Residents’ Section • Pat tern of the Month Runner et al. Gallbladder Wall Thickening
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Residents’ Section Pattern of the Month
Residents
inRadiology Gabriel J. Runner 1 Michael T. Corwin1 Bettina Siewert 2 Ronald L. Eisenberg2 Runner GJ, Corwin MT, Siewert B, Eisenberg RL
Keywords: cholecystitis, gallbladder, wall thickening DOI:10.2214/AJR.12.10386 Received November 15, 2012; accepted after revision March 29, 2013. 1 Department of Radiology, University of California, Davis, Medical Center, Sacramento, CA. 2 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215. Address correspondence to R. L. Eisenberg ([email protected]).
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Gallbladder Wall Thickening
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allbladder wall thickening is a common yet nonspecific finding that can occur in a wide range of gallbladder diseases and extracholecystic conditions (Table 1). Distinguishing among the wide variety of conditions associated with gallbladder wall thickening is important for diagnosis and directing appropriate management. An initial critical diagnostic observation is whether the general pattern of thickening is focal or diffuse. Ancillary findings may be useful in further characterizing the cause of wall thickening. Although ultrasound is the initial imaging modality of choice for the evaluation of suspected acute gallbladder disorders, contrastenhanced CT also can be useful to evaluate gallbladder pathology, particularly when the ultrasound findings are equivocal. CT is also valuable to assess suspected complications of acute cholecystitis and to stage gallbladder malignancy. Nuclear medicine studies and MRI may be used to further characterize difficult diagnostic dilemmas. Contrast-enhanced ultrasound using microbubbles is less well established than routine sonography in the evaluation of gallbladder and biliary disease but has the potential advantage of use in patients with renal impairment. Real-time gallbladder elastography using acoustic radiation force impulse is an emerging technique that uses highintensity focused ultrasound to evaluate tissue stiffness properties. It may be useful in differentiating between benign and malignant causes of gallbladder wall thickening. Diffuse Pattern Diffuse gallbladder wall thickening (> 3 mm by ultrasound) can be seen in such primary gallbladder inflammatory processes as acute, chronic, and acalculous cholecystitis. It also may reflect secondary involvement of the gallbladder due to direct inflammatory spread from adjacent structures, as in patients with pancre-
atitis, acute hepatitis, or severe pyelonephritis. Systemic diseases that may cause diffuse wall thickening include heart and renal failure, liver dysfunction, portal venous hypertension, and sepsis. Other causes of diffuse wall thickening include infiltrative processes, such as gallbladder carcinoma, and hyperplastic changes, as seen in adenomyomatosis, although these may also present with focal thickening. The thickness of the gallbladder wall depends on the degree of gallbladder distention; pseudothickening can occur in the postprandial state due to physiologic contraction. Cholecystitis Acute cholecystitis—Acute cholecystitis occurs in the setting of cystic duct or gallbladder neck obstruction related to cholelithiasis (90–95% of cases) and is the most frequent inflammatory condition of the gallbladder. The presence of cholelithiasis in combination with a positive sonographic Murphy sign is highly specific for acute cholecystitis, with both gallbladder wall thickening and pericholecystic fluid as secondary findings (Fig. 1). Mural thickening is secondary to edema and appears as a sonolucent line between two echogenic lines in the gallbladder wall. Although nonspecific, gallbladder distention (width > 4 cm) is a key feature because lack of any distention makes acute cholecystitis unlikely and should prompt a thorough search for another cause for this appearance. Gangrenous cholecystitis may result from advanced infection, occasionally shown by ultrasound as hyperechoic linear structures within the lumen that represent sloughed membranes of desquamated gallbladder lining, marked wall thickening, and irregular luminal protrusions. A striated pattern of alternating hyperechoic and hypoechoic bands in an irregularly thickened gallbladder has been suggested to represent advanced disease with wall necrosis (Fig. 2), although recent work
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Runner et al. by Teefey et al. [1] suggests that this finding is not predictive of gangrenous changes. The sonographic Murphy sign may also be paradoxically absent, presumably related to necrosis and gallbladder denervation. Emphysematous cholecystitis is an additional severe form of acute cholecystitis that is most common in diabetic patients (50% of cases), with high morbidity and mortality. Dirty shadowing is highly suggestive of intramural gas and diagnostic of emphysematous cholecystitis (Fig. 3). In equivocal cases, nonvisualization of the gallbladder using 99mTc-hepatoiminodiacetic acid (HIDA) scintigraphy is characteristic of acute cholecystitis due to cystic duct obstruction (Fig. 4), whereas visualization of the gallbladder excludes the diagnosis (Fig. 5). Although less sensitive than ultrasound, CT may also show gallbladder wall thickening or distention, cholelithiasis, mucosal hyperenhancement, pericholecystic fluid, inflammatory fat stranding, and enhancement of the adjacent liver parenchyma due to reactive hyperemia (Fig. 6). It is important to note that approximately 20% of gallstones are isodense to bile and therefore will not be visualized on CT. CT is also useful in evaluating for complications of acute cholecystitis, such as gallbladder necrosis, perforation, or abscess formation, and this modality can easily confirm gas within the gallbladder wall in cases of suspected emphysematous cholecystitis (Fig. 7). A recent study has shown the “tensile gallbladder fundus sign” on CT as useful in detection of early acute cholecystitis. This refers to an absence of gallbladder fundus flattening by the anterior abdominal wall because of increased gallbladder pressures from outflow obstruction. Sensitivity of 75% and specificity of 97% in cases of acute cholecystitis has been reported. Most importantly, this sign occurred earlier than other CT findings of acute cholecystitis (e.g., hepatic hyperemia and gallbladder distention). Acalculous cholecystitis—Acalculous cholecystitis most often occurs in hospitalized patients, especially after surgery or trauma, and those who are critically ill or undergoing total parenteral nutrition. This condition is thought to be due to a gradual increase in bile viscosity that eventually leads to functional obstruction of the cystic duct with bile stasis. Compromise of the vascular supply to the mucosa may be a contributing factor. Ultrasound is highly sensitive and specific for the diagnosis of acalculous cholecystitis with characteristic findings including gallbladder wall thickening, pericholecystic fluid or sub-
