Intravascular power flow imaging: theory and potentials for planimetry

The authors present a novel power-mode method of intravascular ultrasound blood flow imaging with in vitro and in vivo results. The normalized power of echo signals after stationary echo subtraction yields the flow parameter; increased power indicates increased velocity. Flow information is superimposed on the IVUS image using a color scale. Power-mode flow estimation is sensitive to axial and transverse flow components, although flow along the beam direction has a dominant effect. The spatial and parametric resolution of the technique allow good depiction of the flow area. Low persistence requirements allows imaging of pulsatile flows. In addition to flow and lumen visualization, the technique may be used for lumen planimetry.