T2-weighted images are superior to other MR image types for the determination of diffuse intrinsic pontine glioma intratumoral heterogeneity

Identifying Subgroups with Rapid Tumor Growth Rate in Adult Pituitary Neuroendocrine Tumors: A Comprehensive Analysis of Clinical and Imaging Features

OBJECTIVE

To comprehensively investigate the clinical and imaging features associated with the tumor growth rate (TGR) of pituitary neuroendocrine tumors (PitNETs).

METHODS

The tumor volume was assessed using magnetic resonance imaging. The potential growth-related parameters were compared among different TGR subgroups. Logistic regression analysis and receiver operating characteristic curves were used to identify risk factors and evaluate their diagnostic accuracy for rapid TGR, respectively.

RESULTS

The study included 81 patients with PitNETs who met the inclusion criteria. Receiver operating characteristic curves were used to determine the optimal cut-off values for age and tumor volume at initial diagnosis. The factors significantly associated with rapid TGR were age <55 years, T2 heterogeneity, and Knosp grade ≥3 (P < 0.05). No significant differences were found among other clinical and imaging subgroups. Multivariate regression analysis confirmed that these factors increased the risk of rapid TGR (P < 0.05). The area under the curve for predicting rapid TGR using age <55 years, T2 heterogeneity, Knosp grade ≥3, and a combined model of these factors were 0.677 (95% confidence interval [CI], 0.564-0.777), 0.705 (95% CI, 0.593-0.801), 0.680 (95% CI, 0.567-0.780), and 0.834 (95% CI, 0.735-0908), respectively. Additionally, the expression of cell lineage-specific transcription factors and Ki-67 exhibited a significant correlation with age <55 years and T2 heterogeneity; however, no association was observed with Knosp grade.

CONCLUSIONS

The TGR of PitNETs is associated with age, T2 heterogeneity, and Knosp grade. Integrating these factors improves the accuracy of prediction for TGR. Therefore, understanding the TGR in PitNETs can provide valuable evidence for tailoring individualized treatment strategies for patients.

Pediatric diffuse intrinsic pontine glioma radiotherapy response prediction: MRI morphology and T2 intensity-based quantitative analyses

OBJECTIVES

An easy-to-implement MRI model for predicting partial response (PR) postradiotherapy for diffuse intrinsic pontine glioma (DIPG) is lacking. Utilizing quantitative T2 signal intensity and introducing a visual evaluation method based on T2 signal intensity heterogeneity, and compared MRI radiomic models for predicting radiotherapy response in pediatric patients with DIPG.

METHODS

We retrospectively included patients with brainstem gliomas aged ≤ 18 years admitted between July 2011 and March 2023. Applying Response Assessment in Pediatric Neuro-Oncology criteria, we categorized patients into PR and non-PR groups. For qualitative analysis, tumor heterogeneity vision was classified into four grades based on T2-weighted images. Quantitative analysis included the relative T2 signal intensity ratio (rT2SR), extra pons volume ratio, and tumor ring-enhancement volume. Radiomic features were extracted from T2-weighted and T1-enhanced images of volumes of interest. Univariate analysis was used to identify independent variables related to PR. Multivariate logistic regression was performed using significant variables (p < 0.05) from univariate analysis.

RESULTS

Of 140 patients (training n = 109, and test n = 31), 64 (45.7%) achieved PR. The AUC of the predictive model with extrapontine volume ratio, rT2SRmax-min (rT2SRdif), and grade was 0.89. The AUCs of the T2-weighted and T1WI-enhanced models with radiomic signatures were 0.84 and 0.81, respectively. For the 31 DIPG test sets, the AUCs were 0.91, 0.83, and 0.81, for the models incorporating the quantitative features, radiomic model (T2-weighted images, and T1W1-enhanced images), respectively.

CONCLUSION

Combining T2-weighted quantification with qualitative and extrapontine volume ratios reliably predicted pediatric DIPG radiotherapy response.

CLINICAL RELEVANCE STATEMENT

Combining T2-weighted quantification with qualitative and extrapontine volume ratios can accurately predict diffuse intrinsic pontine glioma (DIPG) radiotherapy response, which may facilitate personalized treatment and prognostic assessment for patients with DIPG.