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TABLE 1: Causes of Gallbladder Wall Thickening Diffuse Wall Thickening Cholecystitis Acute calculous Gangrenous Emphysematous Acalculous Chronic Xanthogranulomatous Liver disease
Focal Wall Thickening Polyps Adenomatous Cholesterol Malignancy Primary gallbladder carcinoma Metastases Focal adenomyomatosis Focal xanthogranulomatous cholecystitis
Hepatitis Cirrhosis Portal hypertension Extracholecystic inflammation Pancreatitis Colitis Peritonitis Pyelonephritis Systemic diseases Congestive heart failure Renal failure Sepsis Hypoalbuminemia Malignancy Primary gallbladder carcinoma Lymphoma Adenomyomatosis Pseudothickening (contracted state) Atypical infection Tuberculous Dengue hemorrhagic fever
serosal edema, intramural gas, sloughed mucosa, sludge, and hydropic gallbladder (Fig. 8). CT may show a similar appearance if the clinical findings are suggestive despite an equivocal ultrasound examination (Fig. 9). Acalculous cholecystitis in HIV patients has been associated with cytomegalovirus or cryptosporidium infection. Unlike individuals with healthy immune systems, these immunocompromised patients are ambulatory and present with right upper quadrant pain and abnormal liver function tests. Gallbladder wall thickening is a prominent, although nonspecific feature, whereas bile duct strictures and dilation can present a pattern similar to that of primary sclerosing cholangitis (Fig. 10). Chronic cholecystitis—Chronic cholecystitis almost always occurs in the setting of cho-
lelithiasis. The ultrasound findings include lucency of the wall and a distended gallbladder containing sludge, although pericholecystic fluid or inflammation is usually absent. Fibrotic changes involving the gallbladder wall may result in a contracted gallbladder. There is often a decreased gallbladder ejection fraction that may be seen on 99mTc-HIDA scintigraphy after IV cholecystikinin (CCK) administration. Xanthogranulomatous cholecystitis is an uncommon form of chronic cholecystitis. Precipitating factors may include extravasation of bile into the gallbladder wall with involvement of the Rokitansky-Aschoff sinuses or extravasation through small ulcerations in the mucosa with accumulation of lipid-laden macrophages, fibrous tissue, and inflammatory cells. Ultrasound may show a hypoechoic
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Gallbladder Wall Thickening band within a thickened gallbladder wall (Fig. 11). However, the imaging findings usually are nonspecific, with both CT and ultrasound generally showing thickening of the gallbladder wall and calculi. At times, the appearance may mimic carcinoma of the gallbladder at both ultrasound and laparotomy. Liver Disease Both acute and chronic forms of liver disease may cause gallbladder wall thickening. In acute hepatitis, ultrasound findings suggesting the diagnosis include a diffusely thickened and edematous gallbladder wall in conjunction with a diffusely hypoechogenic liver with prominent portal triads (“starry sky” appearance) (Fig. 12). In chronic liver disease or liver failure with portal venous hypertension, gallbladder wall thickening and impaired contractility may occur. Liver disease as the cause for gallbladder wall thickening is suggested by the absence of gallstones or signs of gallbladder inflammation (e.g., pericholecystic fluid, positive Murphy sign) in the presence of cirrhotic liver morphology and stigmata of portal venous hypertension, such as splenomegaly, varices, and reversal of hepatopedal flow (Fig. 13). Systemic Diseases Systemic diseases, such as heart or renal failure, may cause gallbladder wall thickening in the absence of gallbladder inflammation, possibly related to elevated portal venous pressure, low intravascular osmotic pressure, or a combination of these factors. Hypoalbuminemia and sepsis are additional causes of gallbladder wall thickening. The degree of gallbladder wall thickening may be pronounced (> 10 mm) in liver or systemic diseases, and when coexisting gallbladder distention is absent, a cause other than acute cholecystitis is likely (Fig. 14). Extracholecystic Inflammation Acute hepatitis, pancreatitis, pyelonephritis, and peritonitis are inflammatory processes that may secondarily involve the gallbladder and cause wall thickening due either to direct spread of the primary inflammation or, less frequently, an immunologic reaction. There may be pericholecystic stranding within the fat surrounding the gallbladder, and mural thickening and bowel wall edema may occur. Identifying an inflammatory process involving the pancreas, kidney, bowel, or peritoneum is important to suggest the cause (Fig. 15).
Malignancy Primary gallbladder carcinoma—Gallbladder carcinoma most often manifests as a diffusely infiltrating lesion that replaces the gallbladder and extends into the liver. Less frequently, it appears as asymmetric mural thickening or an intraluminal polypoid mass. Cholelithiasis is a well-established risk factor for developing gallbladder carcinoma, and gallstones are present in about 80% of cases. Porcelain gallbladder (calcification of the wall) may also be a risk factor, although this has recently been debated. The CT or ultrasound visualization of pronounced wall thickening (> 10 mm) associated with mural irregularity or marked asymmetry should raise concern for malignancy. In diffusely infiltrating lesions, ultrasound findings suggestive of malignancy include heterogeneous irregular wall thickening and an extraluminal mass extending into the liver (Fig. 16). On contrast-enhanced CT, a hypo- or isoattenuating mass in the gallbladder fossa that invades the liver and shows adjacent lymphadenopathy favors the diagnosis of gallbladder carcinoma (Fig. 17). Less commonly, pronounced diffuse wall thickening with gallstones may be present (Fig. 18). Lymphoma—Lymphoma of the gallbladder, which is exceedingly rare, has been defined previously as extranodal lymphoma localized to the gallbladder, with or without contiguous lymph node involvement. Like adenocarcinoma, lymphoma may present on CT or ultrasound as an intraluminal mass, a large mass replacing the gallbladder, or diffuse wall thickening. Adenomyomatosis Adenomyomatosis is an acquired hyperplastic process of the gallbladder that is characterized by excessive proliferation of surface epithelium with abnormally deepened and branching invaginations (Rokitansky-Aschoff sinuses) that extend deep into the muscular layer of the gallbladder wall. This process may be focal, segmental, or diffuse, with the focal form most common in the fundus. Ultrasound findings include mural thickening with echogenic foci showing comet-tail artifact, which represents cholesterol crystals within the lumina of Rokitansky-Aschoff sinuses (Fig. 19). CT is less specific in the detection of adenomyomatosis, but this modality may show cystic-appearing thickening of the gallbladder wall or enhancing epithelium within intramural diverticula surrounded by relatively unenhanced hypertrophied gallbladder muscularis (Fig. 20).
