Depending on the images produced, ultrasound can take various forms. In veterinary work B-mode (brightness-mode) ultrasound, more commonly called 2-dimensional ultrasound is the most common form. This gives a two dimensional picture of the organ scanned. This is the type of ultrasound that is used to examine abdominal structures, perform pregnancy diagnosis, evaluate cardiac function and examine the eyes for certain eye diseases.
M-mode (motion-mode) is a type of B-mode in which a tracing of the motion of the structure being scanned is displayed. A combination of M-mode and 2-dimensional ultrasound are used for examining the heart walls, chambers and valves to evaluate cardiac function. Cardiac ultrasonography is usually referred to as echocardiography. Doppler ultrasound is a specialized form of cardiac ultrasound in which the direction and speed of blood flow in the heart and blood vessels can be measured. Color-flow Doppler technology makes it even easier to observe the flow of blood through the heart and important blood vessels.