AJR:200, May 2013 1115 OBJECTIVE. In this article, we review the most common posterior fossa and suprasel- lar intracranial neoplasms in the pediatric population. We briefly discuss basic MRI concepts used in the initial evaluation of a pediatric brain tumor and then discuss sophisticated MRI techniques that give insight into the physiology and chemical makeup of these tumors to help the radiologist make a more specific diagnosis. CONCLUSION. Diagnosis and treatment of pediatric CNS tumors necessitate a multi- disciplinary approach and require expertise and diligence of all parties involved. Imaging is an essential component has evolved greatly over the past decade. We are becoming better at making a preoperative diagnosis of that tumor type, detecting recurrence, and guiding surgi- cal management to avoid injury to vital brain structures. Plaza et al. MRI of Posterior Fossa and Suprasellar Tumors Neuroradiology/Head and Neck Imaging Review Posterior Fossa Tumors Pilocytic Astrocytoma Cerebellar astrocytomas account for 30% of all posterior fossa tumors in children, with the most common histologic subtype being JPA [2]. The majority of JPAs, 60%, arise from the cerebellum. Five percent of patients with neu- rofibromatosis type 1 (NF1) will develop a cer- ebellar JPA, although the most common loca- tion for pilocytic astrocytoma in NF1 patients is the optic nerve or optic chiasm [3]. Clinical pre- sentation varies with the site of origin, but most patients present with headache, neck pain, gait disturbance, and vomiting. The classic imaging appearance of a JPA, which is observed in 30–60% of cases, is of a large cyst with a solid mural nodule within one of the cerebellar hemispheres; less commonly, JPA may present on imaging as a predominant- ly solid mass with little to no cystlike compo- nent [4]. On MRI, the cystic portion is hypo- intense relative to gray matter on T1-weighted images and hyperintense relative to gray mat- ter on T2-weighted images. JPA is a low-grade neoplasm (World Health Organization [WHO] grade I [5]) that results in diminished surround- ing vasogenic edema in comparison with high- grade tumors. Enhancement patterns may vary, but JPA most commonly (46%) appears as a cyst with an enhancing wall and an in- tensely enhancing mural nodule [6] (Fig. 1). Conventional and Advanced MRI Features of Pediatric Intracranial Tumors: Posterior Fossa and Suprasellar Tumors Michael J. Plaza 1 Maria J. Borja 1 Nolan Altman 2 Gaurav Saigal 1 Plaza MJ, Borja MJ, Altman N, Saigal G 1 Department of Radiology, University of Miami/Jackson Memorial Hospital, 1611 NW 12th Ave, West Wing 279, Miami, FL 33136. Address correspondence to M. J. Borja ([email protected]). 2 Department of Radiology, Miami Children’s Hospital, Miami, FL. Neuroradiology/Head and Neck Imaging • Review CME/SAM This article is available for CME/SAM credit. AJR 2013; 200:1115–1124 0361–803X/13/2005–1115 © American Roentgen Ray Society I nfratentorial tumors account for 45– 60% of all pediatric brain tumors, and the most common infratentorial tumors include juvenile pilocytic astrocytoma (JPA), medulloblastoma, ependy- moma, and brainstem glioma [1]. Less com- monly we encounter atypical teratoid-rhabdoid tumor (ATRT) and hemangioblastoma, but they are important to recognize and discuss because they mimic the more common tumors radiologically. An accurate diagnosis has im- portant clinical implications related to progno- sis and treatment. Pediatric suprasellar tumors are unique in their differential diagnosis and differ from adult tumors in the same region in incidence and treatment. We focus on craniopharyngio- mas because they are one of the most common tumors arising from the pituitary region in children and on suprasellar gliomas and hypo- thalamic hamartomas because of their unique clinical presentations and imaging features. The differential diagnosis of pediatric brain tumors begins with an accurate assessment of lesion location, which is often the most im- portant diagnostic feature provided by con- ventional MRI. Advanced MR neuroimaging techniques allow assessment of the physi- ologic features of brain tumors, resulting in better preoperative characterization and often in better outcomes. Keywords: advanced neuroimaging, diffusion-weighted imaging, MR spectroscopy, pediatric brain tumors, perfusion MRI, posterior fossa, tractography DOI:10.2214/AJR.12.9725 Received August 5, 2012; accepted after revision November 18, 2012. Downloaded from www.ajronline.org by 171.243.67.90 on 05/24/23 from IP address 171.243.67.90. Copyright ARRS. For personal use only; all rights reserved
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Related Documents
