title: Respiratory variation of the extrahepatic bile duct: evaluation with deep inspiratory and expiratory MRCP.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the respiratory variation of the extrahepatic bile duct in morphology including shape, length and duct diameter on the breath-hold magnetic resonance cholangiopancreatography (MRCP) obtained during deep inspiration and deep expiration in patients with or without biliary diseases.
  
  
  METHODS
  This study included 102 patients with or without biliary diseases. Breath-hold MRCP was obtained twice during the end-inspiration and the end-expiration. MRCP images were evaluated for the length, maximal diameter and "bowing" of the extrahepatic bile duct.
  
  
  RESULTS
  In the normal group, the mean maximal diameter of the extrahepatic bile duct was significantly larger on the end-inspiratory MRCP (8.0 ± 2.0 mm) than on the end-expiratory MRCP (7.3 ± 1.8 mm) (P<.0001), while it was not significantly different in the dilated group. In the normal group, 25 (39%) of 65 patients had an increase in the mean maximal diameter of more than 1 mm at the end-inspiration, whereas 4 (11%) of 37 patients in the dilated group had it. The bowing of the extrahepatic bile duct on the end-inspiratory MRCP was observed in 60 (92%) of 65 normal patients, while it was seen in 22 (60%) of 37 patients with biliary dilatation (P<.0001).
  
  
  CONCLUSIONS
  Deep inspiratory and expiratory MRCP demonstrated the respiratory variations of the extrahepatic bile duct in the shape (bowing), length and maximal duct diameter in patients with nondilated bile ducts. Awareness of this normal phenomenon will be important for the correct interpretation of MRCP in patients with or without biliary diseases.
authors.affiliation: Department of Radiology, Yamaguchi University School of Medicine, Ube, Yamaguchi 755-8505, Japan. itokatsu@med.kawasaki-m.ac.jp
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Ito
authors.forename: Ayame
authors.initials: A
authors.lastname: Shimizu
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tanabe
authors.forename: Naofumi
authors.initials: N
authors.lastname: Matsunaga
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017734:Bile Ducts, Extrahepatic / Q000033:anatomy & histology / Q000473:pathology*; D001660:Biliary Tract Diseases / Q000473:pathology*; D016009:Chi-Square Distribution; D049448:Cholangiopancreatography, Magnetic Resonance / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012119:Respiration; D012189:Retrospective Studies