title: Differential diagnosis of benign and malignant distal biliary strictures: value of adding diffusion-weighted imaging to conventional magnetic resonance cholangiopancreatography.
abstract: OBJECTIVE
  To determine the value of adding diffusion-weighted imaging (DWI) to conventional magnetic resonance cholangiopancreatography (MRCP) for differentiating benign from malignant distal biliary strictures.
  
  
  METHODS
  Two independent readers reviewed three image sets (1: MRCP alone; 2: MRCP and DWI combined; and 3: MRCP, DWI, and contrast-enhanced T1-weighted imaging [T1WI] combined) of 60 patients with suspected distal biliary strictures and rated the probability of malignancy. Diagnostic performance and accuracy were compared using the receiver operating characteristic (ROC) curves and McNemar two-tailed test. κ coefficients were calculated to assess the interobserver agreement.
  
  
  RESULTS
  The Az value and accuracy improved significantly after additional review of DWI for both readers: Az = 0.780 vs. 0.916 (P = 0.003) for Reader 1 and 0.784 vs. 0.853 (P = 0.037) for Reader 2; accuracy = 69% vs. 93% for Reader 1 (P < 0.001) and 57% vs. 85% for Reader 2 (P = 0.002). No significant difference in the Az values and accuracy was found between MRCP and DWI combined, and MRCP, DWI, and contrast-enhanced T1WI combined (P > 0.050). There was substantial interobserver agreement in all three image sets (κ = 0.695-0.732).
  
  
  CONCLUSIONS
  The addition of DWI to MRCP significantly improved diagnostic accuracy in the characterization of distal biliary strictures.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Roh-Eul
authors.initials: RE
authors.lastname: Yoo
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Jeong Hee
authors.initials: JH
authors.lastname: Yoon
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001659:Biliary Tract / Q000473:pathology*; D001661:Biliary Tract Neoplasms / Q000175:diagnosis*; D049448:Cholangiopancreatography, Magnetic Resonance / Q000379:methods*; D002779:Cholestasis / Q000175:diagnosis*; D003251:Constriction, Pathologic / Q000175:diagnosis; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D015588:Observer Variation; D009942:Organometallic Compounds; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol
keywords: added value; characterization; diffusion-weighted imaging; distal biliary strictures; magnetic resonance cholangiopancreatography