KEY POINTS

Early identification is crucial for radiotherapy response and risk stratification in diffuse intrinsic pontine glioma. The model using tumor heterogeneity and quantitative T2 signal metrics achieved an AUC of 0.91. Using a combination of parameters can effectively predict radiotherapy response in this population.

Current status and advances to improving drug delivery in diffuse intrinsic pontine glioma

Diffuse midline glioma (DMG), including tumors diagnosed in the brainstem (diffuse intrinsic pontine glioma - DIPG), is the primary cause of brain tumor-related death in pediatric patients. DIPG is characterized by a median survival of <12 months from diagnosis, harboring the worst 5-year survival rate of any cancer. Corticosteroids and radiation are the mainstay of therapy; however, they only provide transient relief from the devastating neurological symptoms. Numerous therapies have been investigated for DIPG, but the majority have been unsuccessful in demonstrating a survival benefit beyond radiation alone. Although many barriers hinder brain drug delivery in DIPG, one of the most significant challenges is the blood-brain barrier (BBB). Therapeutic compounds must possess specific properties to enable efficient passage across the BBB. In brain cancer, the BBB is referred to as the blood-brain tumor barrier (BBTB), where tumors disrupt the structure and function of the BBB, which may provide opportunities for drug delivery. However, the biological characteristics of the brainstem's BBB/BBTB, both under normal physiological conditions and in response to DIPG, are poorly understood, which further complicates treatment. Better characterization of the changes that occur in the BBB/BBTB of DIPG patients is essential, as this informs future treatment strategies. Many novel drug delivery technologies have been investigated to bypass or disrupt the BBB/BBTB, including convection enhanced delivery, focused ultrasound, nanoparticle-mediated delivery, and intranasal delivery, all of which are yet to be clinically established for the treatment of DIPG. Herein, we review what is known about the BBB/BBTB and discuss the current status, limitations, and advances of conventional and novel treatments to improving brain drug delivery in DIPG.

Diffuse Midline Gliomas: Challenges and New Strategies in a Changing Clinical Landscape

Diffuse intrinsic pontine glioma (DIPG) was first described by Harvey Cushing, the father of modern neurosurgery, a century ago. Since then, the classification of this tumor changed significantly, as it is now part of the broader family of diffuse midline gliomas (DMGs), a heterogeneous group of tumors of midline structures encompassing the entire rostro-caudal space, from the thalamus to the spinal cord. DMGs are characterized by various epigenetic events that lead to chromatin remodeling similarities, as two decades of studies made possible by increased tissue availability showed. This new understanding of tumor (epi)biology is now driving novel clinical trials that rely on targeted agents, with finally real hopes for a change in an otherwise unforgiving prognosis. This biological discovery is being paralleled with equally exciting work in therapeutic drug delivery. Invasive and noninvasive platforms have been central to early phase clinical trials with a promising safety track record and anecdotal benefits in outcome.

MRI and Trouillas' grading system of pituitary tumors: the usefulness of T2 signal intensity volumetric values

PURPOSE

To classify pituitary macroadenomas according to the Trouillas' grading system; to compare this grading system with T2 values of volumetric signal intensity to determine T2 values able to predict the final grade.

METHODS

A total of 106 patients with macroadenomas were grouped according to the grading system score combining proliferation and invasiveness criteria of Trouillas' classification. Normalized volumetric signal intensity values were extracted from coronal T2-weighted images (nT2mean, nT2Max, nT2min) and were compared with the final grading score system.

RESULTS

Thirty-three patients were in grade 1a (non-invasive, non-proliferative tumors), 17 patients in grade 1b (non-invasive, proliferative tumors), 36 patients in grade 2a (invasive, non-proliferative tumors), and 20 patients in grade 2b (invasive, proliferative tumors). No patient was in grade 3 (metastatic tumors). nT2Max and nT2min were the best quantitative values to discriminate invasive from non-invasive grades; in invasive grades, nT2Max intensity values were higher, and nT2min intensity values were lower than in non-invasive grades. Receiver operating characteristic analysis of nT2 values showed that nT2min values had a better diagnostic performance than nT2Max values because they allowed differentiating with a moderate accuracy invasive tumors (2a or 2b grades) from both non-invasive proliferative tumors (1b) and non-invasive-non proliferative tumors (1a) (2a vs 1b: AUCnT2min = 0.78, 2b vs 1b: AUCnT2min = 0.72, 2a vs 1a: AUCnT2min = 0.72, 2b vs 1a AUCnT2min = 0.69).

