***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Endoscopic ultrasonography ( EUS ) appears to be the best imaging method for the diagnosis of choledocholithiasis . The aim of this preliminary , prospect i ve , controlled study was to assess the accuracy of EUS and magnetic resonance cholangiopancreatography ( MRCP ) in the diagnosis of common bile duct stones . METHODS From December 1995 through April 1997 , all patients referred because of suspicion of the presence of common bile duct stones were included in the study .  EUS and MRCP were performed . Each examination was performed by a different operator unaware of the result of the other procedure . The definitive diagnosis was established by means of endoscopic retro grade cholangiography with sphincterotomy or a surgical procedure . RESULTS Forty-three patients ( 18 men , 25 women ) with a mean age of 60.9 + /- 14.5 years ( range 25 to 81 years ) were included in the study . Eleven patients were excluded because of unavailability of magnetic resonance imaging(n = 5 ) or EUS ( n = 6 ) . Ten patients ( 31.2 % ) had choledocholithiasis . For this diagnosis , the sensitivity of EUS  was 100 % , the specificity was 95.4 % , the positive predictive value was 90.9 % , and the negative predictive value was 100 % . The corresponding values for MRCP were 100 % , 72.7 % , 62.5 % , and 100 % , not significantly different from EUS results . The accuracy of EUS  was 96.9 % , and that of MRCP was 82.2 % . CONCLUSION This preliminary study confirmed EUS as an accurate and noninvasive procedure for the diagnosis of common bile duct stones . MRCP , which had a high sensitivity and high negative predictive value , might be an accurate technique for patients with a contraindication to EUS This prospect i ve study compares repetitive thick-slab single-shot projection magnetic resonance cholangiopancreatography ( MRCP ) with endoscopic ultrasonography ( EUS ) for the detection of choledocholithiasis . Fifty-seven consecutive patients ( 36 women , mean age 61 ) referred for suspected choledocholithiasis underwent MRCP , followed by EUS .  Each procedure was performed by different operators blinded to the results of the other investigation . MR technique included a turbo spin-echo T2-weighted axial sequence with selective fat saturation ( SPIR/TSE , TE=70 ms , TR=1,600 ms ) , followed by coronal dynamic MRCP . The same thick-slab slice was sequentially acquired 12 times as breath-hold single-shot projection imaging ( SSh , TE=900 ms , TE=8,000 ms ) centred on the common bile duct ( CBD ) . Two experienced radiologists independently and blindly evaluated MR images for the detection of CBD stones . Their inter-observer agreement kappa was determined . Secondly , the two observers read MR images in consensus again . CBD stones were demonstrated in 18 out of 57 patients ( 31.6 % ) and confirmed by endoscopic retro grade cholangiography ( ERCP , n=17 ) or intraoperative cholangiography ( n=1 ) . Clinical follow-up served as the “ gold st and ard ” in patients with negative results without following invasive procedure ( n=28 ) . Sensitivity , specificity , accuracy , positive and negative predictive value for MRCP result ing from consensus reading were 94.9 % , 94.4 % , 94.7 % , 97.4 % and 89.5 % , respectively . Corresponding values of EUS were 97.4 % , 94.4 % , 96.5 % , 97.4 % and 94.4 % . Inter-observer agreement kappa was 0.81 . Repetitive thick-slab single-shot projection MRCP is an accurate non-invasive imaging modality for suspected choledocholithiasis and should be increasingly used to select those patients who require a subsequent therapeutic procedure , namely ERCP Endoscopic ultrasonography ( EUS ) is a sensitive and specific modality for the detection of  choledocholithiasis .  In experienced h and s , it can be completely effective in almost all patients without significant risk . Prospect i ve studies have shown that the sensitivity and specificity of EUS  for the detection of choledocholithiasis rival that of ERCP . The clinical roles for EUS in these setting s are currently evolving and will also likely be shaped by the continued forces to practice the most effective medicine BACKGROUND AND STUDY AIMS It is still unknown whether there is a difference in diagnostic accuracy and clinical impact between endoscopic ultrasonography ( EUS ) and magnetic resonance cholangiopancreatography ( MRCP ) . PATIENTS AND METHODS The test performance and potential clinical impact of EUS and MRCP , had each investigation been performed as the first examination method , were compared prospect ively in 163 patients admitted for and examined by endoscopic retro grade cholangiopancreatography ( ERCP ) .  