title: Experimental and Automated Analysis Techniques for High-resolution Electrical Mapping of Small Intestine Slow Wave Activity.
abstract: OBJECTIVE
  Small intestine motility is governed by an electrical slow wave activity, and abnormal slow wave events have been associated with intestinal dysmotility. High-resolution (HR) techniques are necessary to analyze slow wave propagation, but progress has been limited by few available electrode options and laborious manual analysis. This study presents novel methods for in vivo HR mapping of small intestine slow wave activity.
  
  
  METHODS
  Recordings were obtained from along the porcine small intestine using flexible printed circuit board arrays (256 electrodes; 4 mm spacing). Filtering options were compared, and analysis was automated through adaptations of the falling-edge variable-threshold (FEVT) algorithm and graphical visualization tools.
  
  
  RESULTS
  A Savitzky-Golay filter was chosen with polynomial-order 9 and window size 1.7 seconds, which maintained 94% of slow wave amplitude, 57% of gradient and achieved a noise correction ratio of 0.083. Optimized FEVT parameters achieved 87% sensitivity and 90% positive-predictive value. Automated activation mapping and animation successfully revealed slow wave propagation patterns, and frequency, velocity, and amplitude were calculated and compared at 5 locations along the intestine (16.4 ± 0.3 cpm, 13.4 ± 1.7 mm/sec, and 43 ± 6 µV, respectively, in the proximal jejunum).
  
  
  CONCLUSIONS
  The methods developed and validated here will greatly assist small intestine HR mapping, and will enable experimental and translational work to evaluate small intestine motility in health and disease.
authors.affiliation: Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand. ; Riddet Institute, Palmerston North, New Zealand.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Angeli
authors.forename: Gregory
authors.initials: G
authors.lastname: O'Grady
authors.forename: Niranchan
authors.initials: N
authors.lastname: Paskaranandavadivel
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Erickson
authors.forename: Peng
authors.initials: P
authors.lastname: Du
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pullan
authors.forename: Ian P
authors.initials: IP
authors.lastname: Bissett
authors.forename: Leo K
authors.initials: LK
authors.lastname: Cheng
keywords: Electrophysiology; Gastrointestinal motility; Interstitial cells of Cajal; Signal processing