title: Automatic detection of small bowel contraction frequencies in motility plots using lomb-scargle periodogram and sinus-fitting method--initial experience.
abstract: OBJECTIVE
  Contraction frequencies are an important parameter for the analysis of bowel motility in MRI. The contraction curve can be rather noisy and the frequency-evaluation might be difficult. The aim was to evaluate manual calculations of small bowel contraction frequency in comparison with automatic calculations using two mathematically established methods.
  
  
  METHODS
  The institutional-review-board approved study consisted of 48 segmental small-bowel motility-plots out of a previous study with 25 patients (15 men/10 women; mean 39 years, standard deviation ± 14.67) undergoing MRI (1.5 T, GE-Medical Systems; two-dimensional-Fiesta, pulse repetition time 2.91, echo time 1.25, flip-angle 45°, matrix 256 × 256, slice thickness 10 mm) were evaluated. Calculations of contraction frequency was performed either manually or using Lomb-Scargle-periodograms and Sinus-Fitting method. The results were compared using intraclass correlation coefficient, Friedman's-test and Wilcoxon-matched-paired-signed-rank-test (P < 0.05 considered statistically significant).
  
  
  RESULTS
  Mean contraction frequency was 5.69 (standard deviation ± 1.99) for manual calculations showing moderate interreader reliability (intraclass correlation coefficient 0.72; 95% confidence-interval: 0.59;0.82). No significant difference (P = 0.776) was found to Lomb-Scargle-periodograms (5.34 contractions-per-minute [cpm], standard deviation ± 2.47; P = 0.174) and to the sinus-fitting-method (5.47 cpm; standard deviation ± 2.57; P = 0.0779). For the latter calculations failed in 3/48 plots, while manual and Lomb-Scargle-periodograms could be performed successfully in all 48/48 plots.
  
  
  CONCLUSIONS
  Herein, we could show that Lomb-Scargle-periodograms and Sinus-Fitting are fast and reliable methods to automatically measure small-bowel contraction frequencies even in noisy small bowel motility plots.
authors.affiliation: Department of Radiology, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bickelhaupt
authors.forename: Roger
authors.initials: R
authors.lastname: Cattin
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Froehlich
authors.forename: Stephan
authors.initials: S
authors.lastname: Raible
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Bouquet
authors.forename: Urs
authors.initials: U
authors.lastname: Bill
authors.forename: Michael A
authors.initials: MA
authors.lastname: Patak
mesh_terms: D000328:Adult; D001331:Automation; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology*; D006801:Humans; D007421:Intestine, Small / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D012984:Software