Pseudothickening The thickness of the gallbladder wall depends on the degree of gallbladder distention, and pseudothickening can occur in the postprandial state. Gallbladder emptying in response to a meal is a physiologic phenomenon, mainly coordinated by the rate of gastric emptying of food in the duodenum and by the subsequent release of CCK. It is important not to mistake this normal physiologic phenomenon for pathologic thickening of the gallbladder wall (Fig. 21). Atypical Infection Tuberculous involvement of the gallbladder is rare. It may develop as part of systemic miliary tuberculosis, abdominal tuberculosis, isolated gallbladder tuberculosis, or acalculous cholecystitis in anergic patients. Radiologic diagnosis is difficult because the imaging features can mimic acute cholecystitis, chronic cholecystitis, and gallbladder malignancy. Most cases are diagnosed after cholecystectomy or at autopsy. Dengue hemorrhagic fever is an acute Flavivirus infection, which may cause a triad of transient wall thickening, ascites, and pleuropericardial effusion. A reticular pattern of the gallbladder wall is apparently typical of plasma leakage in severe disease. Focal Pattern Focal gallbladder wall thickening (> 3 mm by ultrasound) has a more narrow differential diagnosis and can be divided into neoplastic and nonneoplastic processes. Neoplastic causes include adenomatous polyps, gallbladder carcinoma, and metastases. Nonneoplastic causes include cholesterol or inflammatory polyps, focal adenomyomatosis, and focal xanthogranulomatous cholecystitis. Adenomatous Polyps Adenomatous polyps grow as pedunculated tumors that project into the gallbladder lumen and may be premalignant. Ultrasound findings include a nonmobile nonshadowing polypoid intraluminal mass that may have internal flow (Fig. 22). Polyps smaller than 5 mm are unlikely to be malignant; malignant lesions are usually smaller than 1 cm. Polyps measuring 5–10 mm should be followed up at 3–6 month intervals. Cholesterol polyps characteristically appear as echogenic structures with comet-tail reverberation artifact (Fig. 23). It is important to note that some gallbladder “polyps” actually represent small nonshadowing gallstones adherent to the wall.
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Runner et al. Gallbladder Carcinoma Gallbladder carcinoma can also present as focal irregular wall thickening or, less often, as an intraluminal polypoid mass (Fig. 24). Flow within the lesion seen on color Doppler ultrasound can help distinguish a mass from tumefactive sludge. Contrast-enhanced CT and MRI may show asymmetric or irregular wall thickening with marked enhancement during the arterial phase, which persists or becomes isodense or isointense to liver during the portal venous phase. As with the diffuse form of gallbladder carcinoma, the tumor often locally invades the adjacent liver and biliary tree. Metastases Metastatic disease involving the gallbladder is a rare entity and most commonly arises from melanoma. Primary pulmonary and renal malignancies are less frequently reported. Imaging features include focal irregular wall thickening and one or more enhancing polypoid masses (Fig. 25). Focal Adenomyomatosis (Adenomyoma) Adenomyoma represents the focal form of adenomyomatosis and most frequently involves the gallbladder fundus. Ultrasound findings may include echogenic intramural foci that emanate comet-tail reverberation artifacts (Fig. 26). Visualization of a twinkling artifact on color Doppler ultrasound is useful in making a diagnosis of focal adenomyo-
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matosis when reverberation artifact is either difficult to see or not present on gray-scale ultrasound. Twinkling artifact is caused by a strongly reflecting medium that appears as rapidly alternating red and blue color Doppler signal behind stationary objects. The hallmark of adenomyomatosis on T2-weighted MR images is the string-of-beads sign, which refers to cystic high-signal foci in the gallbladder wall that correspond to bile-filled Rokitansky-Aschoff sinuses (Fig. 27). A less common segmental (annular) form appears as a rind of circumferential involvement of the gallbladder body, which narrows the lumen and creates an hourglass configuration of the gallbladder (Fig. 27). Focal Xanthogranulomatous Cholecystitis Focal xanthogranulomatous cholecystitis is much less common than the diffuse form. The ultrasound and CT appearances are nonspecific, frequently consisting of thickening of the gallbladder wall and calculi. The diagnosis is usually made by histopathology. Conclusion Gallbladder wall thickening has a wide differential diagnosis. An important first step is to distinguish between the diffuse and focal forms. Subsequently, identification of ancillary imaging findings and directed use of additional imaging modalities allow an accurate diagnosis to be made.
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Reference 1. Teefey SA, Dahiya N, Middleton WD, Bajaj S, Ylagan L, Hildebolt CF. Acute Cholecystitis: Do sonographic findings and WBC count predict gangrenous changes? AJR 2013; 200:363–369
Selected Reading 1. An C, Park S, Ko S, et al. The usefulness of the tensile gallbladder fundus sign in the diagnosis of early acute cholecystitis. AJR 2013; 201:340– 346 2. Bennett GL, Balthazar EJ. Ultrasound and CT evaluation of emergent gallbladder pathology. Radiol Clin North Am 2003; 41:1203–1216 3. Catalano OA, Sahani DV, Kalva SP, et al. MR imaging of the gallbladder: a pictorial essay. RadioGraphics 2008; 28:135–155 4. Chang BJ, Kim SH, Park HY, et al. Distinguishing xanthogranulomatous cholecystitis from the wall-thickening type of early-stage gallbladder cancer. Gut Liver 2010; 4:518–523 5. Ching BH, Yeh BM, Westphalen AC, Joe BN, Qayyum A, Coakley FV. CT differentiation of adenomyomatosis and gallbladder cancer. AJR 2007; 189:62–66 6. Kapoor A, Mahajan G. Differentiating malignant from benign thickening of the gallbladder wall by the use of acoustic radiation force impulse elastography. J Ultrasound Med 2011; 30:1499–1507 7. van Breda Vriesman AC, Engelbrecht MR, Smithuis RH, Puylaert JB. Diffuse gallbladder wall thickening: differential diagnosis. AJR 2007; 188: 495–501
Fig. 1—Acute cholecystitis in 44-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffusely thickened wall (6.1 mm) (calipers) with multiple shadowing gallstones (arrow, A) and pericholecystic fluid (arrow, B). Patient also had positive sonographic Murphy sign.
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Gallbladder Wall Thickening
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Fig. 2—Acute cholecystitis with gallbladder necrosis in 40-year-old woman. A, Longitudinal ultrasound image of gallbladder shows shadowing gallstones (solid arrow) and diffuse wall thickening (3.5 mm) (calipers) with alternating hyperechoic and hypoechoic bands (dashed arrow). B, Contrast-enhanced abdominal CT image shows hydropic gallbladder, diffuse wall thickening, and lack of wall enhancement, with extensive right upper quadrant mesenteric stranding.
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Fig. 3—Emphysematous cholecystitis. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder area in 64-year-old diabetic man show linear echogenic structures with distal reverberations and dirty shadowing, indicating gas within gallbladder wall. C, Contrast-enhanced abdominal CT image in different patient shows hydropic gallbladder with gas present in gallbladder wall.
