title: Seeing the Invisible: Revealing Atrial Ablation Lesions Using Hyperspectral Imaging Approach.
abstract: BACKGROUND
  Currently, there are limited means for high-resolution monitoring of tissue injury during radiofrequency ablation procedures.
  
  
  OBJECTIVE
  To develop the next generation of visualization catheters that can reveal irreversible atrial muscle damage caused by ablation and identify viability gaps between the lesions.
  
  
  METHODS
  Radiofrequency lesions were placed on the endocardial surfaces of excised human and bovine atria and left ventricles of blood perfused rat hearts. Tissue was illuminated with 365nm light and a series of images were acquired from individual spectral bands within 420-720nm range. By extracting spectral profiles of individual pixels and spectral unmixing, the relative contribution of ablated and unablated spectra to each pixel was then displayed. Results of spectral unmixing were compared to lesion pathology.
  
  
  RESULTS
  RF ablation caused significant changes in the tissue autofluorescence profile. The magnitude of these spectral changes in human left atrium was relatively small (< 10% of peak fluorescence value), yet highly significant. Spectral unmixing of hyperspectral datasets enabled high spatial resolution, in-situ delineation of radiofrequency lesion boundaries without the need for exogenous markers. Lesion dimensions derived from hyperspectral imaging approach strongly correlated with histological outcomes. Presence of blood within the myocardium decreased the amplitude of the autofluorescence spectra while having minimal effect on their overall shapes. As a result, the ability of hyperspectral imaging to delineate ablation lesions in vivo was not affected.
  
  
  CONCLUSIONS
  Hyperspectral imaging greatly increases the contrast between ablated and unablated tissue enabling visualization of viability gaps at clinically relevant locations. Data supports the possibility for developing percutaneous hyperspectral catheters for high-resolution ablation guidance.
authors.affiliation: Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States of America.
authors.forename: Narine
authors.initials: N
authors.lastname: Muselimyan
authors.affiliation: Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States of America.
authors.forename: Luther M
authors.initials: LM
authors.lastname: Swift
authors.affiliation: Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States of America.
authors.forename: Huda
authors.initials: H
authors.lastname: Asfour
authors.affiliation: Strasbourg Medical University, Strasbourg, France.
authors.forename: Tigran
authors.initials: T
authors.lastname: Chahbazian
authors.affiliation: Division of Cardiology, The George Washington University, Medical Faculty Associates, Washington, District of Columbia, United States of America.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Mazhari
authors.affiliation: Division of Cardiology, The George Washington University, Medical Faculty Associates, Washington, District of Columbia, United States of America.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Mercader
authors.affiliation: Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States of America.
authors.forename: Narine A
authors.initials: NA
authors.lastname: Sarvazyan
mesh_terms: D000818:Animals; D002417:Cattle; D003952:Diagnostic Imaging / Q000379:methods*; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D011846:Radio Waves