Document Detail

A diagnostic pitfall for intracranial aneurysms in time-of-flight MR angiography: small intracranial lipomas.
MedLine Citation:
PMID:  18094274     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The sensitivity of MR angiography (MRA) for aneurysms smaller than 3 mm in diameter is limited. Diagnostic pitfalls may arise from primary T1 hyperintense lesions on time-of-flight (TOF) imaging adjacent to a vessel. Independently, three patients were referred from outside facilities for diagnostic workup of suspected aneurysms of the vertebrobasilar system on TOF images. The lesions were identified as small lipomas, which prompted us to systematically analyze characteristics of intracranial lipomas on TOF images. MATERIALS AND METHODS: From our local database, 38,000 cranial MRI scans were searched for intracranial lipomas. If available, TOF images of identified lipomas were analyzed. In addition, in vitro MRI of excised cadaveric lipomas and other fatty specimens were examined for characteristics on TOF images and the presence of chemical shift artifacts. RESULTS: Seventeen intracranial lipomas (0.045%) were identified. Out-of-phase TOF source images available in 12 identified lipomas showed a continuous dark peripheral fringe and a hyperintense center. In vitro out-of-phase chemical shift images of excised cadaveric lipomas revealed the same consistent fringe artifact, known as "india ink," independent of size, shape, surrounding fibrous capsule, or texture of the fatty specimen. In contrast, in-phase chemical shift artifact was variable. CONCLUSION: Small intracranial lipomas close to a cerebral artery are hyperintense on TOF MR images and could be mistaken for partially thrombosed aneurysms and associated flow-related artifact. A defining characteristic of lipomas on TOF source images results from the out-of-phase india ink artifact. This dark fringe in the periphery of the lesions is characteristic and helps avoid potential diagnostic pitfalls.
Andre Kemmling; Ingo Noelte; Lars Gerigk; Stephan Singer; Christoph Groden; Johann Scharf
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  AJR. American journal of roentgenology     Volume:  190     ISSN:  1546-3141     ISO Abbreviation:  AJR Am J Roentgenol     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-12-20     Completed Date:  2008-01-14     Revised Date:  2008-02-15    
Medline Journal Info:
Nlm Unique ID:  7708173     Medline TA:  AJR Am J Roentgenol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  W62-7     Citation Subset:  AIM; IM    
Department of Neuroradiology, University Hospital Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.
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MeSH Terms
Brain Neoplasms / complications,  diagnosis*
Diagnosis, Differential
Headache / etiology
Image Processing, Computer-Assisted
Intracranial Aneurysm / complications,  diagnosis*
Lipoma / complications,  diagnosis*
Magnetic Resonance Angiography*
Middle Aged
Retrospective Studies
Sensitivity and Specificity
Vertigo / etiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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