History and evolution of brain tumor imaging: insights through radiology

Surgical treatment of cystic pituitary adenomas: literature-based definitions and postoperative outcomes

BACKGROUND AND OBJECTIVES

To survey the applied definitions of 'cystic' among pituitary adenomas and evaluate whether postoperative outcomes differ relative to non-cystic counterparts.

METHODS

A literature search and meta-analysis was performed using PRISMA guidelines. Studies were eligible if novel data were reported regarding the applied definition of 'cystic' and postoperative outcomes among cases of surgically treated pituitary adenomas. Data were pooled with random effects meta-analysis models into cohorts based on the applied definition of 'cystic'. Categorical meta-regressions were used to investigate differences between cohorts. Among studies comparing cystic and non-cystic pituitary adenomas, meta-analysis models were applied to determine the Odds Ratio [95% Confidence Interval]. Statistical analyses were performed using Comprehensive Meta-Analysis (CMA, 4.0), with a priori significance defined as P < 0.05.

RESULTS

Ten studies were eligible yielding 283 patients with cystic pituitary adenomas. The definitions of 'cystic' mainly varied between the visual appearance of cystic components on preoperative magnetic resonance imaging and a volumetric definition requiring 50% or greater of tumor volume exhibiting cystic components. Tumor diameter was seldom reported with an associated standard deviation/error, limiting meta-analyses. When the data were pooled in accordance with the definition applied, there were no significant differences in the rates of gross total resection (P = 0.830), endocrinologic remission (P = 0.563), and tumor recurrence (P = 0.320). Meta-analyses on studies comparing cystic versus non-cystic pituitary adenomas indicated no significant difference in the rates of gross total resection (P = 0.729), endocrinologic remission (P = 0.857), and tumor recurrence (P = 0.465).

CONCLUSION

Despite some individual studies describing a significant influence of pituitary adenoma texture on postoperative outcomes, meta-analyses revealed no such differences between cystic and non-cystic pituitary adenomas. This discrepancy may be explained in part by the inconsistent definition of 'cystic' and between-group differences in tumor size. A notion of a field-standard definition of 'cystic' among pituitary adenomas should be established to facilitate inter-study comparisons.

Biosensor-Enhanced Organ-on-a-Chip Models for Investigating Glioblastoma Tumor Microenvironment Dynamics

Glioblastoma, an aggressive primary brain tumor, poses a significant challenge owing to its dynamic and intricate tumor microenvironment. This review investigates the innovative integration of biosensor-enhanced organ-on-a-chip (OOC) models as a novel strategy for an in-depth exploration of glioblastoma tumor microenvironment dynamics. In recent years, the transformative approach of incorporating biosensors into OOC platforms has enabled real-time monitoring and analysis of cellular behaviors within a controlled microenvironment. Conventional in vitro and in vivo models exhibit inherent limitations in accurately replicating the complex nature of glioblastoma progression. This review addresses the existing research gap by pioneering the integration of biosensor-enhanced OOC models, providing a comprehensive platform for investigating glioblastoma tumor microenvironment dynamics. The applications of this combined approach in studying glioblastoma dynamics are critically scrutinized, emphasizing its potential to bridge the gap between simplistic models and the intricate in vivo conditions. Furthermore, the article discusses the implications of biosensor-enhanced OOC models in elucidating the dynamic features of the tumor microenvironment, encompassing cell migration, proliferation, and interactions. By furnishing real-time insights, these models significantly contribute to unraveling the complex biology of glioblastoma, thereby influencing the development of more accurate diagnostic and therapeutic strategies.

Inferior Petrosal Sinus Sampling Tumor Lateralization and the Surgical Treatment of Cushing Disease: A Meta-Analysis and Systematic Review

OBJECTIVE

To determine whether accurate inferior petrosal sinus sampling (IPSS) tumor lateralization is associated with improved clinical outcomes following the surgical treatment of Cushing disease.

METHODS

The presented study was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data regarding patient demographics, IPSS tumor lateralization, and postoperative endocrinologic outcomes were abstracted and pooled with random effects meta-analysis models. Additional meta-regression models were used to examine the association between the accuracy of IPSS tumor lateralization and postoperative outcomes (recurrence/persistence or remission/cure). Statistical analyses were performed using the Comprehensive Meta-Analysis software (significance of P < 0.05).

RESULTS

Seventeen eligible articles were identified, yielding data on 461 patients. Within average follow-up duration (∼59 months), the rate of correct IPSS tumor lateralization was 69% [95% confidence interval: 61%, 76%], and the rate of postoperative remission/cure was 78% [67%, 86%]. Preoperative IPSS tumor lateralization was concordant with magnetic resonance imaging lateralization for 53% of patients [40%, 66%]. There was no significant association between the rate of correct IPSS tumor lateralization and postoperative remission/cure among study-level data (P = 0.735). Additionally, there was no association among subgroup analyses for studies using stimulatory agents during IPSS (corticotropin-releasing hormone or desmopressin, P = 0.635), nor among subgroup analyses for adult (P = 0.363) and pediatric (P = 0.931) patients.

CONCLUSIONS

Limited data suggest that the rate of correct IPSS tumor lateralization may not be positively associated with postoperative remission or cure in patients with Cushing disease. These findings bring into question the utility of IPSS tumor lateralization in the context of preoperative planning and surgical approach rather than confirming a pituitary source.

