Quantifying myocardial deformation throughout the cardiac cycle: a comparison of ultrasound strain rate, grey-scale M-mode and magnetic resonance imaging.
Strain rate imaging (SRI) is a new ultrasound (US) approach to the quantification of regional myocardial deformation. It previously has been validated in vitro and in vivo against other imaging techniques. However, in all such studies, only peak strain values were compared, and the temporal evolution of the strain curve was not studied. Yet, it is the temporal evolution of the strain curves that contains the more important clinical information (e.g., asynchrony, viability, etc). Thus, the aim of this study was to compare the evolution of strain during the complete cardiac cycle as measured by US SRI, US grey-scale M-mode and magnetic resonance imaging (MRI). In 10 healthy volunteers and 20 patients with chronic ischaemic heart disease, radial deformation of the inferolateral segment of the left ventricle was measured by US SRI, US M-mode and MRI. The correspondence of the temporal characteristics of these strain curves were compared by defining an intraclass correlation coefficient (ICC). In healthy volunteers, an overall good agreement (mean ICC: 0.75 and 0.63 for systole and diastole) was found between the different methods. However, in patients with abnormal segmental deformation and low peak strain values, the agreement was less (mean ICC: 0.42 and 0.32), but remained within acceptable limits for clinical decision making. Myocardial deformation measurements using SRI correlated well with MRI and US M-mode measurements throughout the complete cardiac cycle.