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MR Imaging of Acute Biliary Disorders¹

¹ From the Department of Radiology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki 710-8602, Japan. Presented as an education exhibit at the 2003 RSNA Annual Meeting. Received July 22, 2005; revision requested September 27; final revision received June 23, 2006; accepted June 28. All authors have no financial relationships to disclose. Address correspondence to Y.W. (e-mail: yw5904{at}kchnet.or.jp).

	Abstract

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

 
In patients with acute right-sided epigastric pain, jaundice, and a high fever, it is essential to accurately diagnose the cause of the symptoms, differentiate acute biliary disorders from nonbiliary disorders, and evaluate the severity of the disease. Gray-scale ultrasonography (US) and computed tomography (CT) are useful primary imaging modalities, but their results are not always conclusive. Magnetic resonance (MR) imaging, including MR cholangiopancreatography, can be a valuable complement to US and CT when additional information is needed. MR images have excellent tissue contrast and can provide more specific information, allowing diagnosis of complications that arise from acute cholecystitis, such as empyema, gangrenous cholecystitis, gallbladder perforation, enterocholecystic fistula, emphysematous cholecystitis, and hemorrhagic cholecystitis. In addition, causes of obstructive jaundice, acute suppurative cholangitis, and hemobilia can be clearly demonstrated with multisequence MR imaging. Single-section MR cholangiopancreatography and heavily T2-weighted imaging, in combination with fat-suppressed T1- and T2-weighted imaging, provide comprehensive and detailed information about the biliary system around the obstruction site, biliary calculi, inflammatory processes, purulent material, abscesses, gas, and hemorrhage. Contrast-enhanced MR imaging is useful for evaluation of the gallbladder wall; lack of enhancement and disruption of the wall may be findings specific for gangrenous cholecystitis and gallbladder perforation, respectively.

© RSNA, 2007

	LEARNING OBJECTIVES FOR TEST 5

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

 
After reading this article and taking the test, the reader will be able to:

• List the clinical features of various acute biliary disorders.
  
• Describe the characteristic MR imaging findings of acute biliary disorders.
  
• Identify serious complications of acute cholecystitis at MR imaging.
  

	Introduction

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

 
In patients with acute hepatobiliary symptoms such as right-sided epigastric pain, jaundice, and high fever, it is essential to accurately diagnose the cause of the symptoms, to differentiate acute biliary disorders from nonbiliary disorders, and to evaluate the severity of the disease. Complicated acute cholecystitis, such as gangrenous cholecystitis, gallbladder perforation, emphysematous cholecystitis, and acute suppurative cholangitis, often requires an immediate surgical approach or an endoscopic interventional approach. In contrast, acute nonbiliary hepatic disorders, such as acute viral hepatitis and drug-induced hepatitis, can be treated with conservative therapy (1–3). Inappropriate assessment of acute biliary conditions can lead to delay in proper patient care and treatment, which can then lead to potentially life-threatening problems, including septic shock (1–4).

A variety of imaging modalities such as gray-scale ultrasonography (US), color or power Doppler US, and x-ray computed tomography (CT) have been used to diagnose acute biliary disease with high sensitivity and specificity; however, results of these modalities are not always conclusive (1–6). Another imaging modality is required for assessment of acute biliary conditions (2–6). The recent development of fast magnetic resonance (MR) imaging techniques has shortened imaging time enough so that MR imaging can be performed for emergency use. About 15%–30% of patients who have acute biliary disorders are estimated to require MR imaging. Multisequence MR imaging, including MR cholangiopancreatography, allows a more comprehensive and detailed evaluation of the biliary systems, as MR images have excellent tissue contrast (7–19).

It is important to become familiar with the wide spectrum of MR imaging findings in acute biliary disorders. In this article, we present MR imaging findings and their usefulness in patients with acute biliary diseases. MR imaging techniques for biliary diseases and the characteristics of each sequence are also described, as well as clinical features for each disease.

	Techniques and Characteristics of Multisequence MR Imaging

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

 
In acute biliary disorders, MR imaging should be performed in patients with severe symptoms and those suspected of having serious complications, when US and CT findings are inconclusive. Our standard pulse sequences used for MR imaging of the gallbladder and biliary tract, and the advantages of each sequence, are summarized in Table 1. All MR imaging was performed with a 1.5-T MR unit (Gyroscan ACS-Intera; Philips, Best, the Netherlands) and a four-channel synergy body coil. Contrast-enhanced MR imaging should be selectively performed in patients suspected of having acute gangrenous cholecystitis, gallbladder perforation, or a malignant neoplasm (4,7).

	Clinical Applications

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

Multisequence MR imaging has a major advantage over US and CT because it provides specific information about causes, extent of inflammation, presence or absence of necrosis and abscess, and other complications in acute biliary disorders. A summary of the findings in acute biliary disorders and the related MR imaging appearances is given in Table 2.

MR imaging findings of acute uncomplicated cholecystitis include (a) gallstones, often impacted in the gallbladder neck or cystic duct; (b) gallbladder wall thickening (>3 mm); (c) gall-bladder wall edema; (d) gallbladder distention (diameter > 40 mm); (e) pericholecystic fluid; and (f) fluid around the liver, termed the "C sign" (small amount of fluid between the liver and the right hemidiaphragm or the abdominal wall, different from pericholecystic fluid) (7,20–25) (Figs 1–3). The presence of one or more of the six criteria is indicative of acute cholecystitis, yielding a sensitivity of 88% and specificity of 89% (25).

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 1a.  Acute acalculous cholecystitis associated with adenomyomatosis in a 54-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a, b) Image from single-section MR cholangiopancre-atography (a) and coronal heavily T2-weighted image (b) show a distended gallbladder with an enlarged Rokitansky-Aschoff sinus (arrow) at the gallbladder neck. (c) Axial heavily T2-weighted image shows diffuse hypointense thickening of the gallbladder wall (open arrows). There is some purulent bile (solid arrow), which like a sludge forms a lower layer and is hypointense relative to normal bile. Note the small amount of ascites around the liver (arrowhead). (d) Axial fat-suppressed T2-weighted image shows diffuse hyperintense thickening of the gallbladder wall (open arrows), a finding indicative of acute inflammation. It is difficult to identify the purulent bile on this image. Note the small amount of ascites around the liver (arrowhead).