Advances in Diagnostic Tools and Therapeutic Approaches for Gliomas: A Comprehensive Review

Gliomas, a prevalent category of primary malignant brain tumors, pose formidable clinical challenges due to their invasive nature and limited treatment options. The current therapeutic landscape for gliomas is constrained by a "one-size-fits-all" paradigm, significantly restricting treatment efficacy. Despite the implementation of multimodal therapeutic strategies, survival rates remain disheartening. The conventional treatment approach, involving surgical resection, radiation, and chemotherapy, grapples with substantial limitations, particularly in addressing the invasive nature of gliomas. Conventional diagnostic tools, including computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), play pivotal roles in outlining tumor characteristics. However, they face limitations, such as poor biological specificity and challenges in distinguishing active tumor regions. The ongoing development of diagnostic tools and therapeutic approaches represents a multifaceted and promising frontier in the battle against this challenging brain tumor. The aim of this comprehensive review is to address recent advances in diagnostic tools and therapeutic approaches for gliomas. These innovations aim to minimize invasiveness while enabling the precise, multimodal targeting of localized gliomas. Researchers are actively developing new diagnostic tools, such as colorimetric techniques, electrochemical biosensors, optical coherence tomography, reflectometric interference spectroscopy, surface-enhanced Raman spectroscopy, and optical biosensors. These tools aim to regulate tumor progression and develop precise treatment methods for gliomas. Recent technological advancements, coupled with bioelectronic sensors, open avenues for new therapeutic modalities, minimizing invasiveness and enabling multimodal targeting with unprecedented precision. The next generation of multimodal therapeutic strategies holds potential for precision medicine, aiding the early detection and effective management of solid brain tumors. These innovations offer promise in adopting precision medicine methodologies, enabling early disease detection, and improving solid brain tumor management. This review comprehensively recognizes the critical role of pioneering therapeutic interventions, holding significant potential to revolutionize brain tumor therapeutics.

Trends in the epidemiology of small-cell lung cancer: a Dutch nationwide population-based study over 1989-2020

INTRODUCTION

This study describes the evolving characteristics of patients with small-cell lung cancer (SCLC) from 1989 to 2020 in the Netherlands to analyse how the population of patients with SCLC has changed in the last decades, hypothesising that this might explain the little progress made in SCLC.

METHODS

Patients with SCLC diagnosed from 1989 to 2020 were selected from the Dutch cancer registry. Incidence, patient and disease characteristics, treatments, and overall survival (OS) were analysed. Joinpoint analyses were used to test annual percentage changes for statistical significance.

RESULTS

A total of 52,527 patients were diagnosed with SCLC. The absolute numbers of patients with SCLC remained equal over the years; however, the incidence rates decreased from 15.01 to 8.93 per 100,000 person-years. The proportion of women increased from 22% to 50%, and those aged ≥75 years increased from 20% to 25%. The latter coincided with a higher proportion receiving only the best supportive care (BSC) over the years (18-24%). The use of surgery in stage I increased from 2% to 37%. The proportion of patients diagnosed with stage IV increased from 46% to 70% due to better staging. The OS improved for all stages, with a 2-year OS rate for stage IV doubling from 3% to 6%.

CONCLUSION

The incidence of SCLC has significantly decreased over the last 30 years, with an increasing proportion of elderly and women. The male-female ratio became similar, and the OS improved. As a consequence of more elderly and probably more vulnerable patients, more patients received only the BSC.

Comparing Surgical Approaches for Craniopharyngioma Resection Among Adults and Children: A Meta-analysis and Systematic Review

BACKGROUND

Craniopharyngioma treatment often necessitates surgical resection. Conventional approaches, such as transcranial and transsphenoidal approaches, are predominantly used. However, a recently adopted supraorbital approach may be more efficacious. Thus, this meta-analysis and systematic review aimed to compare the efficacy of the transcranial, transsphenoidal, and supraorbital approaches for resection and treatment of craniopharyngiomas.

METHODS

This study was performed following PRISMA guidelines. Analyses were performed according to study design: (1) analyses for studies comparing several surgical approaches; and (2) analyses of all included studies. Random effects meta-analysis models were used to pool odds ratios among studies comparing several approaches. Similarly, categorical meta-regression models were used to examine the effect of surgical approach as a covariate of outcome data for all studies. Statistics were performed using Comprehensive Meta-Analysis software (CMA 3.3, Biostat, Englewood, NJ) (significance set at P < 0.05).

RESULTS

Patients were well-matched for age, sex, and preoperative comorbidities between groups stratified by surgical approach. Analyses including 22 studies that compared several approaches demonstrated that the transsphenoidal group had a greater occurrence of postoperative visual improvement (P < 0.0001), lesser occurrence of visual deterioration (P < 0.0001), and lower tumor recurrence rate (P = 0.015) compared with the transcranial group. Only 2 studies compared the supraorbital approach to another approach, limiting analyses. Analyses including all studies demonstrated that the supraorbital group did not differ to either the transcranial or transsphenoidal group for any examined variables.

CONCLUSIONS

The present study suggests that the transsphenoidal approach is associated with improved clinical outcomes for craniopharyngioma resection. There are limited data regarding the supraorbital approach, warranting future investigation.

