Isocitrate dehydrogenase mutation is associated with tumor location and magnetic resonance imaging characteristics in astrocytic neoplasms

MRI Features and IDH Mutational Status of Grade II Diffuse Gliomas: Impact on Diagnosis and Prognosis

OBJECTIVE

Grade II diffuse gliomas (DGs) with isocitrate dehydrogenase (IDH) mutations are associated with better prognosis than their IDH wild-type counterparts. We sought to determine the MRI characteristics associated with IDH mutational status and ascertain whether MRI considered in combination with IDH mutational status can better predict the clinical outcomes of grade II DGs.

MATERIALS AND METHODS

Preoperative MRI examinations were retrospectively studied for qualitative tumor characteristics, including location, extent, cortical involvement, margin sharpness, cystic component, mineralization or hemorrhage, and contrast enhancement. Quantitative diffusion and perfusion metrics were also assessed. Logistic regression and ROC analyses were used to evaluate the relationship between MRI features and IDH mutational status. The association between IDH mutational status, 1p19q codeletion, MRI features, extent of resection, and clinical outcomes was assessed by Kaplan-Meier and Cox proportional hazards models.

RESULTS

Of 100 grade II DGs, 78 were IDH mutant and 22 were IDH wild type. IDH wild-type tumors were associated with older age, multifocality, brainstem involvement, lack of cystic change, and a lower apparent diffusion coefficient (ADC). Multivariable regression showed that age older than 45 years as well as low minimum ADC (ADC_min), mean ADC, and maximum ADC values were independently associated with IDH mutational status. Of these, an ADC_min threshold of 0.9 × 10^-3 mm²/s or less provided the greatest sensitivity and specificity (91% and 76%, respectively) in defining IDH wild-type grade II DGs. Combining low ADC_min with IDH wild-type status conferred worse outcomes than did IDH wild-type status alone.

CONCLUSION

IDH wild-type grade II DGs are associated with a lower ADC and poor clinical outcomes. Combining IDH mutational status and ADC may allow more accurate prediction of clinical outcomes for patients with grade II DGs.

Imaging correlates for the 2016 update on WHO classification of grade II/III gliomas: implications for IDH, 1p/19q and ATRX status

The 2016 World Health Organization Classification of Tumors of the Central Nervous System incorporates the use of molecular information into the classification of brain tumors, including grade II and III gliomas, providing new prognostic information that cannot be delineated based on histopathology alone. We hypothesized that these genomic subgroups may also have distinct imaging features. A retrospective single institution study was performed on 40 patients with pathologically proven infiltrating WHO grade II/III gliomas with a pre-treatment MRI and molecular data on IDH, chromosomes 1p/19q and ATRX status. Two blinded Neuroradiologists qualitatively assessed MR features. The relationship between each parameter and molecular subgroup (IDH-wildtype; IDH-mutant-1p/19q codeleted-ATRX intact; IDH-mutant-1p/19q intact-ATRX loss) was evaluated with Fisher's exact test. Progression free survival (PFS) was also analyzed. A border that could not be defined on FLAIR was most characteristic of IDH-wildtype tumors, whereas IDH-mutant tumors demonstrated either well-defined or slightly ill-defined borders (p = 0.019). Degree of contrast enhancement and presence of restricted diffusion did not distinguish molecular subgroups. Frontal lobe predominance was associated with IDH-mutant tumors (p = 0.006). The IDH-wildtype subgroup had significantly shorter PFS than the IDH-mutant groups (p < 0.001). No differences in PFS were present when separating by tumor grade. FLAIR border patterns and tumor location were associated with distinct molecular subgroups of grade II/III gliomas. These imaging features may provide fundamental prognostic and predictive information at time of initial diagnostic imaging.

MR Imaging Characteristics Associate with Tumor-Associated Macrophages in Glioblastoma and Provide an Improved Signature for Survival Prognostication

BACKGROUND AND PURPOSE

In glioblastoma, tumor-associated macrophages have tumor-promoting properties. This study determined whether routine MR imaging features could predict molecular subtypes of glioblastoma that differ in the content of tumor-associated macrophages.

MATERIALS AND METHODS

Seven internally derived MR imaging features were assessed in 180 patients, and 25 features from the Visually AcceSAble Rembrandt Images feature set were assessed in 164 patients. Glioblastomas were divided into subtypes based on the telomere maintenance mechanism: alternative lengthening of telomeres positive (ALT+) and negative (ALT-) and the content of tumor-associated macrophages (with [M+] or without [M-] a high content of macrophages). The 3 most frequent subtypes (ALT+/M-, ALT-/M+, and ALT-/M-) were correlated with MR imaging features and clinical parameters. The fourth group (ALT+/M+) did not have enough cases for correlation with MR imaging features.

