Time window for postoperative reactive enhancement after resection of brain tumors: less than 72 hours

Deep learning ensembles for detecting brain metastases in longitudinal multi-modal MRI studies

Metastatic brain cancer is a condition characterized by the migration of cancer cells to the brain from extracranial sites. Notably, metastatic brain tumors surpass primary brain tumors in prevalence by a significant factor, they exhibit an aggressive growth potential and have the capacity to spread across diverse cerebral locations simultaneously. Magnetic resonance imaging (MRI) scans of individuals afflicted with metastatic brain tumors unveil a wide spectrum of characteristics. These lesions vary in size and quantity, spanning from tiny nodules to substantial masses captured within MRI. Patients may present with a limited number of lesions or an extensive burden of hundreds of them. Moreover, longitudinal studies may depict surgical resection cavities, as well as areas of necrosis or edema. Thus, the manual analysis of such MRI scans is difficult, user-dependent and cost-inefficient, and - importantly - it lacks reproducibility. We address these challenges and propose a pipeline for detecting and analyzing brain metastases in longitudinal studies, which benefits from an ensemble of various deep learning architectures originally designed for different downstream tasks (detection and segmentation). The experiments, performed over 275 multi-modal MRI scans of 87 patients acquired in 53 sites, coupled with rigorously validated manual annotations, revealed that our pipeline, built upon open-source tools to ensure its reproducibility, offers high-quality detection, and allows for precisely tracking the disease progression. To objectively quantify the generalizability of models, we introduce a new data stratification approach that accommodates the heterogeneity of the dataset and is used to elaborate training-test splits in a data-robust manner, alongside a new set of quality metrics to objectively assess algorithms. Our system provides a fully automatic and quantitative approach that may support physicians in a laborious process of disease progression tracking and evaluation of treatment efficacy.

Pediatric WNT medulloblastoma predisposition in intraoperative blood loss: a retrospective observational cohort study

Introduction

Molecular subgroups influence the vascular architecture within medulloblastomas, particularly the wingless (WNT) subgroup, which contributes to its propensity for primary tumor hemorrhage. Whether this mechanism affects intraoperative blood loss remains unknown. This study aimed to assess the association between WNT medulloblastoma and the predisposition for blood loss.

Methods

This was a retrospective observational study using data from a neuro-oncology center comprising molecular data on patients treated between December 31, 2014, and April 30, 2023. Differences between WNT and other subgroups in the risk of primary outcome-intraoperative blood loss were assessed using multivariable-adjusted linear regression.

Results

Of the 148 patients included in the analysis, 18 patients (12.2%) had WNT, 42 (28.4%) had sonic hedgehog (SHH) TP53-wildtype, 7 (4.7%) had SHH TP53-mutant, and 81 (54.7%) were non-WNT/ non-SHH. The WNT subgroup more frequently underwent primary intratumoral hemorrhage (22% vs. 3.8%; p = 0.011). The median intraoperative blood loss was 400.00 (interquartile range [IQR] 250, 500) mL for WNT and 300.00 [200, 400] mL for the other subgroups (p = 0.136), with an adjusted β of 135.264 (95% confidence intervals [CI], 11.701-258.827; p = 0.032). Similar results were observed in both midline and noninfiltrative margin medulloblastoma.

Discussion

WNT medulloblastoma is typically associated with primary intratumoral hemorrhage and intraoperative blood loss. The validity of determining the surgical approach based on predicted molecular subtypes from imaging data is questionable. However, attempting to engage in risk communication with patients in a molecular-specific way is worthwhile to validate.

Neurosurgical short-term outcomes for pediatric medulloblastoma patients and molecular correlations: a 10-year single-center observation cohort study

This study examined the risk factors for short-term outcomes, focusing particularly on the associations among molecular subgroups. The analysis focused on the data of pediatric patients with medulloblastoma between 2013 and 2023, as well as operative complications, length of stay from surgery to adjuvant treatment, 30-day unplanned reoperation, unplanned readmission, and mortality. 148 patients were included. Patients with the SHH TP53-wildtype exhibited a lower incidence of complications (45.2% vs. 66.0%, odds ratio [OR] 0.358, 95% confidence interval [CI] 0.160 - 0.802). Female sex (0.437, 0.207 - 0.919) was identified as an independent protective factor for complications, and brainstem involvement (1.900, 1.297 - 2.784) was identified as a risk factor. Surgical time was associated with an increased risk of complications (1.004, 1.001 - 1.008), duration of hospitalization (1.006, 1.003 - 1.010), and reoperation (1.003, 1.001 - 1.006). Age was found to be a predictor of improved outcomes, as each additional year was associated with a 14.1% decrease in the likelihood of experiencing a prolonged length of stay (0.859, 0.772 - 0.956). Patients without metastasis exhibited a reduced risk of reoperation (0.322, 0.133 - 0.784) and readmission (0.208, 0.074 - 0.581). There is a significant degree of variability in the occurrence of operative complications in pediatric patients with medulloblastoma. SHH TP53-wildtype medulloblastoma is commonly correlated with a decreased incidence of complications. The short-term outcomes of patients are influenced by various unmodifiable endogenous factors. These findings could enhance the knowledge of onconeurosurgeons and alleviate the challenges associated with patient/parent education through personalized risk communication. However, the importance of a dedicated center with expertise surgical team and experienced neurosurgeon in improving neurosurgical outcomes appears self-evident.

Prognostic relevance of radiological findings on early postoperative MRI for 187 consecutive glioblastoma patients receiving standard therapy

Several prognostic factors are known to influence survival for patients treated with IDH-wildtype glioblastoma, but unknown factors may remain. We aimed to investigate the prognostic implications of early postoperative MRI findings. A total of 187 glioblastoma patients treated with standard therapy were consecutively included. Patients either underwent a biopsy or surgery followed by an early postoperative MRI. Progression-free survival (PFS) and overall survival (OS) were analysed for known prognostic factors and MRI-derived candidate factors: resection status as defined by the response assessment in neuro-oncology (RANO)-working group (no contrast-enhancing residual tumour, non-measurable contrast-enhancing residual tumour, or measurable contrast-enhancing residual tumour) with biopsy as reference, contrast enhancement patterns (no enhancement, thin linear, thick linear, diffuse, nodular), and the presence of distant tumours. In the multivariate analysis, patients with no contrast-enhancing residual tumour or non-measurable contrast-enhancing residual tumour on the early postoperative MRI displayed a significantly improved progression-free survival compared with patients receiving only a biopsy. Only patients with non-measurable contrast-enhancing residual tumour showed improved overall survival in the multivariate analysis. Contrast enhancement patterns were not associated with survival. The presence of distant tumours was significantly associated with both poor progression-free survival and overall survival and should be considered incorporated into prognostic models.

The clinical significance of sub-total surgical resection in childhood medulloblastoma: a multi-cohort analysis of 1100 patients

Background

Medulloblastoma patients with a sub-total surgical resection (STR; >1.5 cm2 primary tumour residuum post-surgery) typically receive intensified treatment. However, the association of STR with poor outcomes has not been observed consistently, questioning the validity of STR as a high-risk disease feature.

Methods

We collected extent of resection (EOR) data from 1110 patients (from UK CCLG centres (n = 416, collected between September 1990 and July 2014) and published (n = 694) cohorts), the largest cohort of molecularly and clinically annotated tumours assembled to specifically assess the significance of EOR. We performed association and univariable/multivariable survival analyses, assessing overall survival (OS) cohort-wide and with reference to the four consensus medulloblastoma molecular groups and clinical features.

Findings

STR was reported in 20% (226/1110) of patients. Non-WNT (p = 0.047), children <5 years at diagnosis (p = 0.021) and metastatic patients (p < 0.0001) were significantly more likely to have a STR. In cohort-wide analysis, STR was associated with worse survival in univariable analysis (p < 0.0001). Examination of specific disease contexts showed that STR was prognostic in univariate analysis for patients receiving cranio-spinal irradiation (CSI) and chemotherapy (p = 0.016) and for patients with Group 3 tumours receiving CSI (p = 0.039). STR was not independently prognostic in multivariable analyses; outcomes for patients who have STR as their only risk-feature are as per standard-risk disease. Specifically, STR was not prognostic in non-metastatic patients that received upfront CSI.

