The “Freeze” button freezes the real-time image.

That allows the operator to perform measurements on the frozen image, or save the image, or scroll through the images sampled e.g. 15 seconds before freezing the image.

On a frozen image it is possible to activate the “caliper” button in order to make measurements.

By moving a finger tip on the touch pad, the primary measurement point can be chosen. It is fixed by pushing the “Select” button. Then, by moving the finger tip on the touch pad, the second measurement point can be chosen and fixed by pushing the “Select” button. A connecting line and the distance between the two points are then displayed on the monitor.

Press the B-mode (2D button) to return to default 2D greyscale imaging.

Usually M-mode is displayed together with a 2D greyscale ultrasound image to allow spatial reference.

The 2D image has a graphical M-line superimposed to indicate the position of the M-mode beam that samples the data.

M (motion or time-motion) mode displays real-time ultrasound data derived from one single stationary ultrasound beam.

It displays depth along the vertical axis and time along the horizontal axis.

M-mode is primarily used in cardiac and lung ultrasound.

Colour Power Doppler (CPD) like standard colour Doppler detects blood flow through arteries and veins.

CPD does not indicate the velocity or direction of blood flow.

CPD is based on the echo amplitude received from moving cells – not the frequency shifts.

CPD is up to five times more sensitive than colour Doppler in order to detect the velocity of blood flow and can detect low velocity blood flow in veins and within organs. The strong flow sensitivity is the real benefit of CPD.

The operator can adjust the intensity of the colour Doppler signal by using the gain user control.

In colour Doppler mode the function of the gain control is switched to colour Doppler.

Colour Doppler is typically activated by pushing a button.

Colour Doppler is used to confirm whether there is flow in a vessel.

Colour Doppler displays a real-time 2D cross-section of blood flow.

When the colour Doppler is activated, the cross-section is displayed as a frame on the monitor. The shape of the frame depends on the probe. The position of the frame can be moved around using a touch pad.

Spatial orientation is obtained by overlaying the colour Doppler cross-section on top of a 2D greyscale ultrasound image displaying the soft tissues.

Conventionally, red colour is used for blood moving towards the probe, and blue is used for blood moving away from the probe.

The basic imaging mode is B (Brightness) mode, which is the greyscale 2D ultrasound image.

The B-mode button is typically called “B” or “2D” and it also works as a “panic button”. It allows the operator to escape all other modes and return to the default greyscale 2D ultrasound image.

Some simpler ultrasound systems do not allow adjustment of the exact position of the focal zone. Instead it is possible to select among a few steps.