Intraoperative 3D ultrasound-guided resection of diffuse low-grade gliomas: radiological and clinical results

Progress in the application of ultrasound in glioma surgery

Brain glioma, which is highly invasive and has a poor prognosis, is the most common primary intracranial tumor. Several studies have verified that the extent of resection is a considerable prognostic factor for achieving the best results in neurosurgical oncology. To obtain gross total resection (GTR), neurosurgery relies heavily on generating continuous, real-time, intraoperative glioma descriptions based on image guidance. Given the limitations of existing devices, it is imperative to develop a real-time image-guided resection technique to offer reliable functional and anatomical information during surgery. At present, the application of intraoperative ultrasound (IOUS) has been indicated to enhance resection rates and maximize brain function preservation. IOUS, which is promising due to its lower cost, minimal operational flow interruptions, and lack of radiation exposure, can enable real-time localization and precise tumor size and form descriptions while assisting in discriminating residual tumors and solving brain tissue shifts. Moreover, the application of new advancements in ultrasound technology, such as contrast-enhanced ultrasound (CEUS), three-dimensional ultrasound (3DUS), noninvasive ultrasound (NUS), and ultrasound elastography (UE), could assist in achieving GTR in glioma surgery. This article reviews the advantages and disadvantages of IOUS in glioma surgery.

Global health status and fatigue score in isocitrate dehydrogenase-mutant diffuse glioma grades 2 and 3: A longitudinal population-based study from surgery to 12-month follow-up

Background

At the group level, health-related quality of life (HRQoL) in patients with IDH-mutant diffuse glioma grades 2 and 3 seems to remain stable over time. However, clinical experience indicates that there are patients with unfavorable outcomes on key HRQoL subdomains. The aim of this longitudinal population-based study, following patients over a period of 12 months from surgery, was to describe individual-level data on global health status and fatigue score and explore possible predictors of deterioration.

Methods

All patients undergoing surgery for presumed glioma grades 2 or 3 at the Sahlgrenska University Hospital during 2017-2022, were screened for the study. Patients were invited to complete the European Organization of Research and Treatment of Cancer core questionnaires and brain module at baseline, 3 and 12 months postoperatively. Data is reported with respect to minimal clinical important difference (MCID).

Results

We included 51 patients with IDH-mutant diffuse glioma grades 2 or 3. There was no difference in group-level data of either global health status or fatigue score from baseline to the 12-month follow-up (P-value > .05). Unfavorable individual changes (beyond MCID) in global health status and fatigue score were observed in 12 and in 17 patients, respectively (23.5% and 33.3%). A lower proportion of proton radiotherapy was found in patients with unfavorable changes in fatigue (10/15, 66.7%) compared to all other patients undergoing radiotherapy (22/23, 95.7%, P-value .03).

Conclusions

Deterioration beyond MCID was seen in approximately one-third of patients. Changes in global health status could not be predicted, but changes in fatigue may be influenced by tumor-targeted and symptomatic treatment.

Non-navigated 2D intraoperative ultrasound: An unsophisticated surgical tool to achieve high standards of care in glioma surgery

PURPOSE

In an era characterized by rapid progression in neurosurgical technologies, traditional tools such as the non-navigated two-dimensional intraoperative ultrasound (nn-2D-IOUS) risk being overshadowed. Against this backdrop, this study endeavors to provide a comprehensive assessment of the clinical efficacy and surgical relevance of nn-2D-IOUS, specifically in the context of glioma resections.

METHODS

This retrospective study undertaken at a single center evaluated 99 consecutive, non-selected patients diagnosed with both high-grade and low-grade gliomas. The primary objective was to assess the proficiency of nn-2D-IOUS in generating satisfactory image quality, identifying residual tumor tissue, and its influence on the extent of resection. To validate these results, early postoperative MRI data served as the reference standard.

RESULTS

The nn-2D-IOUS exhibited a high level of effectiveness, successfully generating good quality images in 79% of the patients evaluated. With a sensitivity rate of 68% and a perfect specificity of 100%, nn-2D-IOUS unequivocally demonstrated its utility in intraoperative residual tumor detection. Notably, when total tumor removal was the surgical objective, a resection exceeding 95% of the initial tumor volume was achieved in 86% of patients. Additionally, patients in whom residual tumor was not detected by nn-2D-IOUS, the mean volume of undetected tumor tissue was remarkably minimal, averaging at 0.29 cm3.

