Diagnostic imaging of patients with pancreato-biliary diseases: comparison between ultrasound, computed tomography and magnetic resonance

The aim of this study was to directly compare the results of MR cholangio-pancreatography (MRCP) with those of ultrasound (US) and multi-slice computed tomography (MSCT) in patients with pancreatico-biliary diseases. A total of 110 patients (63 M, 48 F), ranging in age from 22 to 89 years, was studied before surgery (n=99) or after cholecystectomy (n=11) for lithiasis. MRCP was performed in all patients while US was acquired in 55 patients and MSCT was performed in 76 patients. Histology (n=34), biopsy (n=38), endoscopic retrograde cholangio-pancreatography (ERCP) (n=28) and/or clinical-imaging follow-up (n=10) data were considered as standard of reference. Patient population was divided in three groups; Group 1 (n=55) consisted of a comparison between MRCP and US in biliary tract diseases; Group 2 (n=37) consisted of a comparison between MRCP and MSCT in biliary tract diseases; Group 3 (n=40) consisted of a comparison between MRCP and MSCT in pancreatic masses. A regional imaging qualitative evaluation of biliary and pancreatic duct system (gallbladder and cystic duct, intra- and extra-hepatic ducts, main pancreatic duct) was performed. In Group 1, the results of MRCP and US were concordant in the majority (92%) of cases, however their findings were significantly discordant only in the evaluation of main extra-hepatic duct, showing 9 (16%) cases of choledocholithiasis abnormal only on MRCP (p<0.01). In Group 2, the results of MRCP and MSCT were concordant in the majority (87%) of cases, however their findings were significantly discordant when intra- and extra-hepatic ducts were analyzed, showing respectively 7 (19%) and 6 (16%) cases of lithiasis abnormal only on MRCP (p<0.01 for both). In Group 3, both for tumor identification and resectability, CT and MR showed comparable diagnostic accuracy with no statistic significant differences; tumor identification MSCT/MRCP: accuracy=98/98%, sensitivity=100/100%, specificity=88/88%, positive predictive value (PPV)=97/97%, negative predictive value (NPV)=100/100%; tumor resectability MSCT/MRCP: accuracy=94/90%, sensitivity=92/88%, specificity=100/100%, PPV=100/100%, NPV=78/70%. The results of this study show the superior role of MRCP for the identification of choledocholitiasis compared to US and MSCT; furthermore, MR imaging represents a valid diagnostic alternative to CT in the evaluation of patients with pancreatic masses, both for the correct identification and characterization of primary lesions and to establish potential surgical resectability in case of malignancies.