Display Modes Chapter 11

Display Modes in Ultrasound Imaging

Overview of Display Modes

  • Display modes are essential in ultrasound imaging, allowing visualization of different aspects of reflected sound pulses. There are three primary modes: Amplitude Mode (A Mode), Brightness Mode (B Mode), and Motion Mode (M Mode).

Amplitude Mode (A Mode)

  • Definition: A mode displays the intensity of echoes as a series of spikes on the display.

  • Operating Principle:

    • A sound pulse is emitted by the transducer.

    • A dot moves at a constant speed across the display.

    • Reflected echoes return to the transducer, where the moving dot is deflected upward.

    • The height of upward deflection corresponds to the amplitude of the returning echo.

  • Characteristics:

    • Strong echoes produce tall spikes.

    • Weaker reflections yield shorter spikes.

  • Axes Used:

    • X-axis: Represents time of flight (the time taken for the pulse to travel to reflectors and back).

    • Y-axis: Represents reflection amplitude.

  • Applications: Commonly used in ophthalmology to accurately measure the depth of structures and thickness.

  • Visualization: Often resembles the New York skyline, with varying heights indicating different amplitude levels.

Brightness Mode (B Mode)

  • Definition: B mode creates a grayscale image, representing different levels of echo intensity.

  • Operating Principle:

    • A sound pulse is emitted from the transducer.

    • An invisible dot moves at a constant speed across the display.

    • Echoes return to the transducer, converting into brightness levels on the display.

  • Characteristics:

    • Brightness of the dot indicates the strength of the reflection:

    • Weaker reflections appear as dark gray dots.

    • Stronger reflections are represented as bright white dots.

  • Axes Used:

    • X-axis: Represents depth relative to the sound pulse.

    • Y-axis: Not applicable as this mode does not use a y-axis for amplitude representation.

  • Image Output: Produces grayscale images that can be interpreted for various diagnostic purposes.

Motion Mode (M Mode)

  • Definition: M mode displays motion over time, particularly useful for assessing moving structures such as heart walls.

  • Operating Principle:

    • A sound pulse is emitted by the transducer.

    • Reflected echoes travel at a constant speed from right to left on the display.

    • The mode depicts an upward-moving line indicating a reflector that is moving closer or farther away.

  • Line Representation:

    • A straight horizontal line indicates a stationary reflector.

  • Axes Used:

    • X-axis: Represents time.

    • Y-axis: Represents depth, allowing for a mapping of motion over time.

  • Applications: M mode is critical in evaluating cardiac walls and structures and helps assess the change in location of reflectors concerning time.

  • Summary of Axis Use:

    • A Mode: X-axis (depth), Y-axis (amplitude).

    • B Mode: X-axis (depth), no Y-axis representation.

    • M Mode: X-axis (time), Y-axis (depth).