Lend Me Your Ears for a Review of Anatomy, Development, and Pathology of the External Ear

J.L. McCarty, J.L. Dornhoffer, E.J.C. Angtuaco, and R.T. Fitzgerald

View Article on Neurographics Website

Date of Activity Release: Dec. 1, 2017
Date of Activity Expiration: Dec. 1, 2020

Target Audience:
Intended for neuroradiologists and neuroradiology trainees with varying degrees of experience.

Learning Objective:
Recognize common and uncommon types of primary CNS lymphomas in patients who are immunocompetent and patients who are immunocompromised as well as variation in the appearance of secondary CNS lymphoma on MRI and to describe characteristic imaging findings by using advanced imaging techniques.

Central nervous system (CNS) lymphoma can occur in isolation as a primary CNS neoplasm or can show systemic lymphoma involvement. Primary CNS lymphomas in patients who are immunocompetent are typically hyperattenuated on CT and iso- to hypointense relative to gray matter on T1- and T2-weighted images. On postcontrast scans, strong homogeneous enhancement is common. Most primary CNS lymphomas contact a CSF surface (either the ventricular ependyma or the pia). Advanced MR imaging may help to differentiate primary CNS lymphomas from other brain lesions. Typical primary CNS lymphomas are highly cellular tumors without necrosis; the lesions are hyperintense on diffusion-weighted images and hypointense on apparent diffusion coefficient maps. The relative cerebral blood volume ratios of primary CNS lymphomas are much lower than those of high-grade gliomas and metastases. On MR spectroscopy, elevated choline as well as a decreased N-acetylaspartate peak and high lipid peak are observed. Unlike high-grade gliomas, hemorrhages and calcifications are rare. Unusual imaging features of primary CNS lymphomas include patchy, streaky, or no enhancement; hemorrhage; necrosis; and calcifications. In patients who are immunocompromised, primary CNS lymphomas show central necrosis and peripheral enhancement. Systemic lymphomas can involve the CNS: two-thirds of patients with secondary CNS lymphoma present with leptomeningeal spread, and one-third present with parenchymal disease. An accurate diagnosis of CNS lymphoma is crucial for proper management and prognosis in both patients who are immunocompetent and those patients who are immunocompromised. The imaging features described herein may allow earlier recognition of CNS lymphoma and thus facilitate optimal treatment.

Commercial Support
No commercial support was received for this activity.

Credit Designation Statement

The American Society of Neuroradiology is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

The American Society of Neuroradiology designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 Credit(s)TM. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Method of Physician Participation:
Each participant will review the corresponding Neurographics article located at Upon completion, each physician will complete and pass a post-test with a score of at least 80% to receive a CME certificate.

All individuals in control of content have disclosed the following relevant financial relationships. All of these relationships were treated as a conflict of interest, and have been resolved (C7 SCS 6.1-6.2, 6.5)

Authors have no relevant financial relationships.





Barton Branstetter 

Editor in Chief

None, N/A

Adam Flanders

Deputy Editor

Royalties, Lippincott Williams and Wilkins

Robert Quencer 

Consulting Editor

None, N/A

Mark Mullins

Associate Editor

Non-remunerative position, AUR6

Meng Law

Associate Editor

Stockholder, Clinical Imaging

Michele Johnson

Associate Editor

Consultant, Boston Scientific, Inc.

Edward Escott

Associate Editor

Grant, Atherysys, Inc.; Royalties, Thieme Medical Publishers

Scott Faro

Associate Editor

None, N/A

Tina Young Poussaint

Associate Editor

None, N/A

Dheeraj Ghandi

Associate Editor

Grant, Arstasis, Axera Inc.; Consultant, Covidien, EV3

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