Imaging Recommendations for the Diagnosis, Staging, and Management of Adult Brain Tumors

Neuroimaging plays a pivotal role in the clinical practice of brain tumors aiding in the diagnosis, genotype prediction, preoperative planning, and prognostication. The brain tumors most commonly seen in adults are extra-axial lesions like meningioma, intra-axial lesions like gliomas and lesions of the pituitary gland. Clinical features may be localizing like partial seizures, weakness, and sensory disturbances or nonspecific like a headache. On clinical suspicion of a brain tumor, the primary investigative workup should focus on imaging. Other investigations like fundoscopy and electroencephalography may be performed depending on the clinical presentation. Obtaining a tissue sample after identifying a brain tumor on imaging is crucial for confirming the diagnosis and planning further treatment. Tissue sample may be obtained by techniques such as stereotactic biopsy or upfront surgery. The magnetic resonance (MR) imaging protocol needs to be standardized and includes conventional sequences like T1-weighted (T1W) imaging with and without contrast, T2w imaging, fluid-attenuated axial inversion recovery, diffusion-weighted imaging (DWI), susceptibility-weighted imaging, and advanced imaging sequences like MR perfusion and MR spectroscopy. Various tumor characteristics in each of these sequences can help us narrow down the differential diagnosis and also predict the grade of the tumor. Multidisciplinary co-ordination is needed for proper management and care of brain tumor patients. Treatment protocols need to be adapted and individualized for each patient depending on the age, general condition of the patient, histopathological characteristics, and genotype of the tumor. Treatment options include surgery, radiotherapy, and chemotherapy. Imaging also plays a vital role in post-treatment follow-up. Sequences like DWI, MR perfusion, and MR spectroscopy are useful to distinguish post-treatment effects like radiation necrosis and pseudoprogression from true recurrence. Radiological reporting of brain tumor images should follow a structured format to include all the elements that could have an impact on the treatment decisions in patients.

Evolution and Revolution of Imaging Technologies in Neurosurgery

We understand only a small fraction of the events happening in our brains; therefore, despite all the progress made thus far, a whole array of questions remains. Nonetheless, neurosurgeons invented new tools to circumvent the challenges that had plagued their predecessors. With the manufacturing boom of the 20th century, technological innovations blossomed enabling the neuroscientific community to study and operate upon the living brain in finer detail and with greater precision while avoiding harm to the nervous system. The purpose of this chronological review is to 1) raise awareness among future neurosurgeons about the latest advances in the field, 2) become familiar with innovations such as augmented reality (AR) that should be included in education given their ready applicability in surgical training, and 3) be comfortable with customizing these technologies to real-life cases like in the case of mixed reality.

Applications of elastography in operative neurosurgery: A systematic review

Elastography is an imaging technology capable of measuring tissue stiffness and consistency. The technology has achieved widespread use in the workup and management of diseases of the liver, breast, thyroid, and prostate. Although elastography is increasingly being applied in neurosurgery, it has not yet achieved widespread adoption and many clinicians remain unfamiliar with the technology. Therefore, we sought to summarize the range of applications and elastography modalities available for neurosurgery, report its effectiveness in comparison with conventional imaging methods, and offer recommendations. All full-text English-language manuscripts on the use of elastography for neurosurgical procedures were screened using the PubMed/MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science databases. Thirty-two studies were included with 990 patients, including 21 studies on intracranial tumors, 5 on hydrocephalus, 4 on epilepsy, 1 on spinal cord compression, and 1 on adolescent scoliosis. Twenty studies used ultrasound elastography (USE) whereas 12 used magnetic resonance elastography (MRE). MRE studies were mostly used in the preoperative setting for assessment of lesion stiffness, tumor-brain adherence, diagnostic workup, and operative planning. USE studies were performed intraoperatively to guide resection of lesions, determine residual microscopic abnormalities, assess the tumor-brain interface, and study mechanical properties of tumors. Elastography can assist with resection of brain tissue, detection of microscopic lesions, and workup of hydrocephalus, among other applications under investigation. Its sensitivity often exceeds that of conventional MRI and ultrasound for identifying abnormal tissue and lesion margins.

Nanoparticles for Diagnosis and Target Therapy in Pediatric Brain Cancers

Pediatric brain tumors represent the most common types of childhood cancer and novel diagnostic and therapeutic solutions are urgently needed. The gold standard treatment option for brain cancers in children, as in adults, is tumor resection followed by radio- and chemotherapy, but with discouraging therapeutic results. In particular, the last two treatments are often associated to significant neurotoxicity in the developing brain of a child, with resulting disabilities such as cognitive problems, neuroendocrine, and neurosensory dysfunctions/deficits. Nanoparticles have been increasingly and thoroughly investigated as they show great promises as diagnostic tools and vectors for gene/drug therapy for pediatric brain cancer due to their ability to cross the blood–brain barrier. In this review we will discuss the developments of nanoparticle-based strategies as novel precision nanomedicine tools for diagnosis and therapy in pediatric brain cancers, with a particular focus on targeting strategies to overcome the main physiological obstacles that are represented by blood–brain barrier.

Diagnosis of Glioblastoma by Immuno-Positron Emission Tomography

Simple Summary

Neuroimaging has transformed the way brain tumors are diagnosed and treated. Although different non-invasive modalities provide very helpful information, in some situations, they present a limited value. By merging the specificity of antibodies with the resolution, sensitivity, and quantitative capabilities of positron emission tomography (PET), “Immuno-PET” allows us to conduct the non-invasive diagnosis and monitoring of patients over time using antibody-based probes as an in vivo, integrated, quantifiable, 3D, full-body “immunohistochemistry”, like a “virtual biopsy”. This review provides and focuses on immuno-PET applications and future perspectives of this promising imaging approach for glioblastoma.

