Low-grade hemispheric gliomas in adults: a critical review of extent of resection as a factor influencing outcome

Extending the resection beyond the contrast-enhancement for glioblastoma: feasibility, efficacy, and outcomes

OBJECT

It is becoming well-established that increasing extent of resection with decreasing residual volume is associated with delayed recurrence and prolonged survival for patients with glioblastoma (GBM). These prior studies are based on evaluating the contrast-enhancing (CE) tumour and not the surrounding fluid attenuated inversion recovery (FLAIR) volume. It therefore remains unclear if the resection beyond the CE portion of the tumour if it translates into improved outcomes for patients with GBM.

METHODS

Adult patients who underwent resection of a primary glioblastoma at a tertiary care institution between January 1, 2007 and December 31, 2012 and underwent radiation and temozolomide chemotherapy were retrospectively reviewed. Pre and postoperative MRI images were measured for CE tumour and FLAIR volumes. Multivariate proportional hazards were used to assess associations with both time to recurrence and death. Values with p < 0.05 were considered statistically significant.

RESULTS

245 patients met the inclusion criteria. The median [IQR] preoperative CE and FLAIR tumour volumes were 31.9 [13.9-56.1] cm³ and 78.3 [44.7-115.6] cm³, respectively. Following surgery, the median [IQR] postoperative CE and FLAIR tumour volumes were 1.9 [0-7.1] cm³ and 59.7 [29.7-94.2] cm³, respectively. In multivariate analyses, the postoperative FLAIR volume was not associated with recurrence and/or survival (p > 0.05). However, the postoperative CE tumour volume was significantly associated with both recurrence [HR (95%CI); 1.026 (1.005-1.048), p = 0.01] and survival [HR (95%CI); 1.027 (1.007-1.032), p = 0.001]. The postoperative FLAIR volume was also not associated with recurrence and/or survival among patients who underwent gross total resection of the CE portion of the tumour as well as those who underwent supratotal resection.

CONCLUSIONS

In this study, the volume of CE tumour remaining after resection is more important than FLAIR volume in regards to recurrence and survival for patients with GBM.

Tumor growth dynamics in serially-imaged low-grade glioma patients

BACKGROUND

Diffuse low-grade gliomas (LGGs) are infiltrative, slow-growing primary brain tumors that remain relatively asymptomatic for long periods of time before progressing into aggressive and fatal high-grade gliomas.

METHODS

We retrospectively identified LGG patients with numerous (≥ 8) serial magnetic resonance imaging (MRI) studies. Tumor volumes were measured by manual segmentation on serial imaging to study the natural history and growth of the lesion. Patient demographic information, tumor characteristics, and histological data were collected from electronic medical records and paper charts.

RESULTS

Out of 74 LGG patients, 10 patients (13.5%) were identified to meet the study criteria with number of MRIs acquired ranging from 8 to 18 (median, 11.5) over a median of 79.7 months (range 39.8-113.8 months). Tumor diameter increased at a median of 2.17 mm/year in a linear trajectory. Cox regression analysis revealed that initial tumor volume was an independent predictor of time to clinical intervention, and Mann-Whitney U test found that patients younger than 50 years old had significantly slower-growing tumors. Clinical intervention was more likely for tumors above a volume threshold of 73.6 mL.

CONCLUSION

We retrospectively analyzed the natural history of LGGs of patients managed at a single institution with numerous serial MRI scans. Comparisons of our cohort to the literature suggest that this is a subset of particularly slow-growing and low-risk tumors.

Oligodendroglioma resection: a Surveillance, Epidemiology, and End Results (SEER) analysis

OBJECTIVE

The available evidence suggests that the clinical benefits of extended resection are limited for chemosensitive tumors, such as primary CNS lymphoma. Oligodendroglioma is generally believed to be more sensitive to chemotherapy than astrocytoma of comparable grades. In this study the authors compare the survival benefit of gross-total resection (GTR) in patients with oligodendroglioma relative to patients with astrocytoma.

METHODS

Using the Surveillance, Epidemiology, and End Results (SEER) Program (1999–2010) database, the authors identified 2378 patients with WHO Grade II oligodendroglioma (O2 group) and 1028 patients with WHO Grade III oligodendroglioma (O3 group). Resection was defined as GTR, subtotal resection, biopsy only, or no resection. Kaplan-Meier and multivariate Cox regression survival analyses were used to assess survival with respect to extent of resection.

RESULTS

Cox multivariate analysis revealed that the hazard of dying from O2 and O3 was comparable between patients who underwent biopsy only and GTR (O2: hazard ratio [HR] 1.06, 95% confidence interval [CI] 0.73–1.53; O3: HR 1.18, 95% CI 0.80–1.72). A comprehensive search of the published literature identified 8 articles without compelling evidence that GTR is associated with improved overall survival in patients with oligodendroglioma.

CONCLUSIONS

This SEER-based analysis and review of the literature suggest that GTR is not associated with improved survival in patients with oligodendroglioma. This finding contrasts with the documented association between GTR and overall survival in anaplastic astrocytoma and glioblastoma. The authors suggest that this difference may reflect the sensitivity of oligodendroglioma to chemotherapy as compared with astrocytomas.

Malignant transformation of a conservatively managed incidental childhood cerebral mass lesion: controversy regarding management paradigm

BACKGROUND

Incidental findings on neuroimaging in the pediatric population are an emerging treatment challenge. Treatment options for these incidental childhood brain mass lesions, which radiologically may be assumed to be low-grade gliomas (LGG), vary, ranging from careful conservative "wait and scan" treatment to surgical biopsy, gross total resection, and upfront radiation and/or chemotherapy. As malignant transformation of LGG in children is extremely rare, some series advocate careful conservative management of these lesions; however, universal treatment protocols are not totally agreed upon.

ILLUSTRATIVE CASE

We present the case of a 10-year-old boy with a fronto-basal incidental cerebral mass lesion, suspected to be a low-grade glial neoplasm. Initially, magnetic resonance imaging (MRI) was done to rule out a pathology causing his growth to be delayed. A treatment with growth hormone was initiated. After close clinical and radiological follow-up of this asymptomatic lesion for 6 years, a minimal growth of the lesion was seen, which we decided to continue following. After 7 years, a clear growth with new contrast enhancement was seen on routine MRI. At this point, the lesion was surgically resected. The diagnosis was, surprisingly, glioblastoma multiforme (WHO grade IV, BRAF V-600E mutation).

DISCUSSION

Malignant transformation of LGGs in children is a very rare phenomenon. This is to our knowledge the first well-documented case describing malignant transformation of a suspected benign pediatric cerebral mass lesion, which did not undergo radiation, in a patient without a cancer predisposition syndrome (e.g., neurofibromatosis), with the transformation occurring after such a long follow-up period. The management of these lesions is still controversial. Unfortunately, radiological risk factors for malignant transformation of such lesions in the pediatric age group are lacking.

CONCLUSION

Conservative treatment of incidental cerebral mass lesions in children seems a valid option. These lesions should probably be followed indefinitely, while carefully watching for changes in imaging characteristics.

Postoperative functional status in patients with supratentorial superficial low-grade glioma

Background

We investigated the functional status of adult supratentorial superficial low-grade glioma (ASS-LGG) after surgery and analyzed its relevant factors to guide the therapeutic strategy and improve the life quality of these patients.

Methods

Clinical materials from January 2008 to December 2010 in 104 adults with ASS-LGG were analyzed retrospectively. The follow-up period ranged from 6 months to 1.5 years. The logistic regression was used to evaluate the preoperative and postoperative variation of functional status in patients to disclose the relevant factors affecting postoperative functional status, such as age, gender, the duration of symptom, size and location of the tumor, hemisphere, resection degree, and tumor pathologic grade and preoperative Karnofsky performance status (Pre-KPS).

Results

Four out of nine candidate factors are related to the postoperative functional status. They are age less than 40 years, the size of tumor less than 5 cm in diameter, tumor located in the right hemisphere, and limited resection of tumor in the eloquent area.

Conclusions

It seems more meaningful to evaluate the functional status of the patients with ASS-LGG on the basis of these clinical features, involving age, tumor size, location, and extent of resection.

Chemotherapy for adult low-grade gliomas: clinical outcomes by molecular subtype in a phase II study of adjuvant temozolomide

Background

Optimal adjuvant management of adult low-grade gliomas is controversial. Recently described tumor classification based on molecular subtype has the potential to individualize adjuvant therapy but has not yet been evaluated as part of a prospective trial.

Methods

Patients aged 18 or older with newly diagnosed World Health Organization grade II low-grade gliomas and gross residual disease after surgical resection were enrolled in the study. Patients received monthly cycles of temozolomide for up to 1 year or until disease progression. For patients with available tissue, molecular subtype was assessed based upon 1p/19q codeletion and isocitrate dehydrogenase-1 R132H mutation status. The primary outcome was radiographic response rate; secondary outcomes included progression-free survival (PFS) and overall survival (OS).