CONCLUSION

Volumetric nT2Max and nT2min values of MRI might be practical and non-invasive markers for assessing tumor invasiveness although nT2 min signal intensity values have more effects in discriminating tumor's invasive behavior.

Radiogenomics of diffuse intrinsic pontine gliomas (DIPGs): correlation of histological and biological characteristics with multimodal MRI features

OBJECTIVES

The diffuse intrinsic pontine gliomas (DIPGs) are now defined by the type of histone H3 mutated at lysine 27. We aimed to correlate the multimodal MRI features of DIPGs, H3K27M mutant, with their histological and molecular characteristics.

METHODS

Twenty-seven treatment-naïve children with histopathologically confirmed DIPG H3K27M mutant were prospectively included. MRI performed prior to biopsy included multi-b-value diffusion-weighted imaging, ASL, and dynamic susceptibility contrast (DSC) perfusion imaging. The ADC and cerebral blood flow (CBF) and blood volume (CBV) were measured at the biopsy site. We assessed quantitative histological data, including microvascular density, nuclear density, and H3K27M-positive nuclear density. Gene expression profiling was also assessed in the samples. We compared imaging and histopathological data according to histone subgroup. We correlated MRI quantitative data with histological data and gene expression.

RESULTS

H3.1K27M mutated tumors showed higher ADC values (median 3151 μm²/s vs 1741 μm²/s, p = 0.003), and lower perfusion values (DSC-rCBF median 0.71 vs 1.43, p = 0.002, and DSC-rCBV median 1.00 vs 1.71, p = 0.02) than H3.3K27M ones. They had similar microvascular and nuclear density, but lower H3K27M-positive nuclear density (p = 0.007). The DSC-rCBV was positively correlated to the H3K27M-positive nuclear density (rho = 0.74, p = 0.02). ADC values were not correlated with nuclear density nor perfusion values with microvascular density. The expression of gated channel activity-related genes tended to be inversely correlated with ADC values and positively correlated with DSC perfusion.

CONCLUSIONS

H3.1K27M mutated tumors have higher ADC and lower perfusion values than H3.3K27M ones, without direct correlation with microvascular or nuclear density. This may be due to tissular edema possibly related to gated channel activity-related gene expression.

KEY POINTS

• H3.1K27M mutant DIPG had higher apparent diffusion coefficient (p = 0.003), lower α (p = 0.048), and lower relative cerebral blood volume (p = 0.02) than H3.3K27M mutant DIPG at their biopsy sites. • Biopsy samples obtained within the tumor's enhancing portion showed higher microvascular density (p = 0.03) than samples obtained outside the tumor's enhancing portion, but similar H3K27M-positive nuclear density (p = 0.84). • Relative cerebral blood volume measured at the biopsy site was significantly correlated with H3K27M-positive nuclear density (rho = 0.74, p = 0.02).

Diffuse infiltrative pontine glioma biopsy in children with neuronavigation, frameless procedure: A single center experience of 10 cases

INTRODUCTION

This study presented pediatric DIPG 's biopsy with frameless Neuronavigation.

PATIENTS AND METHODS

We report our experience about 10 patients who had Diffuse Intrinsic Pontine Glioma between 2014 and 2018. All patients were biopsied with BrainLab Varioguide Neuronavigation®. We always used fusion between specific CT Scan and MRI to selected target, made planning and biopsies. All patients were included in BIOMEDE after scientific and ethic discussions. We always selected a trans-cerebellar trajectory and made same procedure (lot of biopsies at one level). All patients have MRI at J1 to verify site of biopsy and to eliminate complication.

RESULTS

The average age was 8.1 years. Symptoms were common with principally headaches and nystagmus. All biopsies were contributive for histopathological diagnosis and establish molecular profile for molecular study. We have no definitive morbidity and procedure duration was 93minutes in average. All MRI didn't showed intracranial complication after procedure and showed great precision of biopsy compared with the selected target.