RESULTS The accuracies of EUS and MRCP were 0.93 and 0.91 , respectively ( no significant difference , P > 0.05 ) . Had EUS or MRCP been performed as the first investigation in the 75 patients who had a presumed high probability for needing therapeutic ERCP , only 15 and nine patients , respectively , would have avoided ERCP . In this group of patients , one patient needed other diagnostic investigations following EUS compared with 11 patients following MRCP ( P = 0.004 ) . For the 57 patients with an intermediate probability of needing endoscopic therapy , EUS and MRCP would have spared 37 and 38 patients , respectively , from the need to have an ERCP . In 31 patients with a presumed low risk of needing endoscopic therapy , 30 and 29 patients would have been spared from ERCP had EUS and MRCP , respectively , been performed initially . CONCLUSIONS There was no difference in the diagnostic accuracy and clinical impact between EUS and MRCP in the majority of the patients . The impact of EUS or MRCP on the ERCP workload was highly dependent on the presumed probability of needing endoscopic therapy Background Magnetic resonance cholangiography ( MRC ) is a new technique for non-invasive imaging of the biliary tract . Aim To assess the results of MRC in patients with suspected bile duct stones as compared with those obtained with reference imaging methods . Patients / Methods 70 patients ( 34 men and 36 women , mean ( SD ) age 71 ( 15.5 ) years ; median 75 ) with suspected bile duct stones were included ( cholangitis , 33 ; pancreatitis , three ; suspected post-cholecystectomy choledocholithiasis , nine ; cholestasis , six ; stones suspected on ultrasound or computed tomography scan , 19 ) . MR cholangiograms with two dimensional turbo spin echo sequences were acquired . Endoscopic retro grade cholangiography with or without sphincterotomy ( n = 63 ) , endosonography ( n = 5 ) , or intraoperative cho- langiography ( n = 2 ) were the reference imaging techniques used for the study and were performed within 12 hours of MRC . Radiologists were blinded to the results of endoscopic retro grade cholangiography and previous investigations . Results 49 patients ( 70 % ) had bile duct stones on reference imaging ( common bile duct , 44 , six of which impacted in the papilla ; intrahepatic , four ; cystic duct stump , one ) . Stone size ranged from 1 to 20 mm ( mean 6.1 , median 5.5 ) . Twenty seven patients ( 55 % ) had bile duct stones smaller than 6 mm . MRC diagnostic accuracy for bile duct lithiasis was : sensitivity , 57.1 % ; specificity , 100 % ; positive predictive value , 100 % ; negative predictive value , 50 % . Conclusions Stones smaller than 6 mm are still often missed by MRC when st and ard equipment is used . The general introduction of new technical improvements is needed before this method can be considered reliable for the diagnosis of bile duct stones BACKGROUND The management of possible  common bile duct ( CBD ) stones in patients scheduled for laparoscopic cholecystectomy  remains controversial . METHODS Prospect i ve evaluation of 609 patients who underwent laparoscopic cholecystectomy  was carried out in relation to the use of selective preoperative ERCP for detection of common duct stones . Preoperative ERCP was performed if there is or has been ( 1 ) cholangitis , biliary pancreatitis , or jaundice ; ( 2 ) abnormal serum liver tests or ( 3 ) ultrasonogram showing a dilated CBD or ductal stones . RESULTS A total of 139 patients underwent preoperative ERCP  , and cannulation of CBD was successful in 133 patients ( 96 % ) . CBD stones were found in 60 patients ( 45 % ) and extracted after sphincterotomy . High prevalence of CBD stones was noted in patients with acute cholangitis and CBD stones on ultrasonogram . There were six endoscopic sphincterotomy-related complications ( complication rate , 4.5 % ) : bleeding ( 2 ) , pancreatitis ( 3 ) , retroduodenal