View larger version (149K): [in this window] [in a new window] [Download PPT slide]   Figure 1b.  Acute acalculous cholecystitis associated with adenomyomatosis in a 54-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a, b) Image from single-section MR cholangiopancre-atography (a) and coronal heavily T2-weighted image (b) show a distended gallbladder with an enlarged Rokitansky-Aschoff sinus (arrow) at the gallbladder neck. (c) Axial heavily T2-weighted image shows diffuse hypointense thickening of the gallbladder wall (open arrows). There is some purulent bile (solid arrow), which like a sludge forms a lower layer and is hypointense relative to normal bile. Note the small amount of ascites around the liver (arrowhead). (d) Axial fat-suppressed T2-weighted image shows diffuse hyperintense thickening of the gallbladder wall (open arrows), a finding indicative of acute inflammation. It is difficult to identify the purulent bile on this image. Note the small amount of ascites around the liver (arrowhead).

View larger version (163K): [in this window] [in a new window] [Download PPT slide]   Figure 1c.  Acute acalculous cholecystitis associated with adenomyomatosis in a 54-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a, b) Image from single-section MR cholangiopancre-atography (a) and coronal heavily T2-weighted image (b) show a distended gallbladder with an enlarged Rokitansky-Aschoff sinus (arrow) at the gallbladder neck. (c) Axial heavily T2-weighted image shows diffuse hypointense thickening of the gallbladder wall (open arrows). There is some purulent bile (solid arrow), which like a sludge forms a lower layer and is hypointense relative to normal bile. Note the small amount of ascites around the liver (arrowhead). (d) Axial fat-suppressed T2-weighted image shows diffuse hyperintense thickening of the gallbladder wall (open arrows), a finding indicative of acute inflammation. It is difficult to identify the purulent bile on this image. Note the small amount of ascites around the liver (arrowhead).

View larger version (163K): [in this window] [in a new window] [Download PPT slide]   Figure 1d.  Acute acalculous cholecystitis associated with adenomyomatosis in a 54-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a, b) Image from single-section MR cholangiopancre-atography (a) and coronal heavily T2-weighted image (b) show a distended gallbladder with an enlarged Rokitansky-Aschoff sinus (arrow) at the gallbladder neck. (c) Axial heavily T2-weighted image shows diffuse hypointense thickening of the gallbladder wall (open arrows). There is some purulent bile (solid arrow), which like a sludge forms a lower layer and is hypointense relative to normal bile. Note the small amount of ascites around the liver (arrowhead). (d) Axial fat-suppressed T2-weighted image shows diffuse hyperintense thickening of the gallbladder wall (open arrows), a finding indicative of acute inflammation. It is difficult to identify the purulent bile on this image. Note the small amount of ascites around the liver (arrowhead).

View larger version (145K): [in this window] [in a new window] [Download PPT slide]   Figure 2a.  Acute cholecystitis caused by cystic duct obstruction due to an impacted calculus in a 65-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the suspected acute cholecystitis could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with an impacted calculus (arrow) in the gallbladder neck. There is another calculus (*) in the gallbladder body. Note the small amount of pericholecystic fluid (arrowheads), which is markedly hyperintense. (b) Axial fat-suppressed T2-weighted image shows the distended gallbladder caused by the impacted stone (solid arrow). There is diffuse wall thickening with patchy high signal intensity (open arrows). Note the small amount of pericholecystic fluid (arrowhead), which is markedly hyperintense. (c) Coronal steady-state coherent image shows the impacted calculus (arrow) in the gallbladder neck. The impacted stone demonstrates predominant signal loss with a small central region of high signal intensity.

View larger version (146K): [in this window] [in a new window] [Download PPT slide]   Figure 2b.  Acute cholecystitis caused by cystic duct obstruction due to an impacted calculus in a 65-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the suspected acute cholecystitis could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with an impacted calculus (arrow) in the gallbladder neck. There is another calculus (*) in the gallbladder body. Note the small amount of pericholecystic fluid (arrowheads), which is markedly hyperintense. (b) Axial fat-suppressed T2-weighted image shows the distended gallbladder caused by the impacted stone (solid arrow). There is diffuse wall thickening with patchy high signal intensity (open arrows). Note the small amount of pericholecystic fluid (arrowhead), which is markedly hyperintense. (c) Coronal steady-state coherent image shows the impacted calculus (arrow) in the gallbladder neck. The impacted stone demonstrates predominant signal loss with a small central region of high signal intensity.

View larger version (145K): [in this window] [in a new window] [Download PPT slide]   Figure 2c.  Acute cholecystitis caused by cystic duct obstruction due to an impacted calculus in a 65-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the suspected acute cholecystitis could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with an impacted calculus (arrow) in the gallbladder neck. There is another calculus (*) in the gallbladder body. Note the small amount of pericholecystic fluid (arrowheads), which is markedly hyperintense. (b) Axial fat-suppressed T2-weighted image shows the distended gallbladder caused by the impacted stone (solid arrow). There is diffuse wall thickening with patchy high signal intensity (open arrows). Note the small amount of pericholecystic fluid (arrowhead), which is markedly hyperintense. (c) Coronal steady-state coherent image shows the impacted calculus (arrow) in the gallbladder neck. The impacted stone demonstrates predominant signal loss with a small central region of high signal intensity.

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 3a.  Acute cholecystitis caused by cystic duct obstruction due to gallbladder cancer with lymph node metastasis in a 64-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the gallbladder distention could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with a hypointense tumor (arrow) adjacent to the gallbladder neck. The tumor mimics an impacted stone (cf Fig 2). There is a polypoid skip lesion (*) in the gallbladder body. (b) On an axial fat-suppressed T2-weighted image, the gallbladder neck tumor (solid arrow) has intermediate signal intensity. The thickened gallbladder wall has high signal intensity (open arrow). (c) On a coronal steady-state coherent image, the gallbladder neck tumor (arrow) has intermediate signal intensity, as does the liver. The skip lesion in the gallbladder body (*) has an irregular surface. The diagnosis of gallbladder cancer was confirmed at surgery and pathologic analysis.

View larger version (123K): [in this window] [in a new window] [Download PPT slide]   Figure 3b.  Acute cholecystitis caused by cystic duct obstruction due to gallbladder cancer with lymph node metastasis in a 64-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the gallbladder distention could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with a hypointense tumor (arrow) adjacent to the gallbladder neck. The tumor mimics an impacted stone (cf Fig 2). There is a polypoid skip lesion (*) in the gallbladder body. (b) On an axial fat-suppressed T2-weighted image, the gallbladder neck tumor (solid arrow) has intermediate signal intensity. The thickened gallbladder wall has high signal intensity (open arrow). (c) On a coronal steady-state coherent image, the gallbladder neck tumor (arrow) has intermediate signal intensity, as does the liver. The skip lesion in the gallbladder body (*) has an irregular surface. The diagnosis of gallbladder cancer was confirmed at surgery and pathologic analysis.