RESULTS

Tumors with a regular margin and those lacking a fungating margin, an expansive T1/FLAIR ratio, and reduced ependymal extension were more frequent in the subgroup of ALT+/M- (P < .05). Radiologic necrosis, lack of cystic component (by both criteria), and extensive peritumoral edema were more frequent in ALT-/M+ tumors (P < .05). Multivariate testing with a Cox regression analysis found the cystic imaging feature was additive to tumor subtype, and O6-methylguanine methyltransferase (MGMT) status to predict improved patient survival (P < .05).

CONCLUSIONS

Glioblastomas with tumor-associated macrophages are associated with routine MR imaging features consistent with these tumors being more aggressive. Inclusion of cystic change with molecular subtypes and MGMT status provided a better estimate of survival.

Residual Convolutional Neural Network for the Determination of IDH Status in Low- and High-Grade Gliomas from MR Imaging

Purpose: Isocitrate dehydrogenase (IDH) mutations in glioma patients confer longer survival and may guide treatment decision making. We aimed to predict the IDH status of gliomas from MR imaging by applying a residual convolutional neural network to preoperative radiographic data.Experimental Design: Preoperative imaging was acquired for 201 patients from the Hospital of University of Pennsylvania (HUP), 157 patients from Brigham and Women's Hospital (BWH), and 138 patients from The Cancer Imaging Archive (TCIA) and divided into training, validation, and testing sets. We trained a residual convolutional neural network for each MR sequence (FLAIR, T2, T1 precontrast, and T1 postcontrast) and built a predictive model from the outputs. To increase the size of the training set and prevent overfitting, we augmented the training set images by introducing random rotations, translations, flips, shearing, and zooming.Results: With our neural network model, we achieved IDH prediction accuracies of 82.8% (AUC = 0.90), 83.0% (AUC = 0.93), and 85.7% (AUC = 0.94) within training, validation, and testing sets, respectively. When age at diagnosis was incorporated into the model, the training, validation, and testing accuracies increased to 87.3% (AUC = 0.93), 87.6% (AUC = 0.95), and 89.1% (AUC = 0.95), respectively.Conclusions: We developed a deep learning technique to noninvasively predict IDH genotype in grade II-IV glioma using conventional MR imaging using a multi-institutional data set. Clin Cancer Res; 24(5); 1073-81. ©2017 AACR.

IDH1 status is significantly different between high-grade thalamic and superficial gliomas

BACKGROUND

While major progress has been made in diagnosis and treatment of gliomas based on molecules, molecular features of thalamic glioma have rarely been reported till now.

OBJECTIVE

IDH1 mutation is important for prognosis of gliomas and represents a distinctive category of glioma. We intended to survey specific molecular abnormalities in high-grade thalamic gliomas (WHO III-IV).

METHODS

We collected data of 50 and 93 newly diagnosed high-grade thalamic and superficial glioma patients respectively and conducted a comparative analysis of molecular characteristics between them. We analyzed expressions of molecules as follow: IDH1/2, P53, Ki-67, ATRX, PTEN, MMP9 and MGMT by Immunohistochemistry (IHC). Direct gene sequencing was performed to test the IDH1(R 132H) mutation.

RESULTS

We found a significant difference of IDH1 mutation between those high-grade gliomas, with 92% (46/50) of the thalamic tumors and 71% (66/93) of the superficial gliomas showing IDH1 wild-type (p= 0.004). It also showed that IDH1 mutation in superficial glioblastomas 18.6% (13/70) occurred more than thalamic glioblastomas 2.6% (1/39) (p= 0.017). As to high-grade superficial gliomas, there were 26 patients with IDH1 mutation, which contained 7, 13, and 6 high, moderate and low Ki-67 expression gliomas, respectively. The IDH1 wild-type group (62 patients), was composed of 29, 30, and 3 high, moderate and low Ki-67 expression gliomas, respectively. There was a significant distinction between the IDH1 mutation and Ki-67 expressions (p= 0.024). We also noted that the occurrence of low Ki-67 expressions 23.1% (6/26) in IDH1 mutation group was outnumbered than IDH1 wild-type group 4.8% (3/62) (p= 0.018). In addition, we found PTEN negative correlated with MMP9 negative in thalamic high-grade gliomas, whereas no such difference was found in superficial gliomas (p= 0.016).

CONCLUSION

The rare occurrence of IDH1 mutant high-grade thalamic gliomas strongly suggested that the high-grade thalamic glioma is another distinct tumor entity as compared to the high-grade superficial gliomas.