Abstract

Neuroimaging has transformed neuro-oncology and the way that glioblastoma is diagnosed and treated. Magnetic Resonance Imaging (MRI) is the most widely used non-invasive technique in the primary diagnosis of glioblastoma. Although MRI provides very powerful anatomical information, it has proven to be of limited value for diagnosing glioblastomas in some situations. The final diagnosis requires a brain biopsy that may not depict the high intratumoral heterogeneity present in this tumor type. The revolution in “cancer-omics” is transforming the molecular classification of gliomas. However, many of the clinically relevant alterations revealed by these studies have not yet been integrated into the clinical management of patients, in part due to the lack of non-invasive biomarker-based imaging tools. An innovative option for biomarker identification in vivo is termed “immunotargeted imaging”. By merging the high target specificity of antibodies with the high spatial resolution, sensitivity, and quantitative capabilities of positron emission tomography (PET), “Immuno-PET” allows us to conduct the non-invasive diagnosis and monitoring of patients over time using antibody-based probes as an in vivo, integrated, quantifiable, 3D, full-body “immunohistochemistry” in patients. This review provides the state of the art of immuno-PET applications and future perspectives on this imaging approach for glioblastoma.

The role of feature-based radiomics for predicting response and radiation injury after stereotactic radiation therapy for brain metastases: A critical review by the Young Group of the Italian Association of Radiotherapy and Clinical Oncology (yAIRO)

Introduction

differential diagnosis of tumor recurrence and radiation injury after stereotactic radiotherapy (SRT) is challenging. The advances in imaging techniques and feature-based radiomics could aid to discriminate radionecrosis from progression.

Methods

we performed a systematic review of current literature, key references were obtained from a PubMed query. Data extraction was performed by 3 researchers and disagreements were resolved with a discussion among the authors.

Results

we identified 15 retrospective series, one prospective trial, one critical review and one editorial paper. Radiomics involves a wide range of imaging features referred to necrotic regions, rate of contrast-enhancing area or the measure of edema surrounding the metastases. Features were mainly defined through a multistep extraction/reduction/selection process and a final validation and comparison.

Conclusions

feature-based radiomics has an optimal potential to accurately predict response and radionecrosis after SRT of BM and facilitate differential diagnosis. Further validation studies are eagerly awaited to confirm radiomics reliability.

Severity Assessment and Progression Prediction of COVID-19 Patients Based on the LesionEncoder Framework and Chest CT

Automatic severity assessment and progression prediction can facilitate admission, triage, and referral of COVID-19 patients. This study aims to explore the potential use of lung lesion features in the management of COVID-19, based on the assumption that lesion features may carry important diagnostic and prognostic information for quantifying infection severity and forecasting disease progression. A novel LesionEncoder framework is proposed to detect lesions in chest CT scans and to encode lesion features for automatic severity assessment and progression prediction. The LesionEncoder framework consists of a U-Net module for detecting lesions and extracting features from individual CT slices, and a recurrent neural network (RNN) module for learning the relationship between feature vectors and collectively classifying the sequence of feature vectors. Chest CT scans of two cohorts of COVID-19 patients from two hospitals in China were used for training and testing the proposed framework. When applied to assessing severity, this framework outperformed baseline methods achieving a sensitivity of 0.818, specificity of 0.952, accuracy of 0.940, and AUC of 0.903. It also outperformed the other tested methods in disease progression prediction with a sensitivity of 0.667, specificity of 0.838, accuracy of 0.829, and AUC of 0.736. The LesionEncoder framework demonstrates a strong potential for clinical application in current COVID-19 management, particularly in automatic severity assessment of COVID-19 patients. This framework also has a potential for other lesion-focused medical image analyses.

TP53 Mutation and Extraneural Metastasis of Glioblastoma: Insights From an Institutional Experience and Comprehensive Literature Review

Extraneural metastases of glioblastoma (GBM), although rare, are becoming an increasingly recognized occurrence. Currently, the biological mechanism underlying this rare occurrence is not understood. To explore the potential genomic drivers of extraneural metastasis in GBM, we present the molecular features of 4 extraneural metastatic GBMs, along with a comprehensive review and analysis of previously reported cases that had available molecular characterization. In addition to our 4 cases, 42 patients from 35 publications are reviewed. To compare the molecular profiles between GBM cases with extraneural metastasis and the general GBM population, genomic data from GBM samples in The Cancer Genome Atlas (TCGA) database were also analyzed. We found that 64.5% (20/31) of the cases with extraneural metastasis that were tested for TP53 changes had at least 1 TP53 pathogenic variant detected in either 1 or both primary and metastatic tumors. In contrast, TP53 mutation was significantly less frequent in the unselected GBM from TCGA (22.6%, 56/248) (P=0.000). In addition, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation was more common in unselected TCGA GBM cases (48.6%, 170/350) than in cases with extraneural metastasis (31.8%, 7/22), although not statistically significant. Although isocitrate dehydrogenase (IDH) mutation is a rare occurrence in high-grade astrocytomas, IDH-mutant grade 4 astrocytomas are at least as likely to metastasize as IDH wild-type GBMs; 3 metastatic cases definitively harbored an IDH1 (p.R132H) mutation in our analysis. Our findings not only provide potential biomarkers for earlier screening of extraneural metastasis, but could also suggest clues to understanding biological mechanisms underlying GBM metastasis, and for the development of therapeutic modalities.

Clinical applications of diffusion-weighted sequence in brain imaging: beyond stroke

Diffusion-weighted imaging (DWI) is a well-established MRI sequence for diagnosing early stroke and provides therapeutic implications. However, DWI yields pertinent information in various other brain pathologies and helps establish a specific diagnosis and management of other central nervous system disorders. Some of these conditions can present with acute changes in neurological status and mimic stroke. This review will focus briefly on diffusion imaging techniques, followed by a more comprehensive description of the utility of DWI in common neurological entities beyond stroke.

