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CHAPTER 17 M-Mode scanning. First motion detection device M-mode or Time-motion (TM) or Position–motion (PM) mode. Effects on motion. 2D B-mode cause blurring during motion Data are collected along one line of sight only Typical sweep rate is 25 to 100 mm/s
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First motion detection device • M-mode or Time-motion (TM) or Position–motion (PM) mode
Effects on motion • 2D B-mode cause blurring during motion • Data are collected along one line of sight only • Typical sweep rate is 25 to 100 mm/s • The axial position of each interface is displyed as a function of time. • Stationary interfaces are recorded as stright lines on the display • The moving interfaces produce oscillating waveforms
Types of information in M-mode • 2D M-mode trace contain four types of information • Reflected depth • Signal level of each reflector • Relative position of the reflectors at each sampling time • Change in axial position of each reflector with time
M-mode and two dimensional imaging • Both M-mode and B-scan can be shown simultaneously • In this case the CRT is divided by two parts • A line curser is placed on the B-mode image to denote the line of sight for the M-mode acquisition • Color M-Mode: combines M-mode with 2D Doppler information encoded in color • A line cursor on the color Doppler image denotes the sampling direction with respect to flow
Recording • Can be recorded on film, paper etc • Velocity can be calculated using equation v=x/t
Advantages and disadvantages • It is simple • It can be used to measure extent of motion • Axial and temporal is excellent • Lateral resolution is poor • It is based on assumption of geometric shape with measurement on one dimension and extrapolated for other dimensions