Accuracy of the neurosurgeons estimation of extent of resection in glioblastoma

How to evaluate extent of resection in diffuse gliomas: from standards to new methods

PURPOSE OF REVIEW

Maximal safe tumor resection represents the current standard of care for patients with newly diagnosed diffuse gliomas. Recent efforts have highlighted the prognostic value of extent of resection measured as residual tumor volume in patients with isocitrate dehydrogenase (IDH)-wildtype and -mutant gliomas. Accurate assessment of such information therefore appears essential in the context of clinical trials as well as patient management.

RECENT FINDINGS

Current recommendations for evaluation of extent of resection rest upon standardized postoperative MRI including contrast-enhanced T1-weighted sequences, T2-weighted/fluid-attenuated-inversion-recovery sequences, and diffusion-weighted imaging to differentiate postoperative tumor volumes from ischemia and nonspecific imaging findings. In this context, correct timing of postoperative imaging within the postoperative period is of utmost importance. Advanced MRI techniques including perfusion-weighted MRI and MR-spectroscopy may add further insight when evaluating residual tumor remnants. Positron emission tomography (PET) using amino acid tracers proves beneficial in identifying metabolically active tumor beyond anatomical findings on conventional MRI.

SUMMARY

Future efforts will have to refine recommendations on postoperative assessment of residual tumor burden in respect to differences between IDH-wildtype and -mutant gliomas, and incorporate the emerging role of advanced imaging modalities like amino acid PET.

Apparent Diffusion Coefficient Metrics to Differentiate between Treatment-Related Abnormalities and Tumor Progression in Post-Treatment Glioblastoma Patients: A Retrospective Study

Distinguishing treatment-related abnormalities (TRA) from tumor progression (TP) in glioblastoma patients is a diagnostic imaging challenge due to the identical morphology of conventional MR imaging sequences. Diffusion-weighted imaging (DWI) and its derived images of the apparent diffusion coefficient (ADC) have been suggested as diagnostic tools for this problem. The aim of this study is to determine the diagnostic accuracy of different cut-off values of the ADC to differentiate between TP and TRA. In total, 76 post-treatment glioblastoma patients with new contrast-enhancing lesions were selected. Lesions were segmented using a T1-weighted, contrast-enhanced scan. The mean ADC values of the segmentations were compared between TRA and TP groups. Diagnostic accuracy was compared by use of the area under the curve (AUC) and the derived sensitivity and specificity values from cutoff points. Although ADC values in TP (mean = 1.32 × 10-3 mm2/s; SD = 0.31 × 10-3 mm2/s) were significantly different compared to TRA (mean = 1.53 × 10-3 mm2/s; SD = 0.28 × 10-3 mm2/s) (p = 0.003), considerable overlap in their distributions exists. The AUC of ADC values to distinguish TP from TRA was 0.71, with a sensitivity and specificity of 65% and 70%, respectively, at an ADC value of 1.47 × 10-3 mm2/s. These findings therefore indicate that ADC maps should not be used in discerning between TP and TRA at a certain timepoint without information on temporal evolution.

Surgical management of Glioma Grade 4: technical update from the neuro-oncology section of the Italian Society of Neurosurgery (SINch®): a systematic review

PURPOSE

The extent of resection (EOR) is an independent prognostic factor for overall survival (OS) in adult patients with Glioma Grade 4 (GG4). The aim of the neuro-oncology section of the Italian Society of Neurosurgery (SINch®) was to provide a general overview of the current trends and technical tools to reach this goal.

METHODS

A systematic review was performed. The results were divided and ordered, by an expert team of surgeons, to assess the Class of Evidence (CE) and Strength of Recommendation (SR) of perioperative drugs management, imaging, surgery, intraoperative imaging, estimation of EOR, surgery at tumor progression and surgery in elderly patients.

RESULTS

A total of 352 studies were identified, including 299 retrospective studies and 53 reviews/meta-analysis. The use of Dexamethasone and the avoidance of prophylaxis with anti-seizure medications reached a CE I and SR A. A preoperative imaging standard protocol was defined with CE II and SR B and usefulness of an early postoperative MRI, with CE II and SR B. The EOR was defined the strongest independent risk factor for both OS and tumor recurrence with CE II and SR B. For intraoperative imaging only the use of 5-ALA reached a CE II and SR B. The estimation of EOR was established to be fundamental in planning postoperative adjuvant treatments with CE II and SR B and the stereotactic image-guided brain biopsy to be the procedure of choice when an extensive surgical resection is not feasible (CE II and SR B).