The impact of adjuvant therapy for patients with high-risk diffuse WHO grade II glioma

Despite recent randomized, prospective evidence supporting use of RT and chemotherapy (CRT) for high-risk low-grade gliomas (LGG), many patients have historically received RT alone, chemotherapy alone or observation postoperatively. The purpose of this study is to evaluate outcomes for historical treatments in comparison to CRT for high-risk diffuse WHO grade II glioma patients. Records from 309 adults with WHO grade II glioma (1997-2008) eligible for RTOG 9802 (incomplete resection/biopsy or age ≥40 years) were retrospectively reviewed. Kaplan-Meier estimates were used for progression-free survival (PFS) and overall survival (OS). The Cox proportional hazards model was used for estimates of risk ratios for univariate and multivariate analyses. Median follow-up was 10.6 years. Adjuvant treatments included radiotherapy (RT) alone (45%), observation (31%), CRT (21%) and chemotherapy alone (3%). Non-astrocytic histology, TERT promoter mutation, 1p/19q codeletion and extensive resections were associated with improved PFS and OS on univariate analysis (all p < 0.05). IDH mutations and adjuvant CRT was associated with improved PFS (all p < 0.05). On multivariate analysis, histology, molecular grouping and extent of resection were significantly associated with PFS and OS. In addition, multivariate analysis revealed that CRT was associated with improved PFS and OS compared with RT alone, and improved PFS compared with observation. This study confirms the benefit of adding chemotherapy to RT compared with RT alone or observation. These findings emphasize the need for aggressive treatment in patients with high-risk LGG.

Imaging Correlates of Adult Glioma Genotypes

Primary brain tumors, most commonly gliomas, are histopathologically typed and graded as World Health Organization (WHO) grades I-IV according to increasing degrees of malignancy. These grades provide prognostic information and guidance on treatment such as radiation therapy and chemotherapy after surgery. Despite the confirmed value of the WHO grading system, results of a multitude of studies and prospective interventional trials now indicate that tumors with identical morphologic criteria can have highly different outcomes. Molecular markers can allow subtypes of tumors of the same morphologic type and WHO grade to be distinguished and are, therefore, of great interest in personalization of brain tumor treatment. Recent genomic-wide studies have resulted in a far more comprehensive understanding of the genomic alterations in gliomas and provide suggestions for a new molecularly based classification. Magnetic resonance (MR) imaging phenotypes can serve as noninvasive surrogates for tumor genotypes and can provide important information for diagnosis, prognosis, and, eventually, personalized treatment. The newly emerged field of radiogenomics allows specific MR imaging phenotypes to be linked with gene expression profiles. In this article, the authors review the conventional and advanced imaging features of three tumoral genotypes with prognostic and therapeutic consequences: (a) isocitrate dehydrogenase mutation; (b) the combined loss of the short arm of chromosome 1 and the long arm of chromosome 19, or 1p19q codeletion; and (c) methylguanine methyltransferase promoter methylation. ^© RSNA, 2017.

T2-FLAIR Mismatch, an Imaging Biomarker for IDH and 1p/19q Status in Lower-grade Gliomas: A TCGA/TCIA Project

Purpose: Lower-grade gliomas (WHO grade II/III) have been classified into clinically relevant molecular subtypes based on IDH and 1p/19q mutation status. The purpose was to investigate whether T2/FLAIR MRI features could distinguish between lower-grade glioma molecular subtypes.Experimental Design: MRI scans from the TCGA/TCIA lower grade glioma database (n = 125) were evaluated by two independent neuroradiologists to assess (i) presence/absence of homogenous signal on T2WI; (ii) presence/absence of "T2-FLAIR mismatch" sign; (iii) sharp or indistinct lesion margins; and (iv) presence/absence of peritumoral edema. Metrics with moderate-substantial agreement underwent consensus review and were correlated with glioma molecular subtypes. Somatic mutation, DNA copy number, DNA methylation, gene expression, and protein array data from the TCGA lower-grade glioma database were analyzed for molecular-radiographic associations. A separate institutional cohort (n = 82) was analyzed to validate the T2-FLAIR mismatch sign.Results: Among TCGA/TCIA cases, interreader agreement was calculated for lesion homogeneity [κ = 0.234 (0.111-0.358)], T2-FLAIR mismatch sign [κ = 0.728 (0.538-0.918)], lesion margins [κ = 0.292 (0.135-0.449)], and peritumoral edema [κ = 0.173 (0.096-0.250)]. All 15 cases that were positive for the T2-FLAIR mismatch sign were IDH-mutant, 1p/19q non-codeleted tumors (P < 0.0001; PPV = 100%, NPV = 54%). Analysis of the validation cohort demonstrated substantial interreader agreement for the T2-FLAIR mismatch sign [κ = 0.747 (0.536-0.958)]; all 10 cases positive for the T2-FLAIR mismatch sign were IDH-mutant, 1p/19q non-codeleted tumors (P < 0.00001; PPV = 100%, NPV = 76%).Conclusions: Among lower-grade gliomas, T2-FLAIR mismatch sign represents a highly specific imaging biomarker for the IDH-mutant, 1p/19q non-codeleted molecular subtype. Clin Cancer Res; 23(20); 6078-85. ©2017 AACR.

