Intramural stratification with deposition of fat in the submucosal layer of the bowel wall, visualised on computed tomographic (CT) scans of the abdomen, is known as the fat halo sign. (1) Owing to infiltration of the submucosa by fat, the inner layer mucosa are separated from the outer layer of muscularis propria/serosa (both being of soft tissue density) by a layer of fat (of low attenuation) measuring between-18 to-64 Hounsfield units.
Historically, the fat halo sign has been associated with patients suffering from chronic inflammatory bowel disease.
conducted a study in 2003 evaluating the presence and frequency of the fat halo sign in patients undergoing abdominal CT for clinical indications unrelated to the gastrointestinal tract.
Pitfalls associated with interpretation of the fat halo sign specifically involve intestinal distension.
In conclusion: the presence of the fat halo sign may in the absence of clinical and radiological features of inflammatory bowel disease represent a normal finding that may also be related to obesity.