View larger version (159K): [in this window] [in a new window] [Download PPT slide]   Figure 3c.  Acute cholecystitis caused by cystic duct obstruction due to gallbladder cancer with lymph node metastasis in a 64-year-old man with right upper quadrant pain. MR imaging was performed because the cause of the gallbladder distention could not be determined with US. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder with a hypointense tumor (arrow) adjacent to the gallbladder neck. The tumor mimics an impacted stone (cf Fig 2). There is a polypoid skip lesion (*) in the gallbladder body. (b) On an axial fat-suppressed T2-weighted image, the gallbladder neck tumor (solid arrow) has intermediate signal intensity. The thickened gallbladder wall has high signal intensity (open arrow). (c) On a coronal steady-state coherent image, the gallbladder neck tumor (arrow) has intermediate signal intensity, as does the liver. The skip lesion in the gallbladder body (*) has an irregular surface. The diagnosis of gallbladder cancer was confirmed at surgery and pathologic analysis.

A thickened gallbladder wall is observed in acute cholecystitis as well as other conditions such as chronic cholecystitis, adenomyomatosis, malignant neoplasm, and acute hepatitis. However, a thickened wall with a diffuse or patchy distribution of increased signal intensity on fat-suppressed T2-weighted images is suggestive of an acute inflammatory process (Figs 1, 2) (11,21). An acute inflammatory process extending into the adipose tissue surrounding the gallbladder also appears as a reticular or patchy hyperintense area on fat-suppressed T2-weighted images. On contrast-enhanced fat-suppressed T1-weighted images, increased contrast enhancement can be seen in the gallbladder wall, pericholecystic fat, and intrahepatic periportal tissues, findings that are supportive of acute cholecystitis (7).

Complications of Acute Cholecystitis
Complications develop in up to 40% of patients with acute cholecystitis (1–4). Major complications include empyema, gangrenous cholecystitis, perforation with pericholecystic abscess, perforation with biliaryenteric fistula, emphysematous cholecystitis, and hemorrhagic cholecystitis (2–4). MR imaging also plays a very useful role in evaluating suspected complications of acute cholecystitis (26).

Empyema.— Empyema of the gallbladder (suppurative cholecystitis) occurs when pus fills the distended and inflamed gallbladder (Fig 1). This complication typically occurs in diabetic patients and may behave like an intraabdominal abscess, with rapid progression of symptoms. Pus within the gallbladder resembles sludge at US and CT, but those findings are not specific for empyema (4,7). At MR imaging, pus or purulent bile in the distended gallbladder resembles sludge due to viscous contents. Heavily T2-weighted imaging is sensitive enough to demonstrate purulent bile, which is dependent and has lower signal intensity (Fig 1). On other types of MR images, pus or purulent bile is difficult to demonstrate. The diagnosis of empyema can be suggested by the MR imaging finding of pus, when accompanied by an inflamed wall of a distended gallbladder. However, percutaneous needle aspiration of the gall-bladder may be necessary to establish the diagnosis of empyema.

Gangrenous Cholecystitis.— Gangrenous cholecystitis is an advanced, severe form of acute cholecystitis that is more common in men, patients of advanced age, and those with coexisting cardiovascular disease (2–4,7,26,27). Gangrenous cholecystitis results from increased intraluminal pressure due to cystic duct obstruction, leading to marked distention of the gallbladder, ischemic necrosis of the wall, and intramural hemorrhage or abscess (27). Both US and CT are highly specific for identifying acute gangrenous cholecystitis (96%) but have low sensitivity (29.3%) (28–30).

Multisequence MR images demonstrate the features of gangrenous cholecystitis such as ulceration, hemorrhage, necrosis, or microabscess in the gallbladder wall (4,7) (Figs 4, 5). Irregular or asymmetric thickening of the gallbladder wall is well demonstrated on axial fat-suppressed T2-weighted images, fat-suppressed T1-weighted images, and contrast-enhanced fat-suppressed T1-weighted images. The ulceration of the wall may be shown as a concave hyperintense area on fat-suppressed T2-weighted images. In addition, intramural hemorrhage, necrosis, and abscess are frequently shown as an inhomogeneous hyperin-tense area on fat-suppressed T2-weighted images and fat-suppressed T1-weighted images (Figs 4, 5). The ability of MR imaging to demonstrate gangrenous cholecystitis is greater if an intravenous contrast agent is administered (4,7). Inhomogeneous wall enhancement is a characteristic finding when accompanied by lack of enhancement of part of the inflamed wall (Fig 4). Furthermore, disrupted mucosal enhancement can be seen. A pericholecystic fluid collection or abscess caused by associated gallbladder perforation or an intramural abscess may also be observed.

View larger version (142K): [in this window] [in a new window] [Download PPT slide]   Figure 4a.  Acute gangrenous cholecystitis due to an impacted calculus in a 70-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because US and CT findings were inconclusive in regard to the severe symptoms. (a, b) Axial fat-suppressed T2-weighted (a) and fat-suppressed T1-weighted (b) images show irregular thickening of the gallbladder wall with small areas of high signal intensity (arrowheads). The hyperintense bile on the fat-suppressed T1-weighted image (b) is suggestive of concentrated bile. (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows inhomogeneous enhancement of the irregularly thickened gallbladder wall and lack of enhancement at the fundus (arrow). (d) Sagittal contrast-enhanced fat-suppressed T1-weighted image shows that the mucosal layer is disrupted at the gallbladder fundus and body (arrows). MR cholangiopancreatography showed an impacted calculus in the gallbladder neck.

View larger version (144K): [in this window] [in a new window] [Download PPT slide]   Figure 4b.  Acute gangrenous cholecystitis due to an impacted calculus in a 70-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because US and CT findings were inconclusive in regard to the severe symptoms. (a, b) Axial fat-suppressed T2-weighted (a) and fat-suppressed T1-weighted (b) images show irregular thickening of the gallbladder wall with small areas of high signal intensity (arrowheads). The hyperintense bile on the fat-suppressed T1-weighted image (b) is suggestive of concentrated bile. (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows inhomogeneous enhancement of the irregularly thickened gallbladder wall and lack of enhancement at the fundus (arrow). (d) Sagittal contrast-enhanced fat-suppressed T1-weighted image shows that the mucosal layer is disrupted at the gallbladder fundus and body (arrows). MR cholangiopancreatography showed an impacted calculus in the gallbladder neck.