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Fig. 4—Acute cholecystitis in 54-year-old man with equivocal ultrasound. A, Longitudinal ultrasound image of gallbladder shows multiple shadowing gallstones near gallbladder neck (arrow), with borderline wall thickening. B, Subsequent hepatobiliary scintigraphy scan shows prompt liver uptake and excretion of radiotracer into bowel with no filling of gallbladder lumen, finding highly specific for acute cholecystitis.
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Gallbladder Wall Thickening
Fig. 5—Negative hepatobiliary scintigraphy scan in 32-year-old woman with right upper quadrant pain shows prompt liver radiotracer uptake with early gallbladder visualization (arrow), effectively excluding acute cholecystitis.
Fig. 6—Acute cholecystitis in 58-year-old man. Contrast-enhanced CT image shows hyperemic liver parenchyma adjacent to thickened gallbladder wall (full arrow) with pericholecystic fluid (dashed arrow).
Fig. 7—Acute cholecystitis with abscess in 67-year-old man. Contrast-enhanced CT image shows distended gallbladder and thickened wall with adjacent rimenhancing low-density fluid collection (arrow).
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Fig. 8—Acalculous cholecystitis in 42-year-old man. A and B, Longitudinal (A) and transverse (B) images of gallbladder show diffuse wall thickening (4 mm) (calipers) with intraluminal sludge (solid arrow) and pericholecystic fluid (dashed arrow, A).
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Fig. 9—Acalculous cholecystitis in 40-year-old woman. Coronal abdominal CT image in septic patient shows diffuse gallbladder wall thickening. Small amount of perihepatic fluid is also present.
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Fig. 10—HIV cholangiopathy in 36-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffuse wall thickening. Subsequent hepatobiliary scintigraphy scan was negative (not shown).
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Fig. 11— Xanthogranulomatous cholecystitis in 75-year-old woman. A, Longitudinal ultrasound image of gallbladder shows hypoechoic band within diffusely thickened gallbladder wall. B, Contrast-enhanced abdominal CT image shows diffuse gallbladder wall thickening.
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Gallbladder Wall Thickening Fig. 12—Acute hepatitis in 14-year-old girl. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffuse gallbladder wall thickening (4.7 mm) (calipers) without stones. Diffuse liver hypoechogenicity with foci of increased periportal echogenicity in periportal regions (starry sky) is suggestive of hepatitis.
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Fig. 13—Cirrhosis in 57-year-old man. A, Longitudinal ultrasound image of gallbladder shows diffuse gallbladder wall thickening with ascites (arrow). B, Transverse ultrasound image of liver shows coarsened liver echotexture and nodular liver contour with ascites. C, Longitudinal ultrasound image of spleen shows splenomegaly (20 cm) (calipers) related to portal hypertension physiology.
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Fig. 14—Congestive heart failure in 52-year-old woman. A, Longitudinal ultrasound image of gallbladder shows diffusely marked thickened gallbladder wall with decompressed lumen, negative sonographic Murphy sign, and no stones. B, Heart failure on follow-up. CT image shows marked diffuse wall thickening. C, Subsequent hepatobiliary scintigraphy scan was negative, with gallbladder visualization (arrow).
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Runner et al.
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Fig. 15—Pancreatitis in 51-year-old man. A, Longitudinal ultrasound image of gallbladder shows diffuse wall thickening (4 mm) (calipers) without other signs of acute cholecystitis. B, Contrast-enhanced coronal abdominal CT image shows peripancreatic stranding with extension of inflammation into gallbladder fossa. Pancreatic calcifications indicate chronic pancreatitis. Follow-up hepatobiliary scintigraphy scan (not shown) was negative for acute cholecystitis.
Fig. 16—Diffuse gallbladder carcinoma in 67-year-old woman. Longitudinal ultrasound image of gallbladder shows large mass replacing gallbladder in gallbladder fossa, with infiltration of liver.
Fig. 17—Diffuse gallbladder carcinoma in 72-year-old man. Contrast-enhanced CT image shows infiltrative mass that arises from gallbladder fossa and invades liver.
Fig. 18—Diffuse gallbladder carcinoma in 56-year-old woman. Contrast-enhanced CT image shows diffuse gallbladder wall thickening with high-density intraluminal material (arrow), presumed gallstone. Biliary stent is also present (dashed arrow).
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Gallbladder Wall Thickening
Fig. 21—Gallbladder pseudothickening in 32-year-old man. Longitudinal ultrasound image of gallbladder shows contracted gallbladder with apparent wall thickening related to contracted state.
Fig. 20—Adenomyomatosis in 66-year-old man. Contrast-enhanced abdominal CT image shows diffuse mural thickening with multiple small cystic spaces in gallbladder wall (arrows).
Fig. 19—Adenomyomatosis in 55-year-old woman. Transverse ultrasound image of gallbladder shows diffuse mural thickening with areas of ring-down or comet-tail artifact (arrows).
Fig. 22—Gallbladder polyp in 63-year-old woman. Longitudinal ultrasound of gallbladder with Doppler flow shows focal nonmobile nonshadowing echogenic structure near gallbladder fundus (arrow) without internal vascularity.
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Fig. 23—Cholesterol polyp in 43-year-old woman. Longitudinal ultrasound image of gallbladder shows focal echogenic structure near gallbladder fundus (arrow) with ring-down artifact.
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Fig. 24—Focal gallbladder carcinoma in 71-year-old woman. A and B, Longitudinal ultrasound image of gallbladder (A) and longitudinal ultrasound of gallbladder with Doppler flow (B) show 3.6-cm intraluminal gallbladder mass with internal vascularity (arrow). (Fig. 24 continues on next page)
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Fig. 24 (continued)—Focal gallbladder carcinoma in 71-year-old woman. C, Contrast-enhanced CT image shows enhancing polypoid intraluminal mass arising from posterior aspect of gallbladder (arrow).
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Fig. 25—Gallbladder metastases in 62-year-old man with pancreatic adenocarcinoma. Abdominal CT image shows multiple irregular areas of gallbladder wall thickening (arrows).
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Fig. 26—Fundal adenomyoma in 41-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show focal wall thickening (3.7 mm) (calipers) near gallbladder fundus (solid arrow, A) with area of ring-down artifact (dashed arrow, B).
Fig. 27—Adenomyomatosis in 54-year-old man. T2-weighted MR image of gallbladder shows stringof-beads appearance reflecting adenomyomatosis involving gallbladder fundus (dashed arrow). Coexisting annular or segmental form involves gallbladder body, narrowing gallbladder lumen and creating hourglass gallbladder configuration (solid arrows).
