title: The Evolution of Tissue Stiffness at Radiofrequency Ablation Sites During Lesion Formation and in the Peri-Ablation Period.
abstract: BACKGROUND
  Elastography imaging can provide radiofrequency ablation (RFA) lesion assessment due to tissue stiffening at the ablation site. An important aspect of assessment is the spatial and temporal stability of the region of stiffness increase in the peri-ablation period. The aim of this study was to use 2 ultrasound-based elastography techniques, shear wave elasticity imaging (SWEI) and acoustic radiation force impulse (ARFI) imaging, to monitor the evolution of tissue stiffness at ablation sites in the 30 minutes following lesion creation.
  
  
  RESULTS
  In 6 canine subjects, SWEI measurements and 2-D ARFI images were acquired at 6 ventricular endocardial RFA sites before, during, and for 30 minutes postablation. An immediate increase in tissue stiffness was detected during RFA, and the area of the postablation region of stiffness increase (RoSI) as well as the relative stiffness at the RoSI center was stable approximately 2 minutes after ablation. Of note is the observation that relative stiffness in the region adjacent to the RoSI increased slightly during the first 15 minutes, consistent with local fluid displacement or edema. The magnitude of this increase, ∼0.5-fold from baseline, was significantly less than the magnitude of the stiffness increase directly inside the RoSI, which was greater than 3-fold from baseline.
  
  
  CONCLUSIONS
  Ultrasound-based SWEI and ARFI imaging detected an immediate increase in tissue stiffness during RFA, and the stability and magnitude of the stiffness change suggest that consistent elasticity-based lesion assessment is possible 2 minutes after and for at least 30 minutes following ablation.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Eyerly
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
authors.forename: Maryam
authors.initials: M
authors.lastname: Vejdani-Jahromi
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Dumont
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.|Department of Radiology, Duke University, Durham, North Carolina, USA.
authors.forename: Gregg E
authors.initials: GE
authors.lastname: Trahey
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Wolf
keywords: acoustic radiation force impulse imaging; elastography; intraprocedure radiofrequency ablation lesion assessment; shear wave elasticity imaging