The role of imaging in the management of adults with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

Radiomics Strategy for Molecular Subtype Stratification of Lower-Grade Glioma: Detecting IDH and TP53 Mutations Based on Multimodal MRI

BACKGROUND

Noninvasive detection of isocitrate dehydrogenase (IDH) and TP53 mutations are meaningful for molecular stratification of lower-grade gliomas (LrGG).

PURPOSE

To explore potential MRI features reflecting IDH and TP53 mutations of LrGG, and propose a radiomics strategy for detecting them.

STUDY TYPE

Retrospective, radiomics.

POPULATION/SUBJECTS

A total of 103 LrGG patients were separated into development (n = 73) and validation (n = 30) cohorts.

FIELD STRENGTH/SEQUENCE

T₁ -weighted (before and after contrast-enhanced), T₂ -weighted, and fluid-attenuation inversion recovery images from 1.5T (n = 37) or 3T (n = 66) scanners.

ASSESSMENT

After data preprocessing, high-throughput features were derived from patients' volumes of interests of different sequences. The support vector machine-based recursive feature elimination (SVM-RFE) was adopted to find the optimal features for IDH and TP53 mutation detection. SVM models were trained and tested on development and validation cohort. The commonly used metric was used for assessing the efficiency.

STATISTICAL TESTS

One-way analysis of variance (ANOVA), chi-square, or Fisher's exact test were applied on clinical characteristics to confirm whether significant differences exist between three molecular subtypes decided by IDH and TP53 status. Intraclass correlation coefficients were calculated to assess the robustness of the radiomics features.

RESULTS

The constituent ratio of histopathologic subtypes was significantly different among three molecular subtypes (P = 0.017). SVM models for detecting IDH and TP53 mutation were established using 12 and 22 optimal features selected by SVM-RFE. The accuracies and area under the curves for IDH and TP53 mutations on the development cohort were 84.9%, 0.830, and 92.0%, 0.949, while on the validation cohort were 80.0%, 0.792, and 85.0%, 0.869, respectively. Furthermore, the stratified accuracies of three subtypes were 72.8%, 71.9%, and 70%, respectively.

DATA CONCLUSION

Using a radiomics approach integrating SVM model and multimodal MRI features, molecular subtype stratification of LGG patients was implemented through detecting IDH and TP53 mutations. The results suggested that the proposed approach has promising detecting efficiency and T₂ -weighted image features are more important than features from other images.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:916-926.

SEOM clinical guidelines for diagnosis and treatment of glioblastoma (2017)

Glioblastoma (GB) is the most common brain malignancy and accounts for over 50% of all high-grade gliomas. Radiotherapy (RT) with concomitant and adjuvant temozolomide (TMZ) chemotherapy is the current standard of care for patients with newly diagnosed GB up to age 70. Recently, a new standard of care has been adopted for elderly patients (≥ 65 years) based on short course of RT and TMZ. Several clinically relevant molecular markers that assist in diagnosis and prognosis have recently been identified. The treatment for recurrent GB is not well defined, and decision-making is usually based on prior strategies as well as several clinical and radiological factors. The presence of neurologic deficits and seizures can significantly impact quality of life.

Natural history of de novo high grade glioma: first description of growth parabola

Etiopathogenesis and physiopathology of gliomas are largely unknown. Recently, many authors have proved a strict correlation between the velocity of diametric expansion (VDE) on the magnetic resonance imaging (MRI) and the biological behavior of these tumors, especially in low grade gliomas (LGGs). Unfortunately, natural history of High Grade Gliomas (HGGs) has not been well clarified because of its fast progression, late diagnoses and early surgical intervention. We describe, for the first time to our knowledge, the case of asymptomatic patient with an incidentally discovered de novo HGG with a total of 17 months of follow-up. A male patient was referred to our consultation for routinely follow-up after meningioma resection 5 years before. He underwent MRI every year without any neuroradiological alterations. A new MRI image presented a non-enhancing lesion in the right temporal lobe with 3.55 cm of mean tumor diameter (MTD) and 35.6 mm/year of VDE. After two months interval, the lesion had 3.97 cm of MTD and 27.8 mm/year of VDE. Although we have strongly suggested surgical resection, patient have delayed the operation for personal issues. After other 3 months, the tumor showed enhancement with 4.5 of MTD and 17.4 mm/year of VDE. We speculate that the descending parabola is due to initial mass effect and hypoxia of the tumor core. We also underline the crucial role of the VDE determining, in order to predict the nature of the lesion and address the most effective treatment for each patient.

Brain Tumor Imaging

Modern imaging techniques, particularly functional imaging techniques that interrogate some specific aspect of underlying tumor biology, have enormous potential in neuro-oncology for disease detection, grading, and tumor delineation to guide biopsy and resection; monitoring treatment response; and targeting radiotherapy. This brief review considers the role of magnetic resonance imaging and spectroscopy, and positron emission tomography in these areas and discusses the factors that limit translation of new techniques to the clinic, in particular, the cost and difficulties associated with validation in multicenter clinical trials.

