Fat stranding (CT)

Fat stranding is a common sign seen on CT wherever fat can be found. It is most commonly seen in abdomen/pelvis, but can also be seen in retroperitoneum, thorax, neck and subcutaneous tissues. It can be helpful in localizing both acute and chronic pathology.

Radiographic features

CT

Fat stranding is increased attenuation which can be ill-defined, reticular, linear, or in some malignancies, reticulonodular . Fat stranding is a non-specific sign in itself and can be seen in infectious, inflammatory, malignant, or traumatic conditions.

Abdomen/pelvis

There are several patterns of fat stranding in the abdomen which can occur within the mesentery or surrounding solid organs :

• mesenteric fat stranding (misty mesentery)
  • bowel and mesenteric trauma
  • pericolonic fat stranding with bowel wall thickening
    • bowel ischemia
    • colorectal carcinoma
    • inflammatory and infectious colitis/enteritis
  • pericolonic fat stranding disproportionate to bowel wall thickening
    • acute appendicitis
    • acute diverticulitis
    • epiploic appendagitis: asymmetric on the antimesenteric side
    • omental infarction
  • sclerosing mesenteritis
  • tuberculous peritonitis
  • peritoneal malignancy / peritoneal carcinomatosis
• perinephric fat stranding
• peripancreatic fat stranding: acute pancreatitis
• pericholecystic fat stranding: acute cholecystitis

Thorax

Fat stranding can also be seen in the thorax, and is mainly indicative of mediastinal pathology:

• mediastinitis
• epipericardial fat necrosis
• traumatic aortic injury