Diagnosis and management of astrocytomas, oligodendrogliomas and mixed gliomas: a review

Advances in Mass Spectrometry of Gangliosides Expressed in Brain Cancers

Gangliosides are highly abundant in the human brain where they are involved in major biological events. In brain cancers, alterations of ganglioside pattern occur, some of which being correlated with neoplastic transformation, while others with tumor proliferation. Of all techniques, mass spectrometry (MS) has proven to be one of the most effective in gangliosidomics, due to its ability to characterize heterogeneous mixtures and discover species with biomarker value. This review highlights the most significant achievements of MS in the analysis of gangliosides in human brain cancers. The first part presents the latest state of MS development in the discovery of ganglioside markers in primary brain tumors, with a particular emphasis on the ion mobility separation (IMS) MS and its contribution to the elucidation of the gangliosidome associated with aggressive tumors. The second part is focused on MS of gangliosides in brain metastases, highlighting the ability of matrix-assisted laser desorption/ionization (MALDI)-MS, microfluidics-MS and tandem MS to decipher and structurally characterize species involved in the metastatic process. In the end, several conclusions and perspectives are presented, among which the need for development of reliable software and a user-friendly structural database as a search platform in brain tumor diagnostics.

AI in spotting high-risk characteristics of medical imaging and molecular pathology

Medical imaging provides a comprehensive perspective and rich information for disease diagnosis. Combined with artificial intelligence technology, medical imaging can be further mined for detailed pathological information. Many studies have shown that the macroscopic imaging characteristics of tumors are closely related to microscopic gene, protein and molecular changes. In order to explore the function of artificial intelligence algorithms in in-depth analysis of medical imaging information, this paper reviews the articles published in recent years from three perspectives: medical imaging analysis method, clinical applications and the development of medical imaging in the direction of pathological molecular prediction. We believe that AI-aided medical imaging analysis will be extensively contributing to precise and efficient clinical decision.

Predicting Isocitrate Dehydrogenase (IDH) Mutation Status in Gliomas Using Multiparameter MRI Radiomics Features

BACKGROUND

Accurate and noninvasive detection of isocitrate dehydrogenase (IDH, including IDH1 and IDH2) status is clinically meaningful for molecular stratification of glioma, but remains challenging.

PURPOSE

To establish a model for classifying IDH status in gliomas based on multiparametric MRI.

STUDY TYPE

Retrospective, radiomics.

POPULATION

In all, 105 consecutive cases of grade II-IV glioma with 50 IDH1 or IDH2 mutant (IDHm) and 55 IDH wildtype (IDHw) were separated into a training cohort (n = 73) and a test cohort (n = 32).

FIELD STRENGTH/SEQUENCE

Contrast-enhanced T₁ -weighted (CE-T₁ W), T₂ -weighted (T₂ W), and arterial spin labeling (ASL) images were acquired at 3.0T.

ASSESSMENT

Two doctors manually labeled the volume of interest (VOI) on CE-T₁ W, then T₂ W and ASL were coregistered to CE-T₁ W. A total of 851 radiomics features were extracted on each VOI of three sequences. From the training cohort, all radiomics features with age and gender were processed by the Mann-Whitney U-test, Pearson test, and least absolute shrinkage and selection operator to obtain optimal feature groups to train support vector machine models. The accuracy and area under curve (AUC) of all models for classifying the IDH status were calculated on the test cohort. Two subtasks were performed to verify the efficiency of texture features and the Pearson test in IDH status classification, respectively.

STATISTICAL TESTS

The permutation test with Bonferroni correction; chi-square test.

RESULTS

The accuracy and AUC of the classifier, which combines the features of all three sequences, achieved 0.823 and 0.770 (P < 0.05), respectively. The best model established by texture features only had an AUC of 0.819 and an accuracy of 0.761. The best model established without the Pearson test got an AUC of 0.747 and an accuracy of 0.719.

DATA CONCLUSION

IDH genotypes of glioma can be identified by radiomics features from multiparameter MRI. The Pearson test improved the performance of the IDH classification models.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 1.