CONCLUSIONS

A growing number of evidences evidence support the role of maximal safe resection as primary OS predictor in GG4 patients. The ongoing development of intraoperative techniques for a precise real-time identification of peritumoral functional pathways enables surgeons to maximize EOR minimizing the post-operative morbidity.

Deep learning automates bidimensional and volumetric tumor burden measurement from MRI in pre- and post-operative glioblastoma patients

Tumor burden assessment by magnetic resonance imaging (MRI) is central to the evaluation of treatment response for glioblastoma. This assessment is, however, complex to perform and associated with high variability due to the high heterogeneity and complexity of the disease. In this work, we tackle this issue and propose a deep learning pipeline for the fully automated end-to-end analysis of glioblastoma patients. Our approach simultaneously identifies tumor sub-regions, including the enhancing tumor, peritumoral edema and surgical cavity in the first step, and then calculates the volumetric and bidimensional measurements that follow the current Response Assessment in Neuro-Oncology (RANO) criteria. Also, we introduce a rigorous manual annotation process which was followed to delineate the tumor sub-regions by the human experts, and to capture their segmentation confidences that are later used while training deep learning models. The results of our extensive experimental study performed over 760 pre-operative and 504 post-operative adult patients with glioma obtained from the public database (acquired at 19 sites in years 2021-2020) and from a clinical treatment trial (47 and 69 sites for pre-/post-operative patients, 2009-2011) and backed up with thorough quantitative, qualitative and statistical analysis revealed that our pipeline performs accurate segmentation of pre- and post-operative MRIs in a fraction of the manual delineation time (up to 20 times faster than humans). Volumetric measurements were in strong agreement with experts with the Intraclass Correlation Coefficient (ICC): 0.959, 0.703, 0.960 for ET, ED, and cavity. Similarly, automated RANO compared favorably with experienced readers (ICC: 0.681 and 0.866) producing consistent and accurate results. Additionally, we showed that RANO measurements are not always sufficient to quantify tumor burden. The high performance of the automated tumor burden measurement highlights the potential of the tool for considerably improving and simplifying radiological evaluation of glioblastoma in clinical trials and clinical practice.

Repeat resection for recurrent glioblastoma in the temozolomide era: a real-world multi-centre study

INTRODUCTION

In contrast to standard-of-care treatment of newly diagnosed glioblastoma, there is limited consensus on therapy upon disease progression. The role of resection for recurrent glioblastoma remains unclear. This study aimed to identify factors for overall survival (OS) and post-progression survival (PPS) as well as to validate an existing prediction model.

METHODS

This was a multi-centre retrospective study that reviewed consecutive adult patients from 2006 to 2019 that received a repeat resection for recurrent glioblastoma. The primary endpoint was PPS defined as from the date of second surgery until death.

RESULTS

1032 glioblastoma patients were identified and 190 (18%) underwent resection for recurrence. Patients that had second surgery were more likely to be younger (<70 years) (adjusted OR: 0.3; 95% CI: 0.1-0.6), to have non-eloquent region tumours (aOR: 1.7; 95% CI: 1.1-2.6) and received temozolomide chemoradiotherapy (aOR: 0.2; 95% CI: 0.1-0.4). Resection for recurrent tumour was an independent predictor for OS (aOR: 1.5; 95% CI: 1.3-1.7) (mOS: 16.9 months versus 9.8 months). For patients that previously received temozolomide chemoradiotherapy and subsequent repeat resection (137, 13%), the median PPS was 9.0 months (IQR: 5.0-17.5). Independent PPS predictors for this group were a recurrent tumour volume of >50cc (aOR: 0.6; 95% CI: 0.4-0.9), local recurrence (aOR: 1.7; 95% CI: 1.1-3.3) and 5-ALA fluorescence-guided resection during second surgery (aOR: 1.7; 95% CI: 1.1-2.8). A National Institutes of Health Recurrent Glioblastoma Multiforme Scale score of 0 conferred an mPPS of 10.0 months, a score of 1-2, 9.0 months and a score of 3, 4.0 months (log-rank test, p-value < 0.05).