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Residents’ Section Pattern of the Month
Residents
inRadiology Gabriel J. Runner 1 Michael T. Corwin1 Bettina Siewert 2 Ronald L. Eisenberg2 Runner GJ, Corwin MT, Siewert B, Eisenberg RL
Keywords: cholecystitis, gallbladder, wall thickening DOI:10.2214/AJR.12.10386 Received November 15, 2012; accepted after revision March 29, 2013. 1 Department of Radiology, University of California, Davis, Medical Center, Sacramento, CA. 2 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215. Address correspondence to R. L. Eisenberg ([email protected]).
WEB This is a web exclusive article. AJR 2014; 202:W1–W12 0361–803X/14/2021–W1 © American Roentgen Ray Society
Gallbladder Wall Thickening
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allbladder wall thickening is a common yet nonspecific finding that can occur in a wide range of gallbladder diseases and extracholecystic conditions (Table 1). Distinguishing among the wide variety of conditions associated with gallbladder wall thickening is important for diagnosis and directing appropriate management. An initial critical diagnostic observation is whether the general pattern of thickening is focal or diffuse. Ancillary findings may be useful in further characterizing the cause of wall thickening. Although ultrasound is the initial imaging modality of choice for the evaluation of suspected acute gallbladder disorders, contrastenhanced CT also can be useful to evaluate gallbladder pathology, particularly when the ultrasound findings are equivocal. CT is also valuable to assess suspected complications of acute cholecystitis and to stage gallbladder malignancy. Nuclear medicine studies and MRI may be used to further characterize difficult diagnostic dilemmas. Contrast-enhanced ultrasound using microbubbles is less well established than routine sonography in the evaluation of gallbladder and biliary disease but has the potential advantage of use in patients with renal impairment. Real-time gallbladder elastography using acoustic radiation force impulse is an emerging technique that uses highintensity focused ultrasound to evaluate tissue stiffness properties. It may be useful in differentiating between benign and malignant causes of gallbladder wall thickening. Diffuse Pattern Diffuse gallbladder wall thickening (> 3 mm by ultrasound) can be seen in such primary gallbladder inflammatory processes as acute, chronic, and acalculous cholecystitis. It also may reflect secondary involvement of the gallbladder due to direct inflammatory spread from adjacent structures, as in patients with pancre-
atitis, acute hepatitis, or severe pyelonephritis. Systemic diseases that may cause diffuse wall thickening include heart and renal failure, liver dysfunction, portal venous hypertension, and sepsis. Other causes of diffuse wall thickening include infiltrative processes, such as gallbladder carcinoma, and hyperplastic changes, as seen in adenomyomatosis, although these may also present with focal thickening. The thickness of the gallbladder wall depends on the degree of gallbladder distention; pseudothickening can occur in the postprandial state due to physiologic contraction. Cholecystitis Acute cholecystitis—Acute cholecystitis occurs in the setting of cystic duct or gallbladder neck obstruction related to cholelithiasis (90–95% of cases) and is the most frequent inflammatory condition of the gallbladder. The presence of cholelithiasis in combination with a positive sonographic Murphy sign is highly specific for acute cholecystitis, with both gallbladder wall thickening and pericholecystic fluid as secondary findings (Fig. 1). Mural thickening is secondary to edema and appears as a sonolucent line between two echogenic lines in the gallbladder wall. Although nonspecific, gallbladder distention (width > 4 cm) is a key feature because lack of any distention makes acute cholecystitis unlikely and should prompt a thorough search for another cause for this appearance. Gangrenous cholecystitis may result from advanced infection, occasionally shown by ultrasound as hyperechoic linear structures within the lumen that represent sloughed membranes of desquamated gallbladder lining, marked wall thickening, and irregular luminal protrusions. A striated pattern of alternating hyperechoic and hypoechoic bands in an irregularly thickened gallbladder has been suggested to represent advanced disease with wall necrosis (Fig. 2), although recent work
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Runner et al. by Teefey et al. [1] suggests that this finding is not predictive of gangrenous changes. The sonographic Murphy sign may also be paradoxically absent, presumably related to necrosis and gallbladder denervation. Emphysematous cholecystitis is an additional severe form of acute cholecystitis that is most common in diabetic patients (50% of cases), with high morbidity and mortality. Dirty shadowing is highly suggestive of intramural gas and diagnostic of emphysematous cholecystitis (Fig. 3). In equivocal cases, nonvisualization of the gallbladder using 99mTc-hepatoiminodiacetic acid (HIDA) scintigraphy is characteristic of acute cholecystitis due to cystic duct obstruction (Fig. 4), whereas visualization of the gallbladder excludes the diagnosis (Fig. 5). Although less sensitive than ultrasound, CT may also show gallbladder wall thickening or distention, cholelithiasis, mucosal hyperenhancement, pericholecystic fluid, inflammatory fat stranding, and enhancement of the adjacent liver parenchyma due to reactive hyperemia (Fig. 6). It is important to note that approximately 20% of gallstones are isodense to bile and therefore will not be visualized on CT. CT is also useful in evaluating for complications of acute cholecystitis, such as gallbladder necrosis, perforation, or abscess formation, and this modality can easily confirm gas within the gallbladder wall in cases of suspected emphysematous cholecystitis (Fig. 7). A recent study has shown the “tensile gallbladder fundus sign” on CT as useful in detection of early acute cholecystitis. This refers to an absence of gallbladder fundus flattening by the anterior abdominal wall because of increased gallbladder pressures from outflow obstruction. Sensitivity of 75% and specificity of 97% in cases of acute cholecystitis has been reported. Most importantly, this sign occurred earlier than other CT findings of acute cholecystitis (e.g., hepatic hyperemia and gallbladder distention). Acalculous cholecystitis—Acalculous cholecystitis most often occurs in hospitalized patients, especially after surgery or trauma, and those who are critically ill or undergoing total parenteral nutrition. This condition is thought to be due to a gradual increase in bile viscosity that eventually leads to functional obstruction of the cystic duct with bile stasis. Compromise of the vascular supply to the mucosa may be a contributing factor. Ultrasound is highly sensitive and specific for the diagnosis of acalculous cholecystitis with characteristic findings including gallbladder wall thickening, pericholecystic fluid or sub-
