Dynamic contrast-enhanced CT appearances of the intraductal papillary neoplasms of the bile duct

Abstract

Objective To analyze the dynamic contrast-enhanced CT appearances of intraductal papillary neoplasms of the bile duct and improve its diagnostic accuracy. Methods Sixteen patients with intraductal papillary neoplasms of the bile duct confirmed histopathologically after surgical operation underwent dynamic contrast-enhanced multi-detector row CT scans.All imaging data were reviewed and analyzed retrospectively in correlation with surgical and pathological findings.CT values of 38 well-visualized lesions in 12 of the 16 patients at the pre-contrast phase,arterial phase and venous phase were measured.Four of the 12 patients with 17 lesions had benign tumors,and 8 of the 12 patients with 21 lesions had malignant tumors.Comparisons of CT values at the three phases between the two groups were carried out using independent sample t test.The bile CT values were measured in these 12 cases,40 normal volunteers,and 40 subjects with bile duct stones,and the Wilcoxon signed- rank test was applied to compare the bile CT values between tumor group and the normal group and between tumor group and the bile duct stone group.The diameters of the bile ducts proximal to and distal to tumors were also measured,and Fisher exact method was carried to analyze the data. Results Lesions located at the left lobe in 8 out of the 16 patients,the right lobe in 1 case,both the left and right lobes in 1 case,the hepatic hilum in 1 case,the common bile duct in 3 cases,and both the right lobe and the common bile duct in 2 cases.Eleven lesions appeared as papillary masses,3 as flat masses,1 as mixed papillary and flat masses.In one case,tumor mass could not be definitely visualized,and only dilated bile ducts and stones were demonstrated.The mean CT values of the benign tumors were (25.8±8.0),(37.7±10.3) and (51.7±17.1) HU respectively at pre-contrast phase,arterial phase,and venous phase,and the malignant tumors were (38.4±10.2),(56.6±18.0) and (68.4±13.4) HU respectively.The CT values of malignant tumors were higher than the benign tumors at all three phases (t=-3.510,-3.549 and-3.767,P 0.05).Bile duct stones were noted in six cases,three at the tumor area,and the remaining three away from tumor. Conclusions Intraductal papillary neoplasms of the bile duct involve the left lobe more frequently.At pre-contrast CT,the tumor density is low.On dynamic contrast-enhanced CT,tumors show mild to moderate enhancement with gradual delayed enhancement.Malignant tumors show higher CT values than benign ones.Both proximal and distal bile ducts may be dilated.The CT values of the bile in the tumor group are mildly higher than either the normal control group or the group with bile duct stones.Bile duct stones can be noted at or away from the tumor area. Key words: Bile duct neoplasms; Tomography,X-ray computed; Pathology