Influence of various instrument settings on the flow information derived from the power mode.

To evaluate the factors influencing flow information displayed by the power operating mode, color Doppler flow mapping was used to image the flow in an in vitro left heart pulse duplicator system. The effect of changing one instrument setting, such as pulse repetition frequency, color filter and frame rate while keeping all other instrumental settings constant, was noted on the displayed flow areas. The flow areas derived using power and velocity modes were also compared. An increase in pulse repetition frequency and color filter decreased the flow areas significantly, and a flow area increase occurred with a decrease in frame rate. No significant difference was observed between the flow areas derived using the two operating modes. Like the velocity mode, the power mode display is also influenced by instrument settings. Although low velocity flows are better delineated using this mode, however, no significant difference occurred in the flow areas measured by this mode and velocity mode. Further studies need to be conducted to address its potential applications in the clinical setting and in quantitation.