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TABLE 1: Causes of Gallbladder Wall Thickening Diffuse Wall Thickening Cholecystitis Acute calculous Gangrenous Emphysematous Acalculous Chronic Xanthogranulomatous Liver disease
Focal Wall Thickening Polyps Adenomatous Cholesterol Malignancy Primary gallbladder carcinoma Metastases Focal adenomyomatosis Focal xanthogranulomatous cholecystitis
Hepatitis Cirrhosis Portal hypertension Extracholecystic inflammation Pancreatitis Colitis Peritonitis Pyelonephritis Systemic diseases Congestive heart failure Renal failure Sepsis Hypoalbuminemia Malignancy Primary gallbladder carcinoma Lymphoma Adenomyomatosis Pseudothickening (contracted state) Atypical infection Tuberculous Dengue hemorrhagic fever
serosal edema, intramural gas, sloughed mucosa, sludge, and hydropic gallbladder (Fig. 8). CT may show a similar appearance if the clinical findings are suggestive despite an equivocal ultrasound examination (Fig. 9). Acalculous cholecystitis in HIV patients has been associated with cytomegalovirus or cryptosporidium infection. Unlike individuals with healthy immune systems, these immunocompromised patients are ambulatory and present with right upper quadrant pain and abnormal liver function tests. Gallbladder wall thickening is a prominent, although nonspecific feature, whereas bile duct strictures and dilation can present a pattern similar to that of primary sclerosing cholangitis (Fig. 10). Chronic cholecystitis—Chronic cholecystitis almost always occurs in the setting of cho-
lelithiasis. The ultrasound findings include lucency of the wall and a distended gallbladder containing sludge, although pericholecystic fluid or inflammation is usually absent. Fibrotic changes involving the gallbladder wall may result in a contracted gallbladder. There is often a decreased gallbladder ejection fraction that may be seen on 99mTc-HIDA scintigraphy after IV cholecystikinin (CCK) administration. Xanthogranulomatous cholecystitis is an uncommon form of chronic cholecystitis. Precipitating factors may include extravasation of bile into the gallbladder wall with involvement of the Rokitansky-Aschoff sinuses or extravasation through small ulcerations in the mucosa with accumulation of lipid-laden macrophages, fibrous tissue, and inflammatory cells. Ultrasound may show a hypoechoic
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Gallbladder Wall Thickening band within a thickened gallbladder wall (Fig. 11). However, the imaging findings usually are nonspecific, with both CT and ultrasound generally showing thickening of the gallbladder wall and calculi. At times, the appearance may mimic carcinoma of the gallbladder at both ultrasound and laparotomy. Liver Disease Both acute and chronic forms of liver disease may cause gallbladder wall thickening. In acute hepatitis, ultrasound findings suggesting the diagnosis include a diffusely thickened and edematous gallbladder wall in conjunction with a diffusely hypoechogenic liver with prominent portal triads (“starry sky” appearance) (Fig. 12). In chronic liver disease or liver failure with portal venous hypertension, gallbladder wall thickening and impaired contractility may occur. Liver disease as the cause for gallbladder wall thickening is suggested by the absence of gallstones or signs of gallbladder inflammation (e.g., pericholecystic fluid, positive Murphy sign) in the presence of cirrhotic liver morphology and stigmata of portal venous hypertension, such as splenomegaly, varices, and reversal of hepatopedal flow (Fig. 13). Systemic Diseases Systemic diseases, such as heart or renal failure, may cause gallbladder wall thickening in the absence of gallbladder inflammation, possibly related to elevated portal venous pressure, low intravascular osmotic pressure, or a combination of these factors. Hypoalbuminemia and sepsis are additional causes of gallbladder wall thickening. The degree of gallbladder wall thickening may be pronounced (> 10 mm) in liver or systemic diseases, and when coexisting gallbladder distention is absent, a cause other than acute cholecystitis is likely (Fig. 14). Extracholecystic Inflammation Acute hepatitis, pancreatitis, pyelonephritis, and peritonitis are inflammatory processes that may secondarily involve the gallbladder and cause wall thickening due either to direct spread of the primary inflammation or, less frequently, an immunologic reaction. There may be pericholecystic stranding within the fat surrounding the gallbladder, and mural thickening and bowel wall edema may occur. Identifying an inflammatory process involving the pancreas, kidney, bowel, or peritoneum is important to suggest the cause (Fig. 15).
Malignancy Primary gallbladder carcinoma—Gallbladder carcinoma most often manifests as a diffusely infiltrating lesion that replaces the gallbladder and extends into the liver. Less frequently, it appears as asymmetric mural thickening or an intraluminal polypoid mass. Cholelithiasis is a well-established risk factor for developing gallbladder carcinoma, and gallstones are present in about 80% of cases. Porcelain gallbladder (calcification of the wall) may also be a risk factor, although this has recently been debated. The CT or ultrasound visualization of pronounced wall thickening (> 10 mm) associated with mural irregularity or marked asymmetry should raise concern for malignancy. In diffusely infiltrating lesions, ultrasound findings suggestive of malignancy include heterogeneous irregular wall thickening and an extraluminal mass extending into the liver (Fig. 16). On contrast-enhanced CT, a hypo- or isoattenuating mass in the gallbladder fossa that invades the liver and shows adjacent lymphadenopathy favors the diagnosis of gallbladder carcinoma (Fig. 17). Less commonly, pronounced diffuse wall thickening with gallstones may be present (Fig. 18). Lymphoma—Lymphoma of the gallbladder, which is exceedingly rare, has been defined previously as extranodal lymphoma localized to the gallbladder, with or without contiguous lymph node involvement. Like adenocarcinoma, lymphoma may present on CT or ultrasound as an intraluminal mass, a large mass replacing the gallbladder, or diffuse wall thickening. Adenomyomatosis Adenomyomatosis is an acquired hyperplastic process of the gallbladder that is characterized by excessive proliferation of surface epithelium with abnormally deepened and branching invaginations (Rokitansky-Aschoff sinuses) that extend deep into the muscular layer of the gallbladder wall. This process may be focal, segmental, or diffuse, with the focal form most common in the fundus. Ultrasound findings include mural thickening with echogenic foci showing comet-tail artifact, which represents cholesterol crystals within the lumina of Rokitansky-Aschoff sinuses (Fig. 19). CT is less specific in the detection of adenomyomatosis, but this modality may show cystic-appearing thickening of the gallbladder wall or enhancing epithelium within intramural diverticula surrounded by relatively unenhanced hypertrophied gallbladder muscularis (Fig. 20).
