High frequency color flow imaging of the microcirculation

The extension of ultrasound color flow imaging (CFI) techniques to high frequencies (>30 MHz) has the potential to provide valuable non-invasive tools for clinical and scientific investigations of blood flow in the microcirculation. The authors report the development of a combined color flow mapping and pulsed wave system capable of operating in the 20 to 100 MHz range which has been optimized to image the microcirculation. The performance of the system was evaluated at a center frequency of 50 MHz for two PVDF transducers which provided lateral resolutions of 45 and 65 microns. The axial resolution was approximately 60 microns. In vivo validation experiments conducted using the mouse ear demonstrate the detection of flow in vessels down to 15-20 microns in diameter with flow velocities below 1 millimeter per second. Initial experiments examining experimental murine tumors indicate the successful detection of flow in the tumor microcirculation