Choledocholithiasis: diagnosis with oral-contrast-enhanced CT cholangiography

The objective of this investigation was to assess the performance of helical CT cholangiography after administration of an oral biliary contrast agent for the diagnosis of choledocholithiasis.

Helical CT cholangiography was performed on 31 patients referred for endoscopic retrograde cholangiography of suspected choledocholithiasis. Iopanoic acid (6 g) was administered orally 8-12 hr before acquisition of helical CT cholangiograms. Three-dimensional and two-dimensional reformations were generated from a set of axial source images. Two radiologists independently interpreted the helical CT cholangiograms. Sensitivity and specificity were calculated using findings on retrograde cholangiography as the standard of reference. In addition, interobserver agreement was determined using kappa statistics.

Our patients had no adverse reactions to iopanoic acid. The degree of biliary opacification was sufficient to perform three-dimensional and two-dimensional reconstructions in 29 patients (93.5%). Two patients were excluded from statistical analysis because cannulation of the common bile duct during retrograde cholangiography failed. Findings on endoscopic retrograde cholangiography in the remaining 29 patients were the following: choledocholithiasis (n = 14), common bile duct dilatation with no stones (n = 11), and normal bile ducts (n = 4). Sensitivity and specificity of oral-contrast-enhanced CT cholangiography for detection of choledocholithiasis were 92.9% (95% confidence interval [CI], 66.1-99.8%) and 100% (95% CI, 78.2-100%), respectively, for observer 1 and 85.7% (95% CI, 57.2-98.2%) and 100% (95% CI, 78.2-100%), respectively, for observer 2. Interobserver agreement was .92 (excellent).

Helical CT cholangiography performed after oral administration of iopanoic acid appears promising for diagnosis of choledocholithiasis.