Predicting IDH mutation status in grade II gliomas using amide proton transfer-weighted (APTw) MRI

PURPOSE

To assess the amide proton transfer-weighted (APTw) MRI features of isocitrate dehydrogenase (IDH)-wildtype and IDH-mutant grade II gliomas and to test the hypothesis that the APTw signal is a surrogate imaging marker for identifying IDH mutation status preoperatively.

METHODS

Twenty-seven patients with pathologically confirmed low-grade glioma, who were previously scanned at 3T, were retrospectively analyzed. The Mann-Whitney test was used to evaluate relationships between APTw intensities for IDH-mutant and IDH-wildtype groups, and receiver operator characteristic (ROC) analysis was used to assess the diagnostic performance of APTw.

RESULTS

Based on histopathology and molecular analysis, seven cases were diagnosed as IDH-wildtype grade II gliomas and 20 cases as IDH-mutant grade II gliomas. The maximum and minimum APTw values, based on multiple regions of interest, as well as the whole-tumor histogram-based mean and 50th percentile APTw values, were significantly higher in the IDH-wildtype gliomas than in the IDH-mutant groups. This corresponded to the areas under the ROC curves of 0.89, 0.76, 0.75, and 0.75, respectively, for the prediction of the IDH mutation status.

CONCLUSION

IDH-wildtype lesions typically were associated with relatively high APTw signal intensities as compared with IDH-mutant lesions. The APTw signal could be a valuable imaging biomarker by which to identify IDH1 mutation status in grade II gliomas. Magn Reson Med 78:1100-1109, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

[Clinical, immunohistochemical, and molecular genetic prognostic factors in adult patients with glioblastoma]

Glioblastoma is the most common primary malignant glial tumor of the brain in adult patients.

AIM

to define the prognostic value of isocitrate dehydrogenase-1 (IDH-1) mutation and methylguanine-DNA methyltransferase (MGMT) methylation status in patients with glioblastoma (GB) and to analyze the impact of clinical data (gender, age, and tumor site), histological variants of the tumor structure, and time to development of recurrences on the course of the disease.

SUBJECTS AND METHODS

The investigation enrolled 63 GB patients aged 18 to 71 years who had received combined treatment (surgery, chemo- and radiotherapy) at the N.I. Burdenko Research Institute of Neurosurgery, Ministry of Health of the Russian Federation, in the period 2008 to 2011. The investigators performed a morphological examination of all tumor tissue samples and an immunohistochemical examination using anti-IDH-1 R-132 antibody clone («Dianova», Germany) and defined MGMT methylation status by a polymerase chain reaction using the CpGenome DNA Modification Kit («Chemicon International», USA). The data were statistically processed using a package of Statistica 6.0 programs.

RESULTS

Patient age, time to development of recurrent glioblastoma, mutations in the IDH-1 gene and MGMT were found to be prognostic factors for overall survival among adult patients in this category.

CONCLUSION

Analysis of clinical findings and identification of molecular genetic aberrations in the tumor cells will be able to elaborate an individual approach to treating patients with glioblastoma in order to increase their survival rates and to improve quality of life.

Genetically Defined Oligodendroglioma Is Characterized by Indistinct Tumor Borders at MRI

BACKGROUND AND PURPOSE

In 2016, the World Health Organization revised the brain tumor classification, making IDH mutation and 1p/19q codeletion the defining features of oligodendroglioma. To determine whether imaging characteristics previously associated with oligodendroglial tumors are still applicable, we evaluated the MR imaging features of genetically defined oligodendrogliomas.

MATERIALS AND METHODS

One hundred forty-eight adult patients with untreated World Health Organization grade II and III infiltrating gliomas with histologic oligodendroglial morphology, known 1p/19q status, and at least 1 preoperative MR imaging were retrospectively identified. The association of 1p/19q codeletion with tumor imaging characteristics and ADC values was evaluated.

RESULTS

Ninety of 148 (61%) patients had 1p/19q codeleted tumors, corresponding to genetically defined oligodendroglioma, and 58/148 (39%) did not show 1p/19q codeletion, corresponding to astrocytic tumors. Eighty-three of 90 (92%) genetically defined oligodendrogliomas had noncircumscribed borders, compared with 26/58 (45%) non-1p/19q codeleted tumors with at least partial histologic oligodendroglial morphology (P < .0001). Eighty-nine of 90 (99%) oligodendrogliomas were heterogeneous on T1- and/or T2-weighted imaging. In patients with available ADC values, a lower mean ADC value predicted 1p/19q codeletion (P = .0005).

