Imaging Features of Common Pediatric Intracranial Tumours: A Primer for the Radiology Trainee  Daddy Mata-Mbemba, MD, PhD, John Donnellan, MBBChBAO, MSc, MMedSci, FFR(RCSI), Pradeep Krishnan, MD, Manohar Shroff, MD, FRCPC, DABR, Prakash Muthusami, MBBS, MD  Canadian Association of Radiologists Journal  Volume 69, Issue 1, Pages 105-117 (February 2018) DOI: 10.1016/j.carj.2017.10.006 Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 1 Optic pathway glioma: a 3-year-old boy with an infiltrative supratentorial mass lesion. (A) Coronal T2-weighted imaging showing bright signal and (B) axial postcontrast image showing heterogeneous and rim enhancement (panel B obtained 2 years after panel A). The lesion arises from the optic chiasma and extends into the surrounding structures including bilateral basal ganglia, bilateral mesial temporal lobes, and bilateral basal frontal lobes. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 2 Craniopharyngioma. A 2-year-old boy with a large multicystic sellar-suprasellar mass lesion that involves bilateral basal ganglia and frontal lobes, more on the right. (A) Axial plain computed tomography section at the suprasellar level showing coarse peripheral and internal calcifications. (B) Coronal T2-weighted imaging showing hyperintense signal. (C) Sagittal T1-weighted imaging showing intermediate signal in keeping with proteinaceous materials. (D) Following administration of contrast material, the lesion shows heterogeneous and peripheral enhancement. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 3 Pleomorphic xanthoastrocytoma. A 10-year-old girl with a large right temporal lobe cortically-based mass lesion. (A) Axial T2-weighted imaging showing a large cystic component and (B) a peripheral enhancing mural component, the latter expanding the cortex. The histopathologic diagnosis was pleomorphic xanthoastrocytoma. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 4 Dysembryoplastic neuroepithelial tumour. A 7-year-old boy with a large right parietal lobe mass lesion, involving the medial cortex and subcortical white matter. (A) Bright signal on axial T2-weighted imaging magnetic resonance image and (B) central low and peripheral bright signal on axial fluid attenuation inversion recovery image. Despite the relatively large size, the lesion produces no vasogenic oedema. Dysembryoplastic neuroepithelial tumour was confirmed on postresection histopathology. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 5 Ganglioglioma. A 16-year-old girl with seizures. (A) Axial T2-weighted imaging showing a right mesial temporal mass showing solid and cystic components. (B) Axial multiplanar gradient recall (MPGR) image showing foci of susceptibility in keeping with calcifications. (C) Postcontrast coronal T1-weighted imaging showing a small peripheral nodular enhancement medially. Histopathology after resection confirmed ganglioglioma. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 6 Choroid plexus carcinoma. A 3-year-old girl with increasing vomiting and head circumference. (A) Axial plain computed tomography section showing a high-density mass centered in the body-trigone of the right lateral ventricle with marked surrounding vasogenic oedema. (B) Axial fluid attenuation inversion recovery image showing relatively low signal suggesting high cellularity. (C) Axial postcontrast T1-weighted imaging, showing avid enhancement. Histopathology confirmed choroid plexus carcinoma. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 7 Diffuse leptomeningeal and ependymal T2 hyperintense cysts with superficial and subpial predominantly nonenhancing parenchymal nodules. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 8 Pilocytic astrocytoma. A 9-year-old boy with a large posterior fossa mass centered in the left cerebellar hemisphere, compressing and displacing the fourth ventricle. (A) Axial and (B) coronal T2-weighted imaging showing heterogeneous bright signal with extension through the foramen of Magendie and left foramen of Luschka, which may be suggestive of ependymomas. The lack of diffusion restriction (C) and multiple internal cysts were favored to be in keeping with pilocytic astrocytoma. (D) The lesion shows heterogeneous postcontrast enhancement. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 9 Diffuse infiltrative pontine glioma. An 8-year-old girl with ataxia and multiple cranial nerve palsies. (A) Axial plain computed tomography and (B) axial fluid attenuation inversion recovery magnetic resonance images showing an expansile mass centered in the pons and encasing the basilar artery without compressing it. On computed tomography, the lesion shows low attenuation, with high signal on fluid attenuation inversion recovery imaging. (C) Axial T1-weighted imaging showing diffusely low signal and (D) no definite postcontrast enhancement. The mass compresses the fourth ventricle posteriorly. This imaging appearance is considered pathognomonic for diffuse infiltrative pontine glioma. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 10 Medulloblastoma. A 9-year-old boy with features of raised intracranial pressure. (A) Axial T2-weighted imaging showing a large mass in the right cerebellar hemisphere with low signal in keeping with high cellularity, foci of cystic areas, and moderate surrounding vasogenic oedema and mass effect. (B) Another patient with a diffusion restricting posterior fossa mass centered within the fourth ventricle. (C) Sagittal postcontrast T1-weighted imaging showing no postcontrast enhancement and supratentorial hydrocephalus. (D) Postcontrast coronal T1-weighted imaging in a 12year-old boy with medulloblastoma centered in the fourth ventricle, with diffuse leptomeningeal metastasis along the cerebellar surface. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 11 Ependymoma: a 7-year-old boy with large posterior fossa mass centered on the fourth ventricle and right cerebellar hemisphere. (A) Axial plain computed tomography image showing an isodense mass with some calcifications. (B) Axial T2-weighted imaging showing a lobulated iso- to hyperintense mass with (C) diffusion restriction and (D) patchy mild enhancement on postcontrast T1-weighted imaging. The mass fills the fourth ventricle and obliterates the right foramen of Luschka, extends through the foramen magnum, and wraps around the anterior medulla with effacement of the premedullary cistern. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions

Figure 12 A 19-month-old girl with atypical teratoid rhabdoid tumor. (A) Sagittal T2-weighted imaging showing a large posterior fossa mass with low signal, extending transtentorially into the pineal region as well as into the right cerebellopontine angle. The mass shows minimal peritumoral edema, (B) diffusion restriction, and (C) no significant postcontrast enhancement. Canadian Association of Radiologists Journal 2018 69, 105-117DOI: (10.1016/j.carj.2017.10.006) Copyright © 2017 Canadian Association of Radiologists Terms and Conditions