复旦大学上海医学院：《医学影像学》PPT教学课件_胆道超声检查 Ultrasound of the Biliary tract

391 ULTRASOUND CLINICS ELSEVIER SAUNDERS sound clin2(2007391-413 Ultrasound Imaging of the Biliary Tract Deborah」. Rubens,MD Inflammatory disorders: cholecystitis Benign neoplasms of the gallbladder The Sonographic Murphy's Sign Malignant neoplasms of the gallbladder Gallstones Biliary ducts Gallbladder wall thickening a Ultrasound diagnosis of biliary ductal and pericholecystic fluid dilatation Acute acalculous cholecystitis Diagnosis of biliary obstruction Complicated cholecystitis n Causes of biliary obstruction Choledocholithiasis Gallbladder perforation Ne。 plasm Inflammatory disorders of the biliary ducts Chronic cholecystitis Biliary air and biliary necrosis Noninflammatory non-neoplastic gallbladder disorders: the hyperplastic References cholecystoses-cholesterolosis and Patients who have disease of the biliary tract inflammation of the gallbladder wall. There may ommonly present with acute right upper quadrant or may not be associated infection and necrosis pain, nausea or vomiting, mid-epigastric pain, and/ Ninety to ninety-five percent of all cases of acute or jaundice. Etiologies include inflammation with cholecystitis are caused by obstruction of either or without infection, noninflammatory disorders, the cystic duct or the neck of the gallbladder by gal and benign or malignant neoplasms of the gallblad- stones 1. Acute cholecystitis, however, occurs in der or bile ducts. Ultrasound(us) is now accepted only approximately 20% of patients who have gall as the initial imaging modality of choice for the stones [2 This means that most gallstones are work-up of suspected biliary tract disease. asymptomatic. Thus, right upper quadrant pain in This article reviews the most common diseases of a patient who has gallstones often is caused by some- the gallbladder and bile ducts, strategies for evaluat- thing other than acute cholecystitis 3 Further- ing the biliary tract with ultrasound, and specific more, studies have shown that only 20%-35% of imaging patterns that aid in diagnosis patients presenting with right upper quadrant pain are subsequently shown to have acute cholecystitis Inflammatory disorders: cholecystitis 11, 2 Therefore, it is important to understand the sensitivity and specificity of common US findings Acute cholecystitis most often occurs secondary in patients who have acute cholecystitis, because to obstruction of the gallbladder with resultant the presence of gallstones alone is not adequate to University of Rochester Medical Center, Department of Imaging Sciences, 601 Elmwood Avenue, Rochester NY14642-8648,USA E-mail address. deborah rubens@urmc rochester edu 1556-858X/07/S-see front matter e 2007 Elsevier Inc. All rights reserved doi:10.1016/cut200708.00

Ultrasound Imaging of the Biliary Tract Deborah J. Rubens, MD Patients who have disease of the biliary tract commonly present with acute right upper quadrant pain, nausea or vomiting, mid-epigastric pain, and/ or jaundice. Etiologies include inflammation with or without infection, noninflammatory disorders, and benign or malignant neoplasms of the gallblad￾der or bile ducts. Ultrasound (US) is now accepted as the initial imaging modality of choice for the work-up of suspected biliary tract disease. This article reviews the most common diseases of the gallbladder and bile ducts, strategies for evaluat￾ing the biliary tract with ultrasound, and specific imaging patterns that aid in diagnosis. Inflammatory disorders: cholecystitis Acute cholecystitis most often occurs secondary to obstruction of the gallbladder with resultant inflammation of the gallbladder wall. There may or may not be associated infection and necrosis. Ninety to ninety-five percent of all cases of acute cholecystitis are caused by obstruction of either the cystic duct or the neck of the gallbladder by gall￾stones [1]. Acute cholecystitis, however, occurs in only approximately 20% of patients who have gall￾stones [2]. This means that most gallstones are asymptomatic. Thus, right upper quadrant pain in a patient who has gallstones often is caused by some￾thing other than acute cholecystitis [3]. Further￾more, studies have shown that only 20%–35% of patients presenting with right upper quadrant pain are subsequently shown to have acute cholecystitis [1,2]. Therefore, it is important to understand the sensitivity and specificity of common US findings in patients who have acute cholecystitis, because the presence of gallstones alone is not adequate to ULTRASOUND CLINICS Ultrasound Clin 2 (2007) 391–413 University of Rochester Medical Center, Department of Imaging Sciences, 601 Elmwood Avenue, Rochester, NY 14642-8648, USA E-mail address: deborah_rubens@urmc.rochester.edu - Inflammatory disorders: cholecystitis - The Sonographic Murphy’s Sign - Gallstones - Gallbladder wall thickening and pericholecystic fluid - Acute acalculous cholecystitis - Complicated cholecystitis - Gangrenous cholecystitis - Gallbladder perforation - Emphysematous cholecystitis - Chronic cholecystitis - Noninflammatory non-neoplastic gallbladder disorders: the hyperplastic cholecystoses—cholesterolosis and adenomyomatosis Benign neoplasms of the gallbladder Malignant neoplasms of the gallbladder - Biliary ducts - Ultrasound diagnosis of biliary ductal dilatation - Diagnosis of biliary obstruction - Causes of biliary obstruction Choledocholithiasis Neoplasm - Inflammatory disorders of the biliary ducts - Biliary air and biliary necrosis - Summary - References 391 1556-858X/07/$ – see front matter ª 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.cult.2007.08.007 ultrasound.theclinics.com

