title: Imaging characteristics of supratentorial ependymomas: Study on a large single institutional cohort with histopathological correlation.
abstract: BACKGROUND
  Supratentorial ependymoma (STE) is a tumor whose unique clinical and imaging characteristics have not been studied. Histopathologically, they resemble ependymoma elsewhere. We retrospectively reviewed the imaging findings with clinicopathological correlation in a large number of patients with STE to identify these characteristics.
  
  
  METHODS
  Computed tomography (CT) magnetic resonance images (MRI), pathology reports, and clinical information from 41 patients with pathology-confirmed STE from a single institution were retrospectively reviewed. CT and MRI findings including location, size, signal intensity, hemorrhage, and enhancement pattern were tabulated and described separately in intraventricular and intraparenchymal forms.
  
  
  RESULTS
  STE was more common in pediatric age group and intraparenchymal was more common than intraventricular form. The most common presentation was features of raised intracranial tension. There were equal numbers of Grade II and Grade III tumors. The imaging characteristics in adult and pediatric age group were similar. The tumor was large and had both solid and cystic components. Advanced imaging such as diffusion, perfusion, and spectroscopy were suggestive of high-grade tumor. Only differentiating factor between Grade II and Grade III was the presence of calcification. 1234 rule and periwinkle sign which we have described in this article may help characterize this tumor on imaging.
  
  
  CONCLUSIONS
  This series expands the clinical and imaging spectrum of STE and identifies characteristics that should suggest consideration of this uncommon diagnosis.
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neuroscience, Bengaluru, Karnataka, India.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Mangalore
authors.affiliation: Department of Neurosurgery, National Institute of Mental Health and Neuroscience, Bengaluru, Karnataka, India.
authors.forename: Saritha
authors.initials: S
authors.lastname: Aryan
authors.affiliation: Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neuroscience, Bengaluru, Karnataka, India.
authors.forename: Chandrajit
authors.initials: C
authors.lastname: Prasad
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neuroscience, Bengaluru, Karnataka, India.
authors.forename: Vani
authors.initials: V
authors.lastname: Santosh
keywords: Diffusion; imaging; perfusion; spectroscopy; supratentorial ependymoma