Multidetector Computed Tomography (MDCT) Findings of Complications of Acute Cholecystitis. A Pictorial Essay

Abstract

Acute cholecystitis stands out as one of the most common surgical pathologies that should always be considered in a right-upper abdominal pain emergency. For this, the importance of a correct diagnosis is well described. However, it has been demonstrated that the simple combination of clinical (pain, Murphy's sign) and laboratory (leukocytosis) parameters alone does not provide for ruling in or ruling out the diagnosis of this condition, unless accompanied by a radiological exam. For a long time, and still today, ultrasonography (US) is by far the first-to-proceed radiologic exam to perform, thanks to its rapidity and very high sensibility and specificity for the diagnosis of simple acute cholecystitis. However, acute cholecystitis can undergo some complications that US struggles to find. In addition to that, studies suggest that multidetector computed tomography (MDCT) is superior in showing complicated forms of cholecystitis in relation to sensibility and specificity and for its capability of reformatting multiplanar (MPR) reconstructions that give a more detailed view of complications. They have shown to be useful for a precise evaluation of vascular complications, the anatomy of the biliary tree, and the extension of inflammation to surrounding structures (i.e., colitis). Therefore, based also on our experience, in patients with atypical presentation, or in cases with high suspicion for a complicated form, a MDCT abdomen scan is performed. In this review, the principal findings are listed and described to create a CT classification of acute complications based on anatomical and topographic criteria.

Keywords: abscess; aneurysm; cholangitis; colitis; computed tomography; pancreatitis; portal thrombosis; pseudoaneurysm; pylephlebitis.

Figure 1

Acute uncomplicated calculous cholecystitis: (a) overdistended gallbladder with diffuse wall thickening and hyperemia (white arrows) and pericholecystic fluid (arrowheads), (b) pericholecystic parenchymal enhancement (black arrows).

Figure 2

Gangrenous cholecystitis: irregular wall thickening with bulging and focal defects in the gallbladder wall (black arrows, (a)). Coexisting hepatic hyperemia (arrowheads) and pericholecystic fluid (white arrows) (a,b).

Figure 3

Emphysematous cholecystitis: (a) Ultrasonography: diffuse hyperechogenicity due to extended reverberation artifact with poor gallbladder lumen resolution. (b) CT findings: gallbladder wall thickening with intramural air (white arrows). CT was able to detect and characterize the disease.

Figure 4

Gallbladder perforation: transmural defect of the gallbladder wall (black arrow) with pericholecystic effusion (head arrows) and perihepatic peritoneal collection, suggestive of biliary peritonitis (white arrows).

Figure 5

Gallbladder perforation: discontinuity of the gallbladder wall with fluid collection extended posteriorly to the right hepatic lobe (arrows).

Figure 6

Bilioenteric fistula (biliogastric) with gallstone ileus: (a): cholecystogastric fistula (arrow) with the presence of air in the gallbladder lumen (arrowhead); (b) axial image shows a large gallstone in the ileum (arrows) with small bowel overdistension (white arrows); (c) coronal image demonstrates an obstructive gallstone in the ileum (arrows) with small bowel overdistension.

Figure 7

Cholangitis with microabscesses: (a) axial image shows patchy biliary intrahepatic duct dilation (curved arrows) and small hypodense collections due to microabscesses (white arrows); (b) overdistended gallbladder with infundibular stones and thickening of the gallbladder due to calculous cholecystitis; (c) coronal scan shows a dilated common bile duct (arrow) and cystic duct (arrowhead) with wall hyperdensity due to inflammation.

Figure 8

Pericholecystic abscess: (a) axial images show acute cholecystitis findings with wall thickening and hyperdensity; (b) a hypoattenuated sovracholecistic collection (white arrows) due to hepatic pericholecystic abscess; (c) sagittal image evidences the proximity of the two structures (abscess: black arrow; cholecyst: white arrow).

Figure 9

Liver abscess with pylephlebitis: (a) CT arterial phase; (b) CT portal phase. In the right lobe, V segment, a large hypodense collection with hypoattenuating halo due to intrahepatic abscess (black arrows, (a,b)) with the presence of a hypodensity within the left portal vein lumen due to thrombosis and hyperdensity of portal walls indicative of pylephlebitis better defined in CT portal phase (b) (white arrow).

Figure 10

Right portal vein thrombosis: extensive right portal vein hypodensity subsequent to an intraluminal thrombus formation (black arrows) with hepatic hyperemia (white arrows).

Figure 11

Pylephlebitis in cholecystitis exacerbation: (a) massive thrombosis of the portal bifurcation with hyperdensity of portal walls due to pylephlebitis (white arrows) and inhomogeneous attenuation of liver parenchyma in arterial CT scan due to vascular occlusion; (b) axial scan: irregular thickening of cholecystic walls with contrast enhancement of liver parenchyma due to pericholecystic edema.

Figure 12

Right hepatic artery pseudoaneurysm: (a) axial image in the arterial phase shows an abnormal dilation of the right hepatic artery (black arrow); wedge-shaped area of parenchymal hypodensity (white arrow) secondary to hypoperfusion; (b) sagittal image better demonstrates continuity of the abnormal dilation (arrow) with a right hepatic artery branch (arrowhead).

Figure 13

Gangrenous cholecystitis with colitis: axial scan shows the signs of pericholecystic inflammation that extend to the right colic flexure with diffuse colic wall thickening (white arrows).

Figure 14

Acute calculous cholecystitis with pancreatitis (biliary pancreatitis): axial scan shows an acute cholecystitis (white arrow) with edematous hypoattenuating pancreatitis with surrounding peripancreatic fat strands (arrowheads) and fluid (black arrows).