Interpretation

In a cohort of 1100 molecularly characterised medulloblastoma patients, STR (n = 226) predicted significantly lower OS in univariable analysis, but was not an independent prognostic factor. Our data suggest that maximal safe resection can continue to be carried out for patients with medulloblastoma and suggest STR should not inform patient management when observed as a sole, isolated risk-feature.

Funding

Cancer Research UK, Newcastle Hospitals Charity, Children's Cancer North, British Division of the International Academy of Pathology.

Challenges in radiological evaluation of brain metastases, beyond progression

MRI is the cornerstone in the evaluation of brain metastases. The clinical challenges lie in discriminating metastases from mimickers such as infections or primary tumors and in evaluating the response to treatment. The latter sometimes leads to growth, which must be framed as pseudo-progression or radionecrosis, both inflammatory phenomena attributable to treatment, or be considered as recurrence. To meet these needs, imaging techniques are the subject of constant research. However, an exponential growth after radiotherapy must be interpreted with caution, even in the presence of results suspicious of tumor progression by advanced techniques, because it may be due to inflammatory changes. The aim of this paper is to familiarize the reader with inflammatory phenomena of brain metastases treated with radiotherapy and to describe two related radiological signs: "the inflammatory cloud" and "incomplete ring enhancement", in order to adopt a conservative management with close follow-up.

Advances in Imaging Modalities for Pediatric Brain and Spinal Cord Tumors

BACKGROUND

Neuroimaging has evolved from anatomical imaging toward a multi-modality comprehensive anatomical and functional imaging in the past decades, important functional data like perfusion-weighted imaging, permeability imaging, diffusion-weighted imaging (DWI), and diffusion tensor imaging (DTI), tractography, metabolic imaging, connectomics, event-related functional imaging, resting state functional imaging, and much more is now being offered.

SUMMARY

Precision diagnostics has proven to be essential for precision treatment. Many minimal invasive techniques have been developed, taking advantage of digital subtraction angiography and interventional neuroradiology. Furthermore, intraoperative CT and/or MRI and more recently MR-guided focused ultrasound have complemented the diagnostic and therapeutic armamentarium.

KEY MESSAGES

In the current manuscript, we discuss standard imaging sequences including advanced techniques like DWI, DTI, susceptibility-weighted imaging, and 1H magnetic resonance spectroscopy, various perfusion weighted imaging approaches including arterial spin labeling, dynamic contrast enhanced imaging, and dynamic susceptibility contrast imaging. Pre-, intra, and postoperative surgical imaging including visualize imaging will be discussed. The value of connectomics will be presented for its value in neuro-oncology. Minimal invasive therapeutic possibilities of interventional neuroradiology and image-guided laser ablation and MR-guided high-intensity-focused ultrasound will be presented for treatment of pediatric brain and spinal cord tumors. Finally, a comprehensive review of spinal cord tumors and matching neuropathology has been included.

The insertion and management of an external ventricular drain in pediatric patients with hydrocephalus associated with medulloblastoma

An external ventricular drain (EVD) is used to facilitate cerebrospinal fluid (CSF) removal in medulloblastoma patients suffering from hydrocephalus. It is essential to recognize that EVD management plays a crucial role in influencing the incidence of drain-related complications. However, the ideal method for EVD management remains undetermined. Our research sought to examine the safety of EVD placement and the impact of EVD on the incidences of intracranial infections, postresection hydrocephalus, and posterior fossa syndrome (PFS). We conducted a single-center observational study involving a cohort of 120 pediatric medulloblastoma patients who were treated from 2017 to 2020. The rates of intracranial infection, postresection hydrocephalus, and PFS were 9.2%, 18.3%, and 16.7%, respectively. EVD did not influence the occurrence of intracranial infection (p = 0.466), postresection hydrocephalus (p = 0.298), or PFS (p = 0.212). A gradual EVD weaning protocol correlated with an elevated incidence of postresection hydrocephalus (p = 0.033), whereas a rapid weaning approach resulted in 4.09 ± 0.44 fewer drainage days (p < 0.001) than the gradual weaning strategy. EVD placement (p = 0.010) and intracranial infection (p = 0.002) were linked to delayed speech return, whereas a longer duration of drainage was conducive to the recovery of language function (p = 0.010). EVD insertion was not correlated with the incidence of intracranial infection, postoperative hydrocephalus, or PFS. The optimal EVD management method should encompass a rapid EVD weaning strategy, followed by prompt drain closure. We have presented additional evidence to improve the safety of EVD insertion and management in neurosurgical patients to ultimately facilitate the establishment of standardized institutional/national implementation and management protocols.

Incidence and Risk Factors for Necessitating Cerebrospinal Fluid Diversion Following Medulloblastoma Surgery in Children

BACKGROUND

There are insufficient data on pediatric patients with medulloblastoma who require cerebrospinal fluid (CSF) diversion following resection. Therefore, this study aimed to determine the incidence and the characteristics associated with it in this subset of patients.

METHODS

We conducted a single-center, retrospective, observational cohort study of patients aged 18 years or less who underwent medulloblastoma resection at our department between 2010 and 2021. The primary outcome was the incidence of CSF diversion surgery required after resection. Participant demographics, tumor biology, and interventions were analyzed using univariate- and multivariate-adjusted models.

RESULTS

Of the 183 patients admitted to our department, 131 (71.6%) participated in this study. The incidence of permanent CSF diversion was 26.0% (95% confidence interval [CI]: 18.7 to 34.3). Factors independently associated with requirement of permanent CSF diversion were medulloblastoma volume >46.4 cm³ (odds ratio [OR]: 2.919, 95% CI: 1.191 to 7.156) and CSF channel invasion (OR: 2.849, 95% CI: 1.142 to 7.102). The duration of manifestation may be a covariate of tumor volume with increased risk of requirement for permanent CSF diversion (OR: 1.006, 95% CI: 1.000 to 1.013), and tumor volume may be a predictor in patients who underwent subtotal resection (OR: 4.900, 95% CI: 0.992 to 24.208, P = 0.05). Finally, patients who required permanent CSF diversion were divided according to medulloblastoma molecular subgroups, and no significant differences were found.

CONCLUSION

We report major predictive factors for permanent CSF diversion surgery in patients with medulloblastoma. Our study suggests that the presence of postresection hydrocephalus is not high enough to warrant permanent, prophylactic CSF diversion in all patients.

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.

Timing of Early Postoperative MRI following Primary Glioblastoma Surgery-A Retrospective Study of Contrast Enhancements in 311 Patients

An early postoperative MRI is recommended following Glioblastoma surgery. This retrospective, observational study aimed to investigate the timing of an early postoperative MRI among 311 patients. The patterns of the contrast enhancement (thin linear, thick linear, nodular, and diffuse) and time from surgery to the early postoperative MRI were recorded. The primary endpoint was the frequencies of the different contrast enhancements within and beyond the 48-h from surgery. The time dependence of the resection status and the clinical parameters were analysed as well. The frequency of the thin linear contrast enhancements significantly increased from 99/183 (50.8%) within 48-h post-surgery to 56/81 (69.1%) beyond 48-h post-surgery. Similarly, MRI scans with no contrast enhancements significantly declined from 41/183 (22.4%) within 48-h post-surgery to 7/81 (8.6%) beyond 48-h post-surgery. No significant differences were found for the other types of contrast enhancements and the results were robust in relation to the choice of categorisation of the postoperative periods. Both the resection status and the clinical parameters were not statistically different in patients with an MRI performed before and after 48 h. The findings suggest that surgically induced contrast enhancements are less frequent when an early postoperative MRI is performed earlier than 48-h, supporting the recommendation of a 48-h window for an early postoperative MRI.