Advantages of gross total resection in patients with astrocytoma: A population-based study

The present study aimed to investigate the association between surgical methods and survival outcomes in patients with astrocytoma. Patients diagnosed with astrocytoma between January 2004 and December 2015 were identified using the Surveillance, Epidemiology and End Results database. Kaplan-Meier curves and Cox regression were used to analyze the effects of surgical methods on overall survival (OS) and cancer-specific survival (CSS). Among 42,224 eligible patients with astrocytoma, 11,427 (27.1%) patients did not receive surgery, 7,661 (18.1%) received excisional biopsy (EB), 5,520 (13.1%) received a subtotal resection (STR), 6,037 (14.3%) received a gross resection (GR), 5,314 (12.6%) received a partial resection (PR) and 6,265 (14.8%) received a gross total resection (GTR). Patients who underwent GR had the longest survival time (17.00 months). However, over time, the proportion of patients who underwent STR or GR increased, whereas the proportion of patients who did not undergo surgery, PR or GTR decreased. Furthermore, surgical method was an independent prognostic factor for OS and CSS for the patients with astrocytoma. Multivariate Cox regression showed that GTR was associated with the more favorable OS [hazard ratio (HR), 0.80; 95% confidence interval (CI), 0.77-0.83; P<0.001] and CSS (HR, 0.80; 95% CI, 0.77-0.83; P<0.001) times compared with EB. Moreover, similar results were observed in subgroup analyses based on summary stage and grade. In the present study, it was demonstrated that GTR was one of the effective surgical methods for improved OS and CSS time in patients with astrocytoma. However, among the American astrocytoma population, the proportion of patients who underwent GTR decreased. It is necessary to further advocate for the efficacy of GTR.

A multi-sequence and habitat-based MRI radiomics signature for preoperative prediction of MGMT promoter methylation in astrocytomas with prognostic implication

Objectives

Oxygen 6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is a significant prognostic biomarker in astrocytomas, especially for temozolomide (TMZ) chemotherapy. This study aimed to preoperatively predict MGMT methylation status based on magnetic resonance imaging (MRI) radiomics and validate its value for evaluation of TMZ chemotherapy effect.

Methods

We retrospectively reviewed a cohort of 105 patients with grade II-IV astrocytomas. Radiomic features were extracted from the tumour and peritumoral oedema habitats on contrast-enhanced T1-weighted images, T2-weighted fluid-attenuated inversion recovery images and apparent diffusion coefficient (ADC) maps. The following radiomics analysis was structured in three phases: feature reduction, signature construction and discrimination statistics. A fusion radiomics signature was finally developed using logistic regression modelling. Predictive performance was compared between the radiomics signature, previously reported clinical factors and ADC parameters. Validation was additionally performed on a time-independent cohort (n = 31). The prognostic value of the signature on overall survival for TMZ chemotherapy was explored using Kaplan Meier estimation.

Results

The fusion radiomics signature exhibited supreme power for predicting MGMT promoter methylation, with area under the curve values of 0.925 in the training cohort and 0.902 in the validation cohort. Performance of the radiomics signature surpassed that of clinical factors and ADC parameters. Moreover, the radiomics approach successfully divided patients into high-risk and low-risk groups for overall survival after TMZ chemotherapy (p = 0.03).

Conclusions

The proposed radiomics signature accurately predicted MGMT promoter methylation in patients with astrocytomas, and achieved survival stratification for TMZ chemotherapy, thus providing a preoperative basis for individualised treatment planning.

Key Points

• Radiomics using magnetic resonance imaging can preoperatively perform satisfactory prediction of MGMT methylation in grade II-IV astrocytomas.

• Habitat-based radiomics can improve efficacy in predicting MGMT methylation status.

• Multi-sequence radiomics signature has the power to evaluate TMZ chemotherapy effect.

Electronic supplementary material

The online version of this article (10.1007/s00330-018-5575-z) contains supplementary material, which is available to authorized users.

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

Background

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

Methods

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

Results

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

Conclusions

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

Sclerosing Meningioma : Radiological and Clinical Characteristics of 21 Cases

Objective

A rare subtype of meningioma, sclerosing meningioma is not included in the current World Health Organization classification of meningiomas and is classified into the category of other morphological variation subtypes. Sclerosing meningioma is often misdiagnosed to other non-benign meningioma or malignant neoplasm, so it is important to diagnose sclerosing type correctly. We analyzed the radiological and clinical characteristics of a series of sclerosing meningiomas.