CONCLUSION

Surgery for recurrent glioblastoma can be beneficial in selected patients and carries an acceptable morbidity rate. The pattern of recurrence influenced PPS and the NIH Recurrent GBM Scale was a reliable prognostication tool.

The clinical significance of radiological changes associated with gliadel implantation in patients with recurrent high grade glioma

Gliadel occasionally induces edema following its implantation. We aimed to correlate such post-surgical radiological changes to its efficacy and subsequent survival. Fifty-six patients with recurrent high grade glioma were treated between 2005 and 2016 with Gliadel implantation. Volumetric measurements of MRI features, including FLAIR abnormalities, tumor bulk (volume of gadolinium enhancement on T1) and resection cavity volumes over time were conducted. To assess dynamics over time, linear regression trendlines for each of these were calculated and examined to correlate with survival. Median follow-up after resection was 21.5 months. Median survival post-Gliadel implantation and overall survival since diagnosis were 12 months and 22 months, respectively. A subgroup of patients (n = 6) with a transient increase in FLAIR changes volume over time survived significantly longer post-Gliadel compared to those who did not demonstrate such change (36 vs 12 months, p = .03). Positive trends, representing overall growth in volume over time, of tumor bulk and resection cavity predicted survival in multivariate analyses (hazard ratios 7.9 and 84, p = .003 and .002, respectively). Increase in tumor bulk and resection cavity over time were associated with decreased survival, while transient FLAIR increase was a favorable prognostic factor. This may represent a transient inflammatory process in the tumor, possibly stemming from a presumed immune-mediated anti-tumor response.

DeepEOR: automated perioperative volumetric assessment of variable grade gliomas using deep learning

PURPOSE

Volumetric assessments, such as extent of resection (EOR) or residual tumor volume, are essential criterions in glioma resection surgery. Our goal is to develop and validate segmentation machine learning models for pre- and postoperative magnetic resonance imaging scans, allowing us to assess the percentagewise tumor reduction after intracranial surgery for gliomas.

METHODS

For the development of the preoperative segmentation model (U-Net), MRI scans of 1053 patients from the Multimodal Brain Tumor Segmentation Challenge (BraTS) 2021 as well as from patients who underwent surgery at the University Hospital in Zurich were used. Subsequently, the model was evaluated on a holdout set containing 285 images from the same sources. The postoperative model was developed using 72 scans and validated on 45 scans obtained from the BraTS 2015 and Zurich dataset. Performance is evaluated using Dice Similarity score, Jaccard coefficient and Hausdorff 95%.

RESULTS

We were able to achieve an overall mean Dice Similarity Score of 0.59 and 0.29 on the pre- and postoperative holdout sets, respectively. Our algorithm managed to determine correct EOR in 44.1%.

CONCLUSION

Although our models are not suitable for clinical use at this point, the possible applications are vast, going from automated lesion detection to disease progression evaluation. Precise determination of EOR is a challenging task, but we managed to show that deep learning can provide fast and objective estimates.

Surgery for Recurrent Glioblastoma Multiforme: A Retrospective Case Control Study

OBJECTIVE

The role of surgery in recurrent glioblastoma multiforme (GBM) remains a controversial topic. The goal of this study was to perform a case control analysis including time to tumor recurrence as an additional prognostic factor in order to determine which patients benefit most from repeat surgery.

METHODS

Our brain tumor database was reviewed over a 10-year period for all adult (≥18 years old) patients with primary isocitrate dehydrogenase wildtype GBM who received surgery for recurrent disease. These patients were then age, sex, and treatment matched to case controls from our institution who received medical therapy for recurrent disease.

RESULTS

A total of 174 adult patients with GBM were included in the study, 87 patients who received surgery for recurrent GBM (surgery cohort) and 87 patients who did not receive surgery for recurrent GBM (nonsurgery cohort). The surgery cohort had longer overall survival (P = 0.0003) and postrecurrence survival (P = 0.001) than the nonsurgery cohort. When the surgery cohort was split into 2 groups on the basis of time to tumor recurrence, the long time to recurrence group (>6 months) demonstrated significantly increased survival compared with the short time to recurrence group (P < 0.0001). Multivariate analysis of both cohorts demonstrated surgery for recurrent GBM was independently significant after adjusting for age, Karnofsky Performance Scale, and time to tumor recurrence (P < 0.0001).

