title: MRCP compared to diagnostic ERCP for diagnosis when biliary obstruction is suspected: a systematic review.
abstract: BACKGROUND
  Magnetic resonance cholangiopancreatography (MRCP) is an alternative to diagnostic endoscopic retrograde cholangiopancreatography (ERCP) for investigating biliary obstruction. The use of MRCP, a non-invasive procedure, may prevent the use of unnecessary invasive procedures. The aim of the study was to compare the findings of MRCP with those of ERCP by the computation of accuracy statistics.
  
  
  METHODS
  Thirteen electronic bibliographic databases, covering biomedical, science, health economics and grey literature were searched. A systematic review of studies comparing MRCP to diagnostic ERCP in patients with suspected biliary obstruction was conducted. Sensitivity, specificity, likelihood ratios, acceptability and adverse events were reported.
  
  
  RESULTS
  25 studies were identified reporting several conditions including choledocholithiasis (18 studies), malignancy (four studies), obstruction (three studies), stricture (two studies) and dilatation (five studies). Three of the 18 studies reporting choledocholithiasis were excluded from the analysis due to lack of data, or differences in study design. The sensitivity for the 15 studies of choledocholithiasis ranged from 0.50 to 1.00 while specificity ranged from 0.83 to 1.00. The positive likelihood ratio ranged: from 5.44-47.72 and the negative likelihood ratio for the 15 studies ranged from 0.00-0.51. Significant heterogeneity was found across the 15 studies so the sensitivities and specificities were summarised by a Receiver Operating Characteristic (ROC) curve. For malignancy, sensitivity ranged from 0.81 to 0.94 and specificity from 0.92 to 1.00. Positive likelihood ratios ranged from 10.12 to 43 and negative likelihood ratios ranged from 0.15 to 0.21, although these estimates were less reliable.
  
  
  CONCLUSIONS
  MRCP is a comparable diagnostic investigation in comparison to ERCP for diagnosing biliary obstruction.
authors.affiliation: School of Health and Related Research, University of Sheffield, Regent Court, 30 Regent Street, Sheffield S1 4DA, UK. e.kaltenthaler@sheffield.ac.uk
authors.forename: Eva C
authors.initials: EC
authors.lastname: Kaltenthaler
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Walters
authors.forename: Jim
authors.initials: J
authors.lastname: Chilcott
authors.forename: Anthony
authors.initials: A
authors.lastname: Blakeborough
authors.forename: Yolanda Bravo
authors.initials: YB
authors.lastname: Vergel
authors.forename: Steven
authors.initials: S
authors.lastname: Thomas