Infographics / Ultrasound Physics

A-mode, B-mode and M-mode display modes

Three aligned panels showing how the same returning echoes are displayed. A-mode plots echo amplitude as spike height against depth (a 1D trace). B-mode maps echo amplitude to pixel brightness across many swept scan lines to form a 2D grey-scale image (lateral versus depth). M-mode plots a single repeated scan line as depth on the vertical axis against time on the horizontal axis, with brightness encoding amplitude; stationary interfaces appear as straight lines and moving structures such as a cardiac valve trace out their changing position.