Dual rim sign

The dual or double rim sign is seen on MRI in approximately 75% of cerebral abscesses and is helpful in distinguishing an abscess from glioblastoma (GBM)

On both susceptibility weighted imaging (SWI) and T2WI it consists two concentric rims surrounding the abscess cavity, one of which is hypointense (outer rim), and the other relatively more hyperintense (inner rim).

Pathology

It has been postulated that granulation tissue lines the inner part of fibrocollagenous abscess capsule and together they form the histological basis of dual rim sign 1.

Radiographic features

MRI

Cerebral abscesses tend to have low signal rims (capsule) seen best on SWI but also visible on T2/FLAIR. These are smooth (90%) and complete (75%).

In glioblastomas, the low signal rims (thought to represent haemorrhagic products at the outer region of necrotic core) are irregular (85%) and incomplete (85%)  1

In cerebral abscesses on SWI, immediately internal to the low-intensity rim, is a high-intensity line (granulation tissue). This is known as the dual rim sign 1

On contrast enhancement, the ring enhancement corresponds to the T2 hypointense capsule in abscess, whereas it occurs peripheral to the T2 hypointense rim in glioblastoma. 

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Article information

rID: 25074
Section: Signs
Tags: cases, refs
Synonyms or Alternate Spellings:
  • double rim sign

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Cases and figures

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    Case 1: FLAIR
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