Figure 9.

(A–C) Schematic images of a normal (left) gall bladder, gall bladder wall edema also referred to the halo sign (middle), and still ultrasound image of the halo sign (right). With gall bladder wall edema there is a thickening of the gall bladder wall but also a “striated” appearance that arises when anechoic fluid (black) separates the mucosal and serosal surfaces of the gall bladder wall (white). The serosal and mucosal surfaces of the gall bladder wall are indicated by an asterix in the still image. GB, gall bladder.