CONCLUSIONS

Imaging characteristics of World Health Organization 2016 genetically defined oligodendrogliomas differ from the previously considered characteristics of morphologically defined oligodendrogliomas. We found that genetically defined oligodendrogliomas were commonly poorly circumscribed and were almost always heterogeneous in signal intensity.

[The spectrum of genetic alterations in anaplastic gliomas: and anaplastic oligodendrogliomas]

The work explores the molecular genetic features of anaplastic astrocytomas and oligodendrogliomas in a series of 43 cases. The mutational status was studied using domestic chemicals and reagent kits. We revealed clear genetic differences between astrocytic and oligodendroglial tumors and proposed an algorithm to study diagnostic and prognostic markers.

Multimodal MRI features predict isocitrate dehydrogenase genotype in high-grade gliomas

BACKGROUND

High-grade gliomas with mutations in the isocitrate dehydrogenase (IDH) gene family confer longer overall survival relative to their IDH-wild-type counterparts. Accurate determination of the IDH genotype preoperatively may have both prognostic and diagnostic value. The current study used a machine-learning algorithm to generate a model predictive of IDH genotype in high-grade gliomas based on clinical variables and multimodal features extracted from conventional MRI.

METHODS

Preoperative MRIs were obtained for 120 patients with primary grades III (n = 35) and IV (n = 85) glioma in this retrospective study. IDH genotype was confirmed for grade III (32/35, 91%) and IV (22/85, 26%) tumors by immunohistochemistry, spectrometry-based mutation genotyping (OncoMap), or multiplex exome sequencing (OncoPanel). IDH1 and IDH2 mutations were mutually exclusive, and all mutated tumors were collapsed into one IDH-mutated cohort. Cases were randomly assigned to either the training (n = 90) or validation cohort (n = 30). A total of 2970 imaging features were extracted from pre- and postcontrast T1-weighted, T2-weighted, and apparent diffusion coefficient map. Using a random forest algorithm, nonredundant features were integrated with clinical data to generate a model predictive of IDH genotype.

RESULTS

Our model achieved accuracies of 86% (area under the curve [AUC] = 0.8830) in the training cohort and 89% (AUC = 0.9231) in the validation cohort. Features with the highest predictive value included patient age as well as parametric intensity, texture, and shape features.

CONCLUSION

Using a machine-learning algorithm, we achieved accurate prediction of IDH genotype in high-grade gliomas with preoperative clinical and MRI features.

Association of The IDH1 C.395G>A (R132H) Mutation with Histological Type in Malay Brain Tumors

Background:

Brain tumors, constituting one of the most deadly forms of cancer worldwide, result from the accumulation of multiple genetic and epigenetic alterations in genes and signaling pathways. Isocitrate dehydrogenase enzyme isoform 1 (IDH1) mutations are frequently identified in primary brain tumors and acute myeloid leukemia. Studies on IDH1 gene mutations have been extensively performed in various populations worldwide but not in Malaysia. This work was conducted to study the prevalence of IDH1 c.395G>A (R132H) hotspot mutations in a group of Malaysian patients with brain tumors in order to gain local data for the IDH1 mutation profile in our population.

Methods:

Mutation analysis of c.395G>A (R132H) of IDH1 was performed in 40 brain tumor specimens by the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) and then verified by direct sequencing. Associations between the IDH1 c.395G>A (R132H) mutation and clinicopathologic characteristics were also analyzed.

Results:

The IDH1 c.395G>A (R132H) mutation was detected in 14/40 patients (35%). A significant association was found with histological tumor types, but not with age, gender and race.

Conclusions:

IDH1 is frequently mutated and associated with histological subtypes in Malay brain tumors.

Frontal glioblastoma multiforme may be biologically distinct from non-frontal and multilobar tumors

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults and carries a grim prognosis. Lobar GBM, notably those localized to the frontal lobe, are generally more amenable to complete surgical resection, and may carry a better prognosis. The biology of differently localized GBM has been reported scarcely in terms of prognostic markers, including isocitrate dehydrogenase 1 (IDH1) mutation and O(6)-methylguanine-methyltransferase (MGMT) methylation. To our knowledge, there has been no evaluation in the literature of different proliferation indexes in different GBM locations in the brain. We performed a retrospective evaluation of our prospectively collected database to assess the rate of IDH1 positivity, MGMT methylation and Ki67 index for GBM located in the frontal lobes alone, lobar GBM in other supra-tentorial lobes and multilobar GBM. IDH1 mutated tumors were localized in the frontal lobes in 50.0%, whereas only 20.3% of IDH1 wild-type tumors were localized in the frontal lobe (p=0.006); MGMT methylated tumors were localized in the frontal lobe in 32.0% of the cases. Only 13.75% of the MGMT unmethylated tumors were localized to the frontal lobe (p=0.005); Tumors with higher Ki67 proliferation index were more likely to be localized in the frontal lobe (40.6% vs. 19.5%, p=0.019). This is the largest cohort of GBM assessed for these purposes in the literature. Frontal lobe GBMs may be intrinsically biologically distinct from GBM in other lobes and from multilobar tumors.

