Background: Low-signal-intensity (LSI) rim along deep layers of the cerebral cortex is reportedly a susceptibility-weighted imaging (SWI) finding in progressive multifocal leukoencephalopathy (PML). We aimed to evaluate whether this finding can be identified in diseases other than PML.
Methods: We retrospectively reviewed brain MR images from 5605 patients who underwent SWI at 3T; 370 patients with various diseases, who showed cortical and subcortical FLAIR high-signal lesions including U-fiber, were enrolled. The presence or absence of LSI rim on thin-slice SWI and hyperintense cortical signal (HCS) on T1-weighted images adjacent to LSI rim was analyzed. Signal changes of the LSI rim were assessed on serial SWI, if available.
Results: Twenty-five of the 370 patients (6.8%) showed SWI LSI rim, in infarct (n=22) and encephalitis (n=3). HCS was apparent adjacent to SWI LSI rim in 17 patients (15 infarct, 2 encephalitis). Serial SWI was available for 17 patients, of whom 10 patients (8 infarct, 2 encephalitis) presented LSI rim later than 45days after onset.
Conclusion: LSI rim can be observed in infarct and encephalitis. Therefore, this finding is not specific to PML. LSI rim appears to be associated with HCS.
Keywords: Hyperintense cortical signal; Low-signal-intensity rim; Susceptibility-weighted imaging.
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