Purpose
Amide proton transfer‐weighted (APTw) MRI at 3T provides a unique contrast for brain tumor imaging. However, APTw imaging suffers from hyperintensities in liquid compartments such as cystic ...or necrotic structures and provides a distorted APTw signal intensity. Recently, it has been shown that heuristically motivated fluid suppression can remove such artifacts and significantly improve the readability of APTw imaging.
Theory and Methods
In this work, we show that the fluid suppression can actually be understood by the known concept of spillover dilution, which itself can be derived from the Bloch‐McConnell equations in comparison to the heuristic approach. Therefore, we derive a novel post‐processing formula that efficiently removes fluid artifact, and explains previous approaches. We demonstrate the utility of this APTw assessment in silico, in vitro, and in vivo in brain tumor patients acquired at MR scanners from different vendors.
Results
Our results show a reduction of the CEST signals from fluid environments while keeping the APTw‐CEST signal intensity almost unchanged for semi‐solid tissue structures such as the contralateral normal appearing white matter. This further allows us to use the same color bar settings as for conventional APTw imaging.
Conclusion
Fluid suppression has considerable value in improving the readability of APTw maps in the neuro‐oncological field. In this work, we derive a novel post‐processing formula from the underlying Bloch‐McConnell equations that efficiently removes fluid artifact, and explains previous approaches which justify the derivation of this metric from a theoretical point of view, to reassure the scientific and medical field about its use.
Recent epigenomic analyses have revealed the existence of a new DNA methylation class (MC) of infant‐type hemispheric glioma (IHG). Like desmoplastic infantile ganglioglioma/astrocytoma (DIG/DIA), ...these tumors mainly affect infants and are supratentorial. While DIG/DIA is characterized by BRAF or RAF1 alterations, IHG has been shown to have receptor tyrosine kinase (RTK) gene fusions (ALK, ROS1, NTRK1/2/3, and MET). However, in this rapidly evolving field, a more comprehensive analysis of infantile glial/glioneuronal tumors including clinical, radiological, histopathological, and molecular data is needed. Here, we retrospectively investigated data from 30 infantile glial/glioneuronal tumors, consecutively compiled from our center. They were analyzed by two experienced pediatric neuroradiologists in consensus, without former knowledge of the molecular data. We also performed a comprehensive clinical, and histopathological examination (including molecular evaluation by next‐generation sequencing, RNA sequencing, and fluorescence in situ hybridization FISH analyses), as well as DNA methylation profiling for the samples having sufficient material available. The integrative histopathological, genetic, and epigenetic analyses, including t‐distributed stochastic neighbor embedding (t‐SNE) analyses segregated tumors into 10 DIG/DIA (33.3%), six IHG (20.0%), three gangliogliomas (10.0%), two pleomorphic xanthoastrocytomas (6.7%), two pilocytic astrocytomas (6.7%), two supratentorial ependymomas, ZFTA fusion‐positive (6.7%), two supratentorial ependymomas, YAP1 fusion‐positive (6.7%), two embryonal tumors with PLAGL2‐family amplification (6.7%), and one diffuse low‐grade glioma, MAPK‐pathway altered. This study highlights the significant differential features, in terms of histopathology (leptomeningeal infiltration, intense desmoplasia and ganglion cells in DIG/DIA and necrosis, microvascular proliferation, and siderophages in IHG), and radiology between DIG/DIA and IHG. Moreover, these results are consistent with the literature data concerning the molecular dichotomy (BRAF/RAF1 alterations vs. RTK genes' fusions) between DIG/DIA and IHG. This study characterized histopathologically and radiologically two additional cases of the novel embryonal tumor characterized by PLAGL2 gene amplification.
Differences between desmoplastic infantile gangliogliomas/astrocytomas and infant‐type hemispheric gliomas.
Pediatric bithalamic gliomas encompass several histomolecular tumoral types from benign to malignant and underlines the central role of a comprehensive neuropathological review, including ...immunohistochemistry, genetic, and epigenetic analyses, to achieve an accurate diagnosis.
Objective
To quantify whole‐brain functional organization after complete hemispherotomy, characterizing unexplored plasticity pathways and the conscious level of the dissected hemispheres.
Methods
...Evaluation with multimodal magnetic resonance imaging in two pediatric patients undergoing right hemispherotomy including complete callosotomy with a perithalamic section. Regional cerebral blood flow and fMRI network connectivity assessed the functional integrity of both hemispheres after surgery. The level of consciousness was tested by means of a support vector machine classifier which compared the intrinsic organization of the dissected hemispheres with those of patients suffering from disorders of consciousness.
Results
After hemispherotomy, both patients showed typical daily functionality. We found no interhemispheric transfer of functional connectivity in either patient as predicted by the operation. The healthy left hemispheres displayed focal blood hyperperfusion in motor and limbic areas, with preserved network‐level organization. Unexpectedly, the disconnected right hemispheres showed sustained network organization despite low regional cerebral blood flow. Subcortically, functional connectivity was increased in the left thalamo‐cortical loop and between the cerebelli. One patient further showed unusual ipsilateral right cerebello‐cortical connectivity, which was explained by the mediation of the vascular system. The healthy left hemisphere had higher probability to be classified as in a minimally conscious state compared to the isolated right hemisphere.
Significance
Complete hemispherotomy leads to a lateralized whole‐brain organization, with the remaining hemisphere claiming most of the brain's energetic reserves supported by subcortical structures. Our results further underline the contribution of nonneuronal vascular signals on contralateral connectivity, shedding light on the nature of network organization in the isolated tissue. The disconnected hemisphere is characterized by a level of consciousness which is necessary but insufficient for conscious processing, paving the way for more specific inquiries about its role in awareness in the absence of behavioral output.
