Abstract 9116: Ultrasound Speckle Tracking System Using Radiofrequency Data for Simultaneous Computation of Strain and Strain Rate: Validation Against Sonomicrometry
Background: There is significant interest in speckle tracking echo derived mechanical indices to assess myocardial deformation and contractility. Current commercial B-mode feature tracking packages use the envelop signal and operate at lower sampling rates (70 frames/sec). We tested a new prototype speckle tracking system [Dynamic Contractility Imaging (DCI)] that was developed utilizing raw radiofrequency (RF) echo data.
Methods: We studied 10 freshly harvested pig hearts connected to a calibrated pulsatile pump through a balloon secured in the LV cavity. Each heart was mounted in a water bath to facilitate ultrasound scanning and driven passively by a pump at a constant rate of 60/min. Studies were conducted at two stroke volumes (40ml&80ml). Six 2mm sonomicrometry crystals were secured into the myocardium and arranged as two triangles at the apical and mid cavity levels. Cardiac motion was scanned at 3 MHz, 125 frames/sec, along the direction of planes formed by crystals at each stroke volume to acquire two long axis (2ch and 4ch) views and two short axis (apical and mid cavity levels) views.
Results: Increase in stroke volume resulted in increased stretching of myocardium that was detected by both sonomicrometry and DCI. DCI slightly underestimated the strain values (4.5 ± 2.5%) when compared to sonomicrometry but both methods showed a strong positive linear correlation (r=0.85).
Conclusions: DCI is an accurate imaging based method for computing strain and strain rate.
- © 2010 by American Heart Association, Inc.