May respiration affect myocardial contrast echocardiographic results?

Echocardiographic quantification of myocardial perfusion after intravenous (IV) contrast is often based on the intensity of the received signal. The influence of respiration on the second harmonic myocardial intensity measurements was investigated in nine patients with normal coronary angiography before and after an IV bolus of contrast. Results showed that controlled breathing is needed during echocardiography if signal intensity is used for quantification.