Evaluation of patient STress level caused by radiological Investigations in early Postoperative phase After CRANIOtomy (IPAST-CRANIO): protocol of a Swiss prospective cohort study

INTRODUCTION

Postoperative imaging after neurosurgical interventions is usually performed in the first 72 hours after surgery to provide an accurate assessment of postoperative resection status. Patient frequently report that early postoperative examination after craniotomy for tumour and vascular procedures is associated with distress, exertion, nausea and pain. Delayed postoperative imaging (between 36 and 72 hours postoperatively) may have an advantage regarding psychological and physical stress compared with early imaging. The goal of this study is to evaluate and determine the optimal time frame for postoperative imaging with MRI and CT in terms of medical and neuroradiological implications and patient's subjective stress level.

METHODS AND ANALYSIS

Data will be prospectively collected from all patients aged 18-80 years who receive postoperative MRI or CT imaging following a craniotomy for resection of a cerebral tumour (benign and malignant) or vascular surgery. Participants have to complete questionnaires containing visual analogue scores (VAS) for headache and nausea, Body Part Discomfort score and a single question addressing subjective preference of timing of postoperative imaging after craniotomy. The primary endpoint of the study is the difference in subjective stress due to imaging studies after craniotomy, measured just before and after postoperative MRI or CT with the above-mentioned instruments. Subjective stress is defined as a combination of the scores VAS pain, VAS nausea and 0.5* Body Part Discomfort core.This study determines whether proper timing of postoperative imaging can improve patient satisfaction and reduce pain, stress and discomfort caused by postoperative imaging. Factors causing additional postoperative stress are likely responsible for delayed recovery of neurosurgical patients.

ETHICS AND DISSEMINATION

The institutional review board (Kantonale Ethikkommission Zürich) approved this study on 4 August 2020 under case number BASEC 2020-01590. The authors are planning to publish the data of this study in a peer-reviewed paper. After database closure, the data will be exported to the local data repository (Zurich Open Repository and Archive) of the University of Zurich. The sponsor (LR) and the project leader (MR.G) will make the final decision on the publication of the results. The data that support the findings of this study are available on request from the corresponding author LT. The data are not publicly available due to privacy/ethical restrictions.

TRIAL REGISTRATION NUMBER

NCT05112575; ClinicalTrials.gov.

Single-Center Retrospective Analysis of Risk Factors for Hydrocephalus After Lateral Ventricular Tumor Resection

Objective

There is no general consensus on the placement of preoperative and intraoperative external ventricular drainage (EVD) in patients with lateral ventricular tumors (LVTs). The aim of this study was to identify the predictors of postoperative acute and persistent hydrocephalus need for postoperative cerebrospinal fluid (CSF) drainage and guide the management of postoperative EVD in patients with LVTs.

Methods

We performed a single-institution, retrospective analysis of patients who underwent resection of LVTs in our Department between January 2011 and March 2021. Patients were divided between one group that required CSF drainage and another group without the need for CSF drainage. We analyzed the two groups by univariate and multivariate analyses to identify the predictors of the requirement for postoperative CSF drainage due to symptomatic intracranial hypertension caused by hydrocephalus.

Results

A total of 97 patients met the inclusion criteria, of which 31 patients received preoperative or intraoperative EVD. Ten patients without prophylactic EVD received postoperative EVD for postoperative acute hydrocephalus. Eleven patients received postoperative ventriculoperitoneal(VP) shunt subsequently. Logistic regression analysis showed that tumor invasion of the anterior ventricle (OR = 7.66), transependymal edema (OR = 8.76), and a large volume of postoperative intraventricular hemorrhage (IVH) (OR = 6.51) were independent risk factors for postoperative acute hydrocephalus. Perilesional edema (OR = 33.95) was an independent risk factor for postoperative VP shunt due to persistent hydrocephalus.

Conclusion

Postoperative hydrocephalus is a common complication in patients with LVTs. These findings might help to determine whether to conduct earlier interventions.

Management of Posterior Fossa Tumors in Adults Based on the Predictors of Postoperative Hydrocephalus

Objective

This study aims to identify the predictors of postoperative hydrocephalus in patients with posterior fossa tumors (PFTs) and guide the management of perioperative hydrocephalus.

Methods

We performed a single-institution, retrospective analysis of patients who underwent resection of PFTs in our department over a 10-year period (2011–2021). A total of 682 adult patients met the inclusion criteria and were divided into either a prophylactic external ventricular drainage (EVD) group or a nonprophylactic-EVD group. We analyzed data for the nonprophylactic-EVD group by univariate and multivariate analyses to identify predictors of postoperative acute hydrocephalus. We also analyzed all cases by univariate and multivariate analyses to determine the predictors of postoperative ventriculoperitoneal (VP) shunt placement.

Results

Tumor infiltrating the midbrain aqueduct [P = 0.001; odds ratio (OR) = 9.8], postoperative hemorrhage (P &lt; 0.001; OR = 66.7), and subtotal resection (P = 0.006; OR = 9.3) were independent risk factors for postoperative EVD. Tumor infiltrating the ventricular system (P &lt; 0.001; OR = 58.5) and postoperative hemorrhage (P &lt; 0.001; OR = 28.1) were independent risk factors for postoperative VP shunt placement.

Conclusions

These findings may help promote more aggressive monitoring and earlier interventions for postoperative hydrocephalus in patients with PFTs.

Standard clinical approaches and emerging modalities for glioblastoma imaging

Glioblastoma (GBM) is the most common primary adult intracranial malignancy and carries a dismal prognosis despite an aggressive multimodal treatment regimen that consists of surgical resection, radiation, and adjuvant chemotherapy. Radiographic evaluation, largely informed by magnetic resonance imaging (MRI), is a critical component of initial diagnosis, surgical planning, and post-treatment monitoring. However, conventional MRI does not provide information regarding tumor microvasculature, necrosis, or neoangiogenesis. In addition, traditional MRI imaging can be further confounded by treatment-related effects such as pseudoprogression, radiation necrosis, and/or pseudoresponse(s) that preclude clinicians from making fully informed decisions when structuring a therapeutic approach. A myriad of novel imaging modalities have been developed to address these deficits. Herein, we provide a clinically oriented review of standard techniques for imaging GBM and highlight emerging technologies utilized in disease characterization and therapeutic development.

MR Imaging of Pediatric Brain Tumors

Primary brain tumors are the most common solid neoplasms in children and a leading cause of mortality in this population. MRI plays a central role in the diagnosis, characterization, treatment planning, and disease surveillance of intracranial tumors. The purpose of this review is to provide an overview of imaging methodology, including conventional and advanced MRI techniques, and illustrate the MRI appearances of common pediatric brain tumors.

Second window ICG predicts gross-total resection and progression-free survival during brain metastasis surgery

OBJECTIVE

Metastases are the most common intracranial malignancies and complete resection can provide relief of neurological symptoms and reduce recurrence. The authors' prospective pilot study in 2017 demonstrated promising results for the application of high-dose, delayed imaging of indocyanine green (ICG), known as second window ICG (SWIG), in patients undergoing surgery for brain metastases. In this prospective cohort study, the authors evaluated intraoperative imaging and clinical outcomes of treatment using SWIG.

METHODS

Patients were prospectively enrolled in an approved study of high-dose, delayed ICG (SWIG) and received 5 mg/kg (2014-2018) or 2.5 mg/kg (2018-2019) ICG 24 hours preoperatively. Intraoperatively, near-infrared (NIR) imaging was performed using a dedicated NIR exoscope. NIR images were analyzed and the signal-to-background ratio (SBR) was calculated to quantify fluorescence. Residual fluorescence on the postresection NIR view was compared and correlated to the residual gadolinium enhancement on postoperative MRI. Patient survival and predictive factors were analyzed.

