Fat stranding on CT means that the normally dark fat becomes lighter and dirtier looking. Fat stranding on CT can be an important indicator of inflammatory change around an organ or structure. Fat stranding often alerts the radiologist to an important process which in some cases requires medical or surgical treatment.
In some cases, fat stranding around an organ indicates the need for surgery. One of the more common diagnosis is acute appendicitis. Fat stranding around the appendix often indicates appendicitis. The appendix will also be abnormally dilated and thickened in many cases. Fat stranding around the gallbladder will often mean cholecystitis or inflamed gallbladder. An ultrasound is often done which will often confirm the diagnosis.
In many cases, fat stranding around an organ will mean that medical treatment is necessary. For example, an inflamed kidney or pyelonephritis is treated with antibiotics. Often, there will be findings in the kidney which are suggestive of this condition. Pancreatitis or an inflamed pancreas will often have fat stranding surrounding it on CT. This is also treated medically with hospitalization in many cases.
Fat stranding is also seen post trauma when there is bruising or injury to an organ. Fat stranding can also be seen with inflamed skin and tissues from cellulitis. This is treated with antibiotics. Fat stranding is seen around a kidney when someone is passing a stone. Fat stranding is also seen around sites where surgery or procedures have been done. These conditions do not require surgery in many cases.
Fat stranding therefore has a variety of causes. Treatment depends on the specific diagnosis. Surgery is indicated in some cases like an inflamed appendix or gallbladder. Many other causes of fat stranding are treated medically or not at all. Fat stranding is often an important sign of an abnormality. The abnormality can range from life threatening to benign and inconsequential. Often there are additional findings that alert the radiologist to the diagnosis. The clinical history is also helpful. Therefore, not all stranding around organs or structures, indicates the need for surgery,