View larger version (168K): [in this window] [in a new window] [Download PPT slide]   Figure 4c.  Acute gangrenous cholecystitis due to an impacted calculus in a 70-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because US and CT findings were inconclusive in regard to the severe symptoms. (a, b) Axial fat-suppressed T2-weighted (a) and fat-suppressed T1-weighted (b) images show irregular thickening of the gallbladder wall with small areas of high signal intensity (arrowheads). The hyperintense bile on the fat-suppressed T1-weighted image (b) is suggestive of concentrated bile. (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows inhomogeneous enhancement of the irregularly thickened gallbladder wall and lack of enhancement at the fundus (arrow). (d) Sagittal contrast-enhanced fat-suppressed T1-weighted image shows that the mucosal layer is disrupted at the gallbladder fundus and body (arrows). MR cholangiopancreatography showed an impacted calculus in the gallbladder neck.

View larger version (165K): [in this window] [in a new window] [Download PPT slide]   Figure 4d.  Acute gangrenous cholecystitis due to an impacted calculus in a 70-year-old man with right upper quadrant pain and a high fever. MR imaging was performed because US and CT findings were inconclusive in regard to the severe symptoms. (a, b) Axial fat-suppressed T2-weighted (a) and fat-suppressed T1-weighted (b) images show irregular thickening of the gallbladder wall with small areas of high signal intensity (arrowheads). The hyperintense bile on the fat-suppressed T1-weighted image (b) is suggestive of concentrated bile. (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows inhomogeneous enhancement of the irregularly thickened gallbladder wall and lack of enhancement at the fundus (arrow). (d) Sagittal contrast-enhanced fat-suppressed T1-weighted image shows that the mucosal layer is disrupted at the gallbladder fundus and body (arrows). MR cholangiopancreatography showed an impacted calculus in the gallbladder neck.

View larger version (152K): [in this window] [in a new window] [Download PPT slide]   Figure 5a.  Gallbladder perforation associated with acute gangrenous cholecystitis in a 78-year-old woman with right upper quadrant pain and a high fever. MR imaging was performed because of US findings suggestive of a pericholecystic abscess. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder (arrowhead) with an irregular contour of the fundus and stenosis of the common hepatic duct (arrow) due to extrinsic compression by the gallbladder. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show gallbladder wall thickening (arrowhead) and purulent bile (*), which like a sludge forms a lower layer of low signal intensity. A pericholecystic abscess (open arrow) is seen as an area of slightly higher signal intensity. The gallbladder wall is disrupted (solid arrow), and purulent bile is present outside the gallbladder; this bile is contained by the pericholecystic abscess. (d) Axial fat-suppressed T1-weighted image shows the purulent bile (*) as a lower layer of intermediate signal intensity. The purulent bile communicates with the pericholecystic abscess (open arrow) through the site of perforation (solid arrow).

View larger version (172K): [in this window] [in a new window] [Download PPT slide]   Figure 5b.  Gallbladder perforation associated with acute gangrenous cholecystitis in a 78-year-old woman with right upper quadrant pain and a high fever. MR imaging was performed because of US findings suggestive of a pericholecystic abscess. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder (arrowhead) with an irregular contour of the fundus and stenosis of the common hepatic duct (arrow) due to extrinsic compression by the gallbladder. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show gallbladder wall thickening (arrowhead) and purulent bile (*), which like a sludge forms a lower layer of low signal intensity. A pericholecystic abscess (open arrow) is seen as an area of slightly higher signal intensity. The gallbladder wall is disrupted (solid arrow), and purulent bile is present outside the gallbladder; this bile is contained by the pericholecystic abscess. (d) Axial fat-suppressed T1-weighted image shows the purulent bile (*) as a lower layer of intermediate signal intensity. The purulent bile communicates with the pericholecystic abscess (open arrow) through the site of perforation (solid arrow).

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 5c.  Gallbladder perforation associated with acute gangrenous cholecystitis in a 78-year-old woman with right upper quadrant pain and a high fever. MR imaging was performed because of US findings suggestive of a pericholecystic abscess. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder (arrowhead) with an irregular contour of the fundus and stenosis of the common hepatic duct (arrow) due to extrinsic compression by the gallbladder. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show gallbladder wall thickening (arrowhead) and purulent bile (*), which like a sludge forms a lower layer of low signal intensity. A pericholecystic abscess (open arrow) is seen as an area of slightly higher signal intensity. The gallbladder wall is disrupted (solid arrow), and purulent bile is present outside the gallbladder; this bile is contained by the pericholecystic abscess. (d) Axial fat-suppressed T1-weighted image shows the purulent bile (*) as a lower layer of intermediate signal intensity. The purulent bile communicates with the pericholecystic abscess (open arrow) through the site of perforation (solid arrow).

View larger version (172K): [in this window] [in a new window] [Download PPT slide]   Figure 5d.  Gallbladder perforation associated with acute gangrenous cholecystitis in a 78-year-old woman with right upper quadrant pain and a high fever. MR imaging was performed because of US findings suggestive of a pericholecystic abscess. (a) Image from single-section MR cholangiopancreatography shows a distended gallbladder (arrowhead) with an irregular contour of the fundus and stenosis of the common hepatic duct (arrow) due to extrinsic compression by the gallbladder. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show gallbladder wall thickening (arrowhead) and purulent bile (*), which like a sludge forms a lower layer of low signal intensity. A pericholecystic abscess (open arrow) is seen as an area of slightly higher signal intensity. The gallbladder wall is disrupted (solid arrow), and purulent bile is present outside the gallbladder; this bile is contained by the pericholecystic abscess. (d) Axial fat-suppressed T1-weighted image shows the purulent bile (*) as a lower layer of intermediate signal intensity. The purulent bile communicates with the pericholecystic abscess (open arrow) through the site of perforation (solid arrow).

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 6a.  Gallbladder perforation with an enterobiliary fistula in a 68-year-old man with right upper quadrant pain and a high fever. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Axial heavily T2-weighted image shows a distorted gallbladder. Intraluminal gas (*) forms an upper layer and purulent bile (arrow) forms a lower layer of low signal intensity. Note the irregular thick gallbladder wall with a hyperintense focus (arrowhead), which represents a small ulcerative projection. (b) Axial fat-suppressed T2-weighted image shows the intraluminal gas (*) in the gallbladder, which has a diffuse thick hyperintense wall. There is a tiny gas bubble in the ulcerative projection (arrowhead). (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows that the left gallbladder wall has an irregular contour with inhomogeneous intense enhancement (arrowhead), an appearance suggestive of gallbladder perforation. Note the decreased enhancement of the right gallbladder wall (arrows), a finding suggestive of ischemic change and gangrene. A subsequent gastroduodenal barium study and surgery demonstrated a cholecystoduodenal fistula.

