CT without IV contrast can detect some features and complications of AC, such as gallbladder wall thickening, pericholecystic inflammation, gas formation, and hemorrhage, although some important features, such as wall enhancement and adjacent liver parenchymal hyperemia, cannot be detected without IV contrast. Adjacent liver hyperemia is actually one of the earlier findings in AC and can be a very useful problem-solving tool [7]. CT without and with IV contrast is not often viewed as helpful in assessing patients admitted with right upper quadrant abdominal pain. Little additional information is gained by the routine addition of a noncontrast phase to a contrast-enhanced phase in this clinical setting [10]. MRI Abdomen with MRCP The presence of AC can be further explored using abdominal MRI, which often includes the use of an IV gadolinium-based contrast agent, in cases in which other imaging tests are equivocal [7]. As with CT, MRI is not advocated as a primary imaging examination to evaluate acute right upper quadrant pain; however, several studies have suggested that abdominal MRI is a reliable alternative and can be particularly helpful in the patient who is difficult to examine with US [36-38]. Although factors such as longer acquisition times limit its use in the emergency setting, more consistent visualization of the extrahepatic biliary tree is an important advantage of its use [47,48]. MRI is considered the best modality for evaluating hepatic and biliary abnormalities that are not characterized by US. It can perform superiorly to US in cases of gallstones in the gallbladder neck, the cystic duct, or the common bile duct [7]. Few studies have examined the role of MRI in evaluating AC. MRI sensitivity estimates range from 50% to 91%, with specificity ranging from 79% to 89%. According to the meta-analysis by Kiewiet et al, the summary sensitivity is 85% (95% CI, 66%-95%) and the specificity is 81% (95% CI, 69%-90%) [25,38,47,48], similar to those of US.
Right Upper Quadrant Pain. CT without IV contrast can detect some features and complications of AC, such as gallbladder wall thickening, pericholecystic inflammation, gas formation, and hemorrhage, although some important features, such as wall enhancement and adjacent liver parenchymal hyperemia, cannot be detected without IV contrast. Adjacent liver hyperemia is actually one of the earlier findings in AC and can be a very useful problem-solving tool [7]. CT without and with IV contrast is not often viewed as helpful in assessing patients admitted with right upper quadrant abdominal pain. Little additional information is gained by the routine addition of a noncontrast phase to a contrast-enhanced phase in this clinical setting [10]. MRI Abdomen with MRCP The presence of AC can be further explored using abdominal MRI, which often includes the use of an IV gadolinium-based contrast agent, in cases in which other imaging tests are equivocal [7]. As with CT, MRI is not advocated as a primary imaging examination to evaluate acute right upper quadrant pain; however, several studies have suggested that abdominal MRI is a reliable alternative and can be particularly helpful in the patient who is difficult to examine with US [36-38]. Although factors such as longer acquisition times limit its use in the emergency setting, more consistent visualization of the extrahepatic biliary tree is an important advantage of its use [47,48]. MRI is considered the best modality for evaluating hepatic and biliary abnormalities that are not characterized by US. It can perform superiorly to US in cases of gallstones in the gallbladder neck, the cystic duct, or the common bile duct [7]. Few studies have examined the role of MRI in evaluating AC. MRI sensitivity estimates range from 50% to 91%, with specificity ranging from 79% to 89%. According to the meta-analysis by Kiewiet et al, the summary sensitivity is 85% (95% CI, 66%-95%) and the specificity is 81% (95% CI, 69%-90%) [25,38,47,48], similar to those of US.