What are mnemonics for the causes of cerebral ring enhancing lesions?
MAGIC DR. M: metastasis A: abscess G: glioblastoma I: infarct, inflammatory C: contusion D: demyelinating disease R: radiation necrosis or resolving haematoma
What is the dual rim sign of brain abscess on MRI?
Appreciated on T2/T2* weighted imaging, it consists of two concentric rims surrounding the abscess cavity, the outer one of which is hypointense, and the inner one relatively hyperintense.
How is the dual rim sign helpful?
It is helpful in distinguishing an abscess from a glioblastoma. On T2/T2* weighted imaging, cerebral abscesses typically demonstrate a thin, complete, regular dark line overlapping the contrast enhancing rim. In GBM the T2 hypointense line is on the inner surface of the enhancing tissue and is irregular and incomplete.
Rounded lesion in the left temporal lobe which has low signal on T1, ring enhancement, a thin wall with dual rim sign on T2WI/SWI, high signal on DWI, and low signal on ADC. There is extensive perilesional edema. The lesion extends into the left temporal horn of the lateral ventricle.
Layering debris in the occipital horns on FLAIR with restricted diffusion on DWI. Enhancement of the ependymal lining is seen along the left temporal horn of the lateral ventricle.