Results

One hundred twenty patients were enrolled with median follow-up of 7.5 years. Overall response rate was 6%, with median PFS and OS of 4.2 and 9.7 years, respectively. Molecular subtype was associated with rate of disease progression during treatment (P<.001), PFS (P=.007), and OS (P<.001). Patients with 1p/19q codeletion demonstrated a 0% risk of progression during treatment. In an exploratory analysis, pretreatment lesion volume was associated with both PFS (P<.001) and OS (P<.001).

Conclusions

While our study failed to meet the primary endpoint for objective radiographic response, patients with high-risk low-grade glioma receiving adjuvant temozolomide demonstrated a high rate of radiographic stability and favorable survival outcomes while meaningfully delaying radiotherapy. Patients with 1p/19q codeletion are potential candidates for omission of adjuvant radiotherapy, but further work is needed to directly compare chemotherapy with combined modality therapy.

A mathematical model describes the malignant transformation of low grade gliomas: Prognostic implications

Gliomas are the most frequent type of primary brain tumours. Low grade gliomas (LGGs, WHO grade II gliomas) may grow very slowly for the long periods of time, however they inevitably cause death due to the phenomenon known as the malignant transformation. This refers to the transition of LGGs to more aggressive forms of high grade gliomas (HGGs, WHO grade III and IV gliomas). In this paper we propose a mathematical model describing the spatio-temporal transition of LGGs into HGGs. Our modelling approach is based on two cellular populations with transitions between them being driven by the tumour microenvironment transformation occurring when the tumour cell density grows beyond a critical level. We show that the proposed model describes real patient data well. We discuss the relationship between patient prognosis and model parameters. We approximate tumour radius and velocity before malignant transformation as well as estimate the onset of this process.

An extent of resection threshold for seizure freedom in patients with low-grade gliomas

OBJECTIVE Seizures are the most common presenting symptom of newly diagnosed WHO Grade II gliomas (low-grade glioma [LGG]) and significantly impair quality of life. Although gross-total resection of LGG is associated with better seizure control, it remains unclear whether an extent of resection (EOR) "threshold" exists for long-term seizure control. Specifically, what proportion of FLAIR-positive tissue in patients with newly diagnosed LGG must be removed to achieve Engel Class I seizure freedom? To clarify the EOR threshold for long-term seizure control, the authors analyzed data from a consecutive series of patients with newly diagnosed LGG who presented with seizures and subsequently underwent microsurgical resection. METHODS The authors identified consecutive patients with newly diagnosed LGG who presented with seizures and were treated at the Barrow Neurological Institute between 2002 and 2012. Patients were dichotomized into those who were seizure free postoperatively and those who were not. The EOR was calculated by quantitative comparison of pre- and postoperative MRI. Univariate analysis of these 2 groups included the chi-square test and the Mann-Whitney U-test, and a multivariate logistic regression was constructed to predict the impact of multiple independent variables on the likelihood of postoperative seizure freedom. To determine a threshold of EOR that optimizes seizure freedom, a receiver operating characteristic curve was plotted and the optimal point of discrimination was determined. RESULTS Data from 128 patients were analyzed (male/female ratio 1.37:1; mean age 40.8 years). All 128 patients presented with seizures, usually generalized (n = 57, 44.5%) or simple partial (n = 57, 44.5%). The median EOR was 90.0%. Of 128 patients, 46 (35.9%) had 100% volumetric tumor resection, 64 (50.0%) had 90%-99% volumetric tumor resection, and 11 (8.6%) had 80%-89% volumetric tumor resection. Postoperatively, 105 (82%) patients were seizure free (Engel Class I); 23 (18%) were not (Engel Classes II-IV). The proportion of seizure-free patients increased in proportion to the EOR. Predictive variables included in the regression model were preoperative Karnofsky Performance Scale score, seizure type, time from diagnosis to surgery, preoperative number of antiepileptic drugs, and EOR. Only EOR significantly affected the likelihood of postoperative Engel Class I status (OR 11.5, 95% CI 2.4-55.6; p = 0.002). The receiver operating characteristic curve generated based on Engel Class I status showed a sensitivity of 0.65 and 1 - specificity of 0.175, corresponding to an EOR of 80%. CONCLUSIONS For adult patients with LGG who suffer seizures, the results suggest that seizure freedom can be attained when EOR > 80% is achieved. Improvements in both the proportion of seizure-free patients and the durability of seizure freedom were observed beyond this 80% threshold. Interestingly, this putative EOR seizure-freedom threshold closely approximates that reported for the overall survival benefit in newly diagnosed hemispheric LGGs, suggesting that a minimum level of residual tumor burden is necessary for both disease and symptomatic progression.

Biopsy versus resection for the management of low-grade gliomas

BACKGROUND

This is an updated version of the original Cochrane review published in 2013, Issue 4.Low-grade gliomas (LGG) constitute a class of slow-growing primary brain neoplasms. Patients with clinically and radiographically suspected LGG have two initial surgical options, biopsy or resection. Biopsy can provide a histological diagnosis with minimal risk but does not offer a direct treatment. Resection may have additional benefits such as increasing survival and delaying recurrence, but is associated with a higher risk for surgical morbidity. There remains controversy about the role of biopsy versus resection and the relative clinical outcomes for the management of LGG.

OBJECTIVES

To assess the clinical effectiveness of biopsy compared to surgical resection in patients with a new lesion suspected to be a LGG.

SEARCH METHODS

The following electronic databases were searched in 2012 for the first version of the review: Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 11), MEDLINE (1950 to November week 3 2012), Embase (1980 to Week 46 2012). For this updated version, the following electronic databases were searched: Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 5), MEDLINE (Nov 2012 to June week 3 2016), Embase (Nov 2012 to 2016 week 26). All relevant articles were identified on PubMed and by using the 'related articles' feature. We also searched unpublished and grey literature including ISRCTN-metaRegister of Controled Trials, Physicians Data Query and ClinicalTrials.gov for ongoing trials.

SELECTION CRITERIA

We planned to include patients of any age with a suspected intracranial LGG receiving biopsy or resection within a randomized clinical trial (RCT) or controlled clinical trial (CCT). Patients with prior resections, radiation therapy, or chemotherapy for LGG were excluded. Outcome measures included overall survival (OS), progression-free survival (PFS), functionally independent survival (FIS), adverse events, symptom control, and quality of life (QoL).

DATA COLLECTION AND ANALYSIS

A total of 1375 updated citations were searched and critically analyzed for relevance. This was undertaken independently by two review authors. The original electronic database searches yielded a total of 2764 citations. In total, 4139 citations have been critically analyzed for this updated review.

MAIN RESULTS

No new RCTs of biopsy or resection for LGG were identified. No additional ineligible non-randomized studies (NRS) were included in this updated review. Twenty other ineligible studies were previously retrieved for further analysis despite not meeting the pre-specified criteria. Ten studies were retrospective or were literature reviews. Three studies were prospective, however they were limited to tumor recurrence and volumetric analysis and extent of resection. One study was a population-based parallel cohort in Norway, but not an RCT. Four studies were RCTs, however patients were randomized with respect to varying radiotherapy regimens to assess timing and dose of radiation. One RCT was on high-grade gliomas (HGGs) and not LGG. Finally, one RCT evaluated diffusion tensor imaging (DTI)-based neuro-navigation for surgical resection.

AUTHORS' CONCLUSIONS

Since the last version of this review, no new studies have been identified for inclusion and currently there are no RCTs or CCTs available on which to base definitive clinical decisions. Therefore, physicians must approach each case individually and weigh the risks and benefits of each intervention until further evidence is available. Some retrospective studies and non-randomized prospective studies do seem to suggest improved OS and seizure control correlating to higher extent of resection. Future research could focus on RCTs to determine outcomes benefits for biopsy versus resection.

Does early resection of presumed low-grade glioma improve survival? A clinical perspective

Early resection is standard of care for presumed low-grade gliomas. This is based on studies including only tumors that were post-surgically confirmed as low-grade glioma. Unfortunately this does not represent the clinicians’ situation wherein he/she has to deal with a lesion on MRI that is suspect for low-grade glioma (i.e. without prior knowledge on the histological diagnosis). We therefore aimed to determine the optimal initial strategy for patients with a lesion suspect for low-grade glioma, but not histologically proven yet. We retrospectively identified 150 patients with a resectable presumed low-grade-glioma and who were otherwise in good clinical condition. In this cohort we compared overall survival between three types of initital treatment strategy: a wait-and-scan approach (n = 38), early resection (n = 83), or biopsy for histopathological verification (n = 29). In multivariate analysis, no difference was observed in overall survival for early resection compared to wait-and-scan: hazard ratio of 0.92 (95% CI 0.43–2.01; p = 0.85). However, biopsy strategy showed a shorter overall survival compared to wait-and-scan: hazard ratio of 2.69 (95% CI 1.19–6.06; p = 0.02). In this cohort we failed to confirm superiority of early resection over a wait-and-scan approach in terms of overall survival, though longer follow-up is required for final conclusion. Biopsy was associated with shorter overall survival.

