BUTTONS AND CHECKPOINTS
Every commercial house makes different ultrasound machines, but the most needed functions are buttons that are common for all of them (even if they are in a different location in the machine). Take your time to understand your ultrasound machine and make sure that you are familiar with the following list:
1. ON/OFF
Please keep the machine plugged in as much as possible, even in OFF mode!​
Image 1: Two different ultrasound machines with their on/off buttons.
2. New patient
Enter the patient's data (at least the surname and hospital number). It is also recommendable to enter the operator name or physician of record so you will be able to track your exams later.​
Image 2: Example of a new patient screen.
3. Probe (or transducer)
Generally, we will select convex, sectorial or linear (see next section). Keep them always clean, but make sure you use wipes without alcohol to avoid damaging the probe. Be careful with the cables; we don't want them trapped with the wheels!​
Image 3: Transducer selection after entering patient data.
4. Preset (or exam)
One of the most important functions! A preset is a set of imaging parameters that are saved in the ultrasound imaging system. When a user selects one of these preset or mode (examples: abdominal, lung, vascular, etc.), the system automatically operates under the corresponding set of imaging parameters. Each preset also has specific functions associated. In general, when you select a probe, you will have a list of presets that can be used according to the probe selection in two different machines.
Image 4: Exam or preset
REMEMBER
Presets can be readjusted according to your preferences and needs. Contact your ultrasound company's technical support and organize a meeting. Make sure that you have a few patients (from different ages) in order to adjust the presets with the technicians.
You can also label the presets as you wish and even prepare more than one preset for the same application, for example, "lung neonate" and "lung pediatrics".
5. Gain
It is a uniform amplification of the ultrasound signal received by the probe. More gain provides more brightness to the whole image on the monitor. You could start around 80% and adjust as needed. There is no absolute number.​
Image 5: Gain in a tactile screen (left). In a keyboard, there are usually two main options to increase and decrease the gain: rotating the main control button (right) or turning the B mode button.
Image 6: Abdominal right upper quadrant with different gains (done with a handheld device. Deficient gain (left), adequate gain (middle), too much gain, around 95% (right).
6. Depth
It allows us to determine the maximum extent (cm) we want to appear on the screen. Each probe/frequency has a minimum and a maximum depth. Select the one that optimizes the image of the structure we wish to study.
Image 8: right upper quadrant with not enough depth (left), adequate depth (middle) and too much depth (right).
Image 7: Depth in a tactile screen (left). In a keyboard, there are usually two types of buttons, either you find a rotational button (right) or an up/down button (bottom).
7. TGC (“Time Gain Compensation”)
It adjusts the gain to different depths of the image.​
Image 9: time gain compensation on a tactile screen (left) and a keyboard (right)
Image 10: kidney ultrasound image with hight time gain compensator in the superficial plane (left), middle plane (middle) and deep plane (right). None of the pictures are well adjusted and can lead you to misinterpretation.
8. Freeze
The image is frozen when the ultrasound machine stops emitting. Some machines allow you to move back or forward 5 or 10 seconds so you can stop the image at any point, make measurements or save as a picture.​
Image 11: freeze button in a tactile screen (top) and a keyboard (bottom).
9. Save image or clip
It allows us to save images/videos of what has been studied. The save button can be called "Acquire", "Store", "Still", "Clip", etc. If there is only one save button, it is usually predetermined to record a short video. If that is the case and the intention is to store an image, press the freeze button first and then the save button.​
Two Image 12: Save button on the top under the name of “Acquire”. To store a photo on the top machine, you’ll need to press “freeze + acquire”. The machine on the bottom has one specific button to save an image (still) and another one for videos (clip)
ULTRASOUND MODES
1. A-mode (Amplitude mode)
It is the simplest type of ultrasound, unidimensional. Graphic representation of amplitude and distance, the echoes plotted on screen as a function of depth. It is not used anymore as an image mode, but it has its therapeutic uses.​
2. B-mode (Brightness) or 2D (2 dimensions)
It shows up by default, and it’s the primary mode used in ultrasound. The ultrasound beam scans a plane through the body that can be viewed as a two-dimensional image on the screen. ​
3. M-mode (Motion
It shows the movement of the studied area (one single US line) on a time level.​
Image 15: an image of the diaphragm (hyperechoic line) on 2D (top). Observe the vertical line on the top picture that is traduced as M-mode on the bottom where inspiration and expiration movements can be appreciated
4. Colour Doppler:
It is also called CFI (Color Flow Imaging) or CVI (colour velocity imaging). It allows us to “see” the blood flow. The colours represent the speed (mean speed) and direction of blood flow within a specific area of the image (colour box)
Image 16: colour doppler mitral valve.
5. Pulse Waved Doppler (PW)
Allows to accurately measure the velocity of blood in a precise location in real-time. It doesn’t provide information about the structure, so it is usually combined with a 2D image, calling this combination duplex scanning.
THINK ABOUT IT!
Don't confuse red with arteries and blue with vveins! Depending