CONCLUSION

Our study supports nn-2D-IOUS's invaluable role in glioma surgery. The results highlight the utility of traditional technologies for enhanced surgical outcomes, even when compared to advanced alternatives. This is particularly relevant for resource-constrained settings and emphasizes optimizing existing tools for efficient patient care. NCT05873946 - 24/05/2023 - Retrospectively registered.

Thirty years of progress in the management of low-grade gliomas

This paper reviews 30 years of developments in the area of low-grade gliomas. This includes the changes in diagnostics with the incorporation of 1p/19q and IDH mutations in the diagnostic classifier, the improved surgical techniques, improved delivery of radiotherapy and chemotherapy. More recently, the better understanding of the altered cellular processes has lead to the development of novel drugs that may alter completely alter the management of patients early in the course of their disease.

Changes in clinical management of diffuse IDH-mutated lower-grade gliomas: patterns of care in a 15-year period

BACKGROUND

Isocitrate dehydrogenase (IDH) mutated diffuse lower-grade gliomas (dLGG) are infiltrating brain tumors and increasing evidence is in favor of early multimodal treatment. In a Scandinavian population-based setting, we wanted to study treatment patterns over the last 15 years, focusing on the short-term postoperative course to better understand the potential negative consequences of treatment.

METHODS

Patients ≥ 18 years with primary IDH-mutated dLGG grade 2 and 3, operated between January 2007-June 2021 were identified. Patients were divided into subgroups (2007-2011, 2012-2016, and 2017-2021) and comparisons regarding tumor- and disease characteristics, treatment, and postoperative outcome were performed.

RESULTS

We identified 202 patients (n = 61, 2007-2011; n = 72, 2012-2016; n = 69, 2017-2021), where of 193 underwent resection without change in proportion of resections over time. More patients underwent complete resections in recent times (6.1%; 15.7%; 26.1%, respectively; p = 0.016). Forty-two patients had any neurological deficit postoperatively (14.8%; 23.6%; 23.2%; p = 0.379), mostly minor and transient. Differences in oncological therapy were seen between the investigated subgroups. Early radiotherapy alone (32.8%; 7%; 2.9%; p < 0.001), concomitant chemoradiotherapy (23%; 37.5%; 17.4%; p = 0.022), sequential chemoradiotherapy (0%; 18%; 49.3%; p < 0.001), and no adjuvant treatment (42.6%; 23.6%; 18.8%; p = 0.009) shifted during the studied period. Increasingly more patients received proton radiotherapy compared to photon radiotherapy during the later time periods (p < 0.001).

CONCLUSION

Complete resections were performed more often in later time periods without an apparent increase in surgical morbidity. Early adjuvant oncological treatment shifted towards providing chemotherapy and combined chemoradiotherapy more often in later time periods. Protons replaced photons as the radiation modality of choice.

The impact of resection in IDH-mutant WHO grade 2 gliomas: a retrospective population-based parallel cohort study

OBJECTIVE

IDH-mutant diffuse low-grade gliomas (dLGGs; WHO grade 2) are often considered to have a more indolent course. In particular, in patients with 1p19q codeleted oligodendrogliomas, survival can be very long. Therefore, extended follow-up in clinical studies of IDH-mutant dLGG is needed. The authors' primary aim was to determine results after a minimum 10-year follow-up in two hospitals advocating different surgical policies. In one center early resection was favored; in the other center an early biopsy and wait-and-scan approach was the dominant management. In addition, the authors present survival and health-related quality of life (HRQOL) in stratified groups of patients with IDH-mutant astrocytoma and oligodendroglioma.

METHODS

The authors conducted a retrospective, population-based, parallel cohort study with extended long-term follow-up. The inclusion criteria were histopathological diagnosis of IDH-mutant supratentorial dLGG from 1998 through 2009 in patients aged 18 years or older. Follow-up ended January 1, 2021; therefore, all patients had primary surgery more than 10 years earlier. In region A, a biopsy and wait-and-scan approach was favored, while early resections were advocated in region B. Regional referral practice ensured population-based data, since referral to respective centers was based strictly on the patient's residential address. Previous data from EQ-5D-3L, European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, and EORTC BN20 questionnaires were reanalyzed with respect to the current selection of IDH-mutant dLGG and to molecular subgroups. The prespecified primary endpoint was long-term regional comparison of overall survival. Secondarily, between-group differences in long-term HRQOL measures were explored.

