What are we actually measuring by Doppler tissue imaging?

In current Doppler blood flow studies, the low Doppler shift frequencies of high energy generated by the wall motion are purposely filtered out. Since these low Doppler shift frequencies are produced by the contracting myocardium, they are expected to contain potential information for the assessment of myocardial properties. Early descriptions of directional pulsed Doppler tissue imaging (DTI) had already suggested the potential of this original technique for evaluating both systolic and diastolic myocardial function (1–6). Through the more recent technical development of color Doppler imaging, a technique based also on the pulsed Doppler principle, the concept of evaluating myocardial function based on directional pulsed Doppler velocities recording has become popular (7–9).