DISCUSSION

We reviewed the literature and compare our results with series of DIPG biopsies using stereotactic frame or robotic assisted frameless. It was a safe, accuracy and easiness procedure. We always have histopathological and molecular result to proceed next step of treatment. This modality is an alternative possibility to biopsy very young patients with low morbidity.

Response assessment in diffuse intrinsic pontine glioma: recommendations from the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group

Optimising the conduct of clinical trials for diffuse intrinsic pontine glioma involves use of consistent, objective disease assessments and standardised response criteria. The Response Assessment in Pediatric Neuro-Oncology working group, consisting of an international panel of paediatric and adult neuro-oncologists, clinicians, radiologists, radiation oncologists, and neurosurgeons, was established to address issues and unique challenges in assessing response in children with CNS tumours. A working group was formed specifically to address response assessment in children and young adults with diffuse intrinsic pontine glioma and to develop a consensus on recommendations for response assessment. Response should be assessed using MRI of brain and spine, neurological examination, and anti-inflammatory or antiangiogenic drugs. Clinical imaging standards are defined. As with previous consensus recommendations, these recommendations will need to be validated in prospective clinical trials.

Rapid Sequence MRI Protocol in the Evaluation of Pediatric Brain Attacks

BACKGROUND

The objective of our study was to evaluate the clinical utility of rapid sequence magnetic resonance imaging (MRI) utilizing diffusion-weighted imaging and fluid-attenuated inversion recovery sequences in children with acute ischemic strokes and nonstroke brain attacks.

METHODS

We performed a retrospective chart review of patients aged one month to 25 years for whom a pediatric stroke clinical pathway was activated. Diffusion-weighted imaging and fluid-attenuated inversion recovery were obtained followed by a complete MRI. Imaging was interpreted by a pediatric radiologist and the study neurologist. We collected information regarding patient demographics, neuroimaging results, and final diagnosis.

RESULTS

The Pediatric Stroke Clinical Pathway was activated for 59 patients of whom 52 were included for analysis. The majority of patients were female (n = 29, 55.8%) and African American (n = 32, 61.5%), with a median age of 12 years (interquartile range 9, 16). Six patients had an ischemic stroke. Seizures, migraines, and psychosomatic disorders (each with n = 7; 13.5%) were the most common nonstroke diagnoses. Diffusion-weighted imaging was more sensitive (100% [55.0% to 100%] versus 80 % [32% to 99%]) and specific (73.9% [68% to 74%] versus 37.2% [32% to 39%]) compared with fluid-attenuated inversion recovery in identification of an ischemic stroke. However, fluid-attenuated inversion recovery was useful in the identification of inflammatory and metabolic disorders.

CONCLUSION

Rapid sequence MRI can be utilized as a screening imaging modality in children with suspected brain attacks in cases where there may be delays in obtaining full sequence brain imaging.

ABC Transporter Inhibition Plus Dexamethasone Enhances the Efficacy of Convection Enhanced Delivery in H3.3K27M Mutant Diffuse Intrinsic Pontine Glioma

BACKGROUND

An impermeable blood-brain barrier and drug efflux via ATP-binding cassette (ABC) transporters such as p-glycoprotein may contribute to underwhelming efficacy of peripherally delivered agents to treat diffuse intrinsic pontine glioma (DIPG).

OBJECTIVE

To explore the pharmacological augmentation of convection-enhanced delivery (CED) infusate for DIPG.

METHODS

The efficacy of CED dasatinib, a tyrosine kinase inhibitor, in a transgenic H3.3K27M mutant murine model was assessed. mRNA expression of ABCB1 (p-glycoprotein) was analyzed in 14 tumor types in 274 children. In Vitro viability studies of dasatinib, the p-glycoprotein inhibitor, tariquidar, and dexamethasone were performed in 2 H3.3K27M mutant cell lines. Magnetic resonance imaging (MRI) was used to evaluate CED infusate (gadolinium/dasatinib) distribution in animals pretreated with tariquidar and dexamethasone. Histological assessment of apoptosis was performed.