IDH1 mutation may not be prognostically favorable in glioblastoma when controlled for tumor location: A case-control study

Isocitrate dehydrogenase 1 (IDH1) mutation is a known prognostic factor in glioblastoma multiforme (GBM). It has been well documented that patients with IDH1 mutant (IDH1-mu) GBM have a better outcome compared to patients with IDH1 wild-type (IDH1-WT) GBM. IDH1-mu tumors have been shown to be more commonly located in the frontal lobe, and less likely to be in multiple lobes. It is unclear whether differential location is part of the prognostically favorable profile of these tumors. We performed a case-control study, matching IDH1-mu GBMs to IDH1-WT GBMs that are controlled for age, sex and tumor location. There were 21 IDH1-mu tumors and 21 matched IDH1-WT tumors. Age, sex and tumor location were matched between the two groups. After controlling for the factors described, the IDH1-mu tumors were more likely to be secondary GBM (61.9% secondary vs. 14.3%, p=0.004). There was an insignificant trend towards smaller tumor volume in the IDH1-mu group (28.13±6.56 vs. 41.8±7.33 cm³, p=0.173). Extent of surgical resection was similar in both groups (mean 84.49% vs. 89.89%, p=0.419). There was no survival advantage for IDH1-mu tumors when controlled for location: 25.2months overall survival for IDH1-mu patients and 23.6 for IDH1-WT patients, p=0.794. IDH1 mutation may provide part of its prognostic significance by differential localization of tumor, both making IDH1-mu tumors more amenable to gross total resection and placing these tumors in less eloquent areas, thereby lowering neurological morbidity.

IDH mutations may not preclude distant, trans-tentorial spread in gliomas: a case report and review of the literature

Background

IDH mutations have been demonstrated to confer prolonged survival in patients suffering from gliomas, but the mechanisms underlying the improved prognosis are unclear. While some studies have attributed these observations to an enhanced sensitivity to genotoxic therapies, others have postulated that IDH-mutated gliomas exhibit less aggressive intrinsic biological behavior, including the propensity to invade distant sites. Although most gliomas recur local to the site of initial presentation, some tumors demonstrate distant recurrence, the vast majority of which involve the contralateral hemisphere. Trans-tentorial spread has been described once before, in which a supratentorial glioblastoma was reported to recur infratentorially in the cerebellum.

Case presentation

We describe a patient who underwent surgical resection, followed by adjuvant radiation and temozolomide of a World Health Organization (WHO) III anaplastic astrocytoma in the right temporal lobe, exhibiting an IDH1 (R132H) mutation. Twenty-two months after surgery, he developed a second lesion, located in the right cerebellum, suspicious for recurrent tumor versus radiation necrosis. A second surgery was performed, and pathology demonstrated recurrent tumor, consistent with IDH1-mutated anaplastic astrocytoma.

Conclusions

This is the first example of trans-tentorial spread in an IDH-mutated glioma, suggesting that despite improved survival, IDH mutations may not preclude gliomas from exhibiting the ability to invade distant sites of the brain.

Neuroimaging

Imaging is integral to the management of patients with brain tumors. Conventional structural imaging provides exquisite anatomic detail but remains limited in the evaluation of molecular characteristics of intracranial neoplasms. Quantitative and physiologic biomarkers derived from advanced imaging techniques have been increasingly utilized as problem-solving tools to identify glioma grade and assess response to therapy. This chapter provides a comprehensive overview of the imaging strategies used in the clinical assessment of patients with gliomas and describes how novel imaging biomarkers have the potential to improve patient management.

Anatomical specificity of vascular endothelial growth factor expression in glioblastomas: a voxel-based mapping analysis

INTRODUCTION

The expression of vascular endothelial growth factor (VEGF) is a common genetic alteration in malignant gliomas and contributes to the angiogenesis of tumors. This study aimed to investigate the anatomical specificity of VEGF expression levels in glioblastomas using voxel-based neuroimaging analysis.

METHODS

Clinical information, MR scans, and immunohistochemistry stains of 209 patients with glioblastomas were reviewed. All tumor lesions were segmented manually and subsequently registered to standard brain space. Voxel-based regression analysis was performed to correlate the brain regions of tumor involvement with the level of VEGF expression. Brain regions identified as significantly associated with high or low VEGF expression were preserved following permutation correction.

RESULTS

High VEGF expression was detected in 123 (58.9 %) of the 209 patients. Voxel-based statistical analysis demonstrated that high VEGF expression was more likely in tumors located in the left frontal lobe and the right caudate and low VEGF expression was more likely in tumors that occurred in the posterior region of the right lateral ventricle.