The incidence of major subtypes of primary brain tumors in adults in England 1995-2017

Background

Primary brain tumors are a complex heterogenous group of benign and malignant tumors. Reports on their occurrence in the English population by sex, age, and morphological subtype and on their incidence are currently not available. Using data from the National Cancer Registration and Analysis Service (NCRAS), the incidence of adult primary brain tumor by major subtypes in England will be described.

Methods

Data on all adult English patients diagnosed with primary brain tumor between 1995 and 2017, excluding spinal, endocrinal, and other CNS tumors, were extracted from NCRAS. Incidence rates were standardized to the 2013 European Standard Population. Results are presented by sex, age, and morphological subtype.

Results

Between 1995 and 2017, a total of 133 669 cases of adult primary brain tumor were registered in England. Glioblastoma was the most frequent tumor subtype (31.8%), followed by meningioma (27.3%). The age-standardized incidence for glioblastoma increased from 3.27 per 100 000 population per year in 1995 to 7.34 in men in 2013 and from 2.00 to 4.45 in women. Meningioma incidence also increased from 1.89 to 3.41 per 100 000 in men and from 3.40 to 7.46 in women. The incidence of other astrocytic and unclassified brain tumors declined between 1995 and 2007 and remained stable thereafter.

Conclusion

Part of the increase in the incidence of major subtypes of brain tumors in England could be explained by advances in clinical practice including the adoption of new diagnostic tools, classifications and molecular testing, and improved cancer registration practices.

Presenting Psychiatric and Neurological Symptoms and Signs of Brain Tumors before Diagnosis: A Systematic Review

Brain tumors can present with various psychiatric symptoms, with or without neurological symptoms, an aspect that complicates the clinical picture. However, no systematic description of symptoms that should prompt a neurological investigation has been provided. This review aims to summarize available case reports describing patients with brain tumors showing psychiatric symptoms before brain tumor diagnosis, in order to provide a comprehensive description of these symptoms as well as their potential relationship with delay in the diagnosis. A systematic literature review on case reports of brain tumors and psychiatric symptoms from 1970 to 2020 was conducted on PubMed, Ovid, Psych Info, and MEDLINE. Exclusion criteria comprised tumors not included in the World Health Organization (WHO) Classification 4th edition and cases in which psychiatric symptoms were absent or followed the diagnosis. A total of 165 case reports were analyzed. In a subset of patients with brain tumors, psychiatric symptoms can be the only manifestation or precede focal neurological signs by months or even years. The appearance of focal or generalized neurological symptoms after, rather than along with, psychiatric symptoms was associated with a significant delay in the diagnosis in adults. A timely assessment of psychiatric symptoms might help to improve early diagnosis of brain tumors.

Radioresistance in Glioblastoma and the Development of Radiosensitizers

Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma (GBM). Unfortunately, some GBMs are relatively radioresistant and patients have worse outcomes after radiation treatment. The mechanisms underlying intrinsic radioresistance in GBM has been rigorously investigated over the past several years, but the complex interaction of the cellular molecules and signaling pathways involved in radioresistance remains incompletely defined. A clinically effective radiosensitizer that overcomes radioresistance has yet to be identified. In this review, we discuss the current status of radiation treatment in GBM, including advances in imaging techniques that have facilitated more accurate diagnosis, and the identified mechanisms of GBM radioresistance. In addition, we provide a summary of the candidate GBM radiosensitizers being investigated, including an update of subjects enrolled in clinical trials. Overall, this review highlights the importance of understanding the mechanisms of GBM radioresistance to facilitate the development of effective radiosensitizers.

Childhood central nervous system tumors and leukemia: Incidence and familial risk. A comparative population-based study in Utah and Norway

BACKGROUND

In this study, we aimed to evaluate incidence rates and family risk of the most common childhood cancers, tumors in the central nervous system (CNS), and leukemia among individuals from Norway and individuals with Scandinavian ancestry living in Utah.

METHODS

We used the Utah Population Database and the Norwegian National Population Register linked to Cancer registries to identify cancers in children born between 1966 and 2015 and their first-degree relatives. We calculated incidence rates and hazards ratios.

RESULTS

The overall incidence of CNS tumors increased with consecutive birth cohorts similarly in Utah and Norway (both P < 0.001). Incidence rates of leukemia were more stable and similar in both Utah and in Norway with 4.6/100 000 person-years among children (<15 years) born in the last cohort. A family history of CNS tumors was significantly associated with risk of childhood CNS tumors in Utah HR = 3.05 (95% CI 1.80-5.16) and Norway HR = 2.87 (95% CI 2.20-3.74). In Norway, children with a first-degree relative diagnosed with leukemia had high risk of leukemia (HR = 2.39, 95% CI 1.61-3.55).

CONCLUSION

Despite geographical distance and assumed large lifestyle differences, two genetically linked pediatric populations show similar incidences of CNS tumors and leukemia in the period 1966-2015. CNS tumors and leukemia aggregated in families in both countries.

Microwave-induced thermoacoustic tomography through an adult human skull

PURPOSE

To demonstrate the feasibility of microwave-induced thermoacoustic tomography (TAT) of adult human brain.

METHODS

We analyzed the electric field distribution radiated from an antenna to acquire homogeneous illumination. We first imaged the anatomical structures in a rat's trunk to validate the thermoacoustic contrast in vivo. We then imaged an agar cylinder through an adult human skull ex vivo to demonstrate transcranial penetration of both microwave and ultrasound. We also analyzed the specific absorption rate to show the conformance to the safety standard for human electromagnetic exposure.