Methods

Twenty-one patients who underwent surgery in one institute with a histopathologically proven sclerosing meningioma were included from 2006 to 2014. Eighteen tumors were diagnosed as a pure sclerosing-type meningioma, and 3 as mixed type. Magnetic resonance image was taken for all patients including contrast enhancement image. Computed tomography (CT) scan was taken for 16 patients. One neuroradiologist and 1 neurosurgeon reviewed all images retrospectively.

Results

In the all 16 patients with preoperative CT images, higher attenuation was observed in the meningioma than in the brain parenchyma, and calcification was observed in 11 (69%). In 15 of the 21 patients (71%), a distinctive very low signal intensity appeared as a dark color in T2-weighted images. Nine of these 15 tumors (60%) exhibited heterogeneous enhancement, and 6 (40%) exhibited homogeneous enhancement that was unlike the homogeneous enhancing pattern shown by conventional meningiomas. Ten patients had a clear tumor margin without peritumoral edema.

Conclusion

Although these peculiar radiological characteristics are not unique to sclerosing meningioma, we believe that they are distinctive features that may be helpful for distinguishing sclerosing meningioma from other subtypes.

4E-BP1 regulates the sensitivity of human glioma cells to chemotherapy through PI3K/Akt/mTOR-independent pathway

Drug resistance is one of the most formidable obstacles for treatment of glioma. Eukaryotic initiation factor 4E-binding protein (4E-BP1), a key component in the rate-limiting step of protein translation initiation, is closely associated with poor prognosis in multiple tumor types. However, it is unclear whether 4E-BP1 is involved in the drug resistance of human glioma. Herein we show that the expression of 4E-BP1 in human SWOZ2-BCNU drug-resistant glioma cells is significantly lower than that of the parent SWOZ2 cell line. Moreover, down-regulation of 4E-BP1 by short interfering RNA significantly impaired the sensitivity of SWOZ2 and U251 cells to carmustine (BCNU). Furthermore, overexpression of 4E-BP1 with plasmid transfection regained this sensitivity. Clinical studies showed that the expression levels of 4E-BP1 in primary glioma tissues were markedly higher than those of recrudescent glioma tissues. Taken together, our results suggest that 4E-BP1 is a novel protein that contributes to acquired drug resistance and it may be a potential target for reversing drug resistance in human glioma.

Inhibition of T-type Ca²⁺ channels by endostatin attenuates human glioblastoma cell proliferation and migration

BACKGROUND AND PURPOSE

Endostatin (ES) is a c-terminal proteolytic fragment of collagen XVIII with promising antitumour properties in several tumour models, including human glioblastoma. We hypothesized that this peptide could interact with plasma membrane ion channels and modulate their functions.

EXPERIMENTAL APPROACH

Using cell proliferation and migration assays, patch clamp and Western blot analysis, we studied the effects of ES on the proliferation and migration of human glioblastoma U87 cells, mediated by T-type Ca²⁺ channels.

KEY RESULTS

Extracellular application of ES reversibly inhibited T-type Ca²⁺ channel currents (T-currents) in U87 cells, whereas L-type Ca²⁺ currents were not affected. This inhibitory effect was associated with a hyperpolarizing shift in the voltage-dependence of inactivation but was independent of G-protein and protein tyrosine kinase-mediated pathways. All three α₁ subunits of T-type Ca²⁺ channels (Ca(V) 3), α(1G) (Ca(V) 3.1), α(1H) (Ca(V) 3.2) and α(1I) (Ca(V) 3.3), were endogenously expressed in U87 cells. Using transfected HEK293 or CHO cells, we showed that only Ca(V) 3.1 and Ca(V) 3.2, but not Ca(V) 3.3 or Ca(V) 1.2 (L-type), channel currents were significantly inhibited. More interestingly, ES inhibited the proliferation and migration of U87 cells in a dose-dependent manner. Pretreatment of the cells with the specific T-type Ca²⁺ channel blocker mibefradil occluded these inhibitory effects of ES.

CONCLUSION AND IMPLICATIONS

This study provides the first evidence that the antitumour effects of ES on glioblastoma cells is through direct inhibition of T-type Ca²⁺ channels and gives new insights into the future development of a new class of antiglioblastoma agents that target the proliferation and migration of these cells.