Optical-sectioning microscopy of protoporphyrin IX fluorescence in human gliomas: standardization and quantitative comparison with histology

Systemic delivery of 5-aminolevulinic acid leads to enhanced fluorescence image contrast in many tumors due to the increased accumulation of protoporphyrin IX (PpIX), a fluorescent porphyrin that is associated with tumor burden and proliferation. The value of PpIX-guided resection of malignant gliomas has been demonstrated in prospective randomized clinical studies in which a twofold greater extent of resection and improved progression-free survival have been observed. In low-grade gliomas and at the diffuse infiltrative margins of all gliomas, PpIX fluorescence is often too weak to be detected with current low-resolution surgical microscopes that are used in operating rooms. However, it has been demonstrated that high-resolution optical-sectioning microscopes are capable of detecting the sparse and punctate accumulations of PpIX that are undetectable via conventional low-power surgical fluorescence microscopes. To standardize the performance of high-resolution optical-sectioning devices for future clinical use, we have developed an imaging phantom and methods to ensure that the imaging of PpIX-expressing brain tissues can be performed reproducibly. Ex vivo imaging studies with a dual-axis confocal microscope demonstrate that these methods enable the acquisition of images from unsectioned human brain tissues that quantitatively and consistently correlate with images of histologically processed tissue sections.

Identification of Histological Correlates of Overall Survival in Lower Grade Gliomas Using a Bag-of-words Paradigm: A Preliminary Analysis Based on Hematoxylin & Eosin Stained Slides from the Lower Grade Glioma Cohort of The Cancer Genome Atlas

Background:

Glioma, the most common primary brain neoplasm, describes a heterogeneous tumor of multiple histologic subtypes and cellular origins. At clinical presentation, gliomas are graded according to the World Health Organization guidelines (WHO), which reflect the malignant characteristics of the tumor based on histopathological and molecular features. Lower grade diffuse gliomas (LGGs) (WHO Grade II–III) have fewer malignant characteristics than high-grade gliomas (WHO Grade IV), and a better clinical prognosis, however, accurate discrimination of overall survival (OS) remains a challenge. In this study, we aimed to identify tissue-derived image features using a machine learning approach to predict OS in a mixed histology and grade cohort of lower grade glioma patients. To achieve this aim, we used H and E stained slides from the public LGG cohort of The Cancer Genome Atlas (TCGA) to create a machine learned dictionary of “image-derived visual words” associated with OS. We then evaluated the combined efficacy of using these visual words in predicting short versus long OS by training a generalized machine learning model. Finally, we mapped these predictive visual words back to molecular signaling cascades to infer potential drivers of the machine learned survival-associated phenotypes.

Methods:

We analyzed digitized histological sections downloaded from the LGG cohort of TCGA using a bag-of-words approach. This method identified a diverse set of histological patterns that were further correlated with OS, histology, and molecular signaling activity using Cox regression, analysis of variance, and Spearman correlation, respectively. A support vector machine (SVM) model was constructed to discriminate patients into short and long OS groups dichotomized at 24-month.

Results:

This method identified disease-relevant phenotypes associated with OS, some of which are correlated with disease-associated molecular pathways. From these image-derived phenotypes, a generalized SVM model which could discriminate 24-month OS (area under the curve, 0.76) was obtained.

Conclusion:

Here, we demonstrated one potential strategy to incorporate image features derived from H and E stained slides into predictive models of OS. In addition, we showed how these image-derived phenotypic characteristics correlate with molecular signaling activity underlying the etiology or behavior of LGG.

Review of intraoperative optical coherence tomography: technology and applications [Invited]

During microsurgery, en face imaging of the surgical field through the operating microscope limits the surgeon's depth perception and visualization of instruments and sub-surface anatomy. Surgical procedures outside microsurgery, such as breast tumor resections, may also benefit from visualization of the sub-surface tissue structures. The widespread clinical adoption of optical coherence tomography (OCT) in ophthalmology and its growing prominence in other fields, such as cancer imaging, has motivated the development of intraoperative OCT for real-time tomographic visualization of surgical interventions. This article reviews key technological developments in intraoperative OCT and their applications in human surgery. We focus on handheld OCT probes, microscope-integrated OCT systems, and OCT-guided laser treatment platforms designed for intraoperative use. Moreover, we discuss intraoperative OCT adjuncts and processing techniques currently under development to optimize the surgical feedback derivable from OCT data. Lastly, we survey salient clinical studies of intraoperative OCT for human surgery.

Contribution of combined intraoperative electrophysiological investigation with 3-T intraoperative MRI for awake cerebral glioma surgery: comprehensive review of the clinical implications and radiological outcomes

OBJECTIVE

This study aimed to assess the clinical efficiency of combined awake craniotomy with 3-T intraoperative MRI (iMRI)-guided resection of gliomas adjacent to eloquent cortex performed at a single center. It also sought to explore the contribution of iMRI to surgeons' learning process of maximal safe resection of gliomas.

METHODS

All patients who underwent an awake craniotomy and iMRI for resection of eloquent area glioma during the 53 months between January 2011 and June 2015 were included. The cases were analyzed for short- and long-term neurological outcome, progression-free survival (PFS), overall survival (OS), and extent of resection (EOR). The learning curve was assessed after dividing the cohort into Group A (first 27 months) and Group B (last 26 months). Statistical analyses included univariate logistic regression analysis on clinical and radiological variables. Kaplan-Meier and Cox regression models were used for further analysis of OS and PFS. A p value < 0.05 was considered statistically significant.

RESULTS

One hundred six patients were included in the study. Over an average follow-up period of 24.8 months, short- and long-term worsening of the neurological function was noted in 48 (46.2%) and 9 (8.7%) cases, respectively. The median and mean EOR were 100% and 92%, respectively, and complete radiographic resection was achieved in 64 (60.4%) patients. The rate of gross-total resection (GTR) in the patients with low-grade glioma (89.06% ± 19.6%) was significantly lower than that in patients with high-grade glioma (96.4% ± 9.1%) (p = 0.026). Thirty (28.3%) patients underwent further resection after initial iMRI scanning, with a 10.1% increase of the mean EOR. Multivariate Cox proportional hazards modeling demonstrated that the final EOR was a significant predictor of PFS (HR 0.225, 95% CI 0.070-0.723, p = 0.012). For patients with high-grade glioma, the GTR (p = 0.033), the presence of short-term motor deficit (p = 0.027), and the WHO grade (p = 0.005) were independent prognostic factors of OS. Performing further resection after the iMRI (p = 0.083) and achieving GTR (p = 0.05) demonstrated a PFS benefit trend for the patients affected by a low-grade glioma. Over time, the rate of performing further resection after an iMRI decreased by 26.1% (p = 0.005). A nonsignificant decrease in the rate of short-term (p = 0.101) and long-term (p = 0.132) neurological deficits was equally noted.

CONCLUSIONS

Combined awake craniotomy and iMRI is a safe and efficient technique allowing maximal safe resection of eloquent area gliomas with possible subsequent OS and PFS benefits. Although there is a learning curve for applying this technique, it can also improve the surgeon's ability in eloquent glioma surgery.

"Next Door" intraoperative magnetic resonance imaging for awake craniotomy: Preliminary experience and technical note

BACKGROUND

During glioma surgery "maximal safe resection" must be the main goal. Intraoperative magnetic resonance imaging (iMRI) associated with awake craniotomy (AC) is a valuable tool to achieve this objective. In this article, AC with a "next-door" iMRI concept is described in a stepwise protocol.

METHODS

This is a retrospective analysis of 18 patients submitted to AC using iMRI; a stepwise protocol is also discussed.

RESULTS

The mean age was 41.7 years. Hemiparesis, aphasia, and seizures were the main initial symptoms of the patients. Sixty-six percent of the tumors were located in the left hemisphere. All tumors were near or within eloquent areas. Fifty-three percent of the cases were glioblastomas multiforme and 47% of the patients had low grade gliomas. The mean surgical time and iMRI time were 4 h 4 min and 30 min, respectively. New resection was performed in 33% after iMRI. Extent of resection (EOR) higher than 95% was possible in 66.7% of the patients. The main reason of EOR lower than 95% was positive mapping of eloquent areas (6 patients). Eighty percent of the patients experienced improvement of their deficits immediately after the surgery or had a stable clinical status whereas 20% had neurological deterioration, however, all of them improved after 30 days.

CONCLUSION

AC associated with "next-door" iMRI is a complex procedure, but if performed using a meticulous technique, it may improve the overall tumor resection and safety of the patients.

Raman spectroscopy detects distant invasive brain cancer cells centimeters beyond MRI capability in humans

Surgical treatment of brain cancer is limited by the inability of current imaging capabilities such as magnetic resonance imaging (MRI) to detect the entirety of this locally invasive cancer. This results in residual cancer cells remaining following surgery, leading to recurrence and death. We demonstrate that intraoperative Raman spectroscopy can detect invasive cancer cells centimeters beyond pathological T1-contrast-enhanced and T2-weighted MRI signals. This intraoperative optical guide can be used to detect invasive cancer cells and minimize post-surgical cancer burden. The detection of distant invasive cancer cells beyond MRI signal has the potential to increase the effectiveness of surgery and directly lengthen patient survival.