CONCLUSIONS

Surgery for recurrent GBM leads to improved survival independent of age, Karnofsky Performance Scale, and time to tumor recurrence. Patients with time to tumor recurrence >6 months benefit most from additional surgery.

Is It Worth Considering Multicentric High-Grade Glioma a Surgical Disease? Analysis of Our Clinical Experience and Literature Review

INTRODUCTION

The simultaneous presence of multiple foci of high-grade glioma is a rare condition with a poor prognosis. By definition, if an anatomical connection through white matter bundles cannot be hypothesized, multiple lesions are defined as multicentric glioma (MC); on the other hand, when this connection exists, it is better defined as multifocal glioma (MF). Whether surgery can be advantageous for these patients has not been established yet. The aim of our study was to critically review our experience and to compare it to the existing literature.

MATERIALS AND METHODS

Retrospective analysis of patients operated on for MC HGG in two Italian institutions was performed. Distinction between MC and MF was achieved through revision of MR FLAIR images. Clinical and radiological preoperative and postoperative data were analyzed through chart revision and phone interviews. The same data were extracted from literature review. Univariate and multivariate analyses were conducted for the literature review only, and the null hypothesis was rejected for a p-value ≥ 0.05.

RESULTS

Sixteen patients met the inclusion criteria; male predominance and an average age of 66.5 years were detected. Sensory/motor deficit was the main onset symptom both in clinical study and literature review. A tendency to operate on the largest symptomatic lesion was reported and GTR was reached in the majority of cases. GBM was the histological diagnosis in most part of the patients. OS was 8.7 months in our series compared to 7.5 months from the literature review. Age ≤ 70 years, a postoperative KPS ≥ 70, a GTR/STR, a second surgery and adjuvant treatment were shown to be significantly associated with a better prognosis. Pathological examination revealed that MC HGG did not originate by LGG.

CONCLUSIONS

MC gliomas are rare conditions with high malignancy and a poor prognosis. A maximal safe resection should be attempted whenever possible, especially in younger patients with life-threatening large mass.

Perioperative Tranexamic Acid for ACTH-Secreting Pituitary Adenomas: Implementation Protocol Results and Trial Prospectus

OBJECTIVE

Primary resection of adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma has become a front-line standard-of-care treatment for Cushing disease. However, surgical intervention can be challenging because of elevated blood pressure, as well as direct cortisol impacts on endothelial cells, vascular permeability, and tissue friability-potentially resulting in increased intraoperative bleeding. Tranexamic acid (TXA) is a well-studied, widely used intravenous hemostatic; however, the potential benefit during resection of ACTH-secreting pituitary adenoma is unstudied. The purpose of this study was to define an institutional protocol for perioperative administration of TXA in patients undergoing endoscopic endonasal approach for resection of ACTH-secreting pituitary adenoma, and to study the implementation of our novel protocol in a prospective fashion.

METHODS

Criteria for preoperative TXA were defined by age, medical history, and risk factors. Descriptive statistics were reported for all patients receiving perioperative TXA.

RESULTS

Thirty patients met inclusion criteria and underwent perioperative administration of TXA, using a standardized dosing protocol of a 10 mg/kg bolus in 30 minutes prior to incision, followed by maintenance infusion of 2 mg/kg/hour for the duration of the procedure. No incidence of myocardial infarction or postoperative thromboembolic events were noted. Subjective assessments indicated satisfaction with the patient selection protocol, and meaningful reduction in the extent of intraoperative bleeding.

CONCLUSIONS

Perioperative TXA represents a potentially efficacious approach for control of intraoperative bleeding during endonasal resection of ACTH-secreting tumors. Careful preoperative patient selection is emphasized, given the potential for thromboembolic complications; however, initial experience with our institutional protocol suggests a favorable risk/benefit profile when this treatment is applied judiciously.