Proteomic identification of glutamine synthetase as a differential marker for oligodendrogliomas and astrocytomas

OBJECT

Astrocytomas and oligodendrogliomas are primary CNS tumors that remain a challenge to differentiate histologically because of their morphological variability and because there is a lack of reliable differential diagnostic markers. To identify proteins that are differentially expressed between astrocytomas and oligodendrogliomas, the authors analyzed the proteomic expression patterns and identified uniquely expressed proteins in these neoplasms.

METHODS

Proteomes of astrocytomas and oligodendrogliomas were analyzed using 2D gel electrophoresis and subsequent computerized gel analysis to detect differentially expressed proteins. The proteins were identified using high-performance liquid chromatography accompanied by tandem mass spectrometry. To determine the role of the differentially expressed proteins in astrocytes, undifferentiated glial cell cultures were treated with dibutyryl-cyclic adenosine monophosphate (cAMP).

RESULTS

Two-dimensional gel electrophoresis revealed that glutamine synthetase was differentially expressed in astrocytomas and oligodendrogliomas. Western blot and immunohistochemical analyses confirmed the increased expression of glutamine synthetase in astrocytomas compared with oligodendrogliomas. Whereas glutamine synthetase expression was demonstrated across all grades of astrocytomas (Grade II-IV [15 tumors]) and oligoastrocytomas (4 tumors), it was expressed in only 1 oligodendroglioma (6% [16 tumors]). Treatment of undifferentiated glial cell cultures with dibutyryl-cAMP resulted in astrocyte differentiation that was associated with increased levels of glial fibrillary acidic protein and glutamine synthetase.

CONCLUSIONS

These data indicate that glutamine synthetase expression can be used to distinguish astrocytic from oligodendroglial tumors and may play a role in the pathogenesis of astrocytomas.

The use of hsa-miR-21, hsa-miR-181b and hsa-miR-106a as prognostic indicators of astrocytoma

BACKGROUND

The aberrant expression of microRNAs (miRNAs) is associated with a variety of diseases including cancers. In the present study, the miRNA expression profile was examined in astrocytoma, a malignant and prevalent intracranial tumour in adults.

METHODS

We screened the expression profile of 200 miRNAs in a training sample set consisting of 84 astrocytoma samples and 20 normal adjacent tissue (NAT) samples using the method of stem-loop quantitative RT-PCR. The significantly altered miRNAs were validated in another independent sample set consisting of 40 astrocytoma samples and 40 NAT samples. The correlation of the miRNA levels with survival in astrocytoma samples was estimated by performing Kaplan-Meier survival analysis and univariate/multivariate Cox proportional hazard regression analysis.

RESULTS

After a two-phase selection and validation process, seven miRNAs were found to have a significantly different expression profile in astrocytoma samples upon comparison to the NAT samples. Unsupervised clustering analysis further revealed the great potential of the 7-miRNA profile to differentiate between tumours and normal brain tissues. The down-regulation of hsa-miR-137 in astrocytomas was shown to be associated with advanced clinical stages of this disease. Using Kaplan-Meier survival analysis we showed that low expression of hsa-miR-181b or hsa-miR-106a, or high expression of hsa-miR-21 was significantly associated with poor patient survival. Moreover, Cox proportional hazard regression analysis revealed that this prognostic impact was independent of other clinicopathological factors.

CONCLUSIONS

Our results suggest a great potential for the use of miRNA profiling as a powerful diagnostic and prognostic marker in defining the signature of astrocytomas and in predicting the post-surgical outcome.

Long-term outcome and survival of surgically treated supratentorial low-grade glioma in adult patients

PURPOSE

The appropriate management of low-grade gliomas is still a matter of debate. So far, there are no randomized studies that analyze the impact of surgical resection on patient outcome. The value of the data obtained from the few retrospective reports available is often limited.

PATIENTS AND METHODS

In the present study, we performed an analysis on data of 130 adult low-grade glioma patients. Extent of the resection was evaluated in correlation to the overall survival (OS) and progression-free survival (PFS) using Cox regression multivariate analysis.