RESULTS

In total, 51 intracranial metastases were surgically treated in 47 patients in this cohort. All 51 metastatic tumors demonstrated strong NIR fluorescence (mean SBR 4.9). In tumors ≤ 10 mm from the cortical surface, SWIG with 5 mg/kg ICG produced enhanced transdural tumor visibility (91.3%) compared to 2.5 mg/kg (52.9%; p = 0.0047). Neoplastic margin detection using NIR fluorescence compared to white light improved sensitivity, albeit lowered specificity; however, increasing the SBR cutoff for positive fluorescence significantly improved specificity without sacrificing sensitivity, increasing the overall accuracy from 57.5% to 72.5%. A lack of residual NIR fluorescence after resection was closely correlated with a lack of residual enhancement on postoperative MRI (p = 0.007). Among the 16 patients in whom tumor recurred at the site of surgery, postoperative MRI successfully predicted 8 cases, whereas the postresection NIR view predicted 12 cases. Progression-free survival rate at 12 months was greater for patients without residual NIR fluorescence (38%) than for those without residual enhancement on postoperative MRI (29%).

CONCLUSIONS

The current study demonstrates the clinical benefits of the SWIG technique in surgery for patients with brain metastases. Specifically, this technique allows for dose-dependent, transdural localization of neoplasms and improved sensitivity in neoplastic margin detection. Postresection residual fluorescence can be a powerful tool to evaluate extent of resection in conjunction with MRI, and it may guide decisions on brain metastasis management.

European Society for Paediatric Oncology (SIOPE) MRI guidelines for imaging patients with central nervous system tumours

INTRODUCTION

Standardisation of imaging acquisition is essential in facilitating multicentre studies related to childhood CNS tumours. It is important to ensure that the imaging protocol can be adopted by centres with varying imaging capabilities without compromising image quality.

MATERIALS AND METHOD

An imaging protocol has been developed by the Brain Tumour Imaging Working Group of the European Society for Paediatric Oncology (SIOPE) based on consensus among its members, which consists of neuroradiologists, imaging scientists and paediatric neuro-oncologists. This protocol has been developed to facilitate SIOPE led studies and regularly reviewed by the imaging working group.

RESULTS

The protocol consists of essential MRI sequences with imaging parameters for 1.5 and 3 Tesla MRI scanners and a set of optional sequences that can be used in appropriate clinical settings. The protocol also provides guidelines for early post-operative imaging and surveillance imaging. The complementary use of multimodal advanced MRI including diffusion tensor imaging (DTI), MR spectroscopy and perfusion imaging is encouraged, and optional guidance is provided in this publication.

CONCLUSION

The SIOPE brain tumour imaging protocol will enable consistent imaging across multiple centres involved in paediatric CNS tumour studies.

Surgically Induced Contrast Enhancements on Intraoperative and Early Postoperative MRI Following High-Grade Glioma Surgery: A Systematic Review

For the radiological assessment of resection of high-grade gliomas, a 72-h diagnostic window is recommended to limit surgically induced contrast enhancements. However, such enhancements may occur earlier than 72 h post-surgery. This systematic review aimed to assess the evidence on the timing of the postsurgical MRI. PubMed, Embase, Web of Science and Cochrane were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only original research articles describing surgically induced contrast enhancements on MRI after resection for high-grade gliomas were included and analysed. The frequency of different contrast enhancement patterns on intraoperative MRI (iMRI) and early postoperative MRI (epMRI) was recorded. The search resulted in 1443 studies after removing duplicates, and a total of 12 studies were chosen for final review. Surgically induced contrast enhancements were reported at all time points after surgery, including on iMRI, but their type and frequency vary. Thin linear contrast enhancements were commonly found to be surgically induced and were less frequently recorded on postoperative days 1 and 2. This suggests that the optimal time to scan may be at or before this time. However, the evidence is limited, and higher-quality studies using larger and consecutively sampled populations are needed.

Comparison of intraoperative and post-operative 3-T MRI performed at 24-72 h following brain tumour resection in children

PURPOSE

Intraoperative MRI (ioMRI) is a valuable tool aiding paediatric brain tumour resection. There is no published evidence comparing the effectiveness of the final intraoperative MRI and early post-operative (24-72 h) MRI as baseline scans following brain tumour resection. We aimed to evaluate whether the final ioMRI scan could serve as the post-operative baseline scan after paediatric brain tumour resections.

METHODS

This prospective study compared the final ioMRI scan with the immediate post-operative MRI scan performed 24-72 h post-surgery. We included 20 patients aged 6.6-21 years undergoing brain tumour resection using ioMRI and were suitable for MRI scan without general anaesthesia. The scans were independently evaluated by experienced local and external paediatric neuroradiologists. Identical sequences in the final ioMRI and the 24-72-h MRI were compared to assess the extent of resection, imaging characteristics of residual tumour, the surgical field, extent of surgically induced contrast enhancement, and diffusion abnormalities.

RESULTS

In 20 patients undergoing intraoperative and early post-operative MRI, there was no difference between ioMRI and 24-72-h post-op scans in identifying residual tumour. Surgically induced contrast enhancement was similar in both groups. There were more abnormalities on diffusion imaging and a greater degree of oedema around the surgical cavity on the 24-72-h scan.

CONCLUSION

The final 3-T ioMRI scan may be used as a baseline post-operative scan provided standard imaging guidelines are followed and is evaluated jointly by the operating neurosurgeon and neuroradiologist. Advantages of final ioMRI as a baseline scan are identified.

A Critical Review of PET Tracers Used for Brain Tumor Imaging

The brain is a common site for metastases as well as primary tumors. Although evaluation of these malignancies with contrast-enhanced MR imaging defines current clinical practice, ¹⁸F-fluorodeoxyglucose (FDG)-PET has shown considerable utility in this area. In addition, many other tracers targeting various aspects of tumor biology have been developed and tested. This article discusses recent developments in PET imaging and the anticipated role of FDG and other tracers in the assessment of brain tumors.

A Position Statement on the Utility of Interval Imaging in Standard of Care Brain Tumour Management: Defining the Evidence Gap and Opportunities for Future Research

OBJECTIV E

To summarise current evidence for the utility of interval imaging in monitoring disease in adult brain tumours, and to develop a position for future evidence gathering while incorporating the application of data science and health economics.

METHODS

Experts in 'interval imaging' (imaging at pre-planned time-points to assess tumour status); data science; health economics, trial management of adult brain tumours, and patient representatives convened in London, UK. The current evidence on the use of interval imaging for monitoring brain tumours was reviewed. To improve the evidence that interval imaging has a role in disease management, we discussed specific themes of data science, health economics, statistical considerations, patient and carer perspectives, and multi-centre study design. Suggestions for future studies aimed at filling knowledge gaps were discussed.

RESULTS

Meningioma and glioma were identified as priorities for interval imaging utility analysis. The "monitoring biomarkers" most commonly used in adult brain tumour patients were standard structural MRI features. Interval imaging was commonly scheduled to provide reported imaging prior to planned, regular clinic visits. There is limited evidence relating interval imaging in the absence of clinical deterioration to management change that alters morbidity, mortality, quality of life, or resource use. Progression-free survival is confounded as an outcome measure when using structural MRI in glioma. Uncertainty from imaging causes distress for some patients and their caregivers, while for others it provides an important indicator of disease activity. Any study design that changes imaging regimens should consider the potential for influencing current or planned therapeutic trials, ensure that opportunity costs are measured, and capture indirect benefits and added value.

CONCLUSION

Evidence for the value, and therefore utility, of regular interval imaging is currently lacking. Ongoing collaborative efforts will improve trial design and generate the evidence to optimise monitoring imaging biomarkers in standard of care brain tumour management.

Frequency and Evolution of New Postoperative Enhancement on 3 Tesla Intraoperative and Early Postoperative Magnetic Resonance Imaging

BACKGROUND

Intraoperative magnetic resonance imaging (IO-MRI) provides real-time assessment of extent of resection of brain tumor. Development of new enhancement during IO-MRI can confound interpretation of residual enhancing tumor, although the incidence of this finding is unknown.

