Doppler studies of the vascular system.

Ultrasonic Doppler methods are routinely used to study the vascular system. Flow and tissue motion information can be obtained by frequency and time domain processing. Instruments range in complexity from simple continuous wave devices without imaging capability through to advanced real-time 2D colour flow scanners and intravascular devices. 3D display is also possible. Contrast agents can be used to increase the detectability of blood flow signals. The properties of the tissue impose an envelope on achievable ultrasonic imaging. Doppler studies can provide information about flow velocity profile, vessel compliance, wall shear rate, pressure gradient, perfusion, tumour blood flow and the presence of emboli. These capabilities can be integrated in an holistic picture of ultrasonic vascular studies.