On the appearance of bile in clinical MR cholangiopancreatography

Purpose: To study the appearance of bile in clinical MR cholangiopancreatography (MRCP) with special reference to its chemical and physical properties. Material and Methods: Gallbladder bile was collected during surgery from 38 patients and studied with respect to chemical constituents. The relaxation rates 1/T1 and 1/T2 of bile were also determined in vitro . In 16 of these 38 patients, abdominal imaging was performed using MRCP as well as T1-weighted GE sequences. Results: For 9 of the 13 chemical parameters studied, a positive significant correlation with 1/T1 as well as 1/T2 was found. The median relaxation rates 1/T1 and 1/T2 were 0.76 and 1.48 s(-1) , respectively. The corresponding ranges were 0.38-3.13 s(-1) and 0.70-5.75 s(-1) , respectively. On the MRCP images a few patients showed gallbladder of poor visibility due to low signal-to-noise ratio. This coincided with a high relaxation rate 1/T2 of bile. On the T1-weighted GE sequences a few patients showed hyperintense gallbladder relative to liver, coinciding with high relaxation rates 1/T1 of bile. Conclusion: Bile was found to show a large interindividual variation with respect to relaxation rates 1/T1 and 1/T2. The relaxation rates increased with increasing amounts of substances in the bile. For some patients (11%) MRCP imaging is unsuccessful due to high relaxation rate of bile.