392 Rub ↓ GB LO DEC GB LO SITTING LONG G B

392 Rubens

Ultrasound Imaging of the Biliary Tract 393 make the diagnosis of acute cholecystitis. The com- the gallbladder lumen that cast a posterior shadow bination of US findings that is most predictive of (Fig. 1). Although ultrasound has been demon- acute cholecystitis is the presence of a positive sone rated to have an accuracy (>95%)for the identifica Secondary signs on US examination of acute chole- 3 strong internal echoes 1 or gallstones impacted in Bs h ), a distended or hydropic gallbladder(loss of the gallbladder neck or in the cystic duct that may the normal tapered neck and development of an el- not be as readily detectable on US examination as liptic or rounded shape), and pericholecystic fluid. they silhouette with the surrounding echogenic bowel gas or intraperitoneal fat(see Fig. 1)15.If The sonographic Murphy,'s sign the gallbladder is focally tender but no gallstones are appreciated the patient should be examined The sonographic Murphy sign is defined as repro- from multiple positions and scanning planes, ducible point tenderness specifically over the gall- cluding prone, upright and decubitus positions bladder upon application of pressure by the and intercostal scanning, to facilitate complete visu transducer Ralls and colleagues [4] wrote a classic alization of the neck of the gallbladder [3, 61 article that reported a sonographic Murphy sign Harmonic imaging significantly improves visual was 87% specific for the diagnosis of acute ization of small gallstones. This type of ultrasound cholecystitis, in a patient population which only in- transmits the insonating us beam at a fundamental cluded patients who had right upper quadrant pain, frequency, such as 2.5 or 3 MHz, and receives the re- fever and an elevated white blood cell count. Laing turning echoes not only at the fundamental fre and colleagues [5| reported that the presence of quency but also at the second harmonic frequency a positive sonographic Murphys sign in combina- that is twice the fundamental frequency creating tion with the presence of gallstones has a positive the image with the higher harmonic frequency predictive value of 92%for the diagnosis of acute 17-9 By eliminating the fundamental frequency, cholecystitis. In order to avoid false positive exami- this technique significantly reduces degradation of lations, one must be careful to elicit pain directly the image by noise, since lower frequencies easily over the gallbladder, not diffusely in epigastrium, can be filtered out. In addition, scattering of the or over the liver edge. False negative examinations US beam from fat in the anterior abdominal wall may occur in patients who have received pain med- is diminished because the harmonic frequencies icine, patients who are taking steroids, para or are generated after the beam enters the body. The quadriplegics, or any patient who is not able to narrower harmonic beam also has fewer side lobes, give a reliable history or pain response. In addition, and therefore, improved lateral resolution and sig. the sonographic Murphy s sign may be absent in de- nal to noise ratio. Harmonic imaging increases nervated gallbladders, for example, in patients who the echogenicity of gallstones and strengthens have diabetes or gangrenous cholecystitis. A sono. their posterior shadows, permitting visualization diminished if the gallbaldder ruptures because ultrasound(see Fig. 1). Another technique that im this will relieve the obstruction. Therefore, careful proves visualization of stones is spatial compound attention to the patient's clinical status is important ing. Multiple images are acquired slightly off axis when assessing for a sonographic Murphy's sig from one another, which increases the signal from the persistent echoes that comprise the image and Gallstones blurs out some of the random noise. the disadvan- Gallstones are diagnosed on US by the presence of tage of compounding is that posterior shadowing is diminished, which may be a better visual cue to gravity-dependent, mobile, echogenic foci within dete llstones than the actual echoes Fig 1. Gallstones. (A)(Left) Gallstone in the gallbladder neck (arrow) casts no significant shadow and is nearly invisible. Gas in the duodenum(arrowhead)obscures the fundus of the gallbladder and casts a strong sharp shadow(asterisk).(Right) With patient in sitting position, stone (arrow)moves out of the neck and casts a clear shadow (asterisk). Adjacent duodenum(arrowheads) is now separate from the gallbladder but still casts a strong shadow, equivalent to the gallstone. B)(Left)Multiple gallstones(arrowheads), some of which cast shadow (arrows), whereas others do not. (Right) Normal caliber common duct( 6 mm at the porta)with stones(arrows) in the same patient. Choledocholithiasis may be difficult to detect, especially in the distal duct, if the stones do not shadow or are not outlined by fluid (o(Left) Longitudinal ultrasound shows a normal gallbladder. ( Right) Harmonic imaging reveals multiple small stones(arrows).(From Rubens D Hepatobiliary imaging and its pitfalls Radiol Clin North Am 2004: 42: 257-78: with permission