Assessment of accessibility to the diagnosis and treatment of brain tumors in Argentina: Preliminary results

Background:

As far as public health is concerned, brain tumors burden is significant despite their low incidence, because they comprise high direct costs (specific diagnostic resources, high complexity treatments, and rehabilitation) and high-unforeseen costs (labor leave, family, and social issues). Although the Argentine's Health System is supposed to provide healthcare to all the population, it would not guarantee equity of access for brain tumors treatment. In order to analyze this hypothesis we decided to carry out a survey to obtain data on access, availability and resources for tumor management in Argentina.

Methods:

An online questionnaire with eight dimensions and 29 queries was conducted addressing all professionals involved in tumor management. Two variables were generated: (1) type of medical center according to their financial support, and (2) the geographic region (GeoR). Analysis of association between these variables and the accessibility to different resources was performed with Chi-square and Fisher's exact test. Multivariate analyses through multiple logistic regression models were also tested.

Results:

One hundred and fourteen surveys were collected from 56 state-managed centers and 55 private/trade-union managed centers. Responders came from 15 provinces grouped into integrated GeoR. Results and analysis of each dimension were reported.

Conclusion:

The data obtained provides information about the accessibility to brain tumors treatment, exposing the unequal distribution of human and technologic resources in Argentina. This problem exceeds the limits of public health to become a bioethical problem. We think these results could be essentially associated to our health system fragmented structure, and the large geographical extension of our country. Finally, we believe that collaboration of professional associations working together with public and private sector authorities responsible for financial resources and logistic should bring a principle of solution.

Preoperative grading of supratentorial nonenhancing gliomas by high b-value diffusion-weighted 3 T magnetic resonance imaging

The purpose of this study was to determine the difference in discrimination between high- and low-grade supratentorial nonenhancing gliomas (HGGs and LGGs, respectively) when using apparent diffusion coefficient (ADC) values with high or standard b-value. Thirty-nine patients underwent conventional magnetic resonance imaging and diffusion-weighted imaging (DWI) with standard and high b-values (b = 1000 and 3000 s/mm², respectively). Minimum, maximum, and mean ADC values (ADC_MIN, ADC_MAX, and ADC_MEAN, respectively) were measured from ADC maps with both b-values. Receiver operating curve analysis was used to determine the cutoff ADC values for distinguishing between nonenhancing HGGs and LGGs. ADC_MIN, ADC_MAX, and ADC_MEAN values for the nonenhancing HGGs were lower than those for LGGs. These differences were much larger when a high b-value was used (all P < 0.0001) than when a standard b-value was used (P = 0.0001, <0.0001, and <0.0001, respectively). Discriminant analysis indicated that the greatest likelihood for discriminating HGGs and LGGs when ADC_MEAN was obtained with a high b-value, with cutoff value of 0.814 × 10^-3 mm²/s. ADC values obtained with a high b-value can be useful for grading and surgical management of nonenhancing HGGs and LGGs. The lowest degree of overlap was obtained when ADC_MEAN was determined with a b-value of 3000 s/mm².

Demonstration of DCE-MRI as an early pharmacodynamic biomarker of response to VEGF Trap in glioblastoma

Glioblastoma (GBM) is an incurable brain tumor characterized by the expression of pro-angiogenic cytokines. A recent phase II clinical trial studied VEGF Trap in adult patients with temozolomide-resistant GBM. We sought to explore changes in [¹⁸F]Fluorodeoxyglucose positron emission tomography (FDG-PET) or magnetic resonance imaging (MRI) in trial participants correlating these changes with disease response. FDG-PET and MRI images obtained before and after the first dose of VEGF Trap were spatially co-registered. Regions of interest on each image slice were combined to produce a volume of interest representative of the entire tumor. Percent and absolute changes in maximum FDG-avidity, mean apparent diffusion coefficient (ADC), K_trans, and Ve were calculated per lesion. Among the 12 participants that underwent dynamic contrast enhanced MRI (DCE-MRI), there were large, statistically significant reductions in K_trans and Ve (median difference = -41.8 %, p < 0.02 and -42.6 %, p < 0.04, respectively). In contrast, there were no significant reductions in ADC or FDG-PET SUVmax values. DCE-MRI is a useful measure of early pharmacodynamic effects of VEGF Trap on tumor vasculature. The absence of significant changes in FDG-PET and DW-MRI suggest that the early pharmacodynamic effects are specific to tumor perfusion and/or permeability and do not directly inhibit metabolism or induce cell death. DCE-MRI in conjunction with standard imaging may be promising for the identification of anti-angiogenic effects in this patient population with this therapeutic target. Further studies are needed to evaluate the relationship between DCE-MRI response and clinical outcome.