RESULTS

We successfully acquired cross-sectional images of the rat's trunk in vivo. Major blood vessels and organs are clearly visible. The transcranial image shows that TAT can image through the adult human skull and reveal an agar enclosed by the skull.

CONCLUSIONS

Microwave-induced TAT of a rat's trunk in vivo and an agar phantom through an adult human skull ex vivo has been demonstrated experimentally. This study demonstrates both the TAT contrasts in vivo and the capability of transcranial imaging, showing potential of TAT for adult human brain imaging with high contrast and penetration.

Mobile phone use and incidence of brain tumour histological types, grading or anatomical location: a population-based ecological study

OBJECTIVE

Some studies have reported increasing trends in certain brain tumours and a possible link with mobile phone use has been suggested. We examined the incidence time trends of brain tumour in Australia for three distinct time periods to ascertain the influence of improved diagnostic technologies and increase in mobile phone use on the incidence of brain tumours.

DESIGN

In a population-based ecological study, we examined trends of brain tumour over the periods 1982-1992, 1993-2002 and 2003-2013. We further compared the observed incidence during the period of substantial mobile phone use (2003-2013) with predicted (modelled) incidence for the same period by applying various relative risks, latency periods and mobile phone use scenarios.

SETTING

National Australian incidence registration data on primary cancers of the brain diagnosed between 1982 and 2013.

POPULATION

16 825 eligible brain cancer cases aged 20-59 from all of Australia (10 083 males and 6742 females).

MAIN OUTCOME MEASURES

Annual percentage change (APC) in brain tumour incidence based on Poisson regression analysis.

RESULTS

The overall brain tumour rates remained stable during all three periods. There was an increase in glioblastoma during 1993-2002 (APC 2.3, 95% CI 0.8 to 3.7) which was likely due to advances in the use of MRI during that period. There were no increases in any brain tumour types, including glioma (-0.6, -1.4 to 0.2) and glioblastoma (0.8, -0.4 to 2.0), during the period of substantial mobile phone use from 2003 to 2013. During that period, there was also no increase in glioma of the temporal lobe (0.5, -1.3 to 2.3), which is the location most exposed when using a mobile phone. Predicted incidence rates were higher than the observed rates for latency periods up to 15 years.

CONCLUSIONS

In Australia, there has been no increase in any brain tumour histological type or glioma location that can be attributed to mobile phones.

Simultaneous multislice acquisition with multi-contrast segmented EPI for separation of signal contributions in dynamic contrast-enhanced imaging

We present a method to efficiently separate signal in magnetic resonance imaging (MRI) into a base signal S0, representing the mainly T1-weighted component without T2*-relaxation, and its T2*-weighted counterpart by the rapid acquisition of multiple contrasts for advanced pharmacokinetic modelling. This is achieved by incorporating simultaneous multislice (SMS) imaging into a multi-contrast, segmented echo planar imaging (EPI) sequence to allow extended spatial coverage, which covers larger body regions without time penalty. Simultaneous acquisition of four slices was combined with segmented EPI for fast imaging with three gradient echo times in a preclinical perfusion study. Six female domestic pigs, German-landrace or hybrid-form, were scanned for 11 minutes respectively during administration of gadolinium-based contrast agent. Influences of reconstruction methods and training data were investigated. The separation into T1- and T2*-dependent signal contributions was achieved by fitting a standard analytical model to the acquired multi-echo data. The application of SMS yielded sufficient temporal resolution for the detection of the arterial input function in major vessels, while anatomical coverage allowed perfusion analysis of muscle tissue. The separation of the MR signal into T1- and T2*-dependent components allowed the correction of susceptibility related changes. We demonstrate a novel sequence for dynamic contrast-enhanced MRI that meets the requirements of temporal resolution (Δt < 1.5 s) and image quality. The incorporation of SMS into multi-contrast, segmented EPI can overcome existing limitations of dynamic contrast enhancement and dynamic susceptibility contrast methods, when applied separately. The new approach allows both techniques to be combined in a single acquisition with a large spatial coverage.

Development and validation of a new MRI simulation technique that can reliably estimate optimal in vivo scanning parameters in a glioblastoma murine model

BACKGROUND

Magnetic Resonance Imaging (MRI) relies on optimal scanning parameters to achieve maximal signal-to-noise ratio (SNR) and high contrast-to-noise ratio (CNR) between tissues resulting in high quality images. The optimization of such parameters is often laborious, time consuming, and user-dependent, making harmonization of imaging parameters a difficult task. In this report, we aim to develop and validate a computer simulation technique that can reliably provide "optimal in vivo scanning parameters" ready to be used for in vivo evaluation of disease models.

METHODS

A glioblastoma murine model was investigated using several MRI imaging methods. Such MRI methods underwent a simulated and an in vivo scanning parameter optimization in pre- and post-contrast conditions that involved the investigation of tumor, brain parenchyma and cerebrospinal fluid (CSF) CNR values in addition to the time relaxation values of the related tissues. The CNR tissues information were analyzed and the derived scanning parameters compared in order to validate the simulated methodology as a reliable technique for "optimal in vivo scanning parameters" estimation.

RESULTS

The CNRs and the related scanning parameters were better correlated when spin-echo-based sequences were used rather than the gradient-echo-based sequences due to augmented inhomogeneity artifacts affecting the latter methods. "Optimal in vivo scanning parameters" were generated successfully by the simulations after initial scanning parameter adjustments that conformed to some of the parameters derived from the in vivo experiment.