Neural networks improve brain cancer detection with Raman spectroscopy in the presence of operating room light artifacts

Invasive brain cancer cells cannot be visualized during surgery and so they are often not removed. These residual cancer cells give rise to recurrences. <italic<In vivo</italic< Raman spectroscopy can detect these invasive cancer cells in patients with grade 2 to 4 gliomas. The robustness of this Raman signal can be dampened by spectral artifacts generated by lights in the operating room. We found that artificial neural networks (ANNs) can overcome these spectral artifacts using nonparametric and adaptive models to detect complex nonlinear spectral characteristics. Coupling ANN with Raman spectroscopy simplifies the intraoperative use of Raman spectroscopy by limiting changes required to the standard neurosurgical workflow. The ability to detect invasive brain cancer under these conditions may reduce residual cancer remaining after surgery and improve patient survival.

Prognostic value of the extent of resection in supratentorial WHO grade II astrocytomas stratified for IDH1 mutation status: a single-center volumetric analysis

Current evidence supports a maximized extent of resection (EOR) in low-grade gliomas (LGG), regardless of different histological subtypes and molecular markers. We therefore evaluated the prognostic impact of extensive, mainly intraoperative (i)MRI-guided surgery in low-grade astrocytomas stratified for IDH1 mutation status. Retrospective assessment of 46 consecutive cases of newly diagnosed supratentorial WHO grade II astrocytomas treated during the last decade was performed. IDH1 mutation status was obtained for all patients. Volumetric analysis of tumor volumes was performed pre-, intra-, early postoperatively and at first follow-up. Survival analysis was conducted with uni-and multivariate regression models implementing clinical parameters and continuous volumetric variables. Median EOR was 90.4 % (range 17.5–100 %) and was increased to 94.9 % (range 34.8–100 %) in iMRI-guided resections (n = 33). A greater EOR was prognostic for increased progression-free survival (HR 0.23, p = 0.031) and time to re-intervention (TTR) (HR 0.23, p = 0.03). In IDH1 mutant patients, smaller residual tumor volumes were associated with increased TTR (HR 1.01, p = 0.03). IDH1 mutation (38/46 cases) was an independent positive prognosticator for overall survival (OS) in multivariate analysis (HR 0.09, p = 0.002), while extensive surgery had limited impact upon OS. In a subgroup of patients with ≥40 % EOR (n = 39), however, initial and residual tumor volumes were prognostic for OS (HR 1.03, p = 0.005 and HR 1.08, p = 0.007, respectively), persistent to adjustment for IDH1. No association between EOR and neurologic morbidity was found. In this analysis of low-grade astrocytomas stratified for IDH1, extensive tumor resections were prognostic for progression and TTR and, in patients with ≥40 % EOR, for OS.

Assessing behavioral syndromes in patients with brain tumors using the frontal systems behavior scale (FrSBe)

BACKGROUND

Personality changes following brain tumors may be due to disruption of frontal-subcortical networks. The relation between personality changes and tumor parameters such as volumes of the surgical cavity, residual tumor, or nonspecific white matter abnormalities is unknown. In this study we examined the relation between these tumor parameters and abnormal behaviors typically associated with frontal lobe dysfunction.

METHODS

Thirty-one patients with intracranial tumors who completed the Frontal Systems Behavior Scale (FrSBe) during clinical neuropsychological assessment and had a solitary, well-delimited brain lesion on MRI within 3 months of that assessment were included. Tumor parameters were manually segmented using OsiriX. Nonparametric statistics were used to determine the relationship between tumor parameters and frontal behavioral dysfunction as measured by FrSBe scores.

RESULTS

Patients reported significantly more behavior problems after tumor diagnosis. Tumor cavity volume was correlated with self-reported Executive Dysfunction (rho = 0.450, P = .047), and there was a trend in the relationship with self-reported Apathy (rho = 0.438, P = .053). Nonspecific white matter abnormality volume was also correlated with self-reported Apathy (rho = 0.810, P = .01). There were no correlations between FrSBe scores and residual tumor volume or summed volumes of tumor-related parameters.

CONCLUSION

Our results suggest that tumor parameters have differential effects on behaviors associated with frontal-subcortical networks and corroborate the high frequency of behavioral dysfunction in brain tumor patients. Examination of these relationships in a prospective trial is warranted to establish incidence, prevalence, risk factors, and consequences of behavioral disturbances in brain tumor patients.

Cortical plasticity catalyzed by prehabilitation enables extensive resection of brain tumors in eloquent areas

OBJECTIVE The extent of resection is the most important prognostic factor following brain glioma surgery. However, eloquent areas within tumors limit the extent of resection and, thus, critically affect outcomes. The authors hypothesized that presurgical suppression of the eloquent areas within a tumor by continuous cortical electrical stimulation, coupled with appropriate behavioral training ("prehabilitation"), would induce plastic reorganization and enable a more extensive resection. METHODS The authors report on 5 patients harboring gliomas involving eloquent brain areas within tumors as identified on intraoperative stimulation mapping. A grid of electrodes was placed over the residual tumor, and continuous cortical electrical stimulation was targeted to the functional areas. The stimulation intensity was adjusted daily to provoke a mild functional impairment while the function was intensively trained. RESULTS The stimulation intensity required to impair function increased progressively in all patients, and all underwent another operation a mean of 33.6 days later (range 27-37 days), when the maximal stimulation voltage in all active contacts induced no functional deficit. In all cases, a substantially more extensive resection of the tumor was possible. Intraoperative mapping and functional MRI demonstrated a plastic reorganization, and most previously demonstrated eloquent areas within the tumor were silent, while there was new functional activation of brain areas in the same region or toward the contralateral hemisphere. CONCLUSIONS Prehabilitation with continuous cortical electrical stimulation and appropriate behavioral training prior to surgery in patients with WHO Grade II and III gliomas affecting eloquent areas accelerate plastic changes. This can help maximize tumor resection and, thus, improve survival while maintaining function.

Progressive Low-Grade Glioma: Assessment of Prognostic Importance of Histologic Reassessment and MRI Findings

BACKGROUND

In patients with progressive low-grade glioma (LGG), the presence of new magnetic resonance imaging (MRI) enhancement is commonly used as an indicator of malignant degeneration, but its accuracy in this setting is uncertain.

OBJECTIVE

We characterize the ability of new MRI enhancement to serve as a surrogate for histologic grade in patients with progressive LGG, and to explore the prognostic value of new MRI enhancement, pathologic grade, and extent of resection.

METHODS

Patients at our institution with World Health Organization grade II glioma diagnosed between 1994 and 2010 and who underwent repeat biopsy or resection at progression were retrospectively reviewed (n = 108). The positive predictive value, negative predictive value, sensitivity, and specificity of new MRI enhancement were characterized. A multivariable proportional hazards model was used to test associations with overall survival (OS), and Kaplan-Meier curves were constructed to compare OS between patient subsets.

RESULTS

The positive predictive value, negative predictive value, sensitivity, and specificity of new MRI enhancement were 82%, 77%, 92%, and 57%, respectively. In patients without malignant degeneration, new MRI enhancement was associated with inferior median OS (92.5 months vs. not reached; P = 0.03). In patients with malignant degeneration, gross or near total resection was associated with improved median OS (58.8 vs. 28.8 months; P = 0.02).

CONCLUSION

In patients with progressive LGG, new MRI enhancement and pathologic grade were discordant in greater than 20% of cases. Pathologic confirmation of grade should therefore be attempted, when safe, to dictate management. Beyond functioning as a surrogate for pathologic grade, new MRI enhancement may predict for worse outcomes, a concept that merits prospective investigation.

Detection of human brain cancer infiltration ex vivo and in vivo using quantitative optical coherence tomography

More complete brain cancer resection can prolong survival and delay recurrence. However, it is challenging to distinguish cancer from noncancer tissues intraoperatively, especially at the transitional, infiltrative zones. This is especially critical in eloquent regions (for example, speech and motor areas). This study tested the feasibility of label-free, quantitative optical coherence tomography (OCT) for differentiating cancer from noncancer in human brain tissues. Fresh ex vivo human brain tissues were obtained from 32 patients with grade II to IV brain cancer and 5 patients with noncancer brain pathologies. On the basis of volumetric OCT imaging data, pathologically confirmed brain cancer tissues (both high- and low-grade) had significantly lower optical attenuation values at both cancer core and infiltrated zones when compared with noncancer white matter, and OCT achieved high sensitivity and specificity at an attenuation threshold of 5.5 mm(-1) for brain cancer patients. We also used this attenuation threshold to confirm the intraoperative feasibility of performing in vivo OCT-guided surgery using a murine model harboring human brain cancer. Our OCT system was capable of processing and displaying a color-coded optical property map in real time at a rate of 110 to 215 frames per second, or 1.2 to 2.4 s for an 8- to 16-mm(3) tissue volume, thus providing direct visual cues for cancer versus noncancer areas. Our study demonstrates the translational and practical potential of OCT in differentiating cancer from noncancer tissue. Its intraoperative use may facilitate safe and extensive resection of infiltrative brain cancers and consequently lead to improved outcomes when compared with current clinical standards.

