were venous, and 3 (10.7%) were related to hypoperfusion or embolic causes. Intraoperative MRI (iMRI) was used in 11 of the 28 cases, and 6 (55%) infarcts were not detected, all of which were deep. CONCLUSIONS The incidence of stroke following an elective craniotomy is low, with nearly all cases (86%) occurring after tumor resection. Perforator infarcts were most common but may be missed on iMRI. ABBREVIATIONS ACA = anterior cerebral artery; AChA = anterior choroidal artery; ACS NSQIP-P = American College of Surgeons National Surgical Quality Improvement Program–Pediatric; CVA = cerebrovascular accident; DWI = diffusion weighted imaging; iMRI = intraoperative MRI; MCA = middle cerebral artery; mRS = modified Rankin Scale; PCA = posterior cerebral artery.

Insular glioma surgery: an evolution of thought and practice

OBJECTIVEThe goal of this article is to review the history of surgery for low- and high-grade gliomas located within the insula with particular focus on microsurgical technique, anatomical considerations, survival, and postoperative morbidity.METHODSThe authors reviewed the literature for published reports focused on insular region anatomy, neurophysiology, surgical approaches, and outcomes for adults with World Health Organization grade II-IV gliomas.RESULTSWhile originally considered to pose too great a risk, insular glioma surgery can be performed safely due to the collective efforts of many individuals. Similar to resection of gliomas located within other cortical regions, maximal resection of gliomas within the insula offers patients greater survival time and superior seizure control for both newly diagnosed and recurrent tumors in this region. The identification and the preservation of M2 perforating and lateral lenticulostriate arteries are critical steps to preventing internal capsule stroke and hemiparesis. The transcortical approach and intraoperative mapping are useful tools to maximize safety.CONCLUSIONSThe insula's proximity to middle cerebral and lenticulostriate arteries, primary motor areas, and perisylvian language areas makes accessing and resecting gliomas in this region challenging. Maximal safe resection of insular gliomas not only is possible but also is associated with excellent outcomes and should be considered for all patients with low- and high-grade gliomas in this area.

Advanced Ultrasound Imaging in Glioma Surgery: Beyond Gray-Scale B-mode

Introduction: Glioma surgery is aimed at obtaining maximal safe tumor resection while preserving or improving patient's neurological status. For this reason, there is growing interest for intra-operative imaging in neuro-oncological surgery. Intra-operative ultrasound (ioUS) provides the surgeon with real-time, anatomical and functional information. Despite this, in neurosurgery ioUS mainly relies only on gray-scale brightness mode (B-mode). Many other ultrasound imaging modalities, such as Fusion Imaging with pre-operative acquired magnetic resonance imaging (MRI), Doppler modes, Contrast Enhanced Ultrasound (CEUS), and elastosonography have been developed and have been extensively used in other organs. Although these modalities offer valuable real-time intra-operative information, so far their usage during neurosurgical procedures is still limited.

Purpose: To present an US-based multimodal approach for image-guidance in glioma surgery, highlighting the different features of advanced US modalities: fusion imaging with pre-operative acquired MRI for Virtual Navigation, B-mode, Doppler (power-, color-, spectral-), CEUS, and elastosonography.

Methods: We describe, in a step-by-step fashion, the applications of the most relevant advanced US modalities during different stages of surgery and their implications for surgical decision-making. Each US modality is illustrated from a technical standpoint and its application during glioma surgery is discussed.

Results: B-mode offers dynamic morphological information, which can be further implemented with fusion imaging to improve image understanding and orientation. Doppler imaging permits to evaluate anatomy and function of the vascular tree. CEUS allows to perform a real-time angiosonography, providing valuable information in regards of parenchyma and tumor vascularization and perfusion. This facilitates tumor detection and surgical strategy, also allowing to characterize tumor grade and to identify residual tumor. Elastosonography is a promising tool able to better define tumor margins, parenchymal infiltration, tumor consistency and permitting differentiation of high grade and low grade lesions.

Conclusions: Multimodal ioUS represents a valuable tool for glioma surgery being highly informative, rapid, repeatable, and real-time. It is able to differentiate low grade from high grade tumors and to provide the surgeon with relevant information for surgical decision-making. ioUS could be integrated with other intra-operative imaging and functional approaches in a synergistic manner to offer the best image guidance for each patient.

Navigated 3D-ultrasound versus conventional neuronavigation during awake resections of eloquent low-grade gliomas: a comparative study at a single institution

BACKGROUND

The data showing usefulness of navigated 3D-ultrasound (3DUS) during awake resections of eloquent gliomas are sparse. Results of surgeries performed using 3DUS were never compared to procedures guided by standard neuronavigation. The aim of this work is to assess the effectiveness of 3DUS during awake resections of eloquent low-grade gliomas (LGGs) by comparing surgical results of two series of patients operated on using conventional neuronavigation and using 3DUS. To our knowledge, a similar study is lacking in the literature.

METHODS

During a 4-year period (September 2006 to August 2010) 21 awake resections of LGGs guided by neuronavigation (series 1, S1) were consecutively performed in Department of Neurosurgery in Bratislava. During another 4-year period (August 2010 to July 2014) 28 awake resections of LGGs guided by 3DUS (series 2, S2) were consecutively conducted. In both patients series, the eloquent cortical and subcortical structures were intraoperatively detected by direct electrical stimulation. Extent of tumor resection (EOR) and functional outcome in both series were compared.

