Plane Wave Perfusion Ultrasound Imaging Without Contrast

Perfusion imaging with conventional Doppler ultrasound is difficult due to frame rate and tissue clutter limitations. Consequently, conventional methods are only sensitive to velocities above 5-10mm/s for typical clinical imaging frequencies. To overcome this limitation and simultaneously address the frame rate and tissue clutter problems, we propose a technique that uses plane wave sequencing and an adaptive tissue clutter frequency and amplitude demodulation scheme. Suppression of tissue clutter due to sonographer hand motion was tested using phantoms and showed potential for increased Doppler sensitivity to at least as low as 1.17mm/s. Additionally, feasibility of the method is demonstrated in vivo using muscle contractions of a human calf, which resulted in 2.54dB and 0.12dB dynamic ranges of blood flow through slow-time for the proposed and conventional methods, respectively.