make the diagnosis of acute cholecystitis. The com￾bination of US findings that is most predictive of acute cholecystitis is the presence of a positive sono￾graphic Murphy’ sign plus the presence of gallstones. Secondary signs on US examination of acute chole￾cystitis include gallbladder wall thickening (>3 mm), a distended or hydropic gallbladder (loss of the normal tapered neck and development of an el￾liptic or rounded shape), and pericholecystic fluid. The sonographic Murphy’s sign The sonographic Murphy sign is defined as repro￾ducible point tenderness specifically over the gall￾bladder upon application of pressure by the transducer. Ralls and colleagues [4] wrote a classic article that reported a sonographic Murphy sign was 87% specific for the diagnosis of acute cholecystitis, in a patient population which only in￾cluded patients who had right upper quadrant pain, fever and an elevated white blood cell count. Laing and colleagues [5] reported that the presence of a positive sonographic Murphy’s sign in combina￾tion with the presence of gallstones has a positive predictive value of 92% for the diagnosis of acute cholecystitis. In order to avoid false positive exami￾nations, one must be careful to elicit pain directly over the gallbladder, not diffusely in epigastrium, or over the liver edge. False negative examinations may occur in patients who have received pain med￾icine, patients who are taking steroids, para or quadriplegics, or any patient who is not able to give a reliable history or pain response. In addition, the sonographic Murphy’s sign may be absent in de￾nervated gallbladders, for example, in patients who have diabetes or gangrenous cholecystitis. A sono￾graphic Murphy’s sign also may be significantly diminished if the gallbaldder ruptures because this will relieve the obstruction. Therefore, careful attention to the patient’s clinical status is important when assessing for a sonographic Murphy’s sign. Gallstones Gallstones are diagnosed on US by the presence of gravity-dependent, mobile, echogenic foci within the gallbladder lumen that cast a posterior shadow (Fig. 1). Although ultrasound has been demon￾strated to have an accuracy (>95%) for the identifica￾tion of gallstones, stones that are too small, (usually <1 mm to cast a posterior shadow soft stones lacking strong internal echoes [1], or gallstones impacted in the gallbladder neck or in the cystic duct that may not be as readily detectable on US examination as they silhouette with the surrounding echogenic bowel gas or intraperitoneal fat (see Fig. 1) [5]. If the gallbladder is focally tender but no gallstones are appreciated, the patient should be examined from multiple positions and scanning planes, in￾cluding prone, upright and decubitus positions and intercostal scanning, to facilitate complete visu￾alization of the neck of the gallbladder [3,6]. Harmonic imaging significantly improves visual￾ization of small gallstones. This type of ultrasound transmits the insonating US beam at a fundamental frequency, such as 2.5 or 3 MHz, and receives the re￾turning echoes not only at the fundamental fre￾quency but also at the second harmonic frequency that is twice the fundamental frequency creating the image with the higher harmonic frequency [7–9]. By eliminating the fundamental frequency, this technique significantly reduces degradation of the image by noise, since lower frequencies easily can be filtered out. In addition, scattering of the US beam from fat in the anterior abdominal wall is diminished because the harmonic frequencies are generated after the beam enters the body. The narrower harmonic beam also has fewer side lobes, and therefore, improved lateral resolution and sig￾nal to noise ratio. Harmonic imaging increases the echogenicity of gallstones and strengthens their posterior shadows, permitting visualization of stones not seen with conventional grayscale ultrasound (see Fig. 1). Another technique that im￾proves visualization of stones is spatial compound￾ing. Multiple images are acquired slightly off axis from one another, which increases the signal from the persistent echoes that comprise the image and blurs out some of the random noise. The disadvan￾tage of compounding is that posterior shadowing is diminished, which may be a better visual cue to detect typical gallstones than the actual echoes Fig. 1. Gallstones. (A) (Left) Gallstone in the gallbladder neck (arrow) casts no significant shadow and is nearly invisible. Gas in the duodenum (arrowhead) obscures the fundus of the gallbladder and casts a strong sharp shadow (asterisk). (Right) With patient in sitting position, stone (arrow) moves out of the neck and casts a clear shadow (asterisk). Adjacent duodenum (arrowheads) is now separate from the gallbladder but still casts a strong shadow, equivalent to the gallstone. (B) (Left) Multiple gallstones (arrowheads), some of which cast shadows (arrows), whereas others do not. (Right) Normal caliber common duct (6 mm at the porta) with stones (arrows) in the same patient. Choledocholithiasis may be difficult to detect, especially in the distal duct, if the stones do not shadow or are not outlined by fluid. (C) (Left) Longitudinal ultrasound shows a normal gallbladder. (Right) Harmonic imaging reveals multiple small stones (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 393