RESULTS

Continuous delivery CED dasatinib improved median overall survival (OS) of animals harboring DIPG in comparison to vehicle (39.5 and 28.5 d, respectively; P = .0139). Mean ABCB1 expression was highest in K27M gliomas. In Vitro, the addition of tariquidar and dexamethasone further enhanced the efficacy of dasatinib (P < .001). In Vivo, MRI demonstrated no difference in infusion dispersion between animals pretreated with dexamethasone plus tariquidar prior to CED dasatinib compared to the CED dasatinib. However, tumor apoptosis was the highest in the pretreatment group (P < .001). Correspondingly, median OS was longer in the pretreatment group (49 d) than the dasatinib alone group (39 d) and no treatment controls (31.5 d, P = .0305).

CONCLUSION

ABC transporter inhibition plus dexamethasone enhances the efficacy of CED dasatinib, resulting in enhanced tumor cellular apoptosis and improved survival in H3.3K27M mutant DIPG.

Longitudinal Monitoring of Gd-DTPA Following Convection Enhanced Delivery in the Brainstem

BACKGROUND

Convection-enhanced delivery (CED) has been introduced into contemporary therapeutic strategies for incurable brain neoplasms as diffuse intrinsic pontine glioma. Therapeutic benefit in part is predictably dependent on drug distribution within tumors. However, therapeutics can rarely be detected through conventional imaging techniques. Coinfusion of the tracer gadolinium-diethylenetriaminepentacetate (Gd-DTPA) has been advocated to monitor drug distributive features including volume, tumor coverage, and efflux during and after administration. The kinetics of Gd-DTPA are unclear as longitudinal magnetic resonance imaging is rarely performed. Understanding these changes would have important implications related to the timing of diagnostic imaging and reliance on tracers as surrogates of pharmacokinetic drug monitoring.

CASE DESCRIPTION

The behavior of Gd-DTPA as a surrogate is presented in a time-dependent fashion as measured by repeated magnetic resonance imaging based on the case of a child with recurrent diffuse intrinsic pontine glioma treated with an oncolytic virus (ICOVIR-5) delivered by CED with coinfused Gd-DTPA (1 mM, for a volume of 2000 μL). Initial Vd/Vi was 1.46. Gd-DTPA was observed up to 18 hours post CED but not thereafter.

CONCLUSIONS

This longitudinal imaging assessment provides a rare opportunity to better characterize the kinetics of surrogate tracers delivered by CED to the brainstem, highlighting the importance of immediate and longitudinal monitoring.

Diffuse intrinsic pontine glioma cells are vulnerable to low intensity electric fields delivered by intratumoral modulation therapy

Introduction

Diffuse intrinsic pontine glioma (DIPG) is a high fatality pediatric brain cancer without effective treatment. The field of electrotherapeutics offers new potential for other forms of glioma but the efficacy of this strategy has not been reported for DIPG. This pilot study evaluated the susceptibility of patient-derived DIPG cells to low intensity electric fields delivered using a developing technology called intratumoral modulation therapy (IMT).

Methods

DIPG cells from autopsy specimens were treated with a custom-designed, in vitro IMT system. Computer-generated electric field simulation was performed to quantify IMT amplitude and distribution using continuous, low intensity, intermediate frequency stimulation parameters. Treatment groups included sham, IMT, temozolomide (TMZ) chemotherapy and radiation therapy (RT). The impact of single and multi-modality therapy was compared using spectrophotometric and flow cytometry viability analyses.

Results

DIPG cells exhibited robust, consistent susceptibility to IMT fields that significantly reduced cell viability compared to untreated control levels. The ratio of viable:non-viable DIPG cells transformed from ~ 6:1 in sham-treated to ~ 1.5:1 in IMT-treated conditions. The impact of IMT was similar to that of dual modality TMZ–RT therapy and the addition of IMT to this treatment combination dramatically reduced DIPG cell viability to ~ 20% of control values.

Conclusions

This proof-of-concept study provides a novel demonstration of marked DIPG cell susceptibility to low intensity electric fields delivered using IMT. The potent impact as a monotherapy and when integrated into multi-modality treatment platforms justifies further investigations into the potential of IMT as a critically needed biomedical innovation for DIPG.