View larger version (157K): [in this window] [in a new window] [Download PPT slide]   Figure 6b.  Gallbladder perforation with an enterobiliary fistula in a 68-year-old man with right upper quadrant pain and a high fever. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Axial heavily T2-weighted image shows a distorted gallbladder. Intraluminal gas (*) forms an upper layer and purulent bile (arrow) forms a lower layer of low signal intensity. Note the irregular thick gallbladder wall with a hyperintense focus (arrowhead), which represents a small ulcerative projection. (b) Axial fat-suppressed T2-weighted image shows the intraluminal gas (*) in the gallbladder, which has a diffuse thick hyperintense wall. There is a tiny gas bubble in the ulcerative projection (arrowhead). (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows that the left gallbladder wall has an irregular contour with inhomogeneous intense enhancement (arrowhead), an appearance suggestive of gallbladder perforation. Note the decreased enhancement of the right gallbladder wall (arrows), a finding suggestive of ischemic change and gangrene. A subsequent gastroduodenal barium study and surgery demonstrated a cholecystoduodenal fistula.

View larger version (171K): [in this window] [in a new window] [Download PPT slide]   Figure 6c.  Gallbladder perforation with an enterobiliary fistula in a 68-year-old man with right upper quadrant pain and a high fever. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Axial heavily T2-weighted image shows a distorted gallbladder. Intraluminal gas (*) forms an upper layer and purulent bile (arrow) forms a lower layer of low signal intensity. Note the irregular thick gallbladder wall with a hyperintense focus (arrowhead), which represents a small ulcerative projection. (b) Axial fat-suppressed T2-weighted image shows the intraluminal gas (*) in the gallbladder, which has a diffuse thick hyperintense wall. There is a tiny gas bubble in the ulcerative projection (arrowhead). (c) Axial contrast-enhanced fat-suppressed T1-weighted image shows that the left gallbladder wall has an irregular contour with inhomogeneous intense enhancement (arrowhead), an appearance suggestive of gallbladder perforation. Note the decreased enhancement of the right gallbladder wall (arrows), a finding suggestive of ischemic change and gangrene. A subsequent gastroduodenal barium study and surgery demonstrated a cholecystoduodenal fistula.

Multisequence MR imaging has a potential role in detecting gallbladder perforation contained by a pericholecystic abscess or accompanied by a cholecystoenteric fistula (4,7,37,38). MR imaging findings indicative of gallbladder perforation include a disrupted gallbladder wall (Figs 5, 6). Multiplanar imaging may be useful for depiction and confirmation of wall defects and fistulas. Irregular or asymmetric thickening of the gallbladder wall with inhomogeneous high signal intensity on fat-suppressed T2-weighted images and fat-suppressed T1-weighted images can be seen with disruption of the wall (Fig 5). Contrast-enhanced MR imaging more clearly delineates the wall disruption (Fig 6).

When the perforation is contained by a pericholecystic abscess, the gallbladder lumen communicates with the pericholecystic abscess through the disruption of the gallbladder wall (7) (Fig 5). The purulent bile in the gallbladder lumen shows inhomogeneous low signal intensity on heavily T2-weighted images and fat-suppressed T2-weighted images, similar to the complex fluid collection of the pericholecystic abscess. When the gallbladder communicates with an adjacent bowel loop, such as the duodenum or the hepatic flexure of the colon, gas within the gall-bladder lumen can be observed as a signal void area in the upper dependent portion of the gall-bladder lumen (Fig 6). Other MR imaging findings associated with gallbladder perforation include thick peritoneum and loculated ascites with homogeneous high signal intensity on heavily T2-weighted images and fat-suppressed T2-weighted images.

In cases of perforation caused by traumatic injury, MR imaging can depict a large hematoma in the gallbladder fossa and gallbladder lumen by demonstrating the signal intensities of the different stages of hemoglobin on T1- and T2-weighted images (7).

Emphysematous Cholecystitis.— Emphysematous cholecystitis is a rare form of acute cholecystitis; the radiographic appearance of this specific condition was described by Hegner (39) in 1931 (40–46). The majority of patients are between 50 and 70 years of age and have underlying diabetes mellitus and peripheral atherosclerotic disease.

CT is the most sensitive and most specific imaging modality for identifying gas in the gallbladder lumen or wall (43). US may demonstrate characteristic intraluminal and intramural gas as highly echogenic reflectors, which can be mistaken for biliary calculi. In such a clinical setting, MR imaging plays a supplementary role of providing information on intramural necrosis as well as intraluminal gas. Gas in the gallbladder lumen and wall appears as signal void areas (11). A specific MR imaging finding of intraluminal gas consists of numerous floating signal void bubbles in the upper dependent portions of the gallbladder lumen and/or extrahepatic bile duct, whereas gallstones are usually observed in the lower dependent portion (Fig 7).

View larger version (165K): [in this window] [in a new window] [Download PPT slide]   Figure 7a.  Emphysematous cholecystitis in a 62-year-old man with right upper quadrant pain and a high fever followed by symptoms of shock. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Coronal heavily T2-weighted image shows numerous signal void bubbles (arrowheads) in the lumina of the distended gallbladder and the common bile duct. (b) Axial fat-suppressed T2-weighted image shows that the gas bubbles (arrowheads) form an upper layer in the dependent portions of the gallbladder and cystic duct; purulent bile (*) like a sludge forms a lower layer of relatively low signal intensity. Note the thick gallbladder wall with a hyperintense focus (open arrows), an appearance suggestive of an intramural abscess. Pericholecystic fluid is also seen (solid arrows). (c) Axial fat-suppressed T1-weighted image shows similar findings of gas (arrowhead) and an inflamed thick gallbladder wall. The medial gallbladder wall has very high signal intensity (arrows), a finding suggestive of intramural hemorrhage or hemorrhagic necrosis.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 7b.  Emphysematous cholecystitis in a 62-year-old man with right upper quadrant pain and a high fever followed by symptoms of shock. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Coronal heavily T2-weighted image shows numerous signal void bubbles (arrowheads) in the lumina of the distended gallbladder and the common bile duct. (b) Axial fat-suppressed T2-weighted image shows that the gas bubbles (arrowheads) form an upper layer in the dependent portions of the gallbladder and cystic duct; purulent bile (*) like a sludge forms a lower layer of relatively low signal intensity. Note the thick gallbladder wall with a hyperintense focus (open arrows), an appearance suggestive of an intramural abscess. Pericholecystic fluid is also seen (solid arrows). (c) Axial fat-suppressed T1-weighted image shows similar findings of gas (arrowhead) and an inflamed thick gallbladder wall. The medial gallbladder wall has very high signal intensity (arrows), a finding suggestive of intramural hemorrhage or hemorrhagic necrosis.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 7c.  Emphysematous cholecystitis in a 62-year-old man with right upper quadrant pain and a high fever followed by symptoms of shock. MR imaging was performed to search for the cause of gas in the gallbladder lumen seen at US and CT. (a) Coronal heavily T2-weighted image shows numerous signal void bubbles (arrowheads) in the lumina of the distended gallbladder and the common bile duct. (b) Axial fat-suppressed T2-weighted image shows that the gas bubbles (arrowheads) form an upper layer in the dependent portions of the gallbladder and cystic duct; purulent bile (*) like a sludge forms a lower layer of relatively low signal intensity. Note the thick gallbladder wall with a hyperintense focus (open arrows), an appearance suggestive of an intramural abscess. Pericholecystic fluid is also seen (solid arrows). (c) Axial fat-suppressed T1-weighted image shows similar findings of gas (arrowhead) and an inflamed thick gallbladder wall. The medial gallbladder wall has very high signal intensity (arrows), a finding suggestive of intramural hemorrhage or hemorrhagic necrosis.