OBJECTIVE

To determine the frequency of new enhancement during brain tumor resection on intraoperative 3 Tesla (3T) MRI. To optimize the postoperative imaging window after brain tumor resection using 1.5 and 3T MRI.

METHODS

We retrospectively evaluated 64 IO-MRI performed for patients with enhancing brain lesions referred for biopsy or resection as well as a subset with an early postoperative MRI (EP-MRI) within 72 h of surgery (N = 42), and a subset with a late postoperative MRI (LP-MRI) performed between 120 h and 8 wk postsurgery (N = 34). Three radiologists assessed for new enhancement on IO-MRI, and change in enhancement on available EP-MRI and LP-MRI. Consensus was determined by majority response. Inter-rater agreement was assessed using percentage agreement.

RESULTS

A total of 10 out of 64 (16%) of the IO-MRI demonstrated new enhancement. Seven of 10 patients with available EP-MRI demonstrated decreased/resolved enhancement. One out of 42 (2%) of the EP-MRI demonstrated new enhancement, which decreased on LP-MRI. Agreement was 74% for the assessment of new enhancement on IO-MRI and 81% for the assessment of new enhancement on the EP-MRI.

CONCLUSION

New enhancement occurs in intraoperative 3T MRI in 16% of patients after brain tumor resection, which decreases or resolves on subsequent MRI within 72 h of surgery. Our findings indicate the opportunity for further study to optimize the postoperative imaging window.

Risk factors for hydrocephalus following fourth ventricle tumor surgery: A retrospective analysis of 121 patients

BACKGROUND AND AIM

Most patients who present with a fourth ventricle tumor have concurrent hydrocephalus, and some demonstrate persistent hydrocephalus after tumor resection. There is still no consensus on the management of hydrocephalus in patients with fourth ventricle tumor after surgery. The purpose of this study was to identify the factors that predispose to postoperative hydrocephalus and the need for a postoperative cerebrospinal fluid (CSF) diversion procedure.

MATERIALS AND METHODS

We performed a retrospective analysis of patients who underwent surgery of the fourth ventricle tumor between January 2013 and December 2018 at the Department of Neurosurgery in West China Hospital of Sichuan University. The characteristics of patients and the tumor location, tumor size, tumor histology, and preventive external ventricular drainage (EVD) that were potentially correlated with CSF circulation were evaluated in univariate and multivariate analysis.

RESULTS

A total of 121 patients were enrolled in our study; 16 (12.9%) patients underwent postoperative CSF drainage. Univariate analysis revealed that superior extension (p = 0.004), preoperative hydrocephalus (p<0.001), and subtotal resection (p<0.001) were significantly associated with postoperative hydrocephalus. Multivariate analysis revealed that superior extension (p = 0.013; OR = 44.761; 95% CI 2.235-896.310) and subtotal resection (p = 0.005; OR = 0.087; 95% CI 0.016-0.473) were independent risk factors for postoperative hydrocephalus after resection of fourth ventricle tumor.

CONCLUSION

Superior tumor extension (into the aqueduct) and failed total resection of tumor were identified as independent risk factors for postoperative hydrocephalus in patients with fourth ventricle tumor.

Glioblastoma post-operative imaging in neuro-oncology: current UK practice (GIN CUP study)

OBJECTIVES

MRI remains the preferred imaging investigation for glioblastoma. Appropriate and timely neuroimaging in the follow-up period is considered to be important in making management decisions. There is a paucity of evidence-based information in current UK, European and international guidelines regarding the optimal timing and type of neuroimaging following initial neurosurgical treatment. This study assessed the current imaging practices amongst UK neuro-oncology centres, thus providing baseline data and informing future practice.

METHODS

The lead neuro-oncologist, neuroradiologist and neurosurgeon from every UK neuro-oncology centre were invited to complete an online survey. Participants were asked about current and ideal imaging practices following initial treatment.

RESULTS

Ninety-two participants from all 31 neuro-oncology centres completed the survey (100% response rate). Most centres routinely performed an early post-operative MRI (87%, 27/31), whereas only a third performed a pre-radiotherapy MRI (32%, 10/31). The number and timing of scans routinely performed during adjuvant TMZ treatment varied widely between centres. At the end of the adjuvant period, most centres performed an MRI (71%, 22/31), followed by monitoring scans at 3 monthly intervals (81%, 25/31). Additional short-interval imaging was carried out in cases of possible pseudoprogression in most centres (71%, 22/31). Routine use of advanced imaging was infrequent; however, the addition of advanced sequences was the most popular suggestion for ideal imaging practice, followed by changes in the timing of EPMRI.

CONCLUSION

Variations in neuroimaging practices exist after initial glioblastoma treatment within the UK. Multicentre, longitudinal, prospective trials are needed to define the optimal imaging schedule for assessment.

KEY POINTS

• Variations in imaging practices exist in the frequency, timing and type of interval neuroimaging after initial treatment of glioblastoma within the UK. • Large, multicentre, longitudinal, prospective trials are needed to define the optimal imaging schedule for assessment.

Imaging and diagnostic advances for intracranial meningiomas

The archetypal imaging characteristics of meningiomas are among the most stereotypic of all central nervous system (CNS) tumors. In the era of plain film and ventriculography, imaging was only performed if a mass was suspected, and their results were more suggestive than definitive. Following more than a century of technological development, we can now rely on imaging to non-invasively diagnose meningioma with great confidence and precisely delineate the locations of these tumors relative to their surrounding structures to inform treatment planning. Asymptomatic meningiomas may be identified and their growth monitored over time; moreover, imaging routinely serves as an essential tool to survey tumor burden at various stages during the course of treatment, thereby providing guidance on their effectiveness or the need for further intervention. Modern radiological techniques are expanding the power of imaging from tumor detection and monitoring to include extraction of biologic information from advanced analysis of radiological parameters. These contemporary approaches have led to promising attempts to predict tumor grade and, in turn, contribute prognostic data. In this supplement article, we review important current and future aspects of imaging in the diagnosis and management of meningioma, including conventional and advanced imaging techniques using CT, MRI, and nuclear medicine.

Anatomical and functional MR imaging to define tumoral boundaries and characterize lesions in neuro-oncology

Neuroimaging and especially MRI has emerged as a necessary imaging modality to detect, measure, characterize and monitor brain tumours. Advanced MRI sequences such as perfusion MRI, diffusion MRI and spectroscopy as well as new post-processing techniques such as automatic segmentation of tumours and radiomics play a crucial role in characterization and follow up of brain tumours. The purpose of this review is to provide an overview on anatomical and functional MRI use for brain tumours boundaries determination and tumour characterization in the specific context of radiotherapy. The usefulness of anatomical and functional MRI on particular challenges posed by radiotherapy such as pseudo progression and pseudo esponse and new treatment strategies such as dose painting is also described.

Pseudo-continuous arterial spin labelling shows high diagnostic performance in the detection of postoperative residual lesion in hyper-vascularised adult brain tumours

OBJECTIVES

Our aim was to evaluate the contribution of pseudo-continuous arterial spin labelling (pCASL) in the detection of a postoperative residual lesion in adult brain tumours.

METHODS

Seventy-five patients were prospectively included. Following the results of preoperative DSC-PWI assessment, intra-axial lesions, including high-grade gliomas (n = 43) and certain metastases (n = 14), were classified as hyper-vascular (HV+ group, n = 57); other lesions, including low-grade gliomas and certain metastases, were classified as non-hyper-vascular (HV- group, n = 18). To confirm the absence/presence of a residual lesion or disease progression, postoperative MRI including pCASL sequence and follow-up-MRI were performed within 72 h and 1-6 months after the resection, respectively. Two raters evaluated the images. Mean and maximal ASL cerebral blood flow (CBF) values were measured in the perioperative region and normalised to the contralateral tissue. The pCASL-CBF maps and post-contrast T1WI were visually assessed for residual lesion. Quantitative data were analysed with unpaired Student t and Mann-Whitney U tests and the visual diagnostic performance with the McNemar test.

