400 Ruber DEC RUQ L0■ RUQ LO Fig. 8. Acalculous cholecystitis. A 50 year old woman Fig 9 Gallbladder gangrene/mucosal sloughing. Lon presents with fever and right upper quadrant pain gitudinal ultrasound of a patient who had acute cho and a positive sonographic Murphy,'s sign on US exam- lecystitis secondary to stone (arrow) impacted in the ation Longitudinal ultrasound shows a debris-filled Bladder neck. not rows).No stones are visualized At surgery, this was the gallbladder.(From Rubens D Hepatobiliary iaga asterisk) gallbladder with a thick, striated wall (a (arrowheads) that are associated with gangrene acute acalculous cholecystitis (From Rubens D Hepa- ing and its pitfalls. Radiol Clin North Am 2004 42 tobiliary imaging and its pitfalls. Radiol Clin Nor 257-78; with permission Am 2004: 42: 257-78: with permission. of it. In either case, the calcified wall causes only adenomyomatosis(diffuse, focal, or polypoid) a single echogenic arc, not the double arc seen in has been reported in 8.7%22 Cholesterolosis is the WES complex. If calcification in the wall is caused by deposition of lipid-laden macrophages eavy, there is a single echo with a strong posterior in the lamina propria, beneath the normal epithe shadow obscuring the gallbladder. With lesser lium in the mucosa of the gallbladder wall. The dif- degrees of calcification, the gallbladder lumen fuse form, which is more common, is difficult nay be discerned posteriorly(Fig. 13). Another appreciate on imaging 2 Cholesterol polyps rep- manifestation of chronic cholecystitis is xanthogra- resent 20% of cholesterolosis but comprise approx nulomatous cholecystitis(XGP), in which the gall- imately one half of all gallbladder polyps [ 2, 191 bladder wall is infiltrated by foamy histiocytes, They are usually less than 1 cm in size, often multi lymphocytes, polymorphonuclear leukocytes, fi- ple, and have no malignant potential. On ultra- broblasts, and giant cells 19. It presents sono- sound they appear brightly echogenic, round or graphically as diffuse or focal thickening of the lobulated, immobile, non-shadowing masses abut- gallbladder wall, with mural nodularity(Fig. 14). ting the gallbladder wall(Fig. 15).Adenomyomato- Although this is rare, occurring in only 2% of cho- sis, also known as adenomyomatous hyperplasia, lecystectomy specimens 21, the imaging appear- involves the mucosa and the muscular and connec- noninflammatory lesions, such as adenomyomato- lium and muscular layer p ance is often difficult to distinguish from tive tissue layers of the gallbladder wall. The epithe sis and gallbladder carcinoma. Because the hepatic invagination of the epithelial-lined spaces into the surface of the gallbladder lacks a serosal layer, the gallbladder wall produce intramural diverticula, inflammatory process more easily extends to the ad- termed Rokitansky-Aschoff sinuses. These may accu- jacent liver, and the liver-gallbladder margin is fre- mulate bile, cholesterol crystals, or even stones. On quently indistinct 2, 191 US examinations they may be anechoic if large enough and bile containing but more frequently Noninflammatory non-neoplastic are small and contain cholesterol, biliary sludge, or gallbladder disorders: the hyperplasti gallstones that create echogenic foci(Fig. 16), cholecystoses-cholesterolosis often with ring-down or comet tail reverberation ar tifacts23 The most common form of adenomyo- matosis is a focal polypoid lesion, also known as Hyperplastic cholecystoses are common, often an adenomyoma, typically located at the tip of the asymptomatic processes that involve various layers gallbladder fundus. The segmental form consists of of the gallbladder wall. Cholesterolosis, which localized gallbladder wall thickening that typically may be diffuse or polypoid, has been reported narrows the gallbladder body in an hourglass up to 25% of surgical specimens [2), whereas configuration. Diffuse adenomyomatosis involvingof it. In either case, the calcified wall