Hemorrhagic Cholecystitis.— Hemorrhagic cholecystitis is a rare complication of acute chole-cystitis and has been reported in both the presence and absence of gallstones (4,47,48). Arteriosclerotic change in the gallbladder wall is most likely a predisposing factor. Other causes of blood in the gallbladder include neoplasm; vascular abnormalities, such as an aneurysm; trauma; anticoagulation; and ectopic pancreatic or gastric mucosa. The clinical presentation and symptoms include biliary colic, jaundice, hematemesis, and melena. Associated perforation of the gallbladder may lead to hemoperitoneum.

At multisequence MR imaging, hemorrhage in the wall and lumen of the gallbladder is seen as high signal intensity of methemoglobin on T1-weighted images (7) (Fig 8). Blood clots and hemorrhage may be shown as defects or low signal intensity lesions on T2-weighted images, causing lack of visualization of the gallbladder or bile ducts at MR cholangiopancreatography and heavily T2-weighted imaging (Fig 8). A fluid-fluid level can be observed in the lumen of the gallbladder and extrahepatic bile ducts, where hemorrhagic bile appears as a low signal intensity area in the lower dependent layer on both axial heavily T2-weighted images and fat-suppressed T2-weighted images. When there is associated perforation, hemorrhage or encapsulated bile can be seen in the peritoneal cavity (Fig 8).

View larger version (178K): [in this window] [in a new window] [Download PPT slide]   Figure 8a.  Hemorrhagic cholecystitis and gallbladder perforation causing biliary peritonitis in a 72-year-old man with upper abdominal pain and melena. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Coronal heavily T2-weighted image shows multiple defects (arrows) in the common bile duct, which represent clots. The gallbladder is not visualized. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show hemorrhagic bile (thin solid arrows) like a sludge in the common bile duct and gallbladder, forming a lower layer of low signal intensity. The distended and distorted gall-bladder has a focal protrusion (open arrows) and an irregular wall that is disrupted at the fundus (arrowheads). Biliary peritonitis has caused an encapsulated fluid collection (thick solid arrow) beside the spleen. A small amount of ascites is also seen. (d) Axial fat-suppressed T1-weighted image shows high signal intensity of the lower layer of hemorrhagic bile (thin solid arrow). The long disruption of the gallbladder wall (arrowheads) with focal protrusion (open arrows) at the fundus is also seen. Thick solid arrow = encapsulated fluid collection beside the spleen. Subsequent endoscopic retrograde cholangiopancreatography revealed hemobilia. Ten days later, the patient died of multiple organ failure.

View larger version (163K): [in this window] [in a new window] [Download PPT slide]   Figure 8b.  Hemorrhagic cholecystitis and gallbladder perforation causing biliary peritonitis in a 72-year-old man with upper abdominal pain and melena. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Coronal heavily T2-weighted image shows multiple defects (arrows) in the common bile duct, which represent clots. The gallbladder is not visualized. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show hemorrhagic bile (thin solid arrows) like a sludge in the common bile duct and gallbladder, forming a lower layer of low signal intensity. The distended and distorted gall-bladder has a focal protrusion (open arrows) and an irregular wall that is disrupted at the fundus (arrowheads). Biliary peritonitis has caused an encapsulated fluid collection (thick solid arrow) beside the spleen. A small amount of ascites is also seen. (d) Axial fat-suppressed T1-weighted image shows high signal intensity of the lower layer of hemorrhagic bile (thin solid arrow). The long disruption of the gallbladder wall (arrowheads) with focal protrusion (open arrows) at the fundus is also seen. Thick solid arrow = encapsulated fluid collection beside the spleen. Subsequent endoscopic retrograde cholangiopancreatography revealed hemobilia. Ten days later, the patient died of multiple organ failure.

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 8c.  Hemorrhagic cholecystitis and gallbladder perforation causing biliary peritonitis in a 72-year-old man with upper abdominal pain and melena. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Coronal heavily T2-weighted image shows multiple defects (arrows) in the common bile duct, which represent clots. The gallbladder is not visualized. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show hemorrhagic bile (thin solid arrows) like a sludge in the common bile duct and gallbladder, forming a lower layer of low signal intensity. The distended and distorted gall-bladder has a focal protrusion (open arrows) and an irregular wall that is disrupted at the fundus (arrowheads). Biliary peritonitis has caused an encapsulated fluid collection (thick solid arrow) beside the spleen. A small amount of ascites is also seen. (d) Axial fat-suppressed T1-weighted image shows high signal intensity of the lower layer of hemorrhagic bile (thin solid arrow). The long disruption of the gallbladder wall (arrowheads) with focal protrusion (open arrows) at the fundus is also seen. Thick solid arrow = encapsulated fluid collection beside the spleen. Subsequent endoscopic retrograde cholangiopancreatography revealed hemobilia. Ten days later, the patient died of multiple organ failure.

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 8d.  Hemorrhagic cholecystitis and gallbladder perforation causing biliary peritonitis in a 72-year-old man with upper abdominal pain and melena. MR imaging was performed because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Coronal heavily T2-weighted image shows multiple defects (arrows) in the common bile duct, which represent clots. The gallbladder is not visualized. (b, c) Axial heavily T2-weighted (b) and fat-suppressed T2-weighted (c) images show hemorrhagic bile (thin solid arrows) like a sludge in the common bile duct and gallbladder, forming a lower layer of low signal intensity. The distended and distorted gall-bladder has a focal protrusion (open arrows) and an irregular wall that is disrupted at the fundus (arrowheads). Biliary peritonitis has caused an encapsulated fluid collection (thick solid arrow) beside the spleen. A small amount of ascites is also seen. (d) Axial fat-suppressed T1-weighted image shows high signal intensity of the lower layer of hemorrhagic bile (thin solid arrow). The long disruption of the gallbladder wall (arrowheads) with focal protrusion (open arrows) at the fundus is also seen. Thick solid arrow = encapsulated fluid collection beside the spleen. Subsequent endoscopic retrograde cholangiopancreatography revealed hemobilia. Ten days later, the patient died of multiple organ failure.

