Objective To explore the comparative application of phase and diaphragmatic navigation in three-dimensional magnetic resonance cholangiopancreatography(3D-MRCP)thin-layer scanning in elderly patients.Methods A total of 180 elderly patients were scanned by phase and diaphragmatic navigation via Siemens Aera1.5T superconducting MR scanner.The acquired images were reconstructed by 3D reconstruction.The anatomical structure,image quality and disease diagnosis were compared between the phase and diaphragmatic navigation groups.Results In liver of anatomy,the liver of primary bile duct,the superior,middle and inferior extrahepatic bile duct and the gallbladder could be well displayed,and the difference was not statistically significant between the two groups(P＞0.05).The display of pancreatic duct and the liver of secondary bile duct of diaphragmatic navigation was significantly better than those of phase navigation(P＜0.05).In terms of image quality,the excellent rate of diaphragmatic navigation was significantly higher than that of phase navigation,and the difference was statistically significant(P＜0.05).There were no statistically significant differences in the detection rate of pancreatobiliary system diseases,the diagnostic rate of cholelithiasis,common bile duct stones,common bile duct dilatation and pancreatic duct dilatation between the two groups(P＞0.05).Conclusion Diaphragmatic navigation is signifi-cantly better than phase navigation in the display of the anatomical structure of the pancreatic duct,the liver of secondary bile duct,and the excellent rate of image quality.Diaphragmatic navigation is more suitable for thin-layer 3D-MRCP scanning in elderly patients.