causes only a single echogenic arc, not the double arc seen in the WES complex. If calcification in the wall is heavy, there is a single echo with a strong posterior shadow obscuring the gallbladder. With lesser degrees of calcification, the gallbladder lumen may be discerned posteriorly (Fig. 13). Another manifestation of chronic cholecystitis is xanthogra￾nulomatous cholecystitis (XGP), in which the gall￾bladder wall is infiltrated by foamy histiocytes, lymphocytes, polymorphonuclear leukocytes, fi- broblasts, and giant cells [19]. It presents sono￾graphically as diffuse or focal thickening of the gallbladder wall, with mural nodularity (Fig. 14). Although this is rare, occurring in only 2% of cho￾lecystectomy specimens [21], the imaging appear￾ance is often difficult to distinguish from noninflammatory lesions, such as adenomyomato￾sis and gallbladder carcinoma. Because the hepatic surface of the gallbladder lacks a serosal layer, the inflammatory process more easily extends to the ad￾jacent liver, and the liver–gallbladder margin is fre￾quently indistinct [2,19]. Noninflammatory non-neoplastic gallbladder disorders: the hyperplastic cholecystoses—cholesterolosis and adenomyomatosis Hyperplastic cholecystoses are common, often asymptomatic processes that involve various layers of the gallbladder wall. Cholesterolosis, which may be diffuse or polypoid, has been reported in up to 25% of surgical specimens [2], whereas adenomyomatosis (diffuse, focal, or polypoid) has been reported in 8.7% [22]. Cholesterolosis is caused by deposition of lipid-laden macrophages in the lamina propria, beneath the normal epithe￾lium in the mucosa of the gallbladder wall. The dif￾fuse form, which is more common, is difficult to appreciate on imaging [2]. Cholesterol polyps rep￾resent 20% of cholesterolosis but comprise approx￾imately one half of all gallbladder polyps [2,19]. They are usually less than 1 cm in size, often multi￾ple, and have no malignant potential. On ultra￾sound they appear brightly echogenic, round or lobulated, immobile, non-shadowing masses abut￾ting the gallbladder wall (Fig. 15). Adenomyomato￾sis, also known as adenomyomatous hyperplasia, involves the mucosa and the muscular and connec￾tive tissue layers of the gallbladder wall. The epithe￾lium and muscular layers proliferate, and invagination of the epithelial-lined spaces into the gallbladder wall produce intramural diverticula, termed Rokitansky-Aschoff sinuses. These may accu￾mulate bile, cholesterol crystals, or even stones. On US examinations they may be anechoic if large enough and bile containing but more frequently are small and contain cholesterol, biliary sludge, or gallstones that create echogenic foci (Fig. 16), often with ring-down or comet tail reverberation ar￾tifacts [23]. The most common form of adenomyo￾matosis is a focal polypoid lesion, also known as an adenomyoma, typically located at the tip of the gallbladder fundus. The segmental form consists of localized gallbladder wall thickening that typically narrows the gallbladder body in an hourglass configuration. Diffuse adenomyomatosis involving Fig. 8. Acalculous cholecystitis. A 50 year old woman presents with fever and right upper quadrant pain and a positive sonographic Murphy’s sign on US exam￾ination. Longitudinal ultrasound shows a debris-filled (asterisk) gallbladder with a thick, striated wall (ar￾rows). No stones are visualized. At surgery, this was acute acalculous cholecystitis. (From Rubens D. Hepa￾tobiliary imaging and its pitfalls. Radiol Clin North Am 2004;42:257–78; with permission.) Fig. 9. Gallbladder gangrene/mucosal sloughing. Lon￾gitudinal ultrasound of a patient who had acute cho￾lecystitis secondary to stone (arrow) impacted in the gallbladder neck. Note the intraluminal membranes (arrowheads) that are associated with gangrene of the gallbladder. (From Rubens D. Hepatobiliary imag￾ing and its pitfalls. Radiol Clin North Am 2004;42: 257–78; with permission.) 400 Rubens