Pre-Surgical Integration of fMRI and DTI of the Sensorimotor System in Transcortical Resection of a High-Grade Insular Astrocytoma

Herein we report on a patient with a WHO Grade III astrocytoma in the right insular region in close proximity to the internal capsule who underwent a right frontotemporal craniotomy. Total gross resection of insular gliomas remains surgically challenging based on the possibility of damage to the corticospinal tracts. However, maximizing the extent of resection has been shown to decrease future adverse outcomes. Thus, the goal of such surgeries should focus on maximizing extent of resection while minimizing possible adverse outcomes. In this case, pre-surgical planning included integration of functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), to localize motor and sensory pathways. Novel fMRI tasks were individually developed for the patient to maximize both somatosensory and motor activation simultaneously in areas in close proximity to the tumor. Information obtained was used to optimize resection trajectory and extent, facilitating gross total resection of the astrocytoma. Across all three motor-sensory tasks administered, fMRI revealed an area of interest just superior and lateral to the astrocytoma. Further, DTI analyses showed displacement of the corona radiata around the superior dorsal surface of the astrocytoma, extending in the direction of the activation found using fMRI. Taking into account these results, a transcortical superior temporal gyrus surgical approach was chosen in order to avoid the area of interest identified by fMRI and DTI. Total gross resection was achieved and minor post-surgical motor and sensory deficits were temporary. This case highlights the utility of comprehensive pre-surgical planning, including fMRI and DTI, to maximize surgical outcomes on a case-by-case basis.

Intraoperative brain cancer detection with Raman spectroscopy in humans

Cancers are often impossible to visually distinguish from normal tissue. This is critical for brain cancer where residual invasive cancer cells frequently remain after surgery, leading to disease recurrence and a negative impact on overall survival. No preoperative or intraoperative technology exists to identify all cancer cells that have invaded normal brain. To address this problem, we developed a handheld contact Raman spectroscopy probe technique for live, local detection of cancer cells in the human brain. Using this probe intraoperatively, we were able to accurately differentiate normal brain from dense cancer and normal brain invaded by cancer cells, with a sensitivity of 93% and a specificity of 91%. This Raman-based probe enabled detection of the previously undetectable diffusely invasive brain cancer cells at cellular resolution in patients with grade 2 to 4 gliomas. This intraoperative technology may therefore be able to classify cell populations in real time, making it an ideal guide for surgical resection and decision-making.

Resting-State Blood Oxygen Level-Dependent Functional MRI: A Paradigm Shift in Preoperative Brain Mapping

Currently, functional magnetic resonance imaging (fMRI) facilitates a preoperative awareness of an association of an eloquent region with a tumor. This information gives the neurosurgeon helpful information that can aid in creating a surgical strategy. Typically, task-based fMRI has been employed to preoperatively localize speech and motor function. Task-based fMRI depends on the patient's ability to comply with the task paradigm, which often is impaired in the setting of a brain tumor. This problem is overcome by using resting-state fMRI (rs-fMRI) to localize function. rs-fMRI measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal, representing the brain's functional organization. In a neurosurgical context, it allows noninvasive simultaneous assessment of multiple large-scale distributed networks. Compared with task-related fMRI, rs-fMRI provides more comprehensive information on the functional architecture of the brain and is applicable in settings where task-related fMRI may provide inadequate information or could not be performed. Taken together, rs-fMRI substantially expands the preoperative mapping capability in efficiency, effectiveness, and scope. In this article, a brief introduction into rs-fMRI processing methods is followed by a detailed discussion on the role rs-fMRI plays in presurgical planning.

Improved sensitivity to fluorescence for cancer detection in wide-field image-guided neurosurgery

In glioma surgery, Protoporphyrin IX (PpIX) fluorescence may identify residual tumor that could be resected while minimizing damage to normal brain. We demonstrate that improved sensitivity for wide-field spectroscopic fluorescence imaging is achieved with minimal disruption to the neurosurgical workflow using an electron-multiplying charge-coupled device (EMCCD) relative to a state-of-the-art CMOS system. In phantom experiments the EMCCD system can detect at least two orders-of-magnitude lower PpIX. Ex vivo tissue imaging on a rat glioma model demonstrates improved fluorescence contrast compared with neurosurgical fluorescence microscope technology, and the fluorescence detection is confirmed with measurements from a clinically-validated spectroscopic probe. Greater PpIX sensitivity in wide-field fluorescence imaging may improve the residual tumor detection during surgery with consequent impact on survival.

The role of surgery in grade II/III oligodendroglial tumors

Supratentorial gliomas WHO grade II and III with an oligodendroglial phenotype are highly infiltrative lesions that preferentially originate in lobar location. Open tumor resection represents one of the mainstays of management as beneficial decompressive effects for large space-occupying lesions and oncologically relevant cytoreductive effects from complete resection can be expected. In patients not eligible for safe tumor resection meticulous histological and molecular-genetic evaluation can be obtained from advanced stereotactic biopsy techniques. In this perspective, important aspects of open tumor surgery and stereotactic biopsy are discussed within the context of diagnosis, prognosis and treatment of oligodendrogliomas and oligoastrocytomas WHO grade II and III. Practical considerations are provided in order to integrate the place of surgery into an increasingly personalized management concept. For highly selected patients interstitial brachytherapy is introduced as an alternative surgically performed treatment option.

Malignant transformation of diffuse astrocytoma to glioblastoma associated with newly developed BRAF V600E mutation

A 29-year-old man presented with scintillation scotoma. MR imaging demonstrated a diffuse lesion in right parahippocampal gyrus. He underwent a biopsy, and the diagnosis was diffuse astrocytoma. Because of enlargement and new areas of gadolinium enhancement, the tumor was resected 18 months after biopsy. Histological examination revealed malignant transformation to glioblastoma with small areas of epithelioid component. He received radiation and temozolomide chemotherapy. Local recurrence was found 20 months after first resection. He underwent second resection, and the diagnosis was glioblastoma. DNA from the micro-dissected paraffin-embedded sections were analyzed for the mutation of the isocitrate dehydrogenase1 (IDH1) and IDH2 and v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) genes. No mutations of the IDH genes were detected in any tumor specimen. In contrast, missense mutation at codon 600 in the BRAF gene (BRAF V600E) was found exclusively in the malignant areas from both resected glioblastoma specimens. We screened other genetic aberrations commonly seen in glioblastoma with multiplex ligation-dependent probe analysis. Deletion of CDKN2A and CDKN2B loci was found both in diffuse astrocytoma and glioblastoma component, but no other significant alterations were found. This case suggests that the BRAF V600E mutation may be involved in the malignant transformation to glioblastoma.

Proposed therapeutic strategy for adult low-grade glioma based on aggressive tumor resection

OBJECT There is no standard therapeutic strategy for low-grade glioma (LGG). The authors hypothesized that adjuvant therapy might not be necessary for LGG cases in which total radiological resection was achieved. Accordingly, they established a treatment strategy based on the extent of resection (EOR) and the MIB-1 index: patients with a high EOR and low MIB-1 index were observed without postoperative treatment, whereas those with a low EOR and/or high MIB-1 index received radiotherapy (RT) and/or chemotherapy. In the present retrospective study, the authors reviewed clinical data on patients with primarily diagnosed LGGs who had been treated according to the above-mentioned strategy, and they validated the treatment policy. Given their results, they will establish a new treatment strategy for LGGs stratified by EOR, histological subtype, and molecular status. METHODS One hundred fifty-three patients with diagnosed LGG who had undergone resection or biopsy at Tokyo Women's Medical University between January 2000 and August 2010 were analyzed. The patients consisted of 84 men and 69 women, all with ages ≥ 15 years. A total of 146 patients underwent surgical removal of the tumor, and 7 patients underwent biopsy. RESULTS Postoperative RT and nitrosourea-based chemotherapy were administered in 48 and 35 patients, respectively. Extent of resection was significantly associated with both overall survival (OS; p = 0.0096) and progression-free survival (PFS; p = 0.0007) in patients with diffuse astrocytoma but not in those with oligodendroglial subtypes. Chemotherapy significantly prolonged PFS, especially in patients with oligodendroglial subtypes (p = 0.0009). Patients with a mutant IDH1 gene had significantly longer OS (p = 0.034). Multivariate analysis did not identify MIB-1 index or RT as prognostic factors, but it did identify chemotherapy as a prognostic factor for PFS and EOR as a prognostic factor for OS and PFS. CONCLUSIONS The findings demonstrated that EOR was significantly correlated with patient survival; thus, one should aim for maximum tumor resection. In addition, patients with a higher EOR can be safely observed without adjuvant therapy. For patients with partial resection, postoperative chemotherapy should be administered for those with oligodendroglial subtypes, and repeat resection should be considered for those with astrocytic tumors. More aggressive treatment with RT and chemotherapy may be required for patients with a poor prognosis, such as those with diffuse astrocytoma, 1p/19q nondeleted tumors, or IDH1 wild-type oligodendroglial tumors with partial resection.

