Assessment of acute cholangitis by MR imaging

The purpose of this study is to assess the common MRI findings of acute cholangitis compared with those of non-acute cholangitis.

During a 31-month period, we performed MRCP and contrast-enhanced MRI on 173 patients with biliary abnormalities including duct dilatation or stricture. The causes of the biliary abnormalities included biliary stone disease (n=85), cholangiocarcinoma (n=47), periampullary cancer (n=20), GB cancer (n=4), and others (n=17). Among 173 patients, 66 consecutive patients were confirmed with acute cholangitis diagnosed according to the Tokyo guideline, and 107 patients were confirmed as having non-acute cholangitis. Two radiologists retrospectively and independently accessed the MR findings, including the cause of biliary abnormality, increased periductal signal intensity on T2-weighted images, the transient periductal signal difference, and the presence of abscess, thrombosis, and ragged duct. They also measured the dilated duct and the thickened wall. The Student t-test and the Pearson chi-square were used. The κ statistics were used to determine interobserver agreement. Logistic regression was used to identify the MR findings that predicted acute cholangitis.

MRI correctly accessed the cause of biliary abnormality in 163 patients (94%). The statistically common findings for acute cholangitis were as follows: increased periductal signal intensity on T2-weighted imaging (n=26, 39%, p<0.05); transient periductal signal difference (n=31, 47%, p<0.05); abscess (n=18, 27%, p<0.05); thrombosis (n=12, 18%, p<0.05); and ragged duct (n=11, 17%, p<0.05). Interobserver agreement was good to excellent for each finding (κ=0.74-0.97). The wall thickness showed a statistically significant difference between the acute cholangitis and the non-acute cholangitis group (2.65 mm:2.32 mm, p<0.05), however, there was no significant difference in duct dilatation in the two groups. The periductal transient attenuation difference was an independent predictor of acute cholangitis (Exp (B)=6.389, p=0.018).

MRI accurately assesses the cause of biliary abnormality in patients with cholangitis. Using statistically common MR findings for acute cholangitis, MR imaging is very successful in predicting acute cholangitis.