Ultrasound Imaging of the Biliary Tract 397 B RT X LP GB X DEC A=1.38cm 2.36cm cursors an ic fluid within the wall. B) Transverse ultrasound of the lower pole of the enuation area of focal pyelonephritis(arrows).(From Rubens D. Hepatobi and its pitfalls. Radiol Clin North Am 2004: 42: 257-78: with permission. diagnosis and therapy [12 However, the diag- congestive heart failure(CHF), or liver disease are of acalculous cholecystitis is difficult to make considered unlikely to be the cause(Fig. 8). CT clinically and by US, because gallstones are absent can be used to assess for pericholecystic inflamma and the sonographic Murphy sign may not be de- tion to improve diagnostic specificity in patients tected because of diminished mental status, medi- who have a thick gallbladder wall and multiple cation and co-morbid illness. In the series potential etiologies [ 2, 13 reported by Cornwall and colleagues [12 only 50% of patients who had acalculous cholecystitis Complicated cholecystitis had a positive Murphys sign. The diagnosis is therefore, made by distension of the gall bladder Gangrenous cholecystitis, emphysematous chole in a suspicious clinical setting the presence of intra- cystitis, and perforation of the gallbladder occur luminal debris, gallbladder tenderness when in up to 20% of patients who have acute cholecys- resent (w50%)and gallbladder wall thickening titis 5 These complications are important to rec- when other etiologies, such as hypoalbuminemia, ognize, because they are associated with increasedearly diagnosis and therapy [12]. However, the diag￾nosis of acalculous cholecystitis is difficult to make clinically and by US, because gallstones are absent and the sonographic Murphy sign may not be de￾tected because of diminished mental status, medi￾cation and co-morbid illness. In the series reported by Cornwall and colleagues [12], only 50% of patients who had acalculous cholecystitis had a positive Murphy’s sign. The diagnosis is, therefore, made by distension of the gall bladder in a suspicious clinical setting, the presence of intra￾luminal debris, gallbladder tenderness when present (~50%) and gallbladder wall thickening when other etiologies, such as hypoalbuminemia, congestive heart failure (CHF), or liver disease are considered unlikely to be the cause (Fig. 8). CT can be used to assess for pericholecystic inflamma￾tion to improve diagnostic specificity in patients who have a thick gallbladder wall and multiple potential etiologies [2,13]. Complicated cholecystitis Gangrenous cholecystitis, emphysematous chole￾cystitis, and perforation of the gallbladder occur in up to 20% of patients who have acute cholecys￾titis [5]. These complications are important to rec￾ognize, because they are associated with increased Fig. 5. Pyelonephritis with gallbladder wall thickening. (A) Gallbladder wall shows marked 1.3-cm thickening (cursors) and hypoechoic fluid within the wall. (B) Transverse ultrasound of the lower pole of the right kidney shows a 3-cm echogenic mass (arrows). (C) CT through the right lower pole shows a characteristic round, hetero￾geneous, decreased attenuation area of focal pyelonephritis (arrows). (From Rubens D. Hepatobiliary imaging and its pitfalls. Radiol Clin North Am 2004;42:257–78; with permission.) Ultrasound Imaging of the Biliary Tract 397