Background: With the development of high-resolution myocardial imaging there has evolved a need for automated techniques that can accurately quantify regional function.
Objective: To develop a new method for quantification of spatial and temporal parameters of endocardial motion.
Design: Magnetic resonance images were analyzed using a unique, shape-based approach that tracks endocardial surface motion at defined points through the cardiac cycle by minimizing the bending energy.
Setting: Animal instrumentation was performed in the Nuclear Cardiology Experimental Research Laboratory at Yale University, New Haven, Connecticut. Magnetic resonance imaging was performed at the Yale New Haven Hospital Center.
Animals: Eight mongrel canines were used.
Interventions: Electrocardiograph-gated gradient-echo magnetic resonance images were obtained before and after occlusion of the left anterior descending coronary. Thirty-two points along automatically defined endocardial contours were tracked. Average displacements and cumulative path lengths were computed from end-diastole for each point over the entire cardiac cycle. The average cumulative path length was computed for each of four quarters of systole for the normal, border and infarct zones. Shape-based parameters of systolic motion were compared with the centreline approach. Infarct zone was defined by postmortem histochemical staining.
Main results: Displacement and cumulative path length over the cardiac cycle decreased significantly in the infarct and border zones (P<0.05), but did not change in the normal zone (P was not significant). Temporal changes in motion were observed in all zones. Displacement measured using the shape-based algorithm was more consistent than cumulative path length when compared with systolic motion measured using the centreline method.
Conclusions: An automated, shape-based approach permits quantitative evaluation of both spatial and temporal parameters of regional endocardial motion from high-resolution electrocardiograph-gated images. Analysis of endocardial motion and cumulative motion over the entire cardiac cycle discriminated infarcted from normal and border regions.