Brain tumours are the most common solid tumours in children, representing 20% of all cancers. The most frequent posterior fossa tumours are medulloblastomas, pilocytic astrocytomas and ependymomas. Texture analysis (TA) of MR images can be used to support the diagnosis of these tumours by providing additional quantitative information. MaZda software was used to perform TA on T1- and T2-weighted images of children with pilocytic astrocytomas, medulloblastomas and ependymomas of the posterior fossa, who had MRI at Birmingham Children's Hospital prior to treatment. The region of interest was selected on three slices per patient in Image J, using thresholding and manual outlining. TA produced 279 features, which were reduced using principal component analysis (PCA). The principal components (PCs) explaining 95% of the variance were used in a linear discriminant analysis (LDA) and a probabilistic neural network (PNN) to classify the cases, using DTREG statistics software. PCA of texture features from both T1- and T2-weighted images yielded 13 PCs to explain >95% of the variance. The PNN classifier for T1-weighted images achieved 100% accuracy on training the data and 90% on leave-one-out cross-validation (LOOCV); for T2-weighted images, the accuracy was 100% on training the data and 93.3% on LOOCV. A PNN classifier with T1 and T2 PCs achieved 100% accuracy on training the data and 85.8% on LOOCV. LDA classification accuracies were noticeably poorer. The features found to hold the highest discriminating potential were all co-occurrence matrix derived, where adjacent pixels had highly correlated intensities. This study shows that TA can be performed on standard T1- and T2-weighted images of childhood posterior fossa tumours using readily available software to provide high diagnostic accuracy. Discriminatory features do not correspond to those used in the clinical interpretation of the images and therefore provide novel tumour information. Copyright © 2014 John Wiley & Sons, Ltd.

Various chronic hematologic disorders that lead to ineffective hemopoiesis or inadequate bone marrow function (ie, chronic hemolytic anemias, thalassemia, sickle cell anemia, myelofibrosis of many causes, lymphoma, and leukemia) can potentially precipitate extramarrow new blood element creation. Extramarrow soft tissue that produces blood elements is called extramedullary hemopoietic tissue and the process extramedullary hemopoiesis (EMH). Sites commonly involved by EMH include the liver, spleen, lymph nodes, and most commonly, paravertebral regions, although other sites can sometimes be involved. Physicians rarely consider EMH in their differential diagnosis even in cases where it is warranted (diseases of ineffective erythropoiesis). This is likely because of the rarity of the condition and because imaging findings are nonspecific. We present here a systematic review of the imaging findings in EMH.

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Aims: Metabolite levels can be measured non-invasively using in vivo ¹H magnetic resonance spectroscopy (MRS). These tumour metabolite profiles are highly characteristic for tumour type in childhood brain tumours; however, the relationship between metabolite values and conventional histopathological characteristics has not yet been fully established. This study systematically tests the relationship between metabolite levels detected by MRS and specific histological features in a range of paediatric brain tumours. Methods: Single-voxel MRS was performed routinely in children with brain tumours along with the clinical imaging prior to treatment. Metabolites were quantified using LCModel. Histological features were assessed semi-quantitatively for 27 children on H&E and immunostained slides, blind to the metabolite values. Statistical analysis included 2-tailed independent-samples t tests and 2-tailed Spearman rank correlation tests. Results: Ki67, cellular atypia, and mitosis correlated positively with choline metabolites, and phosphocholine in particular. Apoptosis and necrosis were both associated with lipid levels, with the relationship dependent on the use of long or short echo time MRS acquisitions. Neuronal components correlated negatively and glial components positively with N-acetyl-aspartate. Glial components correlated positively with myoinositol. Conclusion: Metabolite levels in children's brain tumours measured by MRS are closely associated with key histological features routinely assessed by histopathologists in the diagnostic process. This further elucidates our understanding of this important non-invasive diagnostic tool and strengthens our understanding of the relationship between metabolites and histological features.