RESULTS

Extended surgery was shown to prolong OS and PFS significantly. Re-surgery in the case of a tumor relapse has a significant impact on OS and PFS, too.

CONCLUSIONS

In summary, we could retrospectively evaluate a large case series of well-defined low-grade gliomas patients with a long follow-up period showing that extended surgery would be the most effective therapy for low-grade glioma patients even in recurrent diseases.

Prise en charge des gliomes de bas grade: série rétrospective de 201 patients

BACKGROUND AND PURPOSE

Optimal treatment for low-grade glioma remains controversial. Moreover, though surgery is recommended for disease management, evidence is lacking concerning the appropriate extent of surgery and the use of adjunctive therapy. Available data is basically retrospective, coming from series with substantial limitations. We reviewed our institution's series in order to evaluate the efficiency of surgical management and the influence of the extent of surgical removal for patients with low-grade glioma.

METHODS

Data were collected from a series of 201 patients who underwent first-intention therapy for low-grade glioma, the standard practice in our institution between 1994 and 2005. After applying certain exclusion criteria, we retained for analysis 123 patients with grade II glioma (WHO classification). We compared progression-free survival curves for the three surgical treatment groups defined as biopsy, partial removal, or total removal.

RESULTS

Statistical evaluation of the progression free survival shows a benefit in total surgery as a first intention treatment. No statistical significance was demonstrated between partial surgery and stereotactic biopsy.

CONCLUSION

For patients with low-grade glioma we recommend total surgical removal as first intention management.

MR-Perfusions- und spektroskopische Bildgebung bei WHO-Grad-II-Astrozytomen

BACKGROUND

This study evaluates whether MR perfusion imaging and spectroscopic imaging (MRSI) can depict anaplastic areas in WHO grade II astrocytomas, whether these areas are co-localized, and whether the prognosis can be better predicted.

MATERIAL AND METHODS

Fifteen patients (nine female, six male, aged 42+/-14 years) with WHO grade II astrocytomas but without preceding radio- or chemotherapy were examined every 3 months with MR perfusion imaging and MRSI (mean follow-up 18 months). Using a region of interest analysis, the regional relative cerebral blood volume (rrCBV) and blood flow (rrCBF) were measured in tumor tissue. In the same areas, choline/creatine (Cho/Cr) and choline/N-acetyl-aspartate (Cho/NAA) ratios were quantified.

RESULTS

During follow-up, nine patients had stable disease. In six patients, the tumor showed progression and contrast-enhancement. The progressing tumors had already had higher perfusion (rrCBF 2.1+/-1.4; rrCBV 1.9+/-1.1) parameters than the stable astrocytomas (rrCBF 1.2+/-0.6, p=0.01; rrCBV 1.4+/-0.8, p=0.05) at first examination. However, the Cho/NAA and Cho/Cr ratios only tended to be higher than in stable astrocytomas (Cho/NAA 2.4+/-1.0 vs. 2.0+/-1.5, p=0.23; Cho/Cr 1.7+/-0.6 vs. 1.4+/-0.5, p=0.06). In all six progressing tumors, areas of maximum perfusion and maximum Cho/NAA and Cho/Cr ratio were co-localized. During follow-up, contrast-enhancement was observed in these areas.

CONCLUSIONS

MR perfusion imaging can depict anaplastic areas in WHO grade II astrocytomas earlier than conventional MRI and thus enables a better prediction of prognosis.

Serum-dependence of AMPA receptor-mediated proliferation in glioma cells

Glutamate may cause Ca(2+) entry through Ca(2+)-permeable glutamate receptors, which in turn stimulates the anti-apoptotic signaling cascade in glioma cells. It was found that a human glioma cell line, U-87 MG, expressed subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate acid-type glutamate receptors (AMPAR). Ca(2+) entry through AMPAR was detected in approximately 40% of U-87 MG cells. AMPAR agonists facilitated cell proliferation in low-serum medium containing 0.5% fetal calf serum (FCS). Unexpectedly, cell proliferation by the activation of AMPAR was not detected in serum-rich medium containing 10% FCS. Overexpression of Ca(2+)-permeable AMPAR facilitated proliferation of U-87 MG cells in the low-serum condition, whereas it had again no effect in the serum-rich condition. Cell proliferation of U-87 MG cells is likely to be under the regulation of both growth factors contained in the serum and Ca(2+) entry through AMPAR, and that the latter regulation becomes evident only when serum factors are deprived of culture medium.

