Blood volume per time measured in: cm³/s.
The sonographic detection of blood flow in vascular ultrasound is limited by factors such as tissue motion (clutter), attenuation properties of the intervening tissue, and slow or low-volume flow.

Different flow types in human body:

See also Antegrade, Bi-directional Flow, Velocity, Poiseulles Law, and Venous Ultrasound.

The flow rate describes the volume of fluid passing through a given vessel per time unit. The flow rate is measured in milliliters per second ml/sec or liters per minute l/min.

See also Poiseulles Law.

A flowmeter is a device to measure velocity or volume of flow of liquids or gases passing a given point per unit of time.

See also Time of Flight.

A flowprobe (or flowsensor) measures flow with a transducer by insonating vessels to calculate and depict volume flow of blood.

The focal zone is the region within the transmitted sound beam in which the beam narrows to its minimum size. The lateral resolution is best within the focal zone of the beam.