Functional preoperative and intraoperative mapping and monitoring: increasing safety and efficacy in glioma surgery

Greater extent of resection (EOR) of low-grade gliomas is associated with improved survival. Proximity to eloquent cortical regions often limits resectability and elevates the risk of surgery-related deficits. Therefore, functional localization of eloquent cortex or subcortical fiber tracts can enhance the EOR and functional outcome. Imaging techniques such as functional MRI and diffusion tensor imaging fiber tracking, and neurophysiological methods like navigated transcranial magnetic stimulation and magnetoencephalography, make it possible to identify eloquent areas prior to resective surgery and to tailor indication and surgical approach but also to assess the surgical risk. Intraoperative monitoring with direct cortical stimulation and subcortical stimulation enables surgeons to preserve essential functional tissue during surgery. Through tailored pre- and intraoperative mapping and monitoring the EOR can be maximized, with reduced rates of surgery-related deficits.

Evaluation of low-grade glioma structural changes after chemotherapy using DTI-based histogram analysis and functional diffusion maps

OBJECTIVES

To explore the role of diffusion tensor imaging (DTI)-based histogram analysis and functional diffusion maps (fDMs) in evaluating structural changes of low-grade gliomas (LGGs) receiving temozolomide (TMZ) chemotherapy.

METHODS

Twenty-one LGG patients underwent 3T-MR examinations before and after three and six cycles of dose-dense TMZ, including 3D-fluid-attenuated inversion recovery (FLAIR) sequences and DTI (b = 1000 s/mm(2), 32 directions). Mean diffusivity (MD), fractional anisotropy (FA), and tensor-decomposition DTI maps (p and q) were obtained. Histogram and fDM analyses were performed on co-registered baseline and post-chemotherapy maps. DTI changes were compared with modifications of tumour area and volume [according to Response Assessment in Neuro-Oncology (RANO) criteria], and seizure response.

RESULTS

After three cycles of TMZ, 20/21 patients were stable according to RANO criteria, but DTI changes were observed in all patients (Wilcoxon test, P ≤ 0.03). After six cycles, DTI changes were more pronounced (P ≤ 0.005). Seventy-five percent of patients had early seizure response with significant improvement of DTI values, maintaining stability on FLAIR. Early changes of the 25th percentiles of p and MD predicted final volume change (R(2) = 0.614 and 0.561, P < 0.0005, respectively). TMZ-related changes were located mainly at tumour borders on p and MD fDMs.

CONCLUSIONS

DTI-based histogram and fDM analyses are useful techniques to evaluate the early effects of TMZ chemotherapy in LGG patients.

KEY POINTS

• DTI helps to assess the efficacy of chemotherapy in low-grade gliomas. • Histogram analysis of DTI metrics quantifies structural changes in tumour tissue. • Functional diffusion maps (fDMs) spatially localize the changes of DTI metrics. • Changes in DTI histograms and fDMs precede changes in conventional MRI. • Early changes in DTI histograms and fDMs correlate with seizure response.

The Value of Pre- and Intraoperative Adjuncts on the Extent of Resection of Hemispheric Low-Grade Gliomas: A Retrospective Analysis

BACKGROUND

To achieve maximal resection with minimal risk of postoperative neurologic morbidity, different neurosurgical adjuncts are being used during low-grade glioma (LGG) surgery.

OBJECTIVES

To investigate the effect of pre- and intraoperative adjuncts on the extent of resection (EOR) of hemispheric LGGs.

METHODS

Medical records were reviewed to identify patients of any sex, ≥ 18 years of age, who underwent LGG surgery at X Hospital between January 2005 and July 2013. Patients were divided into eight subgroups based on the use of various combinations of a neuronavigation system alone (NN), functional MRI-diffusion tensor imaging (fMRI-DTI) guided neuronavigation (FD), intraoperative MRI (MR), and direct electrical stimulation (DES). Initial and residual tumors were measured, and mean EOR was compared between groups.

RESULTS

Of all 128 patients, gross total resection was achieved in 23.4%. Overall mean EOR was 81.3% ± 20.5%. Using DES in combination with fMRI-DTI (mean EOR: 86.7% ± 12.4%) on eloquent tumors improved mean EOR significantly after adjustment for potential confounders when compared with NN alone (mean EOR: 76.4% ± 25.5%; p = 0.001).

CONCLUSIONS

Using DES in combination with fMRI and DTI significantly improves EOR when LGGs are located in eloquent areas compared with craniotomies in which only NN was used.

Early versus delayed postoperative radiotherapy for treatment of low-grade gliomas

BACKGROUND

In most people with low-grade gliomas (LGG), the primary treatment regimen remains a combination of surgery followed by postoperative radiotherapy. However, the optimal timing of radiotherapy is controversial. It is unclear whether to use radiotherapy in the early postoperative period, or whether radiotherapy should be delayed until tumour progression occurs.

OBJECTIVES

To assess the effects of early postoperative radiotherapy versus radiotherapy delayed until tumour progression for low-grade intracranial gliomas in people who had initial biopsy or surgical resection.

SEARCH METHODS

We searched up to September 2014 the following electronic databases: the Cochrane Register of Controlled Trials (CENTRAL, Issue 8, 2014), MEDLINE (1948 to Aug week 3, 2014), and EMBASE (1980 to Aug week 3, 2014) to identify trials for inclusion in this Cochrane review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared early versus delayed radiotherapy following biopsy or surgical resection for the treatment of people with newly diagnosed intracranial LGG (astrocytoma, oligodendroglioma, mixed oligoastrocytoma, astroblastoma, xanthoastrocytoma, or ganglioglioma). Radiotherapy may include conformal external beam radiotherapy (EBRT) with linear accelerator or cobalt-60 sources, intensity-modulated radiotherapy (IMRT), or stereotactic radiosurgery (SRS).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the trials for inclusion and risk of bias, and extracted study data. We resolved any differences between review authors by discussion. Adverse effects were also extracted from the study report. We performed meta-analyses using a random-effects model with inverse variance weighting.

MAIN RESULTS

We included one large, multi-institutional, prospective RCT, involving 311 participants; the risk of bias in this study was unclear. This study found that early postoperative radiotherapy is associated with an increase in time to progression compared to observation (and delayed radiotherapy upon disease progression) for people with LGG but does not significantly improve overall survival (OS). The median progression-free survival (PFS) was 5.3 years in the early radiotherapy group and 3.4 years in the delayed radiotherapy group (hazard ratio (HR) 0.59, 95% confidence interval (CI) 0.45 to 0.77; P value < 0.0001; 311 participants; 1 trail; low quality evidence). The median OS in the early radiotherapy group was 7.4 years, while the delayed radiotherapy group experienced a median overall survival of 7.2 years (HR 0.97, 95% CI 0.71 to 1.33; P value = 0.872; 311 participants; 1 trail; low quality evidence). The total dose of radiotherapy given was 54 Gy; five fractions of 1.8 Gy per week were given for six weeks. Adverse effects following radiotherapy consisted of skin reactions, otitis media, mild headache, nausea, and vomiting. Rescue therapy was provided to 65% of the participants randomised to delayed radiotherapy. People in both cohorts who were free from tumour progression showed no differences in cognitive deficit, focal deficit, performance status, and headache after one year. However, participants randomised to the early radiotherapy group experienced significantly fewer seizures than participants in the delayed postoperative radiotherapy group at one year (25% versus 41%, P value = 0.0329, respectively).

AUTHORS' CONCLUSIONS

Given the high risk of bias in the included study, the results of this analysis must be interpreted with caution. Early radiation therapy was associated with the following adverse effects: skin reactions, otitis media, mild headache, nausea, and vomiting. People with LGG who undergo early radiotherapy showed an increase in time to progression compared with people who were observed and had radiotherapy at the time of progression. There was no significant difference in overall survival between people who had early versus delayed radiotherapy; however, this finding may be due to the effectiveness of rescue therapy with radiation in the control arm. People who underwent early radiation had better seizure control at one year than people who underwent delayed radiation. There were no cases of radiation-induced malignant transformation of LGG. However, it remains unclear whether there are differences in memory, executive function, cognitive function, or quality of life between the two groups since these measures were not evaluated.