RESULTS

Forty-eight patients from region A and 56 patients from region B were included. Early resection was performed in 17 patients (35.4%) from region A compared with 53 patients (94.6%) from region B (p < 0.001). Characteristics at baseline were otherwise similar between cohorts. Overall survival was 7.5 years (95% CI 4.1-10.8) in region A compared with 14.6 years (95% CI 11.5-17.7) in region B (p = 0.04). When stratified according to molecular subgroups, there was only a statistically significant survival benefit in favor of early resection for patients with astrocytomas. The were no apparent differences in the different HRQOL measures between cohorts.

CONCLUSIONS

In an extended follow-up of patients with IDH-mutant dLGGs, early resection was associated with a sustained and clinically relevant survival benefit. The survival benefit was not counteracted by any detectable reduction in HRQOL.

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.

Application of Intraoperative Ultrasound Navigation in Neurosurgery

Effective intraoperative image navigation techniques are necessary in modern neurosurgery. In the last decade, intraoperative ultrasonography (iUS), a relatively inexpensive procedure, has gained widespread acceptance.

Intraoperative MR Imaging during Glioma Resection

One of the major issues in the surgical treatment of gliomas is the concern about maximizing the extent of resection while minimizing neurological impairment. Thus, surgical planning by carefully observing the relationship between the glioma infiltration area and eloquent area of the connecting fibers is crucial. Neurosurgeons usually detect an eloquent area by functional MRI and identify a connecting fiber by diffusion tensor imaging. However, during surgery, the accuracy of neuronavigation can be decreased due to brain shift, but the positional information may be updated by intraoperative MRI and the next steps can be planned accordingly. In addition, various intraoperative modalities may be used to guide surgery, including neurophysiological monitoring that provides real-time information (e.g., awake surgery, motor-evoked potentials, and sensory evoked potential); photodynamic diagnosis, which can identify high-grade glioma cells; and other imaging techniques that provide anatomical information during the surgery. In this review, we present the historical and current context of the intraoperative MRI and some related approaches for an audience active in the technical, clinical, and research areas of radiology, as well as mention important aspects regarding safety and types of devices.

Brain infarctions after glioma surgery: prevalence, radiological characteristics and risk factors

Background

Prevalence, radiological characteristics, and risk factors for peritumoral infarctions after glioma surgery are not much studied. In this study, we assessed shape, volume, and prevalence of peritumoral infarctions and investigated possible associated factors.

Methods

In a prospective single-center cohort study, we included all adult patients operated for diffuse gliomas from January 2007 to December 2018. Postoperative infarctions were segmented using early postoperative MRI images, and volume, shape, and location of postoperative infarctions were assessed. Heatmaps of the distribution of tumors and infarctions were created.

Results

MRIs from 238 (44%) of 539 operations showed restricted diffusion in relation to the operation cavity, interpreted as postoperative infarctions. Of these, 86 (36%) were rim-shaped, 103 (43%) were sector-shaped, 40 (17%) were a combination of rim- and sector-shaped, and six (3%) were remote infarctions. Median infarction volume was 1.7 cm³ (IQR 0.7–4.3, range 0.1–67.1). Infarctions were more common if the tumor was in the temporal lobe, and the map shows more infarctions in the periventricular watershed areas. Sector-shaped infarctions were more often seen in patients with known cerebrovascular disease (47.6% vs. 25.5%, p = 0.024). There was a positive correlation between infarction volume and tumor volume (r = 0.267, p < 0.001) and infarction volume and perioperative bleeding (r = 0.176, p = 0.014). Moreover, there was a significant positive association between age and larger infarction volumes (r = 0.193, p = 0.003). Infarction rates and infarction volumes varied across individual surgeons, p = 0.037 (range 32–72%) and p = 0.026.

Conclusions

In the present study, peritumoral infarctions occurred in 44% after diffuse glioma operations. Infarctions were more common in patients operated for tumors in the temporal lobe but were not more common following recurrent surgeries. Sector-shaped infarctions were more common in patients with known cerebrovascular disease. Increasing age, larger tumors, and more perioperative bleeding were factors associated with infarction volumes. The risk of infarctions and infarction volumes may also be surgeon-dependent.

5-ALA in Suspected Low-Grade Gliomas: Current Role, Limitations, and New Approaches

Radiologically suspected low-grade gliomas (LGG) represent a special challenge for the neurosurgeon during surgery due to their histopathological heterogeneity and indefinite tumor margin. Therefore, new techniques are required to overcome these current surgical drawbacks. Intraoperative visualization of brain tumors with assistance of 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence is one of the major advancements in the neurosurgical field in the last decades. Initially, this technique was exclusively applied for fluorescence-guided surgery of high-grade glioma (HGG). In the last years, the use of 5-ALA was also extended to other indications such as radiologically suspected LGG. Here, we discuss the current role of 5-ALA for intraoperative visualization of focal malignant transformation within suspected LGG. Furthermore, we discuss the current limitations of the 5-ALA technology in pure LGG which usually cannot be visualized by visible fluorescence. Finally, we introduce new approaches based on fluorescence technology for improved detection of pure LGG tissue such as spectroscopic PpIX quantification fluorescence lifetime imaging of PpIX and confocal microscopy to optimize surgery.

