Emphysematous Cholecystitis

Published on 19/07/2015 by admin

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Last modified 19/07/2015

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 Best modality for identifying intramural/intraluminal gallbladder (GB) gas (100% sensitive)

image Gas within pericholecystic abscess or free intraperitoneal air may be present with perforation
image Other CT findings similar to uncomplicated cholecystitis
• Ultrasound

image Gas in GB wall manifests as highly echogenic reflectors with dense posterior acoustic “dirty” shadowing
image Associated with “ring-down” or “comet tail” artifact
image Intraluminal gas bubbles rise up to nondependent portions of GB (champagne sign)
image Cholelithiasis (50%), GB wall thickening, pericholecystic free fluid, and Murphy sign
• Radiography: Insensitive for detection of ectopic gas
• MR: Intraluminal and intramural gas appear as signal voids on all pulse sequences

PATHOLOGY

• Infection of GB with gas-forming organisms such as Clostridium welchii   and  Escherichia coli
• Etiology may reflect vascular compromise of cystic artery
• Major contributing factors: Atherosclerosis, diabetes, advanced age, primary infection with gas-forming organism

CLINICAL ISSUES

• Atypical, mild, or insidious presentations (especially in diabetics or elderly) often delay diagnosis and treatment
• High risk of gangrene, perforation, and sepsis if untreated, with high mortality rate (15-25%)
• Definitive treatment: Urgent cholecystectomy + parenteral antibiotics

image Cholecystostomy (as bridge to cholecystectomy) in high-risk, poor surgical candidates
image
(Left) Ultrasound image in an elderly diabetic man with fever demonstrates echogenic reflectors image in the gallbladder (GB) wall with “dirty” acoustic shadowing and “ring down” artifact image, classic for emphysematous cholecystitis.

image
(Right) Axial CECT in a patient with melanoma shows widespread liver metastases image. Gas is present within the GB lumen image, and the GB wall appears to be perforated image. Gangrenous perforation of the GB was seen at surgery, possibly related to the patient’s chemotherapy.
image
(Left) Color Doppler ultrasound in a diabetic patient shows a distended GB containing heterogeneous material, including some foci of very high-intensity echoes within the lumen and wall of the GB, and virtually no flow within the GB wall.

image
(Right) Axial CECT in the same patient shows the distended GB with gas bubbles image within the wall and lumen corresponding to the echogenic foci identified on sonography, in keeping with emphysematous cholecystitis.

TERMINOLOGY

Synonyms

• Clostridial cholecystitis

Definitions

• Rare form of acute cholecystitis due to secondary infection by a gas-forming organism

IMAGING

General Features

• Best diagnostic clue

image Curvilinear intramural gas or intraluminal gas resulting in a gas-fluid level within the gallbladder (GB)
• Location

image Lumen or wall of GB
• Size

image Ranges from several bubbles to extensive intramural or intraluminal gas
• Morphology

image Curvilinear intramural gas or intraluminal gas resulting in a gas-fluid level

Imaging Recommendations

• Best imaging tool

image NECT or CECT
image Plain radiographs should not be utilized if there is high suspicion for this diagnosis

Radiographic Findings

• Radiography

image Intraluminal (rounded) or intramural (curvilinear) gas in expected position of GB

– Air-fluid level may be present in upright or decubitus films
image Insensitive for detection of emphysematous cholecystitis: Only identified 45% of cases in 1 series

– Cases where findings are apparent on radiography tend to be more severe

CT Findings

• Best modality for identifying intramural or intraluminal GB gas (100% sensitive)

image Gas within pericholecystic abscess or free intraperitoneal air may be present with perforation
image Rarely portal venous gas due to GB wall ischemia
image Extension of gas into remainder of biliary system suggests severe form of infection
• Gallstones seen in only ∼ 50% of patients: Acalculous cholecystitis carries higher risk
• Other findings are similar to uncomplicated cholecystitis

image GB wall thickening (> 3 mm)
image GB distension > 5 cm (in short axis)
image Pericholecystic free fluid and fat stranding
image Irregularity, ulcerations, and absent enhancement of GB wall due to gangrene

MR Findings

• Intraluminal and intramural gas appear as signal voids on all pulse sequences

image Floating signal void due to gas bubbles in nondependent portion of GB (unlike stones which are dependent)
image Low signal intensity rim around margin of GB due to intramural gas
image Gas causes field inhomogeneity and susceptibility artifact at air-tissue interface
• Irregular wall thickening with areas of heterogeneous T1 and T2 hyperintensity indicative of intramural hemorrhagic necrosis
• Other findings similar to uncomplicated cholecystitis

image Low signal (T1WI and T2WI) intensity stones in dependent portion of GB (particularly in neck and cystic duct)
image Wall thickening (> 3 mm), GB distension (> 5 cm), and pericholecystic fluid

Ultrasonographic Findings

• Gas in GB wall manifests as highly echogenic reflectors with dense posterior acoustic “dirty” shadowing

image Shadowing is not anechoic (as is seen with gallstones), but is of intermediate echogenicity
image Echogenic reflectors associated with “ring-down” or “comet tail” artifact
• Intraluminal gas bubbles should be mobile on real-time US and may rise up to nondependent portions of GB similar to bubbles of champagne (champagne sign)

image Gas may change position when patient is moved
• Cholelithiasis (in 50% of patients), GB wall thickening, pericholecystic free fluid, and pericholecystic echogenic fat (due to inflammation)
• US has high specificity, but lower sensitivity, for detection of emphysematous cholecystitis

image Echogenic gas in GB lumen may be misinterpreted as gas-filled bowel, stone-filled GB, or porcelain GB
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