perforation ( 1 ) . No patient required surgery as the result of a complication . The prediction of the occurrence of ductal stones was further analyzed using stepwise logistic regression . Acute cholangitis and CBD stones on ultrasonogram were shown to be independent significant risk factors with odds ratios of 8.9 and 13.5 , respectively . CONCLUSIONS With selective preoperative ERCP , suspected CBD stones can be identified and removed prior to laparoscopic cholecystectomy OBJECTIVES New modalities , namely , endoscopic ultrasonography ( EUS ) , magnetic resonance cholangiopancreatography ( MRCP ) , and helical computed-tomographic cholangiography ( HCT-C ) , have been introduced recently for the detection of common bile duct ( CBD ) stones and shown improved detectability compared to conventional ultrasound or computed tomography . We conducted this study to compare the diagnostic ability of EUS , MRCP , and HCT-C in patients with suspected choledocholithiasis . METHODS Twenty-eight patients clinical ly suspected of having CBD stones were enrolled , excluding those with cholangitis or a definite history of choledocholithiasis . Each patient underwent EUS , MRCP , and HCT-C prior to endoscopic retro grade cholangio-pancreatography ( ERCP ) , the result of which served as the diagnostic gold st and ard . RESULTS CBD stones were detected in 24 ( 86 % ) of 28 patients by ERCP/IDUS . The sensitivity of EUS , MRCP , and HCT-C was 100 % , 88 % , and 88 % , respectively . False negative cases for MRCP and HCT-C had a CBD stone smaller than 5 mm in diameter . No serious complications occurred while one patient complained of itching in the eyelids after the infusion of contrast agent on HCT-C. CONCLUSIONS When examination can be scheduled , MRCP or HCT-C will be the first choice because they were less invasive than EUS . MRCP and HCT-C had similar detectability but the former may be preferable considering the possibility of allergic reaction in the latter . When MRCP is negative , EUS is recommended to check for small CBD stones OBJECTIVE Our purpose was to compare the accuracy of MR cholangiopancreatography and endoscopic sonography for the diagnosis of common bile duct stones in patients with a mild to moderate clinical suspicion of common bile duct stones . SUBJECTS AND METHODS Forty-seven patients were prospect ively enrolled . Inclusion criteria included acute pancreatitis , sub clinical jaundice , and clinical features of common bile duct stone migration .  Radial endoscopic sonography and MR cholangiopancreatography with the single-shot fast spin-echo technique were performed a maximum of 48 hr apart . The gold-st and ard diagnosis was obtained with ERCP ( n = 20 ) or intraoperative cholangiography ( n = 14 ) if the results of endoscopic sonography or MR cholangiopancreatography were abnormal or if a cholecystectomy was performed , or by clinical and biochemical follow-up ( n = 11 ) if the results of endoscopic sonography and MR cholangiopancreatography were normal . RESULTS The final diagnosis was  common bile duct stones in 16 patients , malignant obstructions  in four , and another biliary disease in two ( lithiasis migration aspect with papillary edema ) ; 23 patients had no biliary disease . The sensitivity and specificity of MR cholangiopancreatography  were , respectively , 90.5 % and 87.5 % for etiologic diagnosis and 87.5 % and 96.6 % for the detection of common bile duct stones . The corresponding values for endoscopic sonography were 86.4 % and 91.3 % for etiologic diagnosis and 93.8 % and 96.6 % for visualization of choledocholithiasis . Accuracy did not significantly differ between the techniques . CONCLUSION In cases of mild to moderate suspicion of choledocholithiasis , the accuracies of endoscopic sonography and MR cholangiopancreatography are similar . Because MR cholangiopancreatography is noninvasive , it may be preferred for this indic 
    Output:
    
The analysis demonstrated that , with respect to sensitivity , specificity and accuracy , there was no statistically significant difference between EUS and MRCP for the detection of choledocholithiasis .
Our meta- analysis of prospect i ve comparison of MRCP and EUS for the detection of choledocholithiasis yielded statistically similar diagnostic values for both techniques