Supportive care needs of people with brain tumours and their carers

GOALS OF WORK

The diagnosis and treatment of a brain tumour may result in long-term changes in a patient's functional and social abilities and/or in a greatly reduced life span. A qualitative investigation was conducted to examine the supportive care needs of patients with brain tumour and their carers.

MATERIALS AND METHODS

Overall, 18 patients and 18 carers participated in focus groups or telephone interviews, following a structured interview guide to elicit supportive care services of importance to these patients and carers.

MAIN RESULTS

Six major themes were identified using the framework analysis method, including needs for information and coping with uncertainty, practical support, support to return to pretreatment responsibilities or prepare for long-term care, support to deal with social isolation and organize respite care, support to overcome stigma/discrimination and support to discuss potentially reduced life expectancy.

CONCLUSIONS

Five recommendations to improve service delivery include: assignment of a dedicated member of the care team or case manager; proactive dissemination of information, education and psychosocial support; access to objective assessment of neuropsychological functioning; facilitating easier access to welfare payments; and services facilitating communication about difficult illness-related topics. Provision of services along these recommendations could improve supportive care of brain tumour patients and their carers.

[Nonpituitary tumors of the sellar region]

The pituitary gland, sella turcica and the parasellar region can be involved by a wide variety of lesions, including benign and malignant neoplasms as well as a wide variety of non neoplastic tumor-like lesions. Clinical and radiological aspects could help in the differential diagnosis of these lesions. Nevertheless, in many cases only the histopathological analysis could establish the definitive diagnosis. In this paper, we review the nonpituitary tumors of the sellar region emphasizing the associated hormonal disturbances.

Fluid-attenuated inversion-recovery MR imaging in assessment of intracranial oligodendrogliomas

This retrospective study consisted of 17 consecutive patients with oligodendrogliomas. We qualitatively and quantitatively assessed the diagnostic value of fluid-attenuated inversion-recovery (FLAIR) images compared with T2-weighted fast spin-echo (FSE) images for evaluating intracranial oligodendrogliomas. Qualitative evaluations of signal intensity, tumor conspicuity, definition of tumor margin, distinction between solid and cystic-like parts within tumor, and calcification were performed. Quantitative criteria comparing FLAIR to T2-weighted FSE images included tumor-to-background contrast and contrast-to-noise ratio (CNR) and tumor-to-cerebrospinal fluid (CSF) contrast and CNR. Our results demonstrate that the FLAIR sequence can replace the T2-weighted FSE sequence for evaluating oligodendrogliomas.

Expression of T-type calcium channel splice variants in human glioma

In humans, three isoforms of the T-type (Ca(v)3.1) calcium-channel alpha(1) subunit have been reported as a result of alternate splicing of exons 25 and 26 in the III-IV linker region (Ca(v)3.1a, Ca(v)3.1b or Ca(v)3.1bc). In the present study, we report that human glioma express Ca(v)3.1 channels in situ, that splicing of these exons is uniquely regulated and that there is expression of a glioma-specific novel T-type variant (Ca(v)3.1ac). Seven human glioma samples were collected at surgery, RNA was extracted, and cDNA was produced for RT-PCR analysis. In addition, three glioma cell lines (U87, U563, and U251N), primary cultures of human fetal astrocytes, as well as adult and fetal human brain cDNA were used. Previously described Ca(v)3.1 splice variants were present in glioma samples, cultured cells and whole brain. Consistent with the literature, our results reveal that in the normal adult brain, Ca(v)3.1a transcripts predominate, while Ca(v)3.1b is mostly fetal-specific. RT-PCR results on glioma and glioma cell lines showed that Ca(v)3.1 expression in tumor cells resemble fetal brain expression pattern as Ca(v)3.1bc is predominantly expressed. In addition, we identified a novel splice variant, Ca(v)3.1ac, expressed in three glioma biopsies and one glioma cell line, but not in normal brain or fetal astrocytes. Transient expression of this variant demonstrates that Ca(v)3.1ac displays similar current-voltage and steady-state inactivation properties compared with Ca(v)3.1b, but a slower recovery from inactivation. Taken together, our data suggest glioma-specific Ca(v)3.1 gene regulation, which could possibly contribute to tumor pathogenesis.

