title: Thread sign in biliary intraductal papillary mucinous neoplasm: a novel specific finding for MRI.
abstract: OBJECTIVE
  To evaluate thread sign of biliary intraductal papillary mucinous neoplasm (B-IPMN) on magnetic resonance imaging (MRI).
  
  
  METHODS
  Thread sign was defined as intraductal linear or curvilinear hypointense striations. Two radiologists independently evaluated the presence and location of thread sign on MR cholangiography (thin-slice, thick-slab and 3D MRC) and axial MR images (T2 TSE, T2 HASTE and DWI) in patients with B-IPMN (n = 38) and in matched control groups with benign (n = 36) or malignant (n = 35) biliary diseases. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of thread sign for diagnosing B-IPMN were evaluated.
  
  
  RESULTS
  Thread sign was observed only in patients with B-IPMN on MRC (44.7-52.6 % [17/38-20/38], P < 0.001) and axial MR images (31.6 % [12/38], P < 0.001), except in one patient with recurrent pyogenic cholangitis on MRC (2.8 %, 1/36). The sensitivity, specificity, accuracy, PPV and NPV of thread sign for diagnosing B-IPMN on MRC were 0.53, 0.99, 0.83, 0.95 and 0.80, respectively (reader 1) and 0.45, 1.0, 0.81, 1.0 and 0.77, respectively (reader 2). Thread sign was detected mainly at the extrahepatic bile duct (52.6 %, 20/38).
  
  
  CONCLUSIONS
  B-IPMN can manifest thread sign, a novel specific MR finding, mainly at the extrahepatic bile duct on MRI, especially on MRC.
  
  
  CONCLUSIONS
  • Some B-IPMNs manifest thread sign within the bile ducts on MRI. • Thread sign is a highly specific finding for B-IPMN on MRI. • MRC is superior to axial T2WI and DWI for detecting thread sign.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Gil-Sun
authors.initials: GS
authors.lastname: Hong
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea. jhbyun@amc.seoul.kr.
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Byun
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Hyoung Jung
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Seung-Mo
authors.initials: SM
authors.lastname: Hong
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736, Korea.
authors.forename: Moon-Gyu
authors.initials: MG
authors.lastname: Lee
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology*; D000328:Adult; D000368:Aged; D001650:Bile Duct Neoplasms / Q000473:pathology*; D001652:Bile Ducts / Q000473:pathology; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology*; D002758:Cholangiography / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: Biliary intraductal papillary mucinous neoplasm; Magnetic resonance cholangiography; Magnetic resonance imaging; Mucin; Thread sign