Pseudothickening The thickness of the gallbladder wall depends on the degree of gallbladder distention, and pseudothickening can occur in the postprandial state. Gallbladder emptying in response to a meal is a physiologic phenomenon, mainly coordinated by the rate of gastric emptying of food in the duodenum and by the subsequent release of CCK. It is important not to mistake this normal physiologic phenomenon for pathologic thickening of the gallbladder wall (Fig. 21). Atypical Infection Tuberculous involvement of the gallbladder is rare. It may develop as part of systemic miliary tuberculosis, abdominal tuberculosis, isolated gallbladder tuberculosis, or acalculous cholecystitis in anergic patients. Radiologic diagnosis is difficult because the imaging features can mimic acute cholecystitis, chronic cholecystitis, and gallbladder malignancy. Most cases are diagnosed after cholecystectomy or at autopsy. Dengue hemorrhagic fever is an acute Flavivirus infection, which may cause a triad of transient wall thickening, ascites, and pleuropericardial effusion. A reticular pattern of the gallbladder wall is apparently typical of plasma leakage in severe disease. Focal Pattern Focal gallbladder wall thickening (> 3 mm by ultrasound) has a more narrow differential diagnosis and can be divided into neoplastic and nonneoplastic processes. Neoplastic causes include adenomatous polyps, gallbladder carcinoma, and metastases. Nonneoplastic causes include cholesterol or inflammatory polyps, focal adenomyomatosis, and focal xanthogranulomatous cholecystitis. Adenomatous Polyps Adenomatous polyps grow as pedunculated tumors that project into the gallbladder lumen and may be premalignant. Ultrasound findings include a nonmobile nonshadowing polypoid intraluminal mass that may have internal flow (Fig. 22). Polyps smaller than 5 mm are unlikely to be malignant; malignant lesions are usually smaller than 1 cm. Polyps measuring 5–10 mm should be followed up at 3–6 month intervals. Cholesterol polyps characteristically appear as echogenic structures with comet-tail reverberation artifact (Fig. 23). It is important to note that some gallbladder “polyps” actually represent small nonshadowing gallstones adherent to the wall.
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Runner et al. Gallbladder Carcinoma Gallbladder carcinoma can also present as focal irregular wall thickening or, less often, as an intraluminal polypoid mass (Fig. 24). Flow within the lesion seen on color Doppler ultrasound can help distinguish a mass from tumefactive sludge. Contrast-enhanced CT and MRI may show asymmetric or irregular wall thickening with marked enhancement during the arterial phase, which persists or becomes isodense or isointense to liver during the portal venous phase. As with the diffuse form of gallbladder carcinoma, the tumor often locally invades the adjacent liver and biliary tree. Metastases Metastatic disease involving the gallbladder is a rare entity and most commonly arises from melanoma. Primary pulmonary and renal malignancies are less frequently reported. Imaging features include focal irregular wall thickening and one or more enhancing polypoid masses (Fig. 25). Focal Adenomyomatosis (Adenomyoma) Adenomyoma represents the focal form of adenomyomatosis and most frequently involves the gallbladder fundus. Ultrasound findings may include echogenic intramural foci that emanate comet-tail reverberation artifacts (Fig. 26). Visualization of a twinkling artifact on color Doppler ultrasound is useful in making a diagnosis of focal adenomyo-
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matosis when reverberation artifact is either difficult to see or not present on gray-scale ultrasound. Twinkling artifact is caused by a strongly reflecting medium that appears as rapidly alternating red and blue color Doppler signal behind stationary objects. The hallmark of adenomyomatosis on T2-weighted MR images is the string-of-beads sign, which refers to cystic high-signal foci in the gallbladder wall that correspond to bile-filled Rokitansky-Aschoff sinuses (Fig. 27). A less common segmental (annular) form appears as a rind of circumferential involvement of the gallbladder body, which narrows the lumen and creates an hourglass configuration of the gallbladder (Fig. 27). Focal Xanthogranulomatous Cholecystitis Focal xanthogranulomatous cholecystitis is much less common than the diffuse form. The ultrasound and CT appearances are nonspecific, frequently consisting of thickening of the gallbladder wall and calculi. The diagnosis is usually made by histopathology. Conclusion Gallbladder wall thickening has a wide differential diagnosis. An important first step is to distinguish between the diffuse and focal forms. Subsequently, identification of ancillary imaging findings and directed use of additional imaging modalities allow an accurate diagnosis to be made.
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Reference 1. Teefey SA, Dahiya N, Middleton WD, Bajaj S, Ylagan L, Hildebolt CF. Acute Cholecystitis: Do sonographic findings and WBC count predict gangrenous changes? AJR 2013; 200:363–369
Selected Reading 1. An C, Park S, Ko S, et al. The usefulness of the tensile gallbladder fundus sign in the diagnosis of early acute cholecystitis. AJR 2013; 201:340– 346 2. Bennett GL, Balthazar EJ. Ultrasound and CT evaluation of emergent gallbladder pathology. Radiol Clin North Am 2003; 41:1203–1216 3. Catalano OA, Sahani DV, Kalva SP, et al. MR imaging of the gallbladder: a pictorial essay. RadioGraphics 2008; 28:135–155 4. Chang BJ, Kim SH, Park HY, et al. Distinguishing xanthogranulomatous cholecystitis from the wall-thickening type of early-stage gallbladder cancer. Gut Liver 2010; 4:518–523 5. Ching BH, Yeh BM, Westphalen AC, Joe BN, Qayyum A, Coakley FV. CT differentiation of adenomyomatosis and gallbladder cancer. AJR 2007; 189:62–66 6. Kapoor A, Mahajan G. Differentiating malignant from benign thickening of the gallbladder wall by the use of acoustic radiation force impulse elastography. J Ultrasound Med 2011; 30:1499–1507 7. van Breda Vriesman AC, Engelbrecht MR, Smithuis RH, Puylaert JB. Diffuse gallbladder wall thickening: differential diagnosis. AJR 2007; 188: 495–501
Fig. 1—Acute cholecystitis in 44-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffusely thickened wall (6.1 mm) (calipers) with multiple shadowing gallstones (arrow, A) and pericholecystic fluid (arrow, B). Patient also had positive sonographic Murphy sign.
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Fig. 2—Acute cholecystitis with gallbladder necrosis in 40-year-old woman. A, Longitudinal ultrasound image of gallbladder shows shadowing gallstones (solid arrow) and diffuse wall thickening (3.5 mm) (calipers) with alternating hyperechoic and hypoechoic bands (dashed arrow). B, Contrast-enhanced abdominal CT image shows hydropic gallbladder, diffuse wall thickening, and lack of wall enhancement, with extensive right upper quadrant mesenteric stranding.
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Fig. 3—Emphysematous cholecystitis. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder area in 64-year-old diabetic man show linear echogenic structures with distal reverberations and dirty shadowing, indicating gas within gallbladder wall. C, Contrast-enhanced abdominal CT image in different patient shows hydropic gallbladder with gas present in gallbladder wall.
