The ultrasound image can be optimised by adjusting different user controls

The most important user controls are:
– Gain
– Depth
– Sector angle
– Time Gain Compensation

These user controls will be explained in greater detail in the next slides

It is important that you become familiar with these user controls on your own ultrasound system so you know how to optimise the ultrasound image in order to improve the diagnostic value of the images

This user control is similar to the brightness control of a television set

Some of the emitted echo signal is reflected back to the probe when the emitted beam hits a reflective interface in the tissue

The echo signal returning from the tissue is converted to an electronic signal by the probe

This signal is very weak and has to be amplified before it is processed into a greyscale image. The signal amplification is called “gain”

Undergain: If the user sets the gain control too low, the amplification of the electrical signals is too small, and the 2D greyscale image on the screen becomes too dark.

Overgain: If the gain control is set too high, the 2D greyscale image becomes too bright

The depth of the displayed image can be adjusted using the depth controls

When the depth of the field-of-view (FOV) is increased, it becomes possible to display deeper structures

When the depth is decreased, the FOV is narrowed around structures closer to the probe and deeper structures are omitted

Reduction of the depth means that the time from emitted to received signal is reduced; this allows a higher frame rate

During a “clean” rotation, the direction of the tail of the transducer should be kept 100% stable

Rotation can be:
– Right = clockwise
– Left = counterclockwise

For rotational instructions we do not make use of a secondary reference point

Example:
To obtain the correct subcostal 4 chamber view, alignment with the longitudinal axis of the heart often requires 10-20 degrees counterclockwise rotation

You will therefore often hear the supervisor saying: “Rotate the probe counterclockwise or rotate the transducer to the left”

Tilting is the most difficult transducer movement to communicate because it can take place in two planes

Tilting can be:
1. upwards or downwards
2. side to side

Reference according to the tail of the transducer and a secondary reference point is important during guidance in tilting of the probe

Example:
To obtain the correct LV parasternal short axis view the probe should often have an inclination with the chest wall of 20-30 degrees

You will therefore often hear the supervisor saying: “Lift the tail of the probe towards the right shoulder of the volunteer or patient”

Sliding of the probe can take place in any direction

When sliding the probe no other movements should occur

For sliding instruction a secondary reference point is important

Example:
To get the correct parasternal long axis view the probe should often be closer to the sternum

You will therefore often hear the supervisor saying: “Slide towards the sternum”

The image is generated by the transducer and the ultrasound system and then displayed on the screen

FATE and cardiac ultrasound employs multifrequency phased array probes that display the image as a sector on the screen. The sector is demarcated by the two radii and the arc. In the figure the two radii of the sector are red and blue

The red and the blue radii diverge from the probe at the top of the monitor (the skin surface)

The orientation indicator (OI) is at the right side of the screen by convention in cardiac ultrasound (contrary to all other clinical ultrasound applications where the OI is placed on the left side of the screen)

The blue and red radii on the probe sector always correspond to the radii on the screen

The probe can be moved in three dimensions, but the screen stays neutral

The probe is fitted with an orientation marker (OM)

On the image the OM is indicated by a green arrow

The OM facilitates the correct orientation of the probe on the patient

There are two ways to hold the probe properly during the FATE examination

The screw driver grip:
With either the back or the palm of the operator hand placed on the patient during scanning

The pencil or lipstick grip:
The grip on the probe is made with the first and the second digit
The third digit to fifth digit are placed on the skin during scanning to stabilise the probe

A terminology to describe the movement of the probe during scanning is important in order to optimise the image

During the workshop it makes it easier for the supervisor to give instructions without touching the probe which is crucial for the novice in order to achieve practical skill

There are many available descriptions of the method of manipulation of the probe

We recommend using:
1. rotate
2. tilt
3. slide

These movements are applicable to all scanning locations

As a novice – always move the probe in only one direction at a time