Purpose: Imaging quality of MR cholangiopancreatography (MRCP) has recently made a great advance, and MRCP plays an important part in the diagnosis of pancreticobiliary diseases. The goal of this study was to optimize the methodology of MRCP. Patients and Methods: Fifty patients underwent MRCP prior to endoscopic retrograde cholangiopancreatography (ERCP). MR imaging was performed with a superconducting imager at 1.5T (GE Medical Systems, Wis). MRCP images were obtained as maximum-intensity-projection reconstruction images (SS-MIP) and thick-slice (50-100mm) projection image (SS-P) by using single-shot fast spin-echo sequence with 128 echo train (4000 and 30000, respectively/1001msec [effectiveTR/effective TE]), and MIP reconstruction images by using respiratory-triggered fast spin-echo sequence (RT-MIP) (7500-15000/252msec [effective TR/effective TEl). A gastrointestinal radiologist graded the image quality from 1 to 5 and recorded the diagnosis in a blinded manner. ERCP images were used as standard of reference. Results: Grades of image quality of biliary tracts and pancreatic ducts were 2.8 -+ 0.9 (mean +-. SD) and 1.9 ± 0.8 for SS-MIP, 4.0 -+ 0.9 and 3.3 -+ 1.3 for SS-P, 3.8 +1.0 and 2.5 -+ 1.3 for RT-MIP, respectively. The quality of RT-MIP and SS-P images was significantly greater than the quality of SS-MIP images in biliary tracts (p<0.001) and pancreatic ducts (p<0.005). Diagnostic sensitivity and specificity for biliary diseases were 85 and 98 % for SS-MIP, 93 and 94 % for SS-P, 91 and 98 % for RT-MIP, respectively. Diagnostic sensitivity and specificity with each combination of two methods in biliary tracts were 92 and 98 % for SS-MIP/RT-MIP, 94 and 98 % for SS-MIP/SS-P, 98 and 98 % for RT-MIP/SS-P (p<0.005). Those in pancreatic ducts were 91 and 100 % for SS-MIP/RT-MIP, 91 and 100 % for SS-MIP/SS-P and 92 and 100 % for RT-MIP/SS-P. Conclusion: Combination of SS-P and RT-MIP MRCP images has the highest diagnostic utility in the clinical diagnosis of pancreticobiliary disease.