Purpose To compare arterial spin labeling (ASL) data between low- and high-grade brain tumors in children to establish a cutoff to distinguish low- from high-grade neoplasms and to assess potential ...correlations between cerebral blood flow (CBF) and quantitative histologic microvascular data. Materials and Methods Approval was obtained from the regional review board. ASL data obtained in 129 children between 2011 and 2015 were retrospectively analyzed. CBF and relative CBF in the most perfused area of each neoplasm and contrast enhancement were quantified with a semiquantitative ratio. The correlation between CBF and microvascular density was analyzed in specimens stained with anti-CD34. Results were controlled in two validation cohorts with 1.5- and 3.0-T magnetic resonance (MR) imaging. Results Mean CBF was significantly higher for high-grade than for low-grade hemispheric (116 mL/min/100 g interquartile range {IQR}, 73-131 mL/min/100 g vs 29 mL/min/100 g IQR, 23-35 29 mL/min/100 g, P < .001), thalamic (87 mL/min/100 g IQR, 73-100 mL/min/100 g vs 36 mL/min/100 g IQR, 30-40 mL/min/100 g, P = .016), and posterior fossa (59 mL/min/100 g IQR, 45-91 mL/min/100 g vs 33 mL/min/100 g IQR, 25-40 mL/min/100 g, P < .001) tumors. With a cutoff of 50 mL/min/100 g, sensitivity and specificity were 90% (95% confidence interval CI: 68, 100) and 93% (95% CI: 66, 100), respectively, for hemispheric tumors; 100% (95% CI: 48, 100) and 80% (95% CI: 28, 100), respectively, for thalamic tumors; and 65% (95% CI: 51, 78) and 94% (95% CI: 80, 99), respectively, for posterior fossa tumors. In posterior fossa tumors, additional use of the CBF-to-contrast enhancement ratio yielded sensitivity and specificity of 96% (95% CI: 87, 100) and 97% (95% CI: 84, 100), respectively. Use of a simple algorithm based on these values yielded an accuracy of 93% (95% CI: 87, 97). Validation sets yielded similar results, with grading accuracy of 88% (95% CI: 62, 98) with 1.5-T MR imaging and 77% (95% CI: 46, 95) with 3.0-T MR imaging. CBF was strongly correlated with microvascular density (R = 0.66, P < .001). Conclusion High-grade pediatric brain tumors display higher CBF than do low-grade tumors, and they may be accurately graded by using these values. CBF is correlated with tumor microvascular density.
RSNA, 2016 Online supplemental material is available for this article.
Hydrocephalus frequently occurs with midline posterior fossa cystic collections. The classification of this heterogeneous group of developmental anomalies, including Dandy-Walker malformation, ...persisting Blake's pouch, retrocerebellar arachnoid cysts, and mega cisterna magna, is subject of debate. The absence of diagnostic criteria is confusing regarding the ideal management of PFCC-related hydrocephalus.
To decipher the surgical strategy for the treatment of children with PFCC-related hydrocephalus through a retrospective analysis of the surgical outcome driven by their clinical and radiological presentation.
This study enrolled patients operated of symptomatic PFCC-related hydrocephalus. Clinical and MRI features were examined, as well as the surgical outcome. Unbiased subgroup classification of the patients was performed with multiple component analysis as a function of imaging characteristics and hierarchical clustering on principal component. Outcome was assessed with binomial logistic regression and Kaplan-Meier analysis.
Fifty-four patients were included between 2007 and 2021. Multiple component analysis suggested that cerebellar and vermian hypoplasia, vermian rotation, basal-tentorial angle, and fastigial angle were strongly correlated. Hierarchical clustering and the distribution of the patients in the bidimensional plot showed the clear segregation of 3 major clusters, which correlated with the radiological diagnosis ( P < .01). Binomial logistic regression and survival analysis showed that endoscopic third ventriculostomy was an effective treatment for patients with persisting Blake's pouch, while failing to control hydrocephalus in most of patients with Dandy-Walker malformation.
Preoperative MRI in patients with PFCC-related hydrocephalus is essential to better define the diagnosis. The choice of treatment strategy notably relies on correct radiological diagnosis.
Meningioangiomatosis (MAM) remains a poorly understood lesion responsible for epileptic disease. In the past, MAM was primarily described in the context of neurofibromatosis type 2 before being ...mainly reported sporadically. Moreover, the malformative or tumoral nature is still debated. Because a subset of MAM are associated with meningiomas, some authors argue that MAM corresponds to an infiltration pattern of these tumors. For these reasons, MAM has not been added to the World Health Organization (WHO) Classification of Central Nervous System Tumors as a specific entity. In the present study, we characterized a series of pure MAM (n = 7) and MAM associated with meningiomas (n = 4) using histopathology, immunohistochemistry, genetic (fluorescent in situ and DNA sequencing analyses), and epigenetic (DNA-methylation profiling) data. We evidenced two distinct morphological patterns: MAM with a fibroblastic-like pattern having few lesional cells, and MAM with a more cellular pattern. A subset was associated with the genetic alterations previously reported in meningiomas (such as a KMT2C mutation and a hemizygous deletion of chromosome 22q including the NF2 gene). The DNA-methylation profile, using a t-distributed stochastic neighbor embedding analysis, evidenced that MAM (pure or associated with meningiomas) clustered in a separate group from pediatric meningiomas. The present results seem to suggest that MAM represents a neoplastic lesion and encourage the further study of similar additional series so that it may be included in a future WHO classification.
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