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. 2012 Sep;33(8):1534-8.
doi: 10.3174/ajnr.A2986. Epub 2012 Mar 15.

Differentiation of pyogenic brain abscesses from necrotic glioblastomas with use of susceptibility-weighted imaging

C H Toh  1 , K-C Wei, C-N Chang, P-W Hsu, H-F Wong, S-H Ng, M Castillo, C-P Lin
Affiliations

Differentiation of pyogenic brain abscesses from necrotic glioblastomas with use of susceptibility-weighted imaging

C H Toh et al. AJNR Am J Neuroradiol. 2012 Sep.

Abstract

Background and purpose: A common imaging finding in brain abscess and necrotic glioblastoma is a T2 hypointense margin. The features of this hypointense rim on SWI have not been previously described, to our knowledge. We aimed to differentiate abscesses from glioblastomas by assessing the morphology of their lesion margin by using SWI.

Materials and methods: T2WI and SWI were performed in 12 abscesses and 20 rim-enhancing glioblastomas. On T2WI and SWI, the prevalence and the border types (complete versus incomplete) of hypointense rims were qualitatively assessed. On SWI, the contour (smooth versus irregular) and the location of hypointense rims relative to the contrast-enhancing rims as well as the prevalence of the "dual rim sign," defined as 2 concentric rims at lesion margins with the outer one being hypointense and the inner one hyperintense relative to cavity contents, were also analyzed.

Results: Prevalence and the border types of the hypointense rims on T2WI were not different between abscesses and glioblastomas. On SWI, there were significantly more hypointense rims that were complete (P < .001) and smooth (P < .001), having the same location as the contrast-enhancing rims (P < .001) for abscesses. A dual rim sign was present in 9 of 12 abscesses but absent in all glioblastomas (P < .001).

Conclusions: SWI may be helpful in differentiating pyogenic abscesses from necrotic glioblastomas. The dual rim sign is the most specific imaging feature distinguishing the 2.

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Figures

Fig 1.
Fig 1.
A 56-year-old woman with 2 right occipital pyogenic brain abscesses. A, Transverse contrast-enhanced MPRAGE shows 2 adjoining rim-enhancing masses in the right occipital lobe. B, On the transverse T2-weighted image, an incomplete hypointense rim (arrow) is present at the lesion margin. C, On transverse SWI, the abscesses are bordered by 2 concentric rims, with the outer one being hypointense (arrow), and the inner one, hyperintense (arrowhead) relative to cavity content, forming the dual rim sign. D, On the close-up view of the SWI with the contrast-enhancing rim (red region of interest) overlaid, the hyperintense rim (arrowhead) is inner to the contrast-enhancing rim.
Fig 2.
Fig 2.
A 57-year-old man with a right temporal necrotic glioblastoma. A, Transverse contrast-enhanced MPRAGE shows a rim-enhancing mass in the right temporal lobe. B, On the transverse T2-weighted image, the hypointense rim is absent. C, On the transverse SWI, abundant hypointensities (arrows) with an irregular contour forming an incomplete rim are present at the lesion margin. D, On the close-up view of SWI with a contrast-enhancing rim (red region of interest) overlaid, some of these hypointensities (arrows) are inner to the contrast-enhancing rim, while some are overlapping the contrast-enhancing rim.
Fig 3.
Fig 3.
A 40-year-old woman with a left temporal necrotic glioblastoma. A, Transverse contrast-enhanced MPRAGE shows a rim-enhancing mass in the left temporal lobe. The hypointense rim is absent on both transverse T2W (B) and SW (C) images.
See this image and copyright information in PMC

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