title: Functional luminal imaging probe topography: an improved method for characterizing esophageal distensibility in eosinophilic esophagitis.
abstract: OBJECTIVE
  The aims of this study were to develop a new method for analysis and presentation of esophageal distensibility data using high-resolution impedance planimetry recordings during a volume-controlled distention.
  
  
  METHODS
  Two control subjects and six patients with eosinophilic esophagitis (EoE) with stricture, narrow caliber or normal endoscopy according to EndoFLIP studies were included for analysis. Median filtering and pulse detection techniques were applied to the pressure signal and a wavelet decomposition technique was applied to the 16 channels of raw esophageal diameter data to reduce vascular artifact, respiratory effect and remove esophageal contraction interference. These data were used to generate a functional luminal imaging probe (FLIP) topography plot that describes regional variation of cross-sectional area (CSA). A previously developed computer program was used to calculate and model the CSA-pressure data to derive the slope of line fitting and distension plateau for each individual subject. The results were compared among the four endoscopic phenotypes.
  
  
  RESULTS
  Patients with EoE and normal endoscopy had similar esophageal distensibility parameters to those of normal controls whereas patients with EoE and stricture or narrow caliber had much lower distensibility than patients with EoE and normal endoscopy. The FLIP topography plots provided a global assessment of the esophageal distensibility along the axial plane of measurement that differentiated patients with varying degrees of endoscopic abnormality.
  
  
  CONCLUSIONS
  New techniques can be leveraged to improve data analysis and presentation using EndoFLIP assessment of the esophageal body in EoE. These techniques may be helpful in defining clinically relevant phenotypes and guiding treatment strategies and should be helpful in structuring future outcome trials.
authors.affiliation: Feinberg School of Medicine, Department of Medicine, Northwestern University, 676 St Clair Street, Suite 1400, Chicago, IL 60611-2951, USA.
authors.forename: Zhiyue
authors.initials: Z
authors.lastname: Lin
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kahrilas
authors.forename: Yinglian
authors.initials: Y
authors.lastname: Xiao
authors.forename: Frédéric
authors.initials: F
authors.lastname: Nicodème
authors.forename: Nirmala
authors.initials: N
authors.lastname: Gonsalves
authors.forename: Ikuo
authors.initials: I
authors.lastname: Hirano
authors.forename: John E
authors.initials: JE
authors.lastname: Pandolfino
keywords: cross-sectional area; eosinophilic esophagitis; esophageal distensibility index; functional imaging; wavelet transform