394 Rub GB

394 Rubens

Ultrasound Imaging of the Biliary Tract 395 hile harmonic imaging definitely improves detection, spatial com- pounding remains optional on an individual case basis Other stones such as soft pigment stones may not shadow with any technique. Soft pigment stones are less echogenic than the more cor terol gallstones and may simulate soft tissue asses. Pigmented stones are commonly associated with recurrent pyogenic cholangiohepatitis and are nore often seen in the bile ducts than in the gall bladder. Because of their lack of shadowing, they may be misinterpreted as sludge or debris and result in a false negative examination False positive Us diagnosis of gallstones may oc- cur secondary to side lobe artifacts that can generate Fig 3. Acute cholecystitis. This patient presented with echoes appearing to arise within the gallbladder lu- RUQ pain and had a positive se men but actually te from the wall or outside sign. Longitudinal ultrasound shows stones (arrows) the wall (1 . Similarly, gas in adjacent bowel can cre and diffuse gallbladder wall thickening (cursors) ate a brightly echogenic mass-like area with poste- measuring 5 mm (From Harrow A. The gallbladder rior shadowing which appears to be within the and biliary tree. In: Dogra V, Rubens D, editors. Ultra- gallbladder lumen because of a partial volume art fact and thereby mimics gallstones(Fig. 1A). A cal- p. 113-29: with permission.) cium bile salt precipitate may form in patients taking the antibiotic ceftriaxone and may mimic finding, because numerous other etiologies such gallstones on sonographic examination. These pre- as hepatic congestion or edema, congestive heart e anter patient failure, or hypoproteinemia(often associated with Other fluid-containing structures such as the renal disease or hepatic dysfunction)can cause duodenum,gastric antrum,colon, hematomas, pan- thickening of the gallbladder wall. Adenomyomato- creatic pseudocysts(Fig. 2), or even dilated vascular sis and cancer of the gall bladder also may result in collaterals may be mistaken for the gallbladder on thickening of the gallbladder wall (3).A thickened US examination, especially if the gallbladder is gallbladder wall also can occur in association with out of its normal position or is small and con- viral infections and adjacent inflammatory condi tracted. Mistaking these structures for the gallblad- tions, including hepatitis, peptic ulcer disease der may result in missing pathology in the true (Fig. 4), pancreatitis, perihepatitis(Fitz-Hugh- gallbladder or a false-positive diagnosis of gallblad- Curtis syndrome), and pyelonephritis(Fig. 5).In der disease(ie, obstructed gallbladder or acalculous patients who have thickening of the gallbladder cholecystitis) wall caused by etiologies other than acute cholecys- titis, the gallbladder often is nondistended, imply Gallbladder wall thickening ng a nonobstructive(non-biliary) cause of wall cystic flt thickening(Fig. 6) Thickened gallbladder wall demonstrating a stri Gallbladder wall thickening is defined as a wall ated appearance with alternating hyper- and hypo- diameter greater than 3 mm and is present in echoic layers in the setting of acute cholecystitis is 50%of patients who have acute cholecystitis strongly associated gangrenous cholecystitis [101 (Fig. 3)|1 However, this is a very non-specific However, striations in the gallbladder wall without Fig. 2. Pseudo gallbladders. (A) Transverse image in the right upper gallbladder" does not extend anteriorly and that the aorta (a)is immediately adjacent. B)(Left) CT image of the same area as in(a)showed a fluid-contain ing structure with similar attenuation to blood in the aorta(A). This was a retroperitoneal hematoma in an anti- coagulated patient. B)(Right) The true gallbladder(GB)is lateral to the aorta and extends anteriorly. (o)(Left) Fluid and debris-containing structure believed to represent an abnormal gallbladder(GB)in this patient who had RUQ pain (Right) The true gallbladder(arrows) is compressed and displaced by the adjacent mass, a pan creatic pseudocyst. (D)CT of the pancreatic pseudocyst(P) displacing the gallbladder(arrows).(From Rubens D. Hepatobiliary imaging and its pitfalls. Radiol Clin North Am 2004: 42: 257-78: with permission

