Acute Calculous Cholecystitis

Published on 09/08/2015 by admin

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Last modified 09/08/2015

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 Cholelithiasis, sonographic Murphy sign, and GB wall thickening

• CT findings

image Distended GB (measuring > 5 cm in short axis)
image GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement and pericholecystic fat stranding
image Calcified gallstones may be visualized (15% of cases)
image Hyperenhancement of adjacent liver parenchyma
• Hepatobiliary scintigraphy (Tc99-HIDA)

image Nonvisualization of GB 4 hours after injection of radiotracer (or 30 minutes after administration of morphine)
• Complications

image Gangrenous cholecystitis: GB wall necrosis with ↑ morbidity/mortality
image Perforated cholecystitis: Most often occurs due to progressive GB distension with eventual rupture
image Emphysematous cholecystitis: Secondary infection of GB with gas-forming organisms
image Hemorrhagic cholecystitis: Hemorrhage within GB lumen or wall

TOP DIFFERENTIAL DIAGNOSES

• Acalculous cholecystitis
• Nonspecific GB wall thickening
• Peptic ulcer disease
• Acute pancreatitis
• Hepatic flexure diverticulitis

CLINICAL ISSUES

• Immediate cholecystectomy in patients who are good surgical candidates
• Percutaneous cholecystostomy with antibiotics in patients who are high-risk surgical candidates
image
(Left) Transverse US shows a large echogenic stone image with an acoustic shadow image and a thickened gallbladder (GB) wall. These findings, along with a positive sonographic Murphy sign, suggested acute cholecystitis, confirmed at surgery.

image
(Right) This hepatobiliary scan is of a 48-year-old woman with RUQ pain and surgically confirmed acute cholecystitis. Note the presence of bowel image, absence of GB activity, and a subtle GB fossa rim sign image. Persistent pericholecystic activity may be due to tissue edema and biliary stasis.
image
(Left) Axial CECT demonstrates a tiny stone image within the gallbladder, with thickening of the GB wall, pericholecystic free fluid image, and fat stranding image, a constellation of findings diagnostic of acute cholecystitis.

image
(Right) Axial CECT of a 37-year-old woman shows GB wall thickening and GB fossa hyperenhancement image. This surrounding hepatic parenchymal hyperemia is analogous to the rim sign of hepatobiliary scintigraphy.

TERMINOLOGY

Definitions

• Acute inflammation of gallbladder (GB) precipitated by an obstructing calculus within GB neck or cystic duct

IMAGING

General Features

• Best diagnostic clue

image Cholelithiasis, with an impacted, immobile stone within GB neck or cystic duct
image GB wall thickening
image Positive sonographic Murphy sign: Pain with insonation directly over GB (accentuated during deep inspiration)

– May be absent in elderly, anesthetized, or diabetic patients, or those with GB necrosis
• Location

image Stone impacted in GB neck or cystic duct
• Size

image Distended GB (> 5 cm transverse diameter)
• Morphology

image Distended GB more rounded than normal pear-shaped configuration

Fluoroscopic Findings

• ERCP

image No filling of GB with contrast as result of cystic duct/GB neck obstruction by stone
image May document common bile duct (CBD) stones in patients with associated choledocholithiasis

CT Findings

• Uncomplicated cholecystitis

image Distended GB (measuring > 5 cm in short axis)
image GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement and pericholecystic fat stranding
image Cholesterol/bilirubin stones typically not visible, but calcified gallstones may be visualized (15% of cases)

– Stone visualization may improve at higher kVp settings (140 kVp)
image Hyperenhancement of liver parenchyma adjacent to inflamed GB (particularly in arterial phase)
• Complicated cholecystitis

image Gangrenous cholecystitis:Focal interruption or lack of enhancement of GB wall due to necrosis

– Small ulcerations or outpouchings of GB wall may occur at these sites
– Intraluminal linear membranes (secondary to sloughed mucosa)
– Intramural or pericholecystic abscesses
image Emphysematous cholecystitis: Gas in lumen/wall of GB 

– CT is best modality to identify ectopic gas and make diagnosis of emphysematous cholecystitis
image Hemorrhagic cholecystitis: High-attenuation intraluminal clot ± active extravasation of contrast

– Blood within GB lumen or bile ducts
image Gallbladder perforation:Focal pericholecystic fluid collection or abscess adjacent to disrupted GB wall; extraluminal gallstones

– CT better than US for visualizing GB wall defect

MR Findings

• Distended GB with wall thickening, gallstones, and pericholecystic fat stranding/fluid
• Hyperenhancement of GB wall and mucosa on T1WI C+, with possible enhancement of surrounding liver parenchyma (rim sign)
• Stones in GB or cystic duct on T2WI or MRCP
• Interrupted GB wall/focally absent mucosal enhancement → gangrenous or perforated GB
• Use of hepatobiliary contrast agents (such as Eovist), which are normally secreted into bile, may be helpful

image Lack of filling or delayed filling (> 60 minutes) of GB supports diagnosis of acute cholecystitis
image Normal filling (< 60 minutes) does not exclude cholecystitis
image GB usually fills with contrast in chronic cholecystitis

Ultrasonographic Findings

• Grayscale ultrasound

image Uncomplicated cholecystitis

– Cholelithiasis (usually an immobile, impacted stone in GB neck or cystic duct), sonographic Murphy sign, and GB wall thickening > 3 mm
– GB distension > 5 cm in short axis
– Increased vascularity of GB wall on color Doppler images
image Complicated cholecystitis

– Perforated cholecystitis: Pericholecystic abscess with collapsed GB

image High-frequency transducer may allow better visualization of GB fundus to help exclude early perforation
image Sonographic hole sign: Visualization of GB wall defect on US
– Gangrenous cholecystitis: Asymmetric wall thickening, intraluminal linear membranes, and irregularity and ulcerations of GB wall

image Striated GB, contrary to prior teaching, not convincingly associated with gangrene
image GB wall hyperemia may be absent on color Doppler images as result of wall necrosis
– Emphysematous cholecystitis: Gas in GB lumen and wall (brightly echogenic reflectors with dense “dirty” posterior acoustic shadowing)

image GB itself may be difficult to visualize as result of shadowing from gas
– Hemorrhagic cholecystitis: Echogenic clot within GB lumen or visualized biliary tree
• Color Doppler

image Increased vascularity of GB wall (flow may be absent in gangrenous cholecystitis)

Nuclear Medicine Findings

• Hepatobiliary scintigraphy

image Tc-99m iminodiacetic acid derivatives
image Nonvisualization of GB 4 hours after radiotracer injection (or 30 minutes after morphine administration)
image Increased uptake in GB fossa (rim sign) due to hyperemia in 35% of patients

– Very specific (but not sensitive) for acute cholecystitis
– Positive predictive value of 57% for gangrenous cholecystitis
image Hepatobiliary scintigraphy more sensitive (97%) and specific (90%) compared to US (88% and 80%, respectively)
image False-positive results in patients who have recently eaten, undergone prolonged fasting (> 24 hours), received hyperalimentation, have severe concurrent illness, or who have severe hepatocellular dysfunction

Imaging Recommendations

• Best imaging tool

image US is best screening tool
image Hepatobiliary scintigraphy for confirmation (particularly when US is equivocal)
image CECT to evaluate potential complications
• Protocol advice

image Measure GB wall thickness adjacent to liver
image Move patient during ultrasound to assess stone mobility

DIFFERENTIAL DIAGNOSIS

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