Ultrasonographic quantification of local cardiac dynamics by tracking real reflectors: algorithm development and experimental validation

Quantification of cardiac local contraction across the entire ventricle wall is essential for better diagnosis and therapeutic planning. A new ultrasound B-mode image analysis technique was developed that identifies and tracks real reflectors in successive frames. This study tests the ability the technique to identify the mechanical propagation sequmce. Cardiac function was monitored (sheep open chest studies, n=7) by pressure transducers, sonocrystals, and aortic flow' meter, concurrent with ultrasound image acquisition. Epicardial electrodes mapped electrical propagation, and allowed diflerent LV pacings. Normal SA node derived activity was compared with abnormal LV contractions. Mechanical indices derived from US images correlated well with the sonocrystals measurements, and the sequence of mechanical conrraction with the measured electrical activation. Image analysis allows precise reconstruction of myocardial activation with 16msec time resolution.