RESULTS

In the HV+ group, the mean normalised CBF was 1.97 ± 0.59 and 0.97 ± 0.29 (p < 0.0001, AUC = 0.964, cut-off = 1.27) for patients with or without residual tumours, respectively. The mean normalised CBF was not discriminative for assessing residual tumours in the HV- group (p = 0.454). Visual CBF evaluation allowed 92.98% patients belonging to the HV+ group to be correctly classified (sensitivity 93.02%, specificity 92.86%, p < 0.001). Visual evaluation was correlated with contrast enhancement evaluation and with the mean normalised CBF values (r = 0.505, p < 0.0001 and 0.838, p < 0.0001, respectively).

CONCLUSION

Qualitative and quantitative ASL evaluation shows high diagnostic performance in postoperative assessment of hyper-perfused tumours. In this case, postoperative pCASL may be useful, especially if contrast injection cannot be performed or when contrast enhancement is doubtful.

KEY POINTS

• Evaluation of postoperative residual lesion in the case of brain tumours is an imaging challenge. • This prospective monocentric study showed that increased normalised cerebral blood flow assessed by pseudo-continuous arterial spin labelling (pCASL) correlates well with the presence of a residual tumour in the case of hyper-vascular tumour diagnosed on preoperative MRI. • Qualitative and quantitative pCASL is an informative sequence for hyper-vascular residual tumour, especially if acquired more than 48 h after brain tumour surgery, when contrast enhancement can give ambiguous results due to blood-brain barrier disruption.

A novel grading system for the prediction of the need for cerebrospinal fluid drainage following posterior fossa tumor surgery

OBJECTIVE

Prophylactic placement of an external ventricular drain (EVD) is often performed prior to resection of a posterior fossa tumor (PFT); however, there is no general consensus regarding the indications. The purpose of this study was to establish a novel grading system for the prediction of required CSF drainage due to symptomatic elevated intracranial pressure (ICP) after resection of a PFT to identify patients who require an EVD.

METHODS

The authors performed a retrospective analysis of data from a prospective database. All patients who had undergone resection of a PFT between 2012 and 2017 at the University Hospital, Goethe University Frankfurt, were identified and data from their cases were analyzed. PFTs were categorized as intraparenchymal (iPFT) or extraparenchymal (ePFT). Prior to resection, patients underwent EVD placement, prophylactic burr hole placement, or neither. The authors assessed the amount of CSF drainage (if applicable), rate of EVD placement at a later time point, and complication rate and screened for factors associated with CSF drainage. By applying those factors, they established a grading system to predict the necessity of CSF drainage for elevated ICP.

RESULTS

A total of 197 patients met the inclusion criteria. Of these 197, 70.6% received an EVD, 15.7% underwent prophylactic burr hole placement, and 29.4% required temporary CSF drainage. In the prophylactic burr hole group, 1 of 32 patients (3.1%) required EVD placement at a later time. Independent predictors for postoperative need for CSF drainage due to symptomatic intracranial hypertension in patients with iPFTs were preoperative hydrocephalus (OR 2.9) and periventricular CSF capping (OR 2.9), whereas semi-sitting surgical position (OR 0.2) and total resection (OR 0.3) were protective factors. For patients with ePFTs, petroclival/midline tumor location (OR 12.2/OR 5.7), perilesional edema (OR 10.0), and preoperative hydrocephalus (OR 4.0) were independent predictors of need for CSF drainage. According to our grading system, CSF drainage after resection of iPFT or ePFT, respectively, was required in 16.7% and 5.1% of patients with a score of 0, in 21.1% and 12.5% of patients with a score of 1, in 47.1% and 26.3% of patients with a score of 2, and in 100% and 76.5% of patients with a score ≥ 3 (p < 0.0001). The rate of relevant EVD complications was 4.3%, and 10.1% of patients were shunt-dependent at 3-month follow-up.

CONCLUSIONS

This novel grading system for the prediction of need for CSF drainage following resection of PFT might be of help in deciding in favor of or against prophylactic EVD placement.

Management of hydrocephalus after resection of posterior fossa lesions in pediatric and adult patients-predictors for development of hydrocephalus

The surgical management of hydrocephalus in patients with posterior fossa lesions (PFL) is critical for optimal patient outcome(s). Accordingly, it is prudent to identify patients in need of aggressive surgical intervention (i.e., ventriculoperitoneal [VP] shunting). To analyze prevalence of, and risk factors associated with, the development of post-operative hydrocephalus in both pediatrics and adults. A retrospective institutional analysis and review of patient records in those who had undergone PFL surgery was performed. In so doing, the authors identified patients that went on to develop post-operative hydrocephalus. The study included pediatric and adult patients treated between 2009 and 2017. Fifteen of 40 pediatric (37.5%) and 18 of 262 adult (6.9%) patients developed hydrocephalus after PFL surgery. The most common tumor entity in pediatrics was medulloblastoma (34%), astrocytoma (24.4%), and pilocytic astrocytoma (22%), whereas in adults, metastasis (29.5%), meningioma (22%), and acoustic neuroma (17.8%) were most common. Young age ≤ 2 years, medulloblastoma (OR 13.9), and brain stem compression (OR 5.4) were confirmed as independent predictors for hydrocephalus in pediatrics and pilocytic astrocytoma (OR 15.4) and pre-operative hydrocephalus (OR 3.6) in adults, respectively. All patients received VP shunts for hydrocephalus management and the mean follow-up was 29.5 months in pediatrics vs 19.2 months in adults. Overall complication rates related to VP shunts were 33.3% in pediatrics and 16.7% in adults, respectively. Shunt dependency and associated complications in pediatrics were noted to be higher than in adults. Given the identification of predictors for hydrocephalus, it is authors' contention that certain patients with those predictors may ultimately benefit from an alternative treatment regimen (e.g., pre-operative interventions) prior to PFT surgery.

Evaluation of the extent of resection and detection of ischemic lesions with intraoperative MRI in glioma surgery: is intraoperative MRI superior to early postoperative MRI?

OBJECTIVE

MRI scans obtained within 48-72 hours (early postoperative MRI [epMRI]), prior to any postoperative reactive changes, are recommended for the accurate assessment of the extent of resection (EOR) after glioma surgery. Diffusion-weighted imaging (DWI) enables ischemic lesions to be detected and distinguished from the residual tumor. Prior studies, however, revealed that postoperative reactive changes were often present, even in epMRI. Although intraoperative MRI (iMRI) is widely used to maximize safe resection during glioma surgery, it is unclear whether iMRI is superior to epMRI when evaluating the EOR, because it theoretically shows fewer postoperative reactive changes. In addition, the ability to detect ischemic lesions using iMRI has not been investigated.

METHODS

The authors retrospectively analyzed prospectively collected data in 30 patients with glioma (22 and 8 patients with enhancing and nonenhancing lesions, respectively) who underwent tumor resection. These patients had received preoperative MRI within 24 hours prior to surgery, postresection radiological evaluation with iMRI during surgery, and epMRI within 24 hours after surgery, with all neuroimaging performed using identical 1.5T MRI scanners. The authors compared iMRI or epMRI with preoperative MRI, and defined a postoperative reactive change as a new postoperative enhancement or T2 high-intensity area (HIA), if this lesion was outside of the preoperative original tumor location. In addition, postoperative ischemia was evaluated on DWI. The iMRI and epMRI findings were compared in terms of 1) postoperative reactive changes, 2) evaluation of the EOR, and 3) presence of ischemic lesion on DWI.