CONCLUSION

Voxel-based neuroimaging analysis revealed the anatomic specificity of VEGF expression in glioblastoma, which may further our understanding of genetic heterogeneity during tumor origination. This finding provides primary theoretical support for potential future application of customized antiangiogenic therapy.

Radiological features combined with IDH1 status for predicting the survival outcome of glioblastoma patients

BACKGROUND

Radiological characteristics may reflect the biological features of brain tumors and may be associated with genetic alterations that occur in tumorigenesis. This study aimed to investigate the relationship between radiological features and IDH1 status as well as their predictive value for survival of glioblastoma patients.

METHODS

The clinical information and MR images of 280 patients with histologically confirmed glioblastoma were retrospectively reviewed. The radiological characteristics of tumors were examined on MR images, and the IDH1 status was determined using DNA sequencing for all cases. The Kaplan-Meier method and Cox regression model were used to identify prognostic factors for progression-free and overall survival.

RESULTS

The IDH1 mutation was associated with longer progression-free survival (P = .022; hazard ratio, 0.602) and overall survival (P = .018; hazard ratio, 0.554). In patients with the IDH1 mutation, tumor contrast enhancement and peritumoral edema indicated worse progression-free survival (P = .015 and P = .024, respectively) and worse overall survival (P = .024 and P = .032, respectively). For tumors with contrast enhancement, multifocal contrast enhancement of the tumor lesion was associated with poor progression-free survival (P = .002) and poor overall survival (P = .010) in patients with wild-type IDH1 tumors.

CONCLUSIONS

Combining the radiological features and IDH1 status of a tumor allows more accurate prediction of survival outcomes in glioblastoma patients. The complementary roles of genetic changes and radiological features of tumors should be considered in future studies.

TERT promoter mutated WHO grades II and III gliomas are located preferentially in the frontal lobe and avoid the midline

The promoter region of telomerase reverse transcriptase (TERTp) and isocitrate dehydrogenase (IDH) have been regarded as biomarkers with distinct clinical and phenotypic features. Investigated the possible correlations between tumor location and genetic alterations would enhance our understanding of gliomagenesis and heterogeneity of glioma. We examined mutations of TERTp and IDH by direct sequencing and fluorescence in-situ hybridization in a cohort of 225 grades II and III diffuse gliomas. Correlation analysis between molecular markers and tumor locations was performed by Chi-square tests/Fisher's exact test and multivariate logistic regression analysis. We found gliomas in frontal lobe showed higher frequency of TERTp mutation (P=0.0337) and simultaneously mutations of IDH and TERTp (IDH (mut)-TERTp(mut)) (P=0.0281) than frequency of biomarkers mutation of tumors in no-Frontal lobes, while lower frequency of TERTp mutation (P<0.0001) and simultaneously wild type of IDH and TERTp (IDH (wt)-TERTp(wt)) (P<0.0001) in midline than no-midline lobes. Logistic regression analysis indicated that locations of tumors associated with TERTp mutation (OR=0.540, 95% CI 0.324-0.900, P=0.018) and status of combinations of IDH and TERTp (IDH (mut)-TERTp (mut) vs. IDH (wt)-TERTp (wt) OR=0.162, 95% CI 0.075-0.350, P<0.001). In conclusion, grades II and III gliomas harboring TERTp mutation were located preferentially in the frontal lobe and rarely in midline. Association of IDH-TERTp status and tumor location suggests their potential values in molecular classification of grades II and III gliomas.

Patterns of Tumor Contrast Enhancement Predict the Prognosis of Anaplastic Gliomas with IDH1 Mutation

BACKGROUND AND PURPOSE

It is proposed that isocitrate dehydrogenase 1 (IDH1) mutation predicts the outcome in patients with high-grade glioma. In addition, contrast enhancement on preoperative MR imaging reflects tumor biologic features. Patients with anaplastic glioma with the IDH1 mutation were evaluated by using MR imaging to determine whether tumor enhancement is a prognostic factor and can be used to predict survival.

MATERIALS AND METHODS

A cohort of 216 patients with histologically confirmed anaplastic glioma was reviewed retrospectively. Tumor contrast-enhancement patterns were classified on the basis of preoperative T1 contrast MR images. Tumor IDH1 status was examined by using RNA sequencing. We used univariate analysis and the multivariate Cox model to evaluate the prognostic value of the IDH1 mutation and tumor contrast-enhancement pattern for progression-free survival and overall survival.

RESULTS

In all 216 patients, IDH1 mutation was associated with longer progression-free survival (P = .004, hazard ratio = 0.439) and overall survival (P = .002, hazard ratio = 0.406). For patients with IDH1 mutant anaplastic glioma, the absence of contrast enhancement was associated with longer progression-free survival (P = .038, hazard ratio = 0.473) and overall survival (P = .043, hazard ratio = 0.436). Furthermore, we were able to stratify the progression-free survival and overall survival of patients with IDH1 mutation by using the tumor contrast-enhancement patterns (P = .022 and 0.029, respectively; log-rank).