MR imaging findings include a tapered cystic duct at multisection MR cholangiopancreatography and high signal intensity in the wall at T1-weighted imaging; coagulation necrosis with intramural hemorrhage is also seen with T1-weighted imaging (50). Contrast-enhanced MR imaging may help confirm the diagnosis.

Obstructive Jaundice
Obstructive jaundice results from obstruction of the bile duct caused by various diseases such as impaction of a calculus, postinflammatory or postsurgical strictures, and malignant tumors (11,51–54). The roles of imaging in these clinical settings are to determine the level and severity of the bile duct obstruction and to identify the cause of obstruction of the extrahepatic bile duct, such as a common bile duct stone, sclerosing cholangitis, Mirizzi syndrome, or malignant pancreaticobiliary neoplasm (Figs 9–11).

View larger version (167K): [in this window] [in a new window] [Download PPT slide]   Figure 9a.  Acute suppurative cholangitis caused by ampullary cancer in a 63-year-old woman with abdominal pain, a high fever, and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows a dilated pancreaticobiliary duct and a distended gallbladder caused by an ampullary cancer (arrow), which protruded into the lower common bile duct as a small polypoid nodule. Minimal pericholecystic fluid is evident (arrowhead). (b) Coronal steady-state coherent image shows the polypoid tumor (arrow) as an area of intermediate signal intensity, allowing differentiation from a low-signal-intensity stone (cf Fig 2). (c) Axial heavily T2-weighted image shows that the gallbladder has a thick wall (arrows). Purulent bile (arrowheads) in the gallbladder and common bile duct forms lower layers of low signal intensity. (d) Axial black blood T2-weighted spin-echo echo-planar image shows periportal inflammation of high signal intensity (arrows) extending along the intrahepatic portal vein, which appears as a signal void.

View larger version (169K): [in this window] [in a new window] [Download PPT slide]   Figure 9b.  Acute suppurative cholangitis caused by ampullary cancer in a 63-year-old woman with abdominal pain, a high fever, and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows a dilated pancreaticobiliary duct and a distended gallbladder caused by an ampullary cancer (arrow), which protruded into the lower common bile duct as a small polypoid nodule. Minimal pericholecystic fluid is evident (arrowhead). (b) Coronal steady-state coherent image shows the polypoid tumor (arrow) as an area of intermediate signal intensity, allowing differentiation from a low-signal-intensity stone (cf Fig 2). (c) Axial heavily T2-weighted image shows that the gallbladder has a thick wall (arrows). Purulent bile (arrowheads) in the gallbladder and common bile duct forms lower layers of low signal intensity. (d) Axial black blood T2-weighted spin-echo echo-planar image shows periportal inflammation of high signal intensity (arrows) extending along the intrahepatic portal vein, which appears as a signal void.

View larger version (139K): [in this window] [in a new window] [Download PPT slide]   Figure 9c.  Acute suppurative cholangitis caused by ampullary cancer in a 63-year-old woman with abdominal pain, a high fever, and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows a dilated pancreaticobiliary duct and a distended gallbladder caused by an ampullary cancer (arrow), which protruded into the lower common bile duct as a small polypoid nodule. Minimal pericholecystic fluid is evident (arrowhead). (b) Coronal steady-state coherent image shows the polypoid tumor (arrow) as an area of intermediate signal intensity, allowing differentiation from a low-signal-intensity stone (cf Fig 2). (c) Axial heavily T2-weighted image shows that the gallbladder has a thick wall (arrows). Purulent bile (arrowheads) in the gallbladder and common bile duct forms lower layers of low signal intensity. (d) Axial black blood T2-weighted spin-echo echo-planar image shows periportal inflammation of high signal intensity (arrows) extending along the intrahepatic portal vein, which appears as a signal void.

View larger version (103K): [in this window] [in a new window] [Download PPT slide]   Figure 9d.  Acute suppurative cholangitis caused by ampullary cancer in a 63-year-old woman with abdominal pain, a high fever, and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because the patient presented with severe symptoms and US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows a dilated pancreaticobiliary duct and a distended gallbladder caused by an ampullary cancer (arrow), which protruded into the lower common bile duct as a small polypoid nodule. Minimal pericholecystic fluid is evident (arrowhead). (b) Coronal steady-state coherent image shows the polypoid tumor (arrow) as an area of intermediate signal intensity, allowing differentiation from a low-signal-intensity stone (cf Fig 2). (c) Axial heavily T2-weighted image shows that the gallbladder has a thick wall (arrows). Purulent bile (arrowheads) in the gallbladder and common bile duct forms lower layers of low signal intensity. (d) Axial black blood T2-weighted spin-echo echo-planar image shows periportal inflammation of high signal intensity (arrows) extending along the intrahepatic portal vein, which appears as a signal void.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 10a.  Cholangiocarcinoma of the hepatic hilum in a 62-year-old man with jaundice. MR imaging was performed to determine the extent of a bile duct tumor detected with US and CT. (a) Coronal heavily T2-weighted image shows marked dilatation of the intrahepatic bile ducts and severe stenosis of the hepatic duct (arrow). (b, c) Axial T1-weighted (b) and fat-suppressed T2-weighted (c) images show a cholangiocarcinoma (arrows) at the hepatic hilum. The tumor is hypointense on the T1-weighted image (b) and slightly hyperintense on the fat-suppressed T2-weighted image (c). Subsequently, endoscopic biliary drainage was successfully performed.

View larger version (158K): [in this window] [in a new window] [Download PPT slide]   Figure 10b.  Cholangiocarcinoma of the hepatic hilum in a 62-year-old man with jaundice. MR imaging was performed to determine the extent of a bile duct tumor detected with US and CT. (a) Coronal heavily T2-weighted image shows marked dilatation of the intrahepatic bile ducts and severe stenosis of the hepatic duct (arrow). (b, c) Axial T1-weighted (b) and fat-suppressed T2-weighted (c) images show a cholangiocarcinoma (arrows) at the hepatic hilum. The tumor is hypointense on the T1-weighted image (b) and slightly hyperintense on the fat-suppressed T2-weighted image (c). Subsequently, endoscopic biliary drainage was successfully performed.