RESULTS

In patients with enhancing lesions, a new enhancement was seen in 8 of 22 patients (36.4%) on iMRI and in 12 of 22 patients (54.5%) on epMRI. In patients with nonenhancing lesions, a new T2 HIA was seen in 4 of 8 patients (50.0%) on iMRI and in 7 of 8 patients (87.5%) on epMRI. A discrepancy between the EOR measured on iMRI and epMRI was noted in 5 of the 22 patients (22.7%) with enhancing lesions, and in 3 of the 8 patients (37.5%) with nonenhancing lesions. The occurrence of ischemic lesions on DWI was found in 5 of 30 patients (16.7%) on iMRI, whereas it was found in 16 of 30 patients (53.3%) on epMRI (p = 0.003); ischemic lesions were underestimated on iMRI in 11 patients.

CONCLUSIONS

Overall, given the lower incidence of postoperative reactive changes on iMRI, it was superior to epMRI in evaluating the EOR in patients with glioma, both with enhancing and nonenhancing lesions. However, because ischemic lesions can be overlooked on iMRI, the authors recommend only the additional DWI scan during the early postoperative period. Clinicians need to be mindful about not overestimating the presence of residual tumor on epMRI due to the high incidence of postoperative reactive changes.

Predictive Value of MRI in Diagnosing Brain AVM Recurrence after Angiographically Documented Exclusion in Children

BACKGROUND AND PURPOSE

MRI is routinely performed following brain AVM after treatment in children. Our aim was to determine the predictive values of contrast-enhanced MR imaging and TOF-MRA for brain AVM recurrence in children, compared with conventional angiography and the role of 3D rotational angiography-MR imaging fusion in these cases.

MATERIALS AND METHODS

We included all pediatric patients with brain AVMs during an 18-year period with angiographically documented obliteration after treatment. Patients underwent 3T MR imaging, including contrast-enhanced MR imaging, TOF-MRA, and conventional angiography, with a subset undergoing 3D rotational angiography. The predictive values of contrast-enhanced MR imaging and TOF-MRA for brain AVM recurrence were determined. CTA sections reconstructed from 3D rotational angiography were coregistered with and fused to 3D-T1WI for analysis.

RESULTS

Thirty-nine children (10.8 ± 3.9 years of age; range, 2-17 years; male/female ratio, 19:20; mean Spetzler-Martin grade, 1.9 ± 0.6) met the inclusion criteria. Of these, 13 had angiographically confirmed brain AVM recurrence, 8 following surgery and 5 following embolization. Sensitivity, specificity, and positive and negative predictive values for recurrence were the following: contrast-enhanced MR imaging: 84.6%, 38.5%, 40.7%, 81.8%; TOF-MRA: 50.0%, 96.1%, 85.7%, 79.3%; both: 75.0%, 90.9%, 85.7%, 83.3%. 3D rotational angiography-MR imaging fused images confirmed or excluded recurrence in all available cases (13/13). Embolization-only treatment was a significant predictor of recurrence (OR = 32.4, P = .006). MR imaging features predictive of recurrence included a tuft of vessels on TOF-MRA and nodular juxtamural/linear enhancement with a draining vein on contrast-enhanced MR imaging.

CONCLUSIONS

MR imaging is useful for surveillance after brain AVM treatment in children, but conventional angiography is required for definitive diagnosis of recurrence. TOF-MRA and contrast-enhanced MR imaging provide complementary information for determining brain AVM recurrence and should be interpreted in conjunction. 3D rotational angiography-MR imaging fusion increases the diagnostic confidence regarding brain AVM recurrence and is therefore suited for intraoperative neuronavigation.

Consensus recommendations on standardized magnetic resonance imaging protocols for multicenter canine brain tumor clinical trials

The National Cancer Institute Comparative Brain Tumor Consortium, Patient Outcomes Working Group, propose a consensus document in support of standardized magnetic resonance imaging protocols for canine brain tumor clinical trials. The intent of this manuscript is to address the widely acknowledged need to ensure canine brain tumor imaging protocols are relevant and have sufficient equivalency to translate to human studies such that: (1) multi-institutional studies can be performed with minimal inter-institutional variation, and (2) imaging protocols are consistent with human consensus recommendations to permit reliable translation of imaging data to human clinical trials. Consensus recommendations include pre- and postcontrast three-dimensional T1-weighted images, T2-weighted turbo spin echo in all three planes, T2*-weighted gradient recalled echo, T2-weighted fluid attenuated inversion recovery, and diffusion weighted imaging/diffusion tensor imaging in transverse plane; field of view of ≤150 mm; slice thickness of ≤2 mm, matrix ≥ 256 for two-dimensional images, and 150 or 256 for three-dimensional images.

Dexamethasone-induced leukocytosis is associated with poor survival in newly diagnosed glioblastoma

Despite its well-characterized side effects, dexamethasone is widely used in the pre-, peri- and postoperative neurosurgical setting due to its effective relief of tumor-induced symptoms through the reduction of tumor-associated edema. However, some patients show laboratory-defined dexamethasone induced elevation of white blood cell count, and its impact on glioblastoma progression is unknown. We retrospectively analyzed 113 patients with newly diagnosed glioblastoma to describe the incidence, risk factors and clinical features of dexamethasone-induced leukocytosis in primary glioblastoma patients. We further conducted an immunohistochemical analysis of the granulocyte and lymphocyte tumor-infiltration in the available corresponding histological sections. Patient age was identified to be a risk factor for the development of dexamethasone-induced leukocytosis (p < 0.05). The presence of dexamethasone-induced leukocytosis decreased overall survival (HR 2.25 95% CI [1.15-4.38]; p < 0.001) and progression-free survival (HR 2.23 95% CI [1.09-4.59]; p < 0.01). Furthermore, patients with dexamethasone-induced leukocytosis had significantly reduced CD15 + granulocytic- (p < 0.05) and CD3 + lymphocytic tumour infiltration (p < 0.05). We identified a subgroup of glioblastoma patients that are at particularly high risk for poor outcome upon dexamethasone treatment. Therefore, restrictive dosage or other edema reducing substances should be considered in patients with dexamethasone-induced leukocytosis.

The clinical significance of equivocal findings on spinal MRI in children with medulloblastoma

BACKGROUND

Medulloblastoma (MB) is the most common malignant brain tumor of childhood, with cerebrospinal fluid spread the most common site of metastasis. Currently, children diagnosed with MB and evidence of spinal metastasis are treated with an increased dose of craniospinal radiation (CSI). This report reviewed equivocal abnormalities including nerve root clumping, linear vascular enhancement, nerve root enhancement and/or other vague findings on spinal magnetic resonance imaging (MRI) to elucidate their prognostic significance and aid in risk stratification.

METHODS

This retrospective cohort study identified children (≥3 years) diagnosed with MB between 1988 and 2012. Children treated with upfront CSI were included, and staging spine MRI must have been done preoperatively or within 72 hr of primary tumor resection. Initial MRI of the spine was assessed by two independent reviewers blinded to outcome to evaluate for equivocal findings. Survival analysis was done to determine impact on prognosis.

RESULTS

One hundred of 157 patients were eligible for the analysis. Equivocal findings were identified in 48 (48%) patients, with MRI done preoperatively in 45 (94%) patients. Analysis by subgroup identified a higher proportion of equivocal findings in the sonic hedgehog (SHH) subgroup (P = 0.007). Five-year overall survival (OS) in children with equivocal findings compared to those with normal MRI was not different, 80 vs. 84.8% respectively, while OS in M3 patients was worse at 54.7% (P = 0.02).

CONCLUSION

A higher proportion of equivocal findings was identified in the SHH subgroup. This institutional retrospective review demonstrates equivocal findings are common, not associated with decreased OS and should not prompt increased dose of CSI.

