Detection of Cardiac Quiescence From B-Mode Echocardiography Using a Correlation-Based Frame-to-Frame Deviation Measure

Abstract

Two novel methods for detecting cardiac quiescent phases from B-mode echocardiography using a correlation-based frame-to-frame deviation measure were developed. Accurate knowledge of cardiac quiescence is crucial to the performance of many imaging modalities, including computed tomography coronary angiography (CTCA). Synchronous electrocardiography (ECG) and echocardiography data were obtained from 10 healthy human subjects (four male, six female, 23–45 years) and the interventricular septum (IVS) was observed using the apical four-chamber echocardiographic view. The velocity of the IVS was derived from active contour tracking and verified using tissue Doppler imaging echocardiography methods. In turn, the frame-to-frame deviation methods for identifying quiescence of the IVS were verified using active contour tracking. The timing of the diastolic quiescent phase was found to exhibit both inter- and intra-subject variability, suggesting that the current method of CTCA gating based on the ECG is suboptimal and that gating based on signals derived from cardiac motion are likely more accurate in predicting quiescence for cardiac imaging. Two robust and efficient methods for identifying cardiac quiescent phases from B-mode echocardiographic data were developed and verified. The methods presented in this paper will be used to develop new CTCA gating techniques and quantify the resulting potential improvement in CTCA image quality.

Echocardiography as an indication of continuous-time cardiac quiescence

“…Discrepancies in the last requirement result in increased deviation sensitivity to motion in the direction of the minor axis of the IVS. In practice this has not been an issue and the accuracy of this approach has been verified using two-dimensional IVS tracking (Wick et al 2013). Deviation, D ( i , j ), is defined as $$boldnormalD\left(i,j\right)=1-{\rho }_S\left(i,j\right),$$ where ρ S ( i , j ) is the Pearson correlation coefficient between frames (for echocardiography) or phases (for CT) i and j over a static region of pixels or voxels S .…”

Characterization of cardiac quiescence from retrospective cardiac computed tomography using a correlation‐based phase‐to‐phase deviation measure

“…This correlation between the IVS and the coronary vessels suggests that echocardiographic evaluation of the IVS can be used to analyze cardiac quiescence on a beat-by-beat basis. 6 Thus, echocardiography could potentially form the basis of a real-time gating technique by tracking IVS motion.…”

“…This method is a 3D analog to the method proposed to analyze cardiac quiescence from echocardiography. 6 The Pearson correlation coefficient has been shown to be a strong indicator of image similarity and as such can be interpreted as a measure of the similarity of the feature position between two phases. 7 The correlation coefficient between two phases, i and j, over a volume, V , is given as…”

“…To investigate the motion of the coronary vessels taken in aggregate for each subject, a deviation matrix is formed from the union of the four static volumes representing the LAD, LM, LCX, and RCA found using Eq. (6). That is, the aggregate deviation for all vessels for each subject is defined as…”

“…1 CTCA is a promising alternative to the much more invasive catheter coronary angiography (CCA). More than 1.1 × 10 6 CCAs are performed annually in the United States of America resulting in more than 14 000 major complications and costing approximately $4 × 10 9 for the CCA alone. 4 When hospital stay costs associated with CCA are included, this estimate can reach $40 × 10 9 annually.…”