View larger version (144K): [in this window] [in a new window] [Download PPT slide]   Figure 10c.  Cholangiocarcinoma of the hepatic hilum in a 62-year-old man with jaundice. MR imaging was performed to determine the extent of a bile duct tumor detected with US and CT. (a) Coronal heavily T2-weighted image shows marked dilatation of the intrahepatic bile ducts and severe stenosis of the hepatic duct (arrow). (b, c) Axial T1-weighted (b) and fat-suppressed T2-weighted (c) images show a cholangiocarcinoma (arrows) at the hepatic hilum. The tumor is hypointense on the T1-weighted image (b) and slightly hyperintense on the fat-suppressed T2-weighted image (c). Subsequently, endoscopic biliary drainage was successfully performed.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 11a.  Mirizzi syndrome in a 63-year-old man with abdominal pain and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows severe stenosis of the common hepatic duct (arrowhead) due to extrinsic compression. Note the calculus (arrow) in the lower common bile duct. (b, c) Axial fat-suppressed T2-weighted (b) and fat-suppressed T1-weighted (c) images show an impacted calculus with low signal intensity (arrow) in the gallbladder neck and associated atrophy of the gallbladder (arrowheads). Cholecystectomy was unsuccessful because of severe fibrous adhesions. Subsequent endoscopic dilation of the common hepatic duct was performed.

View larger version (164K): [in this window] [in a new window] [Download PPT slide]   Figure 11b.  Mirizzi syndrome in a 63-year-old man with abdominal pain and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows severe stenosis of the common hepatic duct (arrowhead) due to extrinsic compression. Note the calculus (arrow) in the lower common bile duct. (b, c) Axial fat-suppressed T2-weighted (b) and fat-suppressed T1-weighted (c) images show an impacted calculus with low signal intensity (arrow) in the gallbladder neck and associated atrophy of the gallbladder (arrowheads). Cholecystectomy was unsuccessful because of severe fibrous adhesions. Subsequent endoscopic dilation of the common hepatic duct was performed.

View larger version (152K): [in this window] [in a new window] [Download PPT slide]   Figure 11c.  Mirizzi syndrome in a 63-year-old man with abdominal pain and jaundice. MR imaging was performed to search for the cause of the obstructive jaundice because US and CT findings were inconclusive. (a) Image from single-section MR cholangiopancreatography shows severe stenosis of the common hepatic duct (arrowhead) due to extrinsic compression. Note the calculus (arrow) in the lower common bile duct. (b, c) Axial fat-suppressed T2-weighted (b) and fat-suppressed T1-weighted (c) images show an impacted calculus with low signal intensity (arrow) in the gallbladder neck and associated atrophy of the gallbladder (arrowheads). Cholecystectomy was unsuccessful because of severe fibrous adhesions. Subsequent endoscopic dilation of the common hepatic duct was performed.

Acute Suppurative Cholangitis
Acute suppurative cholangitis is a life-threatening disease and occurs commonly as a manifestation and complication of stone disease concomitantly with acute cholecystitis (55–57). Because of the obstruction of the bile duct, the resulting increased pressure within the hepatobiliary tree produces hepaticovenous reflux of bacteria, facilitating the entry of bacteria into the systemic circulation and contributing to potential sepsis (55).

The specific MR imaging findings indicative of acute suppurative cholangitis are intraductal purulent material with low signal intensity on heavily T2-weighted images and/or intermediate signal intensity on fat-suppressed T1-weighted images (57). MR cholangiopancreatography is useful for detection of obstruction sites and for diagnosis of the underlying causative disease (Fig 9). Periportal inflammation can also be seen as high-signal-intensity areas along the intrahepatic and extrahepatic portal vein and bile duct on black blood T2-weighted spin-echo echo-planar images (Fig 9).

Hemobilia
Biliary tract blood, known as hemobilia, is usually caused by malignant tumors such as hepatocellu-lar carcinoma, blunt trauma, hemorrhagic chole-cystitis, rupture of an aneurysm of the hepatic artery, hemorrhagic diathesis, biopsy, and so on (4,47).

The MR imaging findings indicative of hemobilia are clots, which appear as defects in the gall-bladder and bile duct at MR cholangiopancreatography (Fig 8), and hemorrhagic bile, which has high signal intensity on fat-suppressed T1-weighted images and low signal intensity on heavily T2-weighted images (7) (Fig 12). A fluid-fluid level can be observed in the lumen of the gallbladder and extrahepatic bile ducts, where hemorrhagic bile appears as a low-signal-intensity area in the lower dependent layer on both axial heavily T2-weighted images and fat-suppressed T2-weighted images (Fig 8). In severe cases, the gallbladder and bile duct are not visualized at MR cholangiopancreatography. Dynamic contrast-enhanced MR imaging may be necessary to detect the bleeding point and to diagnose the causative malignant tumor (Fig 12).

View larger version (188K): [in this window] [in a new window] [Download PPT slide]   Figure 12a.  Hemobilia due to biliary invasion by hepatocellular carcinoma in a 72-year-old man with abdominal pain, melena, and jaundice. MR imaging was performed to search for the cause of the melena, since US and CT demonstrated the hepatocellular carcinoma but did not show the cause of the melena. (a) Axial fat-suppressed T1-weighted image shows high signal intensity of dilated intrahepatic ducts (arrows) in the left lobe, an appearance suggestive of intraductal hemorrhage. (b) Image from a dynamic contrast-enhanced study shows an ill-defined hypervascular hepatocellular carcinoma (arrowheads) in the quadrate lobe of the liver. Endoscopic retrograde cholangiopancreatography demonstrated hemorrhage in the common bile duct flowing out into the duodenum.

View larger version (119K): [in this window] [in a new window] [Download PPT slide]   Figure 12b.  Hemobilia due to biliary invasion by hepatocellular carcinoma in a 72-year-old man with abdominal pain, melena, and jaundice. MR imaging was performed to search for the cause of the melena, since US and CT demonstrated the hepatocellular carcinoma but did not show the cause of the melena. (a) Axial fat-suppressed T1-weighted image shows high signal intensity of dilated intrahepatic ducts (arrows) in the left lobe, an appearance suggestive of intraductal hemorrhage. (b) Image from a dynamic contrast-enhanced study shows an ill-defined hypervascular hepatocellular carcinoma (arrowheads) in the quadrate lobe of the liver. Endoscopic retrograde cholangiopancreatography demonstrated hemorrhage in the common bile duct flowing out into the duodenum.

	Conclusions

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

	Acknowledgments

 
We thank our secretaries, Hiroko Suyama and Yoshiko Matsumoto, for preparing the manuscript and figures; Marc Van Cauteren for revision of the manuscript; and the radiologic technologists of the MR division for technical support.

	References

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Techniques and Characteristics... Clinical Applications Conclusions References

 

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