An ultrasound imaging system provides for defining a VOI in an ultrasound imaging space. The system defines an initial frame of the VOI in the ultrasound imaging space, receives a selection of at least one reference point at an arbitrary location in the ultrasound imaging space, creates at least one curved surface using at least one element of the initial frame and the at least one reference point, and then creates VOI based on the curved surface in the ultrasound imaging space.
