B-mode is short for brightness modulation. In its simplest form, it appears as bright spots with varying intensity depending on the amplitude, as in the diagram. The image becomes two-dimensional by virtue of the use of an array of multiple transducer elements, each of which forms a bright spot.

If performed fast enough, rapid update of frames can create a ‘real time’ image. Frame rate is limited by the depth to which the image is set. This is an operator control and should be set to display only the area of interest.

It is two-dimensional real time B-mode scanning which forms the basis for emergency medicine scans, such as FAST and AAA.