title: Investigation of Oddi sphincter structure by optical coherence tomography in patients with biliary-type 1 dysfunction: a pilot in vivo study.
abstract: BACKGROUND
  Type 1 sphincter of Oddi dysfunction is a clinical entity characterised by biliary-type pain, elevated liver biochemical tests, and common bile duct dilation. Sphincter fibrosis is a common finding in this type of dysfunction and may require in some cases a differential diagnosis with a malignant intra-papillary disease. Optical coherence tomography permits high-resolution, real-time imaging of the sphincter of Oddi microstructure by a probe inserted into the common bile duct through an ERCP catheter. No data exist on the evaluation of sphincter of Oddi fibrosis by optical coherence tomography during ERCP in vivo.
  
  
  OBJECTIVE
  To assess the feasibility of optical coherence tomography investigation of the sphincter of Oddi structure and assess its potential for diagnosing type 1 sphincter of Oddi dysfunction.
  
  
  METHODS
  Ten consecutive patients, five with biliary-type 1 sphincter of Oddi dysfunction and five with pancreatic head/mid-body adenocarcinoma not involving the papillary region, who underwent both endoscopic ultrasound and therapeutic ERCP, were investigated by optical coherence tomography immediately before biliary sphincterotomy or stenting.
  
  
  RESULTS
  In all sphincter of Oddi dysfunction patients optical coherence tomography recognised a hyper-reflective intermediate, fibro-muscular layer, significantly thicker than in patients with non-pathological sphincter of Oddi (p<0.0001).
  
  
  CONCLUSIONS
  Optical coherence tomography imaging recognised an increased thickness and reflectance of the fibro-muscular layer of the sphincter of Oddi, very likely determined by fibrosis, and was not time-consuming; it can be safely used during ERCP to confirm the diagnosis in difficult cases. Its use in clinical practice has one important limitation since it requires magnification in the post-procedure computer analysis to obtain images useful for diagnosis.
authors.affiliation: Division of Gastroenterology & Gastrointestinal Endoscopy, Vita-Salute San Raffaele University, Scientific Institute San Raffaele, Milan, Italy. testoni.pieralberto@hsr.it
authors.forename: P A
authors.initials: PA
authors.lastname: Testoni
authors.forename: B
authors.initials: B
authors.lastname: Mangiavillano
authors.forename: A
authors.initials: A
authors.lastname: Mariani
authors.forename: S
authors.initials: S
authors.lastname: Carrara
authors.forename: C
authors.initials: C
authors.lastname: Notaristefano
authors.forename: P G
authors.initials: PG
authors.lastname: Arcidiacono
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000503:physiopathology; D000368:Aged; D002760:Cholangiopancreatography, Endoscopic Retrograde; D003937:Diagnosis, Differential; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D010190:Pancreatic Neoplasms / Q000175:diagnosis / Q000503:physiopathology; D010865:Pilot Projects; D046628:Sphincter of Oddi Dysfunction / Q000175:diagnosis* / Q000503:physiopathology; D041623:Tomography, Optical Coherence