Abdominal imaging  GUT 

Abdominal radiograph of a fifty year diabetic old lady suffering with fever showing abnormal air lucency in the left illiac fossa concerning for emphysematous pyelonephritis- a CT scan confirmed diagnosis patient managed conservatively with  percutaneous drainage catheter and antibiotics 

renal emphysema is fulminant suppurative infection characterised by formation of gas . invariably affects diabetic patient and is fatal if not recognised. 75% of times the offending microbe is Escherichia coli.

Huang and Tseng classified CT findings into following 4 classes for prognostic implication 

class 1. gas in collecting system only

class 2: gas in renal parenchyma with out extension to extrarenal space 

class 3A : extension of gas or abscess to the perinephric space 

class 3B : extension of gas or abscess to the paranephric space 

class 4 : bilateral EPN or solitary kidney EPN 

Wan et al.  classified EPN into two  types 

 Type 1 EPN is acutely more fulminant, and shows  a streaky or mottled  gas pattern and no adjacent fluid collections. Type 2 EPN has a lower mortality rate shows a bubbly gas pattern in the renoureteral unit  and fluid either in the kidney or surrounding the kidney mortality rate is high for type I 68% when compared to type II 18% 
more information from radiographics article in 2008 pyelonephritis - radiologic and pathologic review and also form AJR article in 2010 194 S70-72