title: CT features of renal infarction.
abstract: OBJECTIVE
  To demonstrate the different patterns of renal infarction to avoid pitfalls. To present 'flip-flop enhancement' pattern in renal infarction.
  
  
  METHODS
  Retrospective review of a total of 41 renal infarction in 37 patients were done. These patients underwent initial CT and the diagnosis of renal infarction was confirmed with either follow up CT or at surgery.
  
  
  RESULTS
  Twenty-three patients had wedge-shaped focal infarcts, nine patients had global and five patients had multifocal infarcts of the kidneys. Cortical rim sign was seen predominantly with global infarcts. In five patients, a 'flip-flop enhancement' pattern was observed. In two patients, planned renal biopsies due to tumefactive renal lesions were cancelled because of 'flip-flop enhancement' pattern on follow up CTs.
  
  
  CONCLUSIONS
  Although most of our cases were straightforward for the diagnosis of renal infarction, cases with tumefactive lesions and global infarctions without the well-known cortical rim sign were particularly challenging. We describe a new sign, flip-flop enhancement pattern, which we believe solidified the diagnosis of renal infarction in five of our cases. The authors recommend further investigations for association of flip-flop enhancement and renal infarction.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007238:Infarction / Q000000981:diagnostic imaging*; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media