CONCLUSION

Scanning parameter optimization using the computer simulation was shown to be a valid surrogate to the in vivo approach in a glioblastoma murine model yielding in a better delineation and differentiation of the tumor from the contralateral hemisphere. In addition to drastically reducing the time invested in choosing optimal scanning parameters when compared to an in vivo approach, this simulation program could also be used to harmonize MRI acquisition parameters across scanners from different vendors.

Premature Mortality Due to Malignancies of the Central Nervous System in Canada, 1980-2010

BACKGROUND

In this study, we investigated whether there has been an improvement in premature mortality due to central nervous system (CNS) cancers among the Canadian population from 1980 through 2010.

METHODS

Mortality data for CNS cancers were obtained from World Health Organization mortality database. Years of life lost (YLL) was estimated using Canadian life tables. Average lifespan shortened (ALSS) was calculated and defined as the ratio of YLL relative to the expected lifespan.

RESULTS

Over this study period, we observed decreases in age standardized rates to the World Standard Population for mortality due to CNS cancers from 5.3 to 4.1 per 100,000 men, and from 3.6 to 2.9 per 100,000 women. Average YLL decreased from 23.6 to 21.5 years of life among men, and from 27.0 to 23.1 years among women in 1980 and 2010, respectively. The ALSS showed that men with CNS cancers lost 30.1% of their life span and women lost 32.5% in 1980, whereas they lost 25.8 and 26.6% in 2010, respectively.

CONCLUSION

Our study shows that -Canadian people with CNS cancers have had their lives prolonged at the end of the study period.

An eight-year prospective controlled study about the safety and diagnostic value of cardiac and non-cardiac 1.5-T MRI in patients with a conventional pacemaker or a conventional implantable cardioverter defibrillator

OBJECTIVES

To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD).

METHODS

We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted <6 weeks before enrolment or prior to 01/01/2000, with cPM/cICD-carriers undergoing chest x-ray, CT or follow-up (reference group, RG).

RESULTS

142 MRI (55 cardiac) were performed in 120 patients with cPM (n=71) or cICD (n=71). In the RG 98 measurements were performed in 95 patients with cPM (n=40) or cICD (n=58). No adverse events were observed. No MRI prolonged/interrupted. All cPM/cICD were correctly reprogrammed after MRI without malfunctions. One temporary communication failure was observed in one cPM-carrier. Immediately after MRI, 12/14 device interrogation parameters did not change significantly (clinically negligible changes of battery voltage and cICD charging time), without significant variations for SG versus RG. Three-12 months after MRI, 9/11 device interrogation parameters did not change significantly (clinically negligible changes of battery impedance/voltage). Non-significant changes of three markers of myocardial necrosis. Non-cardiac MRI: 82/87 diagnostic without artefacts; 4/87 diagnostic with artefacts; 1/87 partially diagnostic. Cardiac MRI: in cPM-carriers, 14/15 diagnostic with artefacts, 1/15 partially diagnostic; in cICD-carriers, 9/40 diagnostic with artefacts, 22 partially diagnostic, nine non-diagnostic.

CONCLUSIONS

A favourable risk-benefit ratio of 1.5-T MRI in cPM/cICD carriers was reported.

KEY POINTS

• Cooperation between radiologists and cardiac electrophysiologists allowed safe 1.5-T MRI in cPM/cICD-carriers. • No adverse events for 142 MRI in 71 cPM-carriers and 71 cICD-carriers. • Ninety-nine per cent (86/87) of non-cardiac MRI in cPM/cICD-carriers were diagnostic. • All cPM-carrier cardiac MRIs had artefacts, 14 examinations diagnostic, 1 partially diagnostic. • Twenty-three per cent (9/40) of cardiac MRI in cICD-carriers were non-diagnostic.

The preliminary radiogenomics association between MR perfusion imaging parameters and genomic biomarkers, and their predictive performance of overall survival in patients with glioblastoma

The radiogenomics association of neovascularization is important for overall survival (OS) in glioblastoma patients and remains unclear. The purpose of this study is to assess the association between MR perfusion imaging derived parameters and genomic biomarkers of glioblastoma, and to evaluate their prognostic value. This retrospective study enrolled 41 patients with newly diagnosed glioblastoma. The mean and maximal relative cerebral blood volume (rCBV) ratio (rCBV_mean and rCBV_max), derived from MR perfusion weighted imaging, of the enhancing tumor, as well as maximal rCBV ratio of peri-enhancing tumor area (rCBV_peri-tumor) were measured. The ki-67 labeling index, mammalian target of rapamycin (mTOR) activation, epidermal growth factor receptor (EGFR) amplification, isocitrate dehydrogenase (IDH) mutation and TP53 were assessed. There was a significant correlation between rCBV_max and mTOR based on Pearson's correlations with Benjamini-Hochberg adjustment for controlling false discovery rate, p = 0.047. The rCBV_peri-tumor showed significant correlation with mTOR (p = 0.0183) after adjustment of gender and EGFR status. The mean rCBV_peri-tumor value of the patients with OS shorter than 14 months was significantly higher than patients with OS longer than 14 months, p = 0.002. The rCBV_peri-tumor and age were the two strongest predictors of OS (hazard ratio = 1.29 and 1.063 respectively) by Cox regression analysis. This study showed that hemodynamic abnormalities of glioblastoma were associated with genomics activation status of mTOR-EGFR pathway, however, the radiogenomics associations are different in enhancing and peri-enhancing area of glioblastoma. The rCBV_peri-tumor has better prognostic value than genomic biomarkers alone.