Evidence-based recommendations on categories for extent of resection in diffuse glioma

Surgical resection represents the standard of care in diffuse glioma, and more extensive tumour resection appears to be associated with favourable outcome. Up to now, terminology to describe extent of resection has been inconsistently applied across clinical trials which hampers comparative analysis of cohorts between different studies. Based on a comprehensive literature review, we developed evidence-based expert recommendations on categories for extent of resection. Recommendations are formulated for the categories 'biopsy', 'partial resection', 'subtotal resection', 'near total resection', 'complete resection' and 'supramaximal resection'. Definitions rest on reduction of contrast- and non-contrast-enhancing tumour in glioblastoma, and on reduction of T2/FLAIR-hyperintense tumour in gliomas WHO grade 2 or 3. Both relative reduction of tumour volume (in percentage) as a measurement of surgical efficacy and absolute residual tumour volume (in cm³) as a measurement of remaining tumour burden are incorporated into the categories for extent of resection. Class of evidence for the proposed categories ranges from class IIB to IV. Limitations of the suggested categories are discussed. The proposed categories on extent of resection offer a framework to standardize nomenclature based on previous studies, and will need to be evaluated in prospective, molecularly well-defined cohorts. Our categories may eventually help as a stratification factor for future clinical trials.

Eyebrow supraorbital keyhole craniotomy for olfactory groove meningiomas with endoscope assistance: case series and systematic review of extent of resection, quantification of postoperative frontal lobe injury, anosmia, and recurrence

BACKGROUND

Olfactory groove meningiomas (OGMs) are commonly treated with open craniotomy. Endonasal approaches have also been described.

OBJECTIVE

To present clinical and radiographic outcomes for the minimally invasive eyebrow incision supraorbital keyhole approach with endoscopic assistance for OGMs.

METHODS

We performed a retrospective single-center cohort study and a systematic literature review.

RESULTS

Fifteen patients were identified, all with Grade I meningiomas. Radiographic gross total resection of enhancing tumor was achieved in all patients. Mean frontal lobe fluid-attenuated inversion recovery volume decreased from 11.1 ± 18.3 cm³ preoperatively to 9.9 ± 11.4 cm³ immediately postoperatively, and there was minimal new restricted diffusion (3.2 ± 2.2 cm³; max 7.5 cm³). Median length of stay was 3 days (range 2-8). Vision was improved in 4 (80%) and stable in 1 (20%) of 5 patients with a preoperative deficit. New postoperative anosmia occurred in 3 (23%) of 13 patients with any preoperative olfaction. All patients were satisfied with their cosmetic result at 3 months. After a median follow-up of 32.2 months, there were 2 (13.3%) asymptomatic radiographic recurrences, 1 treated with radiosurgery and the other with endoscopic endonasal approach (EEA). No patients required further craniotomy. Systematic review revealed the present series to be the largest to date reporting disaggregated outcomes for the eyebrow approach to OGM.

CONCLUSION

The eyebrow incision supraorbital keyhole craniotomy with endoscopic assistance is a safe and effective approach to OGM with tumor control rates similar to more invasive open approaches and better than the endonasal approach. Rates of frontal lobe injury, CSF leak and anosmia are comparatively low.

Trimodal therapy in T2-4aN0M0 bladder cancer--How to select the best candidate?

The reported results of trimodal treatment (TMT) in muscle-invasive bladder cancer vary widely. We attempted to characterize the profile of ideal candidates for this approach. Between 2000 and 2019, 105 patients (median age 78 years) with T2-4aN0M0 bladder cancer were treated with TMT and analyzed retrospectively. Mean radiotherapy dose was 62 Gy (SD 8.4). Ten pretreatment prognostic parameters were evaluated including tumor diameter on pre-TURBT CT. Multivariate analyses was performed and combination of parameters was studied. After a median follow-up of 29 months, 53 patients (50.5%) developed recurrence and 70 patients (67.7%) died. Death was disease-specific in 46 patients (65.7%). Tumor diameter was the most significant prognostic parameter with p < 0.0001 for overall, disease-specific and recurrence-free survivals. For every 1 cm increase in tumor diameter, the risk of disease-specific mortality increased by 1.57. Age, cisplatin eligibility and the Charlson Comorbidity Index were significant predictors of overall survival but not of disease-specific or recurrence-free survival. Patients who were cisplatin-eligible with a tumor diameter ≤3 cm had a 5-year disease-specific survival rate of 79.2% as opposed to 33.9% in patients without one of these features (p < 0.001). When tumor diameter exceeded 5 cm (irrelevant of all other parameters), 5-year disease-specific survival rate was only 28.2%. Patient profiles can accurately predict response to TMT. In cisplatin-eligible patients with a tumor diameter ≤3 cm, TMT provides an excellent disease-specific survival rate. In patients with a tumor diameter >5 cm TMT renders unacceptably poor treatment outcomes.

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.