Fluorescence-guided resection of experimental malignant glioma using cetuximab-IRDye 800CW

The standard treatment for glioblastoma multiforme (GBM) remains maximal safe surgical resection. Here, we evaluated the ability of a systemically administered antibody-dye probe conjugate (cetuximab-IRDye 800CW) to provide sufficient fluorescent contrast for surgical resection of disease in both subcutaneous and orthotopic animal models of GBM. Multiple luciferase-positive GBM cell lines (D-54MG, U-87MG, and U-251MG; n = 5) were implanted in mouse flank and tumors were fluorescently imaged daily using a closed-field near-infrared (NIR) system after cetuximab-IRDye 800CW systemic administration. Orthotopic models were also generated (n = 5), and tumor resection was performed under white light and fluorescence guidance using an FDA-approved wide-field NIR imaging system. Residual tumor was monitored using luciferase imaging. Immunohistochemistry was performed to characterize tumor fluorescence, epidermal growth factor receptor (EGFR) expression, and vessel density. Daily imaging of tumors revealed an average tumor-to-background (TBR) of 4.5 for U-87MG, 4.1 for D-54MG, and 3.7 for U-251MG. Fluorescence intensity within the tumors peaked on day-1 after cetuximab-IRDye 800CW administration, however the TBR increased over time in two of the three cell lines. For the orthotopic model, TBR on surgery day ranged from 19 to 23 during wide-field, intraoperative imaging. Surgical resection under white light on day 3 after cetuximab-IRDye 800CW resulted in an average 41% reduction in luciferase signal while fluorescence-guided resection using wide-field NIR imaging resulted in a significantly (P = 0.001) greater reduction in luciferase signal (87%). Reduction of luciferase signal was found to correlate (R (2) = 0.99) with reduction in fluorescence intensity. Fluorescence intensity was found to correlate (P < 0.05) with EGFR expression in D-54MG and U-251MG tumor types but not U-87MG. However, tumor fluorescence was found to correlate with vessel density for the U-87MG tumors. Here we show systemic administration of cetuximab-IRDye 800CW in combination with wide-field NIR imaging provided robust and specific fluorescence contrast for successful localization of disease in subcutaneous and orthotopic animal models of GBM.

Outcomes in Reoperated Low-Grade Gliomas

BACKGROUND:

Low-grade gliomas (LGGs) comprise a diverse set of intrinsic brain tumors that correlate strongly with survival. Data on the effect of reoperation are sparse.

OBJECTIVE:

To evaluate the effect of reoperation on patients with LGG.

METHODS:

Fifty-two consecutive patients with reoperated LGGs treated at the University of Washington between 1986 and 2004 were identified and evaluated in a retrospective analysis.

RESULTS:

The average overall survival (OS) for this cohort was 12.95 ± 0.96 years. The overall 10-year survival rate was 57%. The absence of any residual tumor at either the first or second operation was associated with significantly increased OS. Negative prognostic variables for OS included the use of upfront radiation and pathology at recurrence. The average overall progression-free survival to the first recurrence (PFS1) was 6.23 ± 0.51 years. Positive prognostic factors for improved PFS1 included the use of upfront radiation therapy. Variables not associated with differences in PFS1 included the use of upfront chemotherapy, enhancement, pathology, extent of resection, the presence of residual tumor, and Karnofsky Performance Scale score &lt;80. The average overall progression-free survival to the second recurrence was 2.73 ± 0.39 years. Pathology at recurrence was associated with significant differences in progression-free survival to the second recurrence, as was extent of resection at time of first recurrence, and Karnofsky Performance Scale score &lt;80.

CONCLUSION:

This is among the largest studies to assess variables associated with outcome in patients with reoperated LGG. Reresection appears to provide significant benefit, and extent of resection remains the strongest predictor of OS.

Molecular features assisting in diagnosis, surgery, and treatment decision making in low-grade gliomas

The preferred management of suspected low-grade gliomas (LGGs) has been disputed, and the implications of molecular changes for medical and surgical management of LGGs are important to consider. Current strategies that make use of molecular markers and imaging techniques and therapeutic considerations offer additional options for management of LGGs. Mutations in the isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) genes suggest a role for this abnormal metabolic pathway in the pathogenesis and progression of these primary brain tumors. Use of magnetic resonance spectroscopy can provide preoperative detection of IDH-mutated gliomas and affect surgical planning. In addition, IDH1 and IDH2 mutation status may have an effect on surgical resectability of gliomas. The IDH-mutated tumors exhibit better prognosis throughout every grade of glioma, and mutation may be an early genetic event, preceding lineage-specific secondary and tertiary alterations that transform LGGs into secondary glioblastomas. The O6-methylguanine-DNAmethyltransferase (MGMT) promoter methylation and 1p19q codeletion status can predict sensitivity to chemotherapy and radiation in low- and intermediate-grade gliomas. Thus, these recent advances, which have led to a better understanding of how molecular, genetic, and epigenetic alterations influence the pathogenicity of the different histological grades of gliomas, can lead to better prognostication and may lead to specific targeted surgical interventions and medical therapies.

Clinical value of O-(2-[(18)F]-fluoroethyl)-L-tyrosine positron emission tomography in patients with low-grade glioma

Progress in morphological imaging has facilitated the diagnosis of low-grade glioma (LGG) and plays a decisive role in therapeutic decisions. To date, the method of choice is contrast-enhanced MRI including T1-/T2-weighted and FLAIR sequences. However, tumor delineation and the differentiation between neoplastic and normal brain tissue can be difficult when using morphological MRI and may complicate the identification of anaplastic foci for biopsy and further treatment planning. Furthermore, therapy monitoring and the differentiation of tumor recurrence from unspecific post-therapeutic changes in the tissue are challenging. Additional information about tumor metabolism may be very helpful for the diagnostic assessment of LGG and can be provided by PET. In recent years, the PET amino acid tracer O-(2-[(18)F]-fluoroethyl)-L-tyrosine ((18)F-FET) has been clinically validated for brain tumor diagnosis. This tracer has logistical advantages over the widely used PET tracer (11)C-methyl-L-methionine due to the longer half-life of the (18)F-label (109 vs 20 minutes, respectively). Additionally, it has been demonstrated that both tracers provide comparable diagnostic information. The authors provide an overview of the recent literature regarding the value of various clinical applications of (18)F-FET PET in patients with LGG.

Improved survival in the largest national cohort of adults with cerebellar versus supratentorial low-grade astrocytomas

OBJECT

Low-grade gliomas (LGGs) are indolent tumors that have the potential to dedifferentiate into malignant high-grade tumors. Recent studies have demonstrated that cerebellar low-grade tumors have a better prognosis than supratentorial tumors, although no study has focused on the risk factors for poor prognosis in cerebellar LGGs in adults. The authors of the current study aimed to address both of these concerns by using a large cohort derived from a national cancer registry and a smaller cohort derived from their institution's experience.

METHODS

Adults with diagnosed Grade I and Grade II gliomas of the cerebellum were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Multivariate Cox proportional hazard models were used to predict rates of survival, and the log-rank test was applied to evaluate differences in Kaplan-Meier survival curves. An institutional cohort was created by isolating all patients whose surgical pathology revealed an LGG of the cerebellum. Excluded from analysis were patients in whom a glioma was first diagnosed under the age of 18 years and those whose tumors could not be definitively determined to arise from the cerebellum. Results Data from the local cohort (11 patients) demonstrated that the most common presenting symptom was headache, which occurred in more than 70% of the cohort. Approximately half of the patients in this cohort had symptomatic improvement after treatment.

RESULTS

from the SEER cohort (166 patients) revealed that adults with Grade I gliomas were slightly younger than those with Grade II tumors (p < 0.01), but no other demographic differences were observed. Patients with Grade I tumors were twice as likely to undergo gross-total resection (54% vs 21%), and those with Grade II gliomas were much more likely to receive postoperative radiation (3% vs 48%). Five-year survival was greater in the patients with Grade I gliomas than in those with Grade II lesions (91% vs 70%). Multivariate analysis revealed that an age ≥ 40 years (HR 7.30, 95% CI 3.55-15.0, p < 0.0001) and Grade II tumors (HR 2.76, 95% CI 1.12-6.84, p = 0.028) were risk factors for death, whereas female sex was protective (HR 0.28, 95% CI 0.14-0.59, p < 0.001). Log-rank tests revealed that a cerebellar location was protective (p < 0.0001), but this relationship was only true for Grade II tumors (p < 0.0001). Survival in patients with Grade I gliomas was not different based on the various lesion locations (p = 0.21).

CONCLUSIONS

Taken together, adults with cerebellar WHO Grade I and II astrocytomas have a much more favorable survival curve than those with similar supratentorial tumors. Research demonstrates that the primary driver of this phenomenon is the improved survival in patients with cerebellar Grade II gliomas.

Strategies to maximize resection of complex, or high surgical risk, low-grade gliomas

OBJECT

Early and aggressive resection of low-grade gliomas (LGGs) leads to increased overall patient survival, decreased malignant progression, and better seizure control. This case series describes the authors' approach to achieving optimal neurological and surgical outcomes in patients referred by outside neurosurgeons for stereotactic biopsy of tumors believed to be complex or a high surgical risk, due to their diffuse nature on neuroimaging and their obvious infiltration of functional cortex.

METHODS

Seven patients underwent individualized neuroimaging evaluation preoperatively, which included routine brain MRI with and without contrast administration for intraoperative neuronavigation, functional MRI with speech and motor mapping, diffusion tensor imaging to delineate white matter tracts, and MR perfusion to identify potential foci of higher grade malignancy within the tumor. Awake craniotomy with intraoperative motor and speech mapping was performed in all patients. Tumor removal was initiated through a transsylvian approach for insular lesions, and through multiple corticotomies in stimulation-confirmed noneloquent areas for all other lesions. Resection was continued until neuronavigation indicated normal brain, cortical or subcortical stimulation revealed functional cortex, or the patient began to experience a minor neurological deficit on intraoperative testing.