Multimodal integrated approaches in low grade glioma surgery

Surgical management of Diffuse Low-Grade Gliomas (DLGGs) has radically changed in the last 20 years. Awake surgery (AS) in combination with Direct Electrical Stimulation (DES) and real-time neuropsychological testing (RTNT) permits continuous intraoperative feedback, thus allowing to increase the extent of resection (EOR). The aim of this study was to evaluate the impact of the technological advancements and integration of multidisciplinary techniques on EOR. Two hundred and eighty-eight patients affected by DLGG were enrolled. Cases were stratified according to the surgical protocol that changed over time: 1. DES; 2. DES plus functional MRI/DTI images fused on a NeuroNavigation system; 3. Protocol 2 plus RTNT. Patients belonging to Protocol 1 had a median EOR of 83% (28–100), while those belonging to Protocol 2 and 3 had a median EOR of 88% (34–100) and 98% (50–100) respectively (p = 0.0001). New transient deficits with Protocol 1, 2 and 3 were noted in 38.96%, 34.31% and 31,08% of cases, and permanent deficits in 6.49%, 3.65% and 2.7% respectively. The average follow-up period was 6.8 years. OS was influenced by molecular class (p = 0.028), EOR (p = 0.018) and preoperative tumor growing pattern (p = 0.004). Multimodal surgical approach can provide a safer and wider removal of DLGG with potential subsequent benefits on OS. Further studies are necessary to corroborate our findings.

State of Radiomics in Glioblastoma

Radiomics is an emerging discipline that aims to make intelligent predictions and derive medical insights based on quantitative features extracted from medical images as a means to improve clinical diagnosis or outcome. Pertaining to glioblastoma, radiomics has provided powerful, noninvasive tools for gaining insights into pathogenesis and therapeutic responses. Radiomic studies have yielded meaningful biological understandings of imaging features that are often taken for granted in clinical medicine, including contrast enhancement on glioblastoma magnetic resonance imaging, the distance of a tumor from the subventricular zone, and the extent of mass effect. They have also laid the groundwork for noninvasive detection of mutations and epigenetic events that influence clinical outcomes such as isocitrate dehydrogenase (IDH) and O6-methylguanine-DNA methyltransferase (MGMT). In this article, we review advances in the field of glioblastoma radiomics as they pertain to prediction of IDH mutation status and MGMT promoter methylation status, as well as the development of novel, higher order radiomic parameters.

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.

Clinical Management of Diffuse Low-Grade Gliomas

Diffuse low-grade gliomas (LGG) represent a heterogeneous group of primary brain tumors arising from supporting glial cells and usually affecting young adults. Advances in the knowledge of molecular profile of these tumors, including mutations in the isocitrate dehydrogenase genes, or 1p/19q codeletion, and in neuroradiological techniques have contributed to the diagnosis, prognostic stratification, and follow-up of these tumors. Optimal post-operative management of LGG is still controversial, though radiation therapy and chemotherapy remain the optimal treatments after surgical resection in selected patients. In this review, we report the most important and recent research on clinical and molecular features, new neuroradiological techniques, the different therapeutic modalities, and new opportunities for personalized targeted therapy and supportive care.

Advancements in predicting outcomes in patients with glioma: a surgical perspective

Introduction: Diffuse glioma is a challenging neurosurgical entity. Although surgery does not provide a cure, it may greatly influence survival, brain function, and quality of life. Surgical treatment is by nature highly personalized and outcome prediction is very complex. To engage and succeed in this balancing act it is important to make best use of the information available to the neurosurgeon.Areas covered: This narrative review provides an update on advancements in predicting outcomes in patients with glioma that are relevant to neurosurgeons.Expert opinion: The classical 'gut feeling' is notoriously unreliable and better prediction strategies for patients with glioma are warranted. There are numerous tools readily available for the neurosurgeon in predicting tumor biology and survival. Predicting extent of resection, functional outcome, and quality of life remains difficult. Although machine-learning approaches are currently not readily available in daily clinical practice, there are several ongoing efforts with the use of big data sets that are likely to create new prediction models and refine the existing models.