History of surgery for temporal lobe epilepsy

The history of epilepsy and its treatment goes back to ancient times when it included medicinal herbs, lifestyle modifications, and even surgery. Trepanation is considered the oldest surgical procedure for the treatment of epilepsy. The first series of temporal lobectomies for the treatment of drug-resistant epilepsy were reported by Penfield and Flanigin (1950). During the years since then, neuroimaging and other technologies have had remarkable and revolutionary progress. This progress has resulted in tremendous advancements in understanding the underlying causes and pathophysiology of epilepsies. With the help of these technologies and advancements, we may now offer surgery as a safer therapeutic option to more patients who are suffering from drug-resistant temporal lobe epilepsy. However, the degree of improvement in surgery outcome has not been proportionate to the technological progress.

The Empirical Foundations of Teleradiology and Related Applications: A Review of the Evidence

INTRODUCTION

Radiology was founded on a technological discovery by Wilhelm Roentgen in 1895. Teleradiology also had its roots in technology dating back to 1947 with the successful transmission of radiographic images through telephone lines. Diagnostic radiology has become the eye of medicine in terms of diagnosing and treating injury and disease. This article documents the empirical foundations of teleradiology.

METHODS

A selective review of the credible literature during the past decade (2005-2015) was conducted, using robust research design and adequate sample size as criteria for inclusion.

FINDINGS

The evidence regarding feasibility of teleradiology and related information technology applications has been well documented for several decades. The majority of studies focused on intermediate outcomes, as indicated by comparability between teleradiology and conventional radiology. A consistent trend of concordance between the two modalities was observed in terms of diagnostic accuracy and reliability. Additional benefits include reductions in patient transfer, rehospitalization, and length of stay.

Advanced Neuroimaging in the Evaluation of Spinal Cord Tumors and Tumor Mimics: Diffusion Tensor and Perfusion-Weighted Imaging

Spinal cord tumors are an important component of pathologic diseases involving the spinal cord. Conventional magnetic resonance (MR) imaging only provides anatomical information. MR diffusion tensor imaging (DTI) and MR perfusion-weighted imaging (PWI) may detect microstructure diffusion and hemodynamic changes in these tumors. We review recent application studies of MR DTI and PWI in spinal cord tumors. Overall, MR DTI and MR PWI are promising imaging tools that are especially useful in improving differential diagnosis between spinal cord tumors and tumor mimics, preoperative evaluation of resectability, and providing assistance in surgical navigation.

Application of Ultrahigh Field Magnetic Resonance Imaging in the Treatment of Brain Tumors: A Meta-Analysis

BACKGROUND

Magnetic resonance imaging (MRI) is the imaging modality of choice for the clinical management of brain tumors, and the majority of scanners operate with static magnetic field strengths of 1.5 or 3.0 Tesla (T). During the past decade, ultrahigh field (UHF) MRI has been investigated for its clinical applicability. This meta-analysis evaluates studies pertaining to the application of UHF MRI to patients with brain tumors.

METHODS

The authors performed a systematic review of the literature. Articles relating to application of UHF MRI to brain anatomy and brain tumors with living subjects were included. Studies were grouped into 1 of 3 categories based on area of focus: "Anatomical Structures Involved with Brain Tumors," "Tumor characterization," and "Treatment Monitoring." Comparison studies with extractable outcomes measure data were analyzed for performance of UHF MRI versus clinical field strengths (1.5 T and 3 T).

RESULTS

Twenty-four studies (361 subjects) met inclusion criteria. The field of study was heterogeneous and rigorous statistical analysis was not possible. Overall, 279 patients with brain tumors scanned at UHF MRI have been reported. Of these, glioma and glioblastoma multiforme are the most commonly studied lesions (38.9% and 24.4%, respectively). In comparison studies between UHF MRI and clinical field strengths, 24 of 51 patients had outcome measures that were better with UHF MRI, 17 of 24 were equivalent at both field strengths, and 9 were worse at UHF MRI. The most common causes of a worse performance were susceptibility artifacts and magnetic field inhomogeneities (3 of 9). Imaging of the pituitary gland, pineal gland veins, cranial nerves, and tumor microvasculature were all shown to be feasible.

CONCLUSIONS

UHF MRI shows promise to improve detection and characterization of brain tumors, preoperative planning for neurosurgical resection, and longitudinal monitoring of the effects of radiation and antibody-based therapies. Technical innovations are needed to overcome field inhomogeneity and susceptibility artifacts in certain regions of the skull. Finally, larger studies comparing 1.5 T, 3.0 T, and 7.0 T or greater will determine whether UHF MRI gains acceptance as a clinical standard.

Errors in neuroradiology

Approximately 4 % of radiologic interpretation in daily practice contains errors and discrepancies that should occur in 2-20 % of reports. Fortunately, most of them are minor degree errors, or if serious, are found and corrected with sufficient promptness; obviously, diagnostic errors become critical when misinterpretation or misidentification should significantly delay medical or surgical treatments. Errors can be summarized into four main categories: observer errors, errors in interpretation, failure to suggest the next appropriate procedure, failure to communicate in a timely and a clinically appropriate manner. Misdiagnosis/misinterpretation percentage should rise up in emergency setting and in the first moments of the learning curve, as in residency. Para-physiological and pathological pitfalls in neuroradiology include calcification and brain stones, pseudofractures, and enlargement of subarachnoid or epidural spaces, ventricular system abnormalities, vascular system abnormalities, intracranial lesions or pseudolesions, and finally neuroradiological emergencies. In order to minimize the possibility of error, it is important to be aware of various presentations of pathology, obtain clinical information, know current practice guidelines, review after interpreting a diagnostic study, suggest follow-up studies when appropriate, communicate significant abnormal findings appropriately and in a timely fashion directly with the treatment team.