The Uniform Cortex Sign: A Diagnostic Sign of Diffuse Cortical Injury on MR Imaging of the Brain at 1.5 T.

BACKGROUND: To introduce the "uniform cortex sign" (UCS) and evaluate its performance as a diagnostic test for the presence of diffuse cortical injury (DCI). METHODS: The study was approved by our institutional review board. Three experienced neuroradiologists were given a tutorial on the UCS. They were subsequently presented with 14 cases (7 control patients and 7 DCI patients with the UCS) in random order and asked to determine whether the UCS was present. Each case consisted of selected DWI, T2-weighted, and FLAIR images from unenhanced 1.5T MRI examinations. A consensus result for each case was determined by unanimity or majority rule. RESULTS: All control patients were correctly identified as normal by all neuroradiologists (7/7). The UCS was correctly identified in 86% of DCI patients (6/7). UCS interrater agreement was high (multirater κ=0.81). CONCLUSIONS: This small study shows that the UCS can identify DCI, especially in patients with hypoxic-ischemic encephalopathy. The UCS can be subtle, hence the reader must be vigilant for this finding. The accuracy of the UCS may depend on the extent of cortical injury and time between injury and MRI. Also, a UCS may be reversible, as in our case of viral meningoencephalitis.