The wedges of reduced enhancement seen in the setting of acute pyelonephritis represent oedema and ischaemia which involves the whole wedge or renal parenchyma, from medulla to the capsule.
In segmental infarcts, the later blood supply to the very outer aspect of the cortex is derived from perforating branches of the renal capsular artery which is an early branch of the renal artery. As such, when a branch of the renal artery is occluded (by thromboembolim, dissection etc..) perfusion is preserved to a thin rim (2 - 4mm) of cortex which enhances normally.
Unfortunately the cortical rim sign is only seen in approximately half of renal infarcts.
- 1. Zagoria RJ. Genitourinary radiology, the requisites. Mosby Inc. (2004) ISBN:0323018424. Read it at Google Books - Find it at Amazon
- 2. Lin E, Garg K, Escott E et-al. Practical differential diagnosis for CT and MRI. Thieme Medical Pub. (2008) ISBN:1588906558. Read it at Google Books - Find it at Amazon
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Rim sign (of renal infarction)||✗|
|Renal cortical rim sign||✗|