12B-2 Functional Doppler Imaging: A Feasibility Study

We have developed a new method, called 2D flow index mapping (2D-FIM), for quantitative imaging of functional hemodynamic indices, such as resistive index (RI), by retrospective analysis of power Doppler flow waveforms from one complete cardiac cycle. To evaluate this method, a feasibility study was performed in renal transplant patients undergoing routine duplex examination and normal volunteers. Baseband quadrature-demodulated ultrasound echoes were acquired from the parenchyma of the transplant kidneys (n=9) and from normal native kidneys (n=4). The RI values computed from arterial Doppler signals were measured using 2D-FIM. These indices showed a high correlation (Pearson´s r=0.8, P<0.0004) with the values measured using spectral Doppler waveforms. Our preliminary results demonstrate the feasibility of 2D-FIM in renal transplant patients. Further refinement of these methods could lead to visualizing the functional hemodynamics in various complex vascular beds as well as for a more complete functional hemodynamic assessment in renal transplant patients.