Modified Criteria for Radiographic Response Assessment in Glioblastoma Clinical Trials

Radiographic endpoints including response and progression are important for the evaluation of new glioblastoma therapies. The current RANO criteria was developed to overcome many of the challenges identified with previous guidelines for response assessment, however, significant challenges and limitations remain. The current recommendations build on the strengths of the current RANO criteria, while addressing many of these limitations. Modifications to the current RANO criteria include suggestions for volumetric response evaluation, use contrast enhanced T1 subtraction maps to increase lesion conspicuity, removal of qualitative non-enhancing tumor assessment requirements, use of the post-radiation time point as the baseline for newly diagnosed glioblastoma response assessment, and "treatment-agnostic" response assessment rubrics for identifying pseudoprogression, pseudoresponse, and a confirmed durable response in newly diagnosed and recurrent glioblastoma trials.

The use of amino acid PET and conventional MRI for monitoring of brain tumor therapy

Routine diagnostics and treatment monitoring of brain tumors is usually based on contrast-enhanced MRI. However, the capacity of conventional MRI to differentiate tumor tissue from posttherapeutic effects following neurosurgical resection, chemoradiation, alkylating chemotherapy, radiosurgery, and/or immunotherapy may be limited. Metabolic imaging using PET can provide relevant additional information on tumor metabolism, which allows for more accurate diagnostics especially in clinically equivocal situations. This review article focuses predominantly on the amino acid PET tracers 11C-methyl-l-methionine (MET), O-(2-[18F]fluoroethyl)-l-tyrosine (FET) and 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine (FDOPA) and summarizes investigations regarding monitoring of brain tumor therapy.

Value of Early Postoperative FLAIR Volume Dynamic in Glioma with No or Minimal Enhancement

OBJECTIVE

The evaluation of postoperative magnetic resonance imaging (MRI) in glioma with no or minimal enhancement is controversial because the evaluation of residual tumor volume can be biased. The purpose of this study was to clarify the value of early postoperative and 3-month MRI regarding its validity in predicting recurrent disease.

METHODS

For this retrospective, single-center study, overall fluid attenuated inversion recovery (FLAIR) volumes (early postoperative [<48 hours] and 3-month MRI including FLAIR and T1-weighted sequences with and without contrast agent) of 99 patients were assessed using manual segmentation. FLAIR volume dynamic over the first 3 months after surgery and its effect on disease recurrence were evaluated while considering histopathologic features.

RESULTS

Overall FLAIR-hyperintense volume significantly decreased between early postoperative and 3-month follow-up MRIs (P < 0.001). Early FLAIR volume increase had a high positive predictive value for overall disease recurrence after resection (85.71% [95%-CI: 62.64-96.24]). Early FLAIR volume dynamic (P < 0.001), isocitrate dehydrogenase 1/2 status (P = 0.002), and preoperative Karnofsky Performance Status (P = 0.012) were observed as independent factors for progression-free survival in multivariate analysis.

CONCLUSION

Early postoperative FLAIR volume assessment in gliomas with no or minimal enhancement is susceptible to a systematic overestimation of residual tumors. Nevertheless, early FLAIR volume dynamic is an independent factor for tumor recurrence that should be evaluated in order timely adapt surveillance and therapy regimens accordingly.

Patterns and Time Dependence of Unspecific Enhancement in Postoperative Magnetic Resonance Imaging After Glioblastoma Resection

OBJECTIVE

Postoperative magnetic resonance imaging (MRI) is recommended soon after glioma surgery to avoid reactive nonneoplastic contrast enhancement indistinguishable from tumor. The purpose of this study was to analyze these patterns of postoperative contrast enhancement at 3 T to define the optimal time frame for postoperative MRI.

METHODS

MRI for 206 glioblastoma surgeries in 173 patients who underwent pre- and postoperative and at least 1 follow-up 3T MRI for each surgery were analyzed retrospectively. Postoperative MRI was assessed in consensus by 2 neuroradiologists, blinded to the time after surgery. Postoperative contrast enhancement marginal to the resection cavity was analyzed and classified as vascular, linear, or nodular. The cause of the contrast enhancement (ie, reactive vs. tumor) was assessed by comparing pre-, postoperative, and follow-up MRI.

RESULTS

Within 45 hours after surgery, reactive enhancement appeared in 17.9% of cases. After 45 hours, the fraction of reactive changes increased to 34.1%. Linear enhancement was more often reactive (66.1%, 39/59 cases), whereas nodular enhancement was mainly residual tumor (93.2%, 68/73 cases). Specificity of nodular enhancement was high for tumor recurrence/tumor progression (91.5%).

CONCLUSIONS

To avoid an increasing number of MRIs with reactive contrast enhancement, postoperative MRI at 3 T should be performed within 45 hours after surgery. However, reactive contrast enhancement can occur at all time points. In these cases, the pattern of the contrast enhancement may help to differentiate its cause.

(18)F-Fluoroethyl-l-Thyrosine Positron Emission Tomography to Delineate Tumor Residuals After Glioblastoma Resection: A Comparison with Standard Postoperative Magnetic Resonance Imaging

OBJECTIVE

Complete resection of contrast-enhancing tumor is an important prognostic factor in glioblastoma therapy. The current clinical standard for control of resection is magnetic resonance imaging (MRI). (18)F-Fluoroethyl-l-thyrosine (FET) is a positron emission tomography (PET) radiopharmaceutical applicable for widespread use because of its long half-life radionuclide. We assessed the sensitivity of postoperative MRI versus FET-PET to detect residual tumor and the impact of the time interval between resection and FET-PET.

METHODS

MRI and FET-PET were performed preoperatively and postoperatively in 62 patients undergoing 63 operations. FET-PET was performed in 43 cases within 72 hours after resection and in 20 cases >72 hours after resection. Detection and measurement of volume of residual tumors were compared. Correlations between residual tumor detection and timing of PET after resection and recurrence were examined.

RESULTS

Complete resection was confirmed by both imaging modalities in 44% of cases, and residual tumor was detected consistently in 37% of cases. FET-PET detected residual tumor in 14% of cases in which MRI showed no residual tumor. MRI showed residual tumors in 5% of cases that were not identified by PET. Average PET-based residual tumor volume was higher than MRI-based volume (3.99 cm(3) vs. 1.59 cm(3)). Detection of and difference in volume of residual tumor were not correlated with timing of PET after resection or recurrence status.

CONCLUSIONS

Postoperative FET-PET revealed residual tumor with higher sensitivity than MRI and showed larger tumor volumes. In this series, performing PET >72 hours after resection did not influence the results of PET. We recommend FET-PET as a helpful adjunct in addition to MRI for postoperative assessment of residual tumor.

Combination of 5-ALA and iMRI in re-resection of recurrent glioblastoma

Background Tumour resection plays a role in the initial treatment but also in the setting of recurrent glioblastoma (rGBM). To achieve maximum resection, 5-aminolevulinic acid (5-ALA) and intraoperative MRI (iMRI) are used as surgical tools. Aiming at complete tumour re-resection, we started combining iMRI with 5-ALA to find out if this leads to better surgical results. Methods We performed tumour resections in seven patients with rGBM, combining 5-ALA (20 mg/kg bodyweight) with iMRI (0.15 T). Radiologically complete resections were intended in all seven patients. We assessed intraoperative fluorescence findings and compared these with intraoperative imaging. All patients had early postoperative MRI (3 T) to verify final iMRI scans and received adjuvant treatment according to interdisciplinary tumour board decision. Results Median patient age was 63 years. Median KPS score was 90, and median tumour volume was 8.2 cm(3). In six of seven patients (85%), 5-ALA induced fluorescence of tumour-tissue was detected intraoperatively. All tumours were good to visualise with iMRI and contrast media. One patient received additional resection of residual contrast enhancing tissue on intraoperative imaging, which did not show fluorescence. Radiologically complete resections according to early postoperative MRI were achieved in all patients. Median survival since second surgery was 7.6 months and overall survival since diagnosis was 27.8 months. Conclusions 5-ALA and iMRI are important surgical tools to maximise tumour resection also in rGBM. However, not all rGBMs exhibit fluorescence after 5-ALA administration. We propose the combined use of 5-ALA and iMRI in the surgery of rGBM.