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Fig. 4—Acute cholecystitis in 54-year-old man with equivocal ultrasound. A, Longitudinal ultrasound image of gallbladder shows multiple shadowing gallstones near gallbladder neck (arrow), with borderline wall thickening. B, Subsequent hepatobiliary scintigraphy scan shows prompt liver uptake and excretion of radiotracer into bowel with no filling of gallbladder lumen, finding highly specific for acute cholecystitis.
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Fig. 5—Negative hepatobiliary scintigraphy scan in 32-year-old woman with right upper quadrant pain shows prompt liver radiotracer uptake with early gallbladder visualization (arrow), effectively excluding acute cholecystitis.
Fig. 6—Acute cholecystitis in 58-year-old man. Contrast-enhanced CT image shows hyperemic liver parenchyma adjacent to thickened gallbladder wall (full arrow) with pericholecystic fluid (dashed arrow).
Fig. 7—Acute cholecystitis with abscess in 67-year-old man. Contrast-enhanced CT image shows distended gallbladder and thickened wall with adjacent rimenhancing low-density fluid collection (arrow).
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Fig. 8—Acalculous cholecystitis in 42-year-old man. A and B, Longitudinal (A) and transverse (B) images of gallbladder show diffuse wall thickening (4 mm) (calipers) with intraluminal sludge (solid arrow) and pericholecystic fluid (dashed arrow, A).
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Fig. 9—Acalculous cholecystitis in 40-year-old woman. Coronal abdominal CT image in septic patient shows diffuse gallbladder wall thickening. Small amount of perihepatic fluid is also present.
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Fig. 10—HIV cholangiopathy in 36-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffuse wall thickening. Subsequent hepatobiliary scintigraphy scan was negative (not shown).
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Fig. 11— Xanthogranulomatous cholecystitis in 75-year-old woman. A, Longitudinal ultrasound image of gallbladder shows hypoechoic band within diffusely thickened gallbladder wall. B, Contrast-enhanced abdominal CT image shows diffuse gallbladder wall thickening.
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Gallbladder Wall Thickening Fig. 12—Acute hepatitis in 14-year-old girl. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show diffuse gallbladder wall thickening (4.7 mm) (calipers) without stones. Diffuse liver hypoechogenicity with foci of increased periportal echogenicity in periportal regions (starry sky) is suggestive of hepatitis.
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Fig. 13—Cirrhosis in 57-year-old man. A, Longitudinal ultrasound image of gallbladder shows diffuse gallbladder wall thickening with ascites (arrow). B, Transverse ultrasound image of liver shows coarsened liver echotexture and nodular liver contour with ascites. C, Longitudinal ultrasound image of spleen shows splenomegaly (20 cm) (calipers) related to portal hypertension physiology.
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Fig. 14—Congestive heart failure in 52-year-old woman. A, Longitudinal ultrasound image of gallbladder shows diffusely marked thickened gallbladder wall with decompressed lumen, negative sonographic Murphy sign, and no stones. B, Heart failure on follow-up. CT image shows marked diffuse wall thickening. C, Subsequent hepatobiliary scintigraphy scan was negative, with gallbladder visualization (arrow).
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Fig. 15—Pancreatitis in 51-year-old man. A, Longitudinal ultrasound image of gallbladder shows diffuse wall thickening (4 mm) (calipers) without other signs of acute cholecystitis. B, Contrast-enhanced coronal abdominal CT image shows peripancreatic stranding with extension of inflammation into gallbladder fossa. Pancreatic calcifications indicate chronic pancreatitis. Follow-up hepatobiliary scintigraphy scan (not shown) was negative for acute cholecystitis.
Fig. 16—Diffuse gallbladder carcinoma in 67-year-old woman. Longitudinal ultrasound image of gallbladder shows large mass replacing gallbladder in gallbladder fossa, with infiltration of liver.
Fig. 17—Diffuse gallbladder carcinoma in 72-year-old man. Contrast-enhanced CT image shows infiltrative mass that arises from gallbladder fossa and invades liver.
Fig. 18—Diffuse gallbladder carcinoma in 56-year-old woman. Contrast-enhanced CT image shows diffuse gallbladder wall thickening with high-density intraluminal material (arrow), presumed gallstone. Biliary stent is also present (dashed arrow).
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Fig. 21—Gallbladder pseudothickening in 32-year-old man. Longitudinal ultrasound image of gallbladder shows contracted gallbladder with apparent wall thickening related to contracted state.
Fig. 20—Adenomyomatosis in 66-year-old man. Contrast-enhanced abdominal CT image shows diffuse mural thickening with multiple small cystic spaces in gallbladder wall (arrows).
Fig. 19—Adenomyomatosis in 55-year-old woman. Transverse ultrasound image of gallbladder shows diffuse mural thickening with areas of ring-down or comet-tail artifact (arrows).
Fig. 22—Gallbladder polyp in 63-year-old woman. Longitudinal ultrasound of gallbladder with Doppler flow shows focal nonmobile nonshadowing echogenic structure near gallbladder fundus (arrow) without internal vascularity.
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Fig. 23—Cholesterol polyp in 43-year-old woman. Longitudinal ultrasound image of gallbladder shows focal echogenic structure near gallbladder fundus (arrow) with ring-down artifact.
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Fig. 24—Focal gallbladder carcinoma in 71-year-old woman. A and B, Longitudinal ultrasound image of gallbladder (A) and longitudinal ultrasound of gallbladder with Doppler flow (B) show 3.6-cm intraluminal gallbladder mass with internal vascularity (arrow). (Fig. 24 continues on next page)
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Fig. 24 (continued)—Focal gallbladder carcinoma in 71-year-old woman. C, Contrast-enhanced CT image shows enhancing polypoid intraluminal mass arising from posterior aspect of gallbladder (arrow).
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Fig. 25—Gallbladder metastases in 62-year-old man with pancreatic adenocarcinoma. Abdominal CT image shows multiple irregular areas of gallbladder wall thickening (arrows).
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Fig. 26—Fundal adenomyoma in 41-year-old woman. A and B, Longitudinal (A) and transverse (B) ultrasound images of gallbladder show focal wall thickening (3.7 mm) (calipers) near gallbladder fundus (solid arrow, A) with area of ring-down artifact (dashed arrow, B).
Fig. 27—Adenomyomatosis in 54-year-old man. T2-weighted MR image of gallbladder shows stringof-beads appearance reflecting adenomyomatosis involving gallbladder fundus (dashed arrow). Coexisting annular or segmental form involves gallbladder body, narrowing gallbladder lumen and creating hourglass gallbladder configuration (solid arrows).
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