Tissue Doppler

Tissue Doppler Imaging, TDI, is a medical ultrasound technology, specifically a form of echocardiography that measures the velocity of the myocardium, the heart muscle, through the phases of one or more heartbeats by the Doppler effect, frequency shift, of the reflected ultrasound. It is commonly used for assessing the systolic function of the ventricles, as well as the diastolic function of the left ventricle. The image shows a Pulsed Tissue Doppler with the sample volume placed at the base of the right ventricular free wall - measuring the systolic function of the right ventricle.

You can see an example below:

Figure 1. Tissue Doppler imaging