Radiological Findings in Mesenteric Fat

Definitions and Characteristics

• Mesenteric fat stranding appears as abnormally increased attenuation in the mesentery, often associated with regional or mesenteric free fluid or edema, and represents inflammatory changes in the mesenteric fat 1
• Thickening of mesenteric fat, also called "creeping fat" or "fibrofatty proliferation", refers to increased volume of mesenteric fat adjacent to abnormal bowel, displacing bowel loops, and represents a chronic process 2, 3

Radiological Characteristics

• Mesenteric fat stranding appears as hazy increased density on CT or high T2 signal on MRI, and is associated with more severe inflammation 1, 4
• Mesenteric fat thickening displaces bowel loops rather than just showing increased attenuation, and is considered a chronic finding that develops over time, particularly in Crohn's disease 2, 3

Clinical Significance

• Mesenteric fat stranding is a highly sensitive sign for bowel injury in trauma, with 34% sensitivity and 92% specificity, and indicates active inflammation in inflammatory bowel disease 1, 5
• Mesenteric fat thickening represents a more chronic process, often seen in longstanding Crohn's disease, and may respond to medical therapy but more slowly than acute inflammatory changes 1, 2

Differential Diagnosis

• Conditions associated with mesenteric fat stranding include acute diverticulitis, bowel injury in trauma, active inflammatory bowel disease, and mesenteric ischemia 1, 5, 6, 7
• Conditions associated with mesenteric fat thickening include chronic Crohn's disease, and segmental misty mesentery 2, 3

Imaging Considerations

• Both findings are best visualized on contrast-enhanced CT, and MRI can also detect both findings with high sensitivity, especially with fat-suppressed sequences 4, 7
• Non-contrast CT has lower sensitivity for detecting subtle fat stranding, and when evaluating for inflammatory bowel disease, both findings should be reported as they represent different aspects of disease activity 1, 4, 8