from the stones themselves. So, while harmonic imaging definitely improves detection, spatial com￾pounding remains optional on an individual case basis. Other stones such as soft pigment stones may not shadow with any technique. Soft pigment stones are less echogenic than the more common choles￾terol gallstones and may simulate soft tissue masses. Pigmented stones are commonly associated with recurrent pyogenic cholangiohepatitis and are more often seen in the bile ducts than in the gall￾bladder. Because of their lack of shadowing, they may be misinterpreted as sludge or debris and result in a false negative examination. False positive US diagnosis of gallstones may oc￾cur secondary to side lobe artifacts that can generate echoes appearing to arise within the gallbladder lu￾men but actually originate from the wall or outside the wall [1]. Similarly, gas in adjacent bowel can cre￾ate a brightly echogenic mass-like area with poste￾rior shadowing, which appears to be within the gallbladder lumen because of a partial volume arti￾fact and thereby mimics gallstones (Fig. 1A). A cal￾cium bile salt precipitate may form in patients taking the antibiotic ceftriaxone and may mimic gallstones on sonographic examination. These pre￾cipitates resolve after the patient ends therapy. Other fluid-containing structures such as the duodenum, gastric antrum, colon, hematomas, pan￾creatic pseudocysts (Fig. 2), or even dilated vascular collaterals may be mistaken for the gallbladder on US examination, especially if the gallbladder is out of its normal position or is small and con￾tracted. Mistaking these structures for the gallblad￾der may result in missing pathology in the true gallbladder or a false-positive diagnosis of gallblad￾der disease (ie, obstructed gallbladder or acalculous cholecystitis). Gallbladder wall thickening and pericholecystic fluid Gallbladder wall thickening is defined as a wall diameter greater than 3 mm and is present in 50% of patients who have acute cholecystitis (Fig. 3) [1]. However, this is a very non-specific finding, because numerous other etiologies such as hepatic congestion or edema, congestive heart failure, or hypoproteinemia (often associated with renal disease or hepatic dysfunction) can cause thickening of the gallbladder wall. Adenomyomato￾sis and cancer of the gall bladder also may result in thickening of the gallbladder wall [3]. A thickened gallbladder wall also can occur in association with viral infections and adjacent inflammatory condi￾tions, including hepatitis, peptic ulcer disease (Fig. 4), pancreatitis, perihepatitis (Fitz-Hugh￾Curtis syndrome), and pyelonephritis (Fig. 5). In patients who have thickening of the gallbladder wall caused by etiologies other than acute cholecys￾titis, the gallbladder often is nondistended, imply￾ing a nonobstructive (non-biliary) cause of wall thickening (Fig. 6). A thickened gallbladder wall demonstrating a stri￾ated appearance with alternating hyper- and hypo￾echoic layers in the setting of acute cholecystitis is strongly associated gangrenous cholecystitis [10]. However, striations in the gallbladder wall without Fig. 2. Pseudo gallbladders. (A) Transverse image in the right upper quadrant (RUQ) with structure identified as the gallbladder (arrows) containing debris (asterisk). Note that the ‘‘gallbladder’’ does not extend anteriorly and that the aorta (A) is immediately adjacent. (B) (Left) CT image of the same area as in (A) showed a fluid-contain￾ing structure with similar attenuation to blood in the aorta (A). This was a retroperitoneal hematoma in an anti￾coagulated patient. (B) (Right) The true gallbladder (GB) is lateral to the aorta and extends anteriorly. (C) (Left) Fluid and debris-containing structure believed to represent an abnormal gallbladder (GB) in this patient who had RUQ pain. (Right) The true gallbladder (arrows) is compressed and displaced by the adjacent mass, a pan￾creatic pseudocyst. (D) CT of the pancreatic pseudocyst (P) displacing the gallbladder (arrows). (From Rubens D. Hepatobiliary imaging and its pitfalls. Radiol Clin North Am 2004;42:257–78; with permission.) : Fig. 3. Acute cholecystitis. This patient presented with RUQ pain and had a positive sonographic Murphy sign. Longitudinal ultrasound shows stones (arrows) and diffuse gallbladder wall thickening (cursors) measuring 5 mm. (From Harrow A. The gallbladder and biliary tree. In: Dogra V, Rubens D, editors. Ultra￾sound secrets. Philadelphia: Hanley and Belfus; 2004. p. 113–29; with permission.) Ultrasound Imaging of the Biliary Tract 395

396 Rube 105cm Fig. 4. Peptic ulcer perforation and thick gallbladder wall. (A)Patient who had rUQ pain d elevate white blood cell count (WBC). Ultrasound shows focal gallbladder wall thickening(7 mm; cur ( asterisks) and could be interpreted as cholecystitis. the free air with reverberation shadow to the correct diagnosis could be easily overlooked. (B) Transverse ultrasound shows wall thicken so heads), cursors) and extraluminal accumulated air(paired arrowheads)in perforated duodenal ulcer(From Rubens D Hepato- biliary imaging and its pitfalls. Radiol Clin North Am 2004: 42: 257-78: with permission. evidence of acute cholecystitis is a nonspecific find- ing and is often noted in patients who have hepati- ute acalculous cholecystitis Pericholecystic fluid is also a nonspecific finding, 5%-14% of cases of acute cholecystitis//l,o Acute acalculous cholecystitis account for up often occurring secondary to localized inflamma- seen most commonly in critically ill patients often tion from other causes, such as peptic ulcer disease following trauma, surgery, or major burns. The ex- 31(see Fig. 4)or identified in patients who have act etiology is unknown, but ischemia, hypotension ascites. Teefey and colleagues [10 have described or sepsis are likely cotributing factors [12]. These two specific patterns of pericholecystic fluid. Type critically ill patients are often medicated witI L, a thin anechoic crescent-shaped collection adja- narcotics, placed on ventilators, and receive hyper cent to the gallbladder wall, is a nonspecific find- alimentation that contribute to biliary stasis and ing(see Fig. 4B). Type Il, a round or irregularly functional obstruction of the cystic duct obst aped collection with thick walls, septations, or tion. Gangrene of the gallbladder develops in ap- internal debris, is more likely to be associated proximately 40% to 60% of patients who have with gallbladder perforation and abscess formation associated increased risk for perforation 2 Mortal ity ranges from 6% to 44% but can be reduced by

