Cortical rim sign – useful in distinguishing renal…
Segmental renal infarct
Lobar nephronia (pyelonephritis)
Cortical rim sign – useful in distinguishing renal infarct from lobar nephronia on contrast enhanced CT or MRI. Both pathologies appear as wedge-shaped regions of reduced enhancement, however in approximately 50% of segmental infarcts the very outer few millimetres of cortex enhances as perfusion is maintained by the renal capsular artery (left image ‘cortical rim sign’). In contradistinction the oedema and hypoperfusion of pyelonephritis involves the entire cortex (right image).
from our tumblr blog: http://radiologysigns.tumblr.com/post/23729422999