RESULTS

Gross-total resection was achieved in 1 patient and subtotal resection (> 80%) in 6 patients, as assessed by postoperative MRI. Over the average follow-up duration of 31 months, no patient experienced a progression or recurrence. Long-term seizure control was excellent in 6 patients who achieved Engel Class I outcomes. Neurologically, all 7 patients experienced mild temporary deficits or seizures that completely resolved, and 1 patient continues to have mild expressive aphasia.

CONCLUSIONS

Significant resection of diffuse, infiltrating LGGs is possible, even in presumed eloquent cortex. Aggressive resection maximizes seizure control and does not necessarily cause permanent neurological deficits. Individualized preoperative neuroimaging evaluation, including tractography and awake craniotomy with intraoperative speech and motor mapping, is an essential tool in achieving these outcomes.

Use of high-field intraoperative magnetic resonance imaging to enhance the extent of resection of enhancing and nonenhancing gliomas

BACKGROUND

Intraoperative magnetic resonance imaging (IoMRI) is used to improve the extent of resection of brain tumors. Most previous studies evaluating the utility of IoMRI have focused on enhancing tumors.

OBJECTIVE

To report our experience with the use of high-field IoMRI (1.5 T) for both enhancing and nonenhancing gliomas.

METHODS

An institutional review board-approved retrospective review was performed of 102 consecutive glioma patients (104 surgeries, 2010-2012). Pre-, intra-, and postoperative tumor volumes were assessed. Analysis was performed with the use of volumetric T2 images in 43 nonenhancing and 13 minimally enhancing tumors and with postcontrast volumetric magnetization-prepared rapid gradient-echo images in 48 enhancing tumors.

RESULTS

In 58 cases, preoperative imaging showed tumors likely to be amenable to complete resection. Intraoperative electrocorticography was performed in 32 surgeries, and 14 cases resulted in intended subtotal resection of tumors due to involvement of deep functional structures. No further resection (complete resection before IoMRI) was required in 25 surgeries, and IoMRI showed residual tumor in 79 patients. Of these, 25 surgeries did not proceed to further resection (9 due to electrocorticography findings, 14 due to tumor in deep functional areas, and 2 due to surgeon choice). Additional resection that was performed in 54 patients resulted in a final median residual tumor volume of 0.21 mL (0.6%). In 79 patients amenable to complete resection, the intraoperative median residual tumor volume for the T2 group was higher than for the magnetization-prepared rapid gradient-echo group (1.088 mL vs 0.437 mL; P = .049), whereas the postoperative median residual tumor volume was not statistically significantly different between groups.

CONCLUSION

IoMRI enhances the extent of resection, particularly for nonenhancing gliomas.

Resting-state blood oxygen level-dependent functional magnetic resonance imaging for presurgical planning

Resting-state functional MR imaging (rsfMR imaging) measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal and can be used to elucidate the brain's functional organization. It is used to simultaneously assess multiple distributed resting-state networks. Unlike task-based functional MR imaging, rsfMR imaging does not require task performance. This article presents a brief introduction of rsfMR imaging processing methods followed by a detailed discussion on the use of rsfMR imaging in presurgical planning. Example cases are provided to highlight the strengths and limitations of the technique.

Cystic glioblastoma: an evaluation of IDH1 status and prognosis

BACKGROUND

Controversy exists regarding the prognostic significance of cystic features in newly diagnosed glioblastoma multiforme (GBM) and the pathological origin of cystic GBMs.

OBJECTIVE

To determine whether cystic GBMs develop from low-grade gliomas by evaluating IDH1 status and to evaluate the differences in overall survival between patients with cystic and noncystic tumors.

METHODS

We retrospectively reviewed the records of 351 consecutive newly diagnosed adult GBM patients treated at our institution from October 1997 to November 2011; patients with >50% cystic tumor composition were further identified. IDH1 mutation was determined by immunohistochemical staining. Patient characteristics and treatment were reported for cystic and noncystic tumors separately. Overall survival was reported for cystic and noncystic cohorts by using the Kaplan-Meier estimates.

RESULTS

Of 351 patients, 27 (7.7%) had cystic tumors and 324 (92.3%) had noncystic tumors. Tumor samples for patients with cystic GBMs were immunohistochemically analyzed for IDH1 mutations. Two (7.4%) of the 27 tumor samples were documented as having IDH1 mutations. Characteristics such as age, sex, perioperative Karnofsky Performance Status, tumor size, extent of resection, postsurgery radiation, and temozolomide therapy were comparable in the and noncystic cohorts. Patients in the cystic cohort had a median overall survival of 15.0 months compared with 18.2 months for the noncystic cohort (log-rank P = .77).

CONCLUSION

The low frequency of IDH1 mutation status in our cystic cohort strongly suggests that most newly diagnosed cystic GBMs do not arise from malignant transformation of previously undiagnosed low-grade gliomas. Furthermore, there is no difference in overall survival between patients newly diagnosed with cystic and noncystic GBMs.

Awake craniotomy for gliomas in a high-field intraoperative magnetic resonance imaging suite: analysis of 42 cases

OBJECTIVES

The object of this study was to describe the experience of combining awake craniotomy techniques with high-field (1.5 T) intraoperative MRI (iMRI) for tumors adjacent to eloquent cortex.

METHODS

From a prospective database the authors obtained and evaluated the records of all patients who had undergone awake craniotomy procedures with cortical and subcortical mapping in the iMRI suite. The integration of these two modalities was assessed with respect to safety, operative times, workflow, extent of resection (EOR), and neurological outcome.

RESULTS

Between February 2010 and December 2011, 42 awake craniotomy procedures using iMRI were performed in 41 patients for the removal of intraaxial tumors. There were 31 left-sided and 11 right-sided tumors. In half of the cases (21 [50%] of 42), the patient was kept awake for both motor and speech mapping. The mean duration of surgery overall was 7.3 hours (range 4.0-13.9 hours). The median EOR overall was 90%, and gross-total resection (EOR ≥ 95%) was achieved in 17 cases (40.5%). After viewing the first MR images after initial resection, further resection was performed in 17 cases (40.5%); the mean EOR in these cases increased from 56% to 67% after further resection. No deficits were observed preoperatively in 33 cases (78.5%), and worsening neurological deficits were noted immediately after surgery in 11 cases (26.2%). At 1 month after surgery, however, worsened neurological function was observed in only 1 case (2.3%).

CONCLUSIONS

There was a learning curve with regard to patient positioning and setup times, although it did not adversely affect patient outcomes. Awake craniotomy can be safely performed in a high-field (1.5 T) iMRI suite to maximize tumor resection in eloquent brain areas with an acceptable morbidity profile at 1 month.

A novel data-driven approach to preoperative mapping of functional cortex using resting-state functional magnetic resonance imaging

Supplemental Digital Content is Available in the Text.

BACKGROUND:

Recent findings associated with resting-state cortical networks have provided insight into the brain's organizational structure. In addition to their neuroscientific implications, the networks identified by resting-state functional magnetic resonance imaging (rs-fMRI) may prove useful for clinical brain mapping.

OBJECTIVE:

To demonstrate that a data-driven approach to analyze resting-state networks (RSNs) is useful in identifying regions classically understood to be eloquent cortex as well as other functional networks.

METHODS:

This study included 6 patients undergoing surgical treatment for intractable epilepsy and 7 patients undergoing tumor resection. rs-fMRI data were obtained before surgery and 7 canonical RSNs were identified by an artificial neural network algorithm. Of these 7, the motor and language networks were then compared with electrocortical stimulation (ECS) as the gold standard in the epilepsy patients. The sensitivity and specificity for identifying these eloquent sites were calculated at varying thresholds, which yielded receiver-operating characteristic (ROC) curves and their associated area under the curve (AUC). RSNs were plotted in the tumor patients to observe RSN distortions in altered anatomy.

RESULTS:

The algorithm robustly identified all networks in all patients, including those with distorted anatomy. When all ECS-positive sites were considered for motor and language, rs-fMRI had AUCs of 0.80 and 0.64, respectively. When the ECS-positive sites were analyzed pairwise, rs-fMRI had AUCs of 0.89 and 0.76 for motor and language, respectively.

CONCLUSION:

A data-driven approach to rs-fMRI may be a new and efficient method for preoperative localization of numerous functional brain regions.

ABBREVIATIONS:

AUC, area under the curve

BA, Brodmann area

BOLD, blood oxygen level dependent

ECS, electrocortical stimulation

fMRI, functional magnetic resonance imaging

ICA, independent component analysis

MLP, multilayer perceptron

MP-RAGE, magnetization-prepared rapid gradient echo

ROC, receiver-operating characteristic

rs-fMRI, resting-state functional magnetic resonance imaging

RSN, resting-state network