CONCLUSIONS

Tumor enhancement on postcontrast MR imaging is a valuable prognostic factor for patients with anaplastic glioma and IDH1 mutation. Furthermore, the contrast-enhancement patterns could potentially be used to stratify the survival outcome of such patients.

Genomic predictors of patterns of progression in glioblastoma and possible influences on radiation field design

We present a retrospective investigation of the role of genomics in the prediction of central versus marginal disease progression patterns for glioblastoma (GBM). Between August 2000 and May 2010, 41 patients with GBM and gene expression and methylation data available were treated with radiotherapy with or without concurrent temozolomide. Location of disease progression was categorized as within the high dose (60 Gy) or low dose (46 Gy) volume. Samples were grouped into previously described TCGA genomic groupings: Mesenchymal (m), classical (c), proneural (pn), and neural (n); and were also classified by MGMT-Methylation status and G-Cimp methylation phenotype. Genomic groupings and methylation status were investigated as a possible predictor of disease progression in the high dose region, progression in the low dose region, and time to progression. Based on TCGA category there was no difference in OS (p = 0.26), 60 Gy progression (PN: 71 %, N: 60 %, M: 89 %, C: 83 %, p = 0.19), 46 Gy progression (PN: 57 %, N: 40 %, M: 61 %,C: 50 %, p = 0.8) or time to progression (PN: 9 months, N:15 months, M: 9 months, C: 7 months, p = 0.58). MGMT methylation predicted for improved OS (median 25 vs. 13 months, p = 0.01), improved DFS (median 13 vs. 8 months, p = 0.007) and decreased 60 Gy (p = 0.003) and 46 Gy (p = 0.006) progression. There was a cohort of MGMT methylated patients with late marginal disease progression (4/22 patients, 18 %). TCGA groups demonstrated no difference in survival or progression patterns. MGMT methylation predicted for a statistically significant decrease in in-field and marginal disease progression. There was a cohort of MGMT methylated patients with late marginal progression. Validations of these findings would have implications that could affect radiation field size.

Identifying the association of contrast enhancement with vascular endothelia growth factor expression in anaplastic gliomas: a volumetric magnetic resonance imaging analysis

Contrast enhancement is a crucial radiologic feature of malignant brain tumors, which are associated with genetic changes of the tumor. The purpose of the current study was to investigate the potential relationship among tumor contrast enhancement with MR imaging, vascular endothelial growth factor (VEGF) expression, and survival outcome in anaplastic gliomas. MR images from 240 patients with histologically confirmed anaplastic gliomas were retrospectively analyzed. The volumes of T2 hyperintense, contrast enhanced regions and necrotic regions on postcontrast T1-weighted images were measured. The ratio of the enhanced volume to necrotic volume was compared between patients with high versus low levels of VEGF expression and was further used in the survival analysis. The volumetric ratio of enhancement to necrosis was significantly higher in patients with low VEGF expression than in those with high VEGF expression (Mann-Whitney, p = 0.009). In addition, the enhancement/necrosis ratio was identified as a significant predictor of progression-free survival (Cox regression model, p = 0.004) and overall survival (Cox regression model, p = 0.006) in the multivariate analysis. These results suggest that the volumetric ratio of enhancement to necrosis could serve as a noninvasive radiographic marker associated with VEGF expression and that this ratio is an independent predictor for progression-free survival and overall survival in patients with anaplastic gliomas.

Association between molecular alterations and tumor location and MRI characteristics in anaplastic gliomas

The aim of this study was to determine if molecular alterations are associated with tumor location and radiological characteristics in anaplastic gliomas. We performed a retrospective analysis of 122 anaplastic gliomas for molecular alterations (IDH1/2 mutations, TP53 mutations, and 1p19q co-deletion) to compare MRI features (location and image characteristics). We observed that IDH mutation is strongly associated with frontal location (P = 0.001). However, 13 tumors not located in the cerebral cortex were IDH intact tumors (P < 0.0001). While IDH mutation and TP53 mutation are significantly associated with AA (p < 0.0001), IDH mutation and 1p19q co-deletion were significantly associated with AO/AOA (p < 0.0001). No tumors with IDH mutation and 1p19q co-deletion infiltrated the temporal lobe (P = 0.003). The tumors with 1p19q co-deletion and histologically diagnosed as AO/AOA were associated with contrast enhancement on MR images (p = 0.007, p = 0.002, respectively) and those with TP53 mutation had a weak association with sharp tumor borders (p = 0.043). MRI features might be useful to predict molecular profiles in anaplastic gliomas.