title: Ideal combination of MRI sequences for perianal fistula classification and the evaluation of additional findings for readers with varying levels of experience.
abstract: OBJECTIVE
  The aim of our study was to assess the contribution of various magnetic resonance imaging (MRI) sequences in determining the type of perianal fistula and in obtaining critical information for surgical decisions, as well as to define the optimal combination of sequences for readers with varying levels of experience.
  
  
  METHODS
  The study included 33 MRI examinations in 26 patients with suspected perianal fistula. The following sequences were obtained in both the coronal and axial planes: thin slice, high resolution T1-weighted (W) spin echo; T2-weighted turbo spin echo; short tau inversion recovery (STIR); and native and contrast enhanced T1-weighted gradient echo fast low-angle shot (FLASH) images with fat suppression (FS-CE-T1W-GRE). The examinations were interpreted by three radiologists with varying degrees of experience in two different sessions, and the inter-reader agreement was assessed. Seventeen of the patients underwent surgery. The agreement between the surgical findings and the MRI results were evaluated.
  
  
  RESULTS
  A statistically significant concordance between the fistula classification and surgery was achieved with the FS-CE-T1W-GRE sequence for Reader 1 (Cramer's V=0.701, P = 0,022) and Reader 3 (Cramer's V=0.716, P = 0,043). For Reader 2, statistically significant concordance between fistula classification and surgery was achieved with the FS-CE-T1W-GRE (Cramer's V=0.703, P = 0,011) and the T2W images (Cramer's V=0.648, P = 0,027). For all sequences, there was statistically significant agreement between readers for fistula classification, internal opening location, and the presence of sinus tracts, abscess, a horseshoe component, and inflammation.
  
  
  CONCLUSIONS
  For experienced readers, combining FS-CE-T1W-GRE images with either T2W or STIR images collected in both the coronal and axial planes was sufficient to make an assessment before deciding the surgical extent of the procedure.
authors.affiliation: Department of Radiology, Uludağ University School of Medicine, Bursa, Turkey. nalanmed76@hotmail.com
authors.forename: Nalan
authors.initials: N
authors.lastname: Yildirim
authors.forename: Gökhan
authors.initials: G
authors.lastname: Gökalp
authors.forename: Ersin
authors.initials: E
authors.lastname: Öztürk
authors.forename: Abdullah
authors.initials: A
authors.lastname: Zorluoğlu
authors.forename: Tuncay
authors.initials: T
authors.lastname: Yilmazlar
authors.forename: Ilker
authors.initials: I
authors.lastname: Ercan
authors.forename: Gürsel
authors.initials: G
authors.lastname: Savci
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001004:Anus Diseases / Q000175:diagnosis*; D002983:Clinical Competence; D005260:Female; D006801:Humans; D007412:Intestinal Fistula / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards*; D008297:Male; D008875:Middle Aged; D012003:Rectal Fistula / Q000175:diagnosis*; D012189:Retrospective Studies