The rim sign refers to an area of increased hepatic activity surrounding the gallbladder on HIDA. It is also known as a rim of increased hepatic activity (RIHA), and is thought to be due to the spread of inflammation from the gallbladder to the liver.
The rim sign is very specific (up to 100%) and has a high positive predictive value (up to 100%) for complicated acute cholecystitis (ulceration, necrosis, fibrous exudation, perforation, empyema, or gangrene). Unfortunately, its sensitivity and negative predictive value are only 45% and 39%, respectively.
Because of its high specificity and positive predictive value for complicated acute cholecystitis, it has been suggested that 2- to 4-hour delayed images for excluding chronic cholecystitis can be skipped when the rim sign is present with nonvisualization of the gallbladder.
Special thanks to Jon Sweany for corrections.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.