PURPOSE: The purpose of this study is to prospectively evaluate the effectiveness of MR perfusion imaging relative cerebral blood volume (rCBV) measurements in distinguishing low grade (slow growing) from high grade (fast growing) pediatric brain tumors. As brain tumors in children differ significantly from adult lesions, testing the utility of rCBV values as a biomarker for grading pediatric brain tumors is essential. METHODS: After IRB approval was obtained, 18 patients (ages 0 -20) (9 girls and 9 boys) with brain tumors were recruited. Two patients were excluded from the study because inadequate technically limited measurements were obtained. Therefore the rCBV values of 16 patients were measured and mapped. Tumors were classified as low grade (WHO I or II) or as high grade (WHO III or IV) based on histology and/or change in size during serial imaging. RESULTS: The rCBV of high grade tumors differed significantly from the values obtained for low grade lesions, except in the case of an outlying low grade juvenile pilocytic astrocytoma with a rCBV value approximately 1000 points higher than the values for high grade tumors. CONCLUSION: Because MR perfusion rCBV reflects cerebral hemodynamics at the microcirculation level we hypothesized that rCBV is proportional to the degree of tumor angiogenesis. The results of this study verify this hypothesis, except in the case of a highly vascular juvenile pilocytic astrocytoma (JPA) which exhibited an rCBV value even greater than that for high grade tumors. This may be related to the tendancy of JPAs to avidly enhance with contrast. In all other brain tumor cases, rCBV values served as an excellent biomarker for separating high grade from low grade brain neoplasms. Therefore, this study represents an important step toward applying rCBV values as a useful biomarker for distinguishing tumor grade in pediatric brain tumors. An 11-year old girl presented with headache and vomiting for several months. Neuroimaging revealed a lesion in the inferior right frontal lobe. The family declined surgical intervention and she was monitored by serial scans and clinical evaluation. Several years later the tumor showed progression on MRI scans. A subtotal resection was performed and the pathology was consistent with a papillary glioneuronal tumor (PGNT). Her symptoms resolved following surgery. PGNTs are rare neoplasms of the central nervous system which have been recently included as a distinct entity in the 2007 WHO classification. They are indolent tumors which show a biphasic pattern with both glial and neuronal differentiation. Though the morphological pattern is now well defined, to date the molecular pathogenesis remains unclear. Magnetic resonance imaging (MRI) findings for PGNT usually show a well-delineated solid mass located peri-ventricularly, with or without a cystic component, often with contrast enhancement, and presence of a mural nodule as was seen in our case. Our patient's tumor also showed evidence of diffusion restriction. To date use of magnetic resonance spectroscop...

DIG (Desmoplastic Infantile Ganglioglioma) is a rare intracranial neoplasm classified as WHO grade I tumor under neuronal and mixed neuronal glial tumors (under 2007 World Health Organization brain tumor classification). It is usually considered to have a good prognosis but 40% of the cases require additional medical, radiation and/or further surgical intervention and 15% of infants and children develop leptomeningeal spread or die from DIG. We report a case of DIG presenting at 2 mo of age that showed aggressive behavior, requiring debulking at 2.5 mo age and subsequently at 10 mo age following a tumor recurrence. Chemotherapy following surgery was successful in suppressing the tumor growth for 7.5 yrs. He then presented with malignant transformation into glioblastoma. Successful debulking followed by chemotherapy was given. At 1 yr follow up, the child had moderate neurological deficits but had a subsequent rapid progression and died. Chromosome microarray analysis (CMA) using oligo array performed on the biopsy specimen obtained at 2 mo age did not show any significant abnormality. However, CMA of the glioblastoma was very abnormal showing significant genomic deletions and duplications. Genomic next generation sequencing showed a somatic single nucleotide non-synonymous variant, p.R248Q in Exon 7 of TP53 in the primary DIG and the GBM tumors. The non-synonymous variant in TP53 gene is predicted to be deleterious, altering the structure of the L2/L3 motif of the DNA binding domain tp53 protein. The TP53 gene which is a known primary site of genetic alteration that predisposes to malignant tumors provides a reason for the transformation of DIG to glioblastoma in our case. Therefore, molecular genetic testing is recommended on some DIG tumors which may provide a prognostic biological marker.

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