RESULTS

EOR was significantly greater (p = 0.022) in S2 (median = 93.25%; mean = 86.79%), as compared to S1 (median 87.1%; mean = 75.85%). One permanent minor deficit in S1 and 2 minor deficits in S2 occurred, the difference was not significant (p = 0.999).

CONCLUSIONS

Our work represents the first study comparing results of surgeries guided by 3DUS versus conventional navigation. The extent of awake resections of eloquent LGG guided by 3DUS was greater comparing to awake resections guided by standard neuronavigation; use of 3DUS had no impact on the number of new permanent deficits.

Analogous Three-Dimensional Constructive Interference in Steady State Sequences Enhance the Utility of Three-Dimensional Time of Flight Magnetic Resonance Angiography in Delineating Lenticulostriate Arteries in Insular Gliomas: Evidence from a Prospective Clinicoradiologic Analysis of 48 Patients

BACKGROUND

Three-dimensional (3D) time of flight (TOF) imaging is the current gold standard for noninvasive, preoperative localization of lenticulostriate arteries (LSAs) in insular gliomas; however, the utility of this modality depends on tumor intensity.

METHODS

Over a 3-year period, 48 consecutive patients with insular gliomas were prospectively evaluated. Location of LSAs and their relationship with the tumor were determined using a combination of contrast-enhanced coronal 3D TOF magnetic resonance angiography and coronal 3D constructive interference in steady state (CISS) sequences. These findings were analyzed with respect to extent of tumor resection and early postoperative motor outcome.

RESULTS

Tumor was clearly visualized in 29 (60.4%) patients with T1-hypointense tumors using 3D TOF and in all patients using CISS sequences. Using combined 3D TOF and CISS, LSA-tumor interface was well seen in 47 patients, including all patients with T1-heterointense or T1-isointense tumors. Extent of resection was higher in the LSA-pushed group compared with the LSA-encased group. In the LSA-encased group, 6 (12.5%) patients developed postoperative hemiparesis; 2 (4.2%) cases were attributed to LSA injury.

CONCLUSIONS

Contrast-enhanced 3D TOF can delineate LSAs in almost all insular gliomas but is limited in identifying the LSA-tumor interface. This limitation can be overcome by addition of analogous CISS sequences that delineate the LSA-tumor interface regardless of tumor intensity. Combined 3D TOF and 3D CISS is a useful tool for surgical planning and safer resections of insular tumors and may have added surgical relevance when included as an intraoperative adjunct.

Insular gliomas: a surgical reappraisal based on a systematic review of the literature

INTRODUCTION

Insular gliomas are heterogeneous lesions whose management presents multiple challenges for their tendency to affect young patients in good neurological and cognitive conditions, their deep anatomic location and proximity with critical functional and vascular structures. The appropriate management of insular gliomas requires a multidisciplinary evidence-centred teamwork grounded on the best anatomic, neurophysiological and oncological knowledge. The present study provides a reappraisal of the management of insular gliomas based on a systematic review of the literature with the aim of guiding clinicians in the management of such tumors.

EVIDENCE ACQUISITION

A systematic review of the literature from the Medline, Embase and Cochrane Central databases was performed. From 2006 to 2016, all articles meeting specific inclusion criteria were included.

EVIDENCE SYNTHESIS

The present work summarizes the most relevant evidence about insular gliomas management. The anatomy and physiology of the insula, the new WHO 2016 classification and clinico-radiological presentation of insular gliomas are reviewed. Surgical pearls of insular gliomas resection as well as oncologic and functional outcomes after insular gliomas treatment are discussed.

CONCLUSIONS

Management of insular gliomas remains challenging despite improvement in surgical and oncological techniques. However, the literature review supports a growing evidence that recent developments in the multidisciplinary care account for constant improvements of survival and quality of life.

Applications of Ultrasound in the Resection of Brain Tumors

Neurosurgery makes use of preoperative imaging to visualize pathology, inform surgical planning, and evaluate the safety of selected approaches. The utility of preoperative imaging for neuronavigation, however, is diminished by the well-characterized phenomenon of brain shift, in which the brain deforms intraoperatively as a result of craniotomy, swelling, gravity, tumor resection, cerebrospinal fluid (CSF) drainage, and many other factors. As such, there is a need for updated intraoperative information that accurately reflects intraoperative conditions. Since 1982, intraoperative ultrasound has allowed neurosurgeons to craft and update operative plans without ionizing radiation exposure or major workflow interruption. Continued evolution of ultrasound technology since its introduction has resulted in superior imaging quality, smaller probes, and more seamless integration with neuronavigation systems. Furthermore, the introduction of related imaging modalities, such as 3-dimensional ultrasound, contrast-enhanced ultrasound, high-frequency ultrasound, and ultrasound elastography, has dramatically expanded the options available to the neurosurgeon intraoperatively. In the context of these advances, we review the current state, potential, and challenges of intraoperative ultrasound for brain tumor resection. We begin by evaluating these ultrasound technologies and their relative advantages and disadvantages. We then review three specific applications of these ultrasound technologies to brain tumor resection: (1) intraoperative navigation, (2) assessment of extent of resection, and (3) brain shift monitoring and compensation. We conclude by identifying opportunities for future directions in the development of ultrasound technologies.