Comparison of blood flow imaging concepts with coherent and incoherent RF carriers in the 50 MHz region for application in dermatology

Pulsed Wave Doppler (PWD) concepts can be classified with respect to the applied bandwidth (narrowband/wideband), the signal generation process (coherent/incoherent RF carrier) and the data acquisition scheme (I/Q/direct RF signal sampling). The different system concepts are discussed, resulting in a transition from frequency domain approaches for velocity estimation to time domain and combined time/frequency domain approaches. A high frequency imaging system (50 MHz range) for applications in dermatology was implemented. Different modalities for PWD processing are compared (color flow, power mode, duplex mode). Additionally, a pseudo-continuous wave Doppler (CWD) mode was implemented for sensitive lateral vessel topography imaging. Results from phantom measurements and from measurements in vivo are presented