FLAIR MR sequence in the diagnosis and follow-up of low-grade astrocytomas

Aim. To evaluate the sensitivity of fluid-attenuated inversion recovery (FLAIR) sequence in the diagnosis and follow-up of the patients with low-grade astrocytomas compared with T2-weighted (T2W) sequence. Methods. Twenty-four patients with biopsy- confirmed low-grade astrocytoma (age range, 15-66 years) underwent T1- weighted (T1W), T2W and FLAIR imaging with a superconducting unit 1.0 T. FLAIR images were qualitatively evaluated by comparison with T2W images by the three experienced neuroradiologists. To evaluate the diagnostic value of FLAIR, the neuroradiologists individually assessed the possibilities of the detection of lesions, as well as the possibilities of the differentiation of tumor from the surrounding edema on FLAIR vs. T2W images. Every examiner ranked FLAIR sequence vs. T2W in three degrees: worse, equal and better. Results. The comparison of FLAIR with T2W spin-echo (SE) images with regard to the detection of the lesions showed that 82.8% of FLAIR studies were superior, 17.2% were of similar diagnostic value, and none was inferior to the T2W images. The comparison of images with regard to the differentiation of tumor boundaries vs. surrounding edema showed that 92.5% of FLAIR studies were superior, 7.5% were of similar diagnostic value, and none was inferior to the T2W images. Conclusion. Our results were similar to the previous studies' results concerning the advantages of FLAIR sequence in the diagnosis of low grade astrocytomas over T2W sequence. FLAIR was better at showing different tumor components, and at distinguishing CSF from the cystic component, and the postoperative cavity, compared with T2W images. Our conclusion was that FLAIR could be routinely used in the evaluation and follow-up of low-grade astrocytomas.

Central neurocytoma: a clinicopathological and neuroradiological study

Central neurocytoma (CNC) is an uncommon benign tumor of the central nervous system (CNS) occurring in adults and is more likely to be located in the region of the foramina of Monra. Few studies have described the neuroradiological features of CNC, and most are single case reports. Our aim was to analyze the clinicopathological and neuroradiological characteristics of CNC. We retrospectively studied the preoperative CT (n=2) and MRI (n=5) of three men and two women (mean age 45 years, ranging from 30 to 63 years) with pathologically proven CNC. The tumors were primarily located in the region of the foramina of Monra. Two of them occupied the lateral ventricle, appearing to be attached to the septum pellucidum, and the other three tumors arose from the septum pellucidum and extended into the lateral ventricles. The tumors were of mixed density with cystic features and patchy or fine calcification on noncontrast CT scans, and they were of low or isointense signal on T1- and heterogeneously hyperintense signal on T2- and FLAIR weighted images. Contrast enhancement varied greatly from very slight to intense. Immunohistochemical staining showed a positive reaction for synaptophysin (Syn), neuro-specific enclase (NSE), neurofilament protein (NF) in the tumor cells and glial fibrillary acid protein (GFAP) in the fibrillar zones. CNC should be taken into consideration first if a tumor arises from the region of the foramina of Monra with CNC neuroradiological characteristics and the patient is an adult.

Pathology and molecular genetics of oligodendroglial tumors

Oligodendroglial gliomas are second only to astrocytic gliomas in frequency. The lack of stringent diagnostic criteria cause high interobserver variation in regard to classification and grading of these tumors. Previous studies have described oligodendrogliomas with features that overlap with those of neurocytic tumors, thus further complicating diagnostic decisions. The increasing need for standardized diagnostic criteria in this subset of gliomas is emphasized by the benefit of adjuvant therapies in patients with anaplastic oligodendrogliomas. Characteristic chromosomal aberrations have been successfully determined for oligodendroglial tumors in recent years. In contrast to astrocytomas, however, no genes in the affected regions have been clearly linked to their pathogenesis. However, the molecular findings promise to be helpful for diagnostic and therapeutic decisions. This review compiles clinical, pathological, and molecular genetic findings on WHO grades II and III oligodendrogliomas and oligoastrocytomas.