evidence of acute cholecystitis is a nonspecific find￾ing and is often noted in patients who have hepati￾tis [11] (see Fig. 6). Pericholecystic fluid is also a nonspecific finding, often occurring secondary to localized inflamma￾tion from other causes, such as peptic ulcer disease [3] (see Fig. 4) or identified in patients who have ascites. Teefey and colleagues [10] have described two specific patterns of pericholecystic fluid. Type I, a thin anechoic crescent-shaped collection adja￾cent to the gallbladder wall, is a nonspecific find￾ing (see Fig. 4B). Type II, a round or irregularly shaped collection with thick walls, septations, or internal debris, is more likely to be associated with gallbladder perforation and abscess formation (Fig. 7). Acute acalculous cholecystitis Acute acalculous cholecystitis account for up to 5%–14% of cases of acute cholecystitis [11]. It is seen most commonly in critically ill patients often following trauma, surgery, or major burns. The ex￾act etiology is unknown, but ischemia, hypotension or sepsis are likely cotributing factors [12]. These critically ill patients are often medicated with narcotics, placed on ventilators, and receive hyper￾alimentation that contribute to biliary stasis and functional obstruction of the cystic duct obstruc￾tion. Gangrene of the gallbladder develops in ap￾proximately 40% to 60% of patients who have an associated increased risk for perforation [2]. Mortal￾ity ranges from 6% to 44% but can be reduced by Fig. 4. Peptic ulcer perforation and thick gallbladder wall. (A) Patient who had RUQ pain, fever, and elevated white blood cell count (WBC). Ultrasound shows focal gallbladder wall thickening (7 mm; cursors) and gallstones (asterisks) and could be interpreted as cholecystitis. The free air with reverberation shadows (arrows) that leads to the correct diagnosis could be easily overlooked. (B) Transverse ultrasound shows wall thickening (cursors) and simple pericholecystic fluid (arrow). (C) CT image shows pericholecystic fluid (arrows), free air (arrowheads), and extraluminal accumulated air (paired arrowheads) in perforated duodenal ulcer. (From Rubens D. Hepato￾biliary imaging and its pitfalls. Radiol Clin North Am 2004;42:257–78; with permission.) 396 Rubens

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 increased

early 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

398 Rub in association with gangrenous cholecystitis 3 The fundus is the most common site for perfora- tion, because it has the least blood supply. Acute gallbladder perforation with an intraperitoneal bile leak will result in peritonitis but is much less common than subacute perforation, which typi cally leads to pericholecystic abscess formation 12 These abscesses may occur within or adjacent to the gallbladder wall in the gallbladder fossa, within the liver, parenchyma, or along the free margin of the gallbladder within the peritoneal avity 10. These are complex fluid collections Inflammatory changes in the adjacent fat can be detected ultrasound or ig.7C)|21 Patients who have intraperitoneal abscesses re- quire immediate surgery, although liver abscesses can be treated effectively with percutaneous drain Fig. 6. Hepatitis with striated gallbladder wall thick ladder with a thickened striated wall(arrowy) e/k age Abscesses in the gallbladder wall or gallblad- ening. Longitudinal ultrasound of contracted g der fossa may espond to conservative ternating echogenic and hypoechoic layers. This pa management 161 Pericholecystic fluid adjacent to the gallbladder ests, and a negative sonographic Murphy sign. She wall may mimic perforation. However, with careful tested positive for hepatitis b and also had clinically inspection, the gallbladder wall will be intact, and pecific for gallbladder disease. (From Hazle H, collecting within the gallbladder wall has been re- Rubens D. The liver. In: Dogra V, Rubens D, editors. ported in one case to precede perforation 1 Ultrasound secrets. Philadelpha: Hanley and Belfus; However, no other specific ultrasound features 2004. p. 130-49: with permission. have been identified that will accurately predict which inflamed gallbladders will perfo orbidity(10%)and mortality(15%)[14 and require emergency surgery 2 - There is also approx imately a 30%conversion rate for laparoscopic cho- Emphysematous cholecystitis lecystectomy to an open procedure in the setting of This is a rare complication of acute cholecystitis, ac- complicated cholecystitis 14 counting for less than 1% of all complicated cases of acute cholecystitis, and is caused by gas-forming Gangrenous cholecystitis bacteria in the gallbladder lumen or in the gallblad der wall. As many as 40% of patients who have Gangrenous cholecystitis is defined histologically emphysematous cholecystitis have diabetes 21 as coagulative necrosis of the mucosa or the entire Emphysematous cholecystitis is more common in gallbladder wall associated with acute or chronic men and patients often do not have gallstones inflammation (10 It occurs in up to 20% of pa- The clinical course is rapidly progressive, with tients who have acute cholecystitis and has an in- a 75% indidence of gallbladder ganges p8 creased risk for perforation 3]. Unfortunately a 20% incidence of gallbladder perforation ultrasound is nonspecific for the diagnosis of Emphysematous cholecystitis can be recognized eno on US examination by the extremely echogenic graphic Murphy sign is absent in up to two thirds gas which casts a distal shadow and layers nonde- of patients [15 A specific finding is the presence pendently within the gallbladder lumen(Fig. 10) of intraluminal membranes or stranding caused Intramural gas is more difficult to identify, because by sloughing of the gallbladder mucosa, necrosis it may mimic the mural calcification seen in a porce- of the gallbladder wall or fibrous exudate lain gallbladder. The type of shadowing(ie,clean (Fig 9). This finding is present on US examina versus"dirty")does not differentiate between cal- tion, however, in only 5% of patients 101 cium and air. The nondependent location of the mobile echoes within the lumen or mobile bubbles Gallbladder perforation within the wall can document gas. If the US find ings are equivocal, either CT or plain film radiogra- Perforation of the gallbladder occurs in 5% to 10% phy can be used to differentiate between gas and of patients who have acute cholecystitis, most often calcification 191

morbidity (10%) and mortality (15%) [14] and require emergency surgery [2]. There is also approx￾imately a 30% conversion rate for laparoscopic cho￾lecystectomy to an open procedure in the setting of complicated cholecystitis [14]. Gangrenous cholecystitis Gangrenous cholecystitis is defined histologically as coagulative necrosis of the mucosa or the entire gallbladder wall associated with acute or chronic inflammation [10]. It occurs in up to 20% of pa￾tients who have acute cholecystitis and has an in￾creased risk for perforation [3]. Unfortunately ultrasound is nonspecific for the diagnosis of gangrenous cholecystitis. This is because the sono￾graphic Murphy sign is absent in up to two thirds of patients [15]. A specific finding is the presence of intraluminal membranes or stranding caused by sloughing of the gallbladder mucosa, necrosis of the gallbladder wall or fibrous exudate (Fig. 9). This finding is present on US examina￾tion, however, in only 5% of patients [10]. Gallbladder perforation Perforation of the gallbladder occurs in 5% to 10% of patients who have acute cholecystitis, most often in association with gangrenous cholecystitis [3]. The fundus is the most common site for perfora￾tion, because it has the least blood supply. Acute gallbladder perforation with an intraperitoneal bile leak will result in peritonitis but is much less common than subacute perforation, which typi￾cally leads to pericholecystic abscess formation [2]. These abscesses may occur within or adjacent to the gallbladder wall in the gallbladder fossa, within the liver, parrenchyma, or along the free margin of the gallbladder within the peritoneal cavity [10]. These are complex fluid collections. Inflammatory changes in the adjacent fat can be detected on ultrasound or CT (Fig. 7C) [2]. Patients who have intraperitoneal abscesses re￾quire immediate surgery, although liver abscesses can be treated effectively with percutaneous drain￾age. Abscesses in the gallbladder wall or gallblad￾der fossa may respond to conservative management [16]. Pericholecystic fluid adjacent to the gallbladder wall may mimic perforation. However, with careful inspection, the gallbladder wall will be intact, and the fluid is typically anechoic (see Fig. 4B). Fluid collecting within the gallbladder wall has been re￾ported in one case to precede perforation [17]. However, no other specific ultrasound features have been identified that will accurately predict which inflamed gallbladders will perforate. Emphysematous cholecystitis This is a rare complication of acute cholecystitis, ac￾counting for less than 1% of all complicated cases of acute cholecystitis, and is caused by gas-forming bacteria in the gallbladder lumen or in the gallblad￾der wall. As many as 40% of patients who have emphysematous cholecystitis have diabetes [2]. Emphysematous cholecystitis is more common in men and patients often do not have gallstones. The clinical course is rapidly progressive, with a 75% incidence of gallbladder gangrene and a 20% incidence of gallbladder perforation [18]. Emphysematous cholecystitis can be recognized on US examination by the extremely echogenic gas which casts a distal shadow and layers nonde￾pendently within the gallbladder lumen (Fig. 10). Intramural gas is more difficult to identify, because it may mimic the mural calcification seen in a porce￾lain gallbladder. The type of shadowing (ie, ‘‘clean’’ versus ‘‘dirty’’) does not differentiate between cal￾cium and air. The nondependent location of the mobile echoes within the lumen or mobile bubbles within the wall can document gas. If the US find￾ings are equivocal, either CT or plain film radiogra￾phy can be used to differentiate between gas and calcification [19]. Fig. 6. Hepatitis with striated gallbladder wall thick￾ening. Longitudinal ultrasound of contracted gall￾bladder with a thickened striated wall (arrows) with alternating echogenic and hypoechoic layers. This pa￾tient had RUQ pain, fever, abnormal liver function tests, and a negative sonographic Murphy sign. She tested positive for hepatitis B and also had clinically acute alcoholic hepatitis. The striated wall is not specific for gallbladder disease. (From Ghazle H, Rubens D. The liver. In: Dogra V, Rubens D, editors. Ultrasound secrets. Philadelpha: Hanley and Belfus; 2004. p. 130–49; with permission.) 398 Rubens

Ultrasound Imaging of the Biliary Tract 399 GB LO RT Fig. 7. Complicated cholecystitis with gallbladder perforation (A)Longitudinal ultrasound of the gallbladder with adjacent irregularly marginated pericholecystic intrahepatic fluid (arrows). This patient presented with sep- sis 2 weeks after prostate surgery and was found to have acute cholecystitis with an adjacent liver abscess. B Longitudinal ultrasound of gallbladder containing stones shows a pericholecystic collection(arrows) containing debris. The collection abuts the free wall of the gallbladder and is not contained within the gallbladder wall (double arrow).(O) CT shows an enhancing rim around the fluid (arrows)and inflammatory edema in the adja- cent fat consistent with abscess(arrowheads).(From Rubens D. Hepatobiliary imaging and its pitfalls. Radiol Clin North Am 2004: 42: 257-78: with permission Chronic cholecystitis sign or wall-echo-shadow(WES) complex (201 (Fig. 11). The first echogenic arc of the WES com Chronic cholecystitis is defined histologically as plex is created by the near wall of the gallbladder chronic inflammation of the gallbladder wall and and the second by the gallstone. The two echoes is routinely associated with gallstones. It can gener- are discernible because they are separated by ally be differentiated from acute cholecystitis by the a thin crescent of anechoic bile in the residual gall absence of acute clinical symptoms, although it can bladder lumen. The WES complex can be mimicked be exacerbated by episodes of superimposed acute by a collapsed duodenum(Fig. 12)or, rarely, by cholecystitis. The chronic inflammation causes a porcelain gallbladder. Porcelain gallbladder is thickening and fibrosis of the gallbladder wall more common in males, is seen in conjunction and, ultimately, contraction of the gallbladder with chronic cholecystitis, and is the result of mural hich when severe can result in almost complete calcification of the gallbladder wall. It is a rare dis- obliteration of the gallbladder lumen. This order, seen in 0.06% to 0. 8% of cholecystectomy duces an US image with two brightly colored arcs specimens 2 The calcification pattern on ultra and a posterior shadow, the so-called" double arc" sound may involve the entire wall or only a portion

Chronic cholecystitis Chronic cholecystitis is defined histologically as chronic inflammation of the gallbladder wall and is routinely associated with gallstones. It can gener￾ally be differentiated from acute cholecystitis by the absence of acute clinical symptoms, although it can be exacerbated by episodes of superimposed acute cholecystitis. The chronic inflammation causes thickening and fibrosis of the gallbladder wall and, ultimately, contraction of the gallbladder which when severe can result in almost complete obliteration of the gallbladder lumen. This pro￾duces an US image with two brightly colored arcs and a posterior shadow, the so-called ‘‘double arc’’ sign or wall-echo-shadow (WES) complex [20] (Fig. 11). The first echogenic arc of the WES com￾plex is created by the near wall of the gallbladder and the second by the gallstone. The two echoes are discernible because they are separated by a thin crescent of anechoic bile in the residual gall￾bladder lumen. The WES complex can be mimicked by a collapsed duodenum (Fig. 12) or, rarely, by a porcelain gallbladder. Porcelain gallbladder is more common in males, is seen in conjunction with chronic cholecystitis, and is the result of mural calcification of the gallbladder wall. It is a rare dis￾order, seen in 0.06% to 0.8% of cholecystectomy specimens [2]. The calcification pattern on ultra￾sound may involve the entire wall or only a portion Fig. 7. Complicated cholecystitis with gallbladder perforation. (A) Longitudinal ultrasound of the gallbladder with adjacent irregularly marginated pericholecystic intrahepatic fluid (arrows). This patient presented with sep￾sis 2 weeks after prostate surgery and was found to have acute cholecystitis with an adjacent liver abscess. (B) Longitudinal ultrasound of gallbladder containing stones shows a pericholecystic collection (arrows) containing debris. The collection abuts the free wall of the gallbladder and is not contained within the gallbladder wall (double arrow). (C) CT shows an enhancing rim around the fluid (arrows) and inflammatory edema in the adja￾cent fat consistent with abscess (arrowheads). (From Rubens D. Hepatobiliary imaging and its pitfalls. Radiol Clin North Am 2004;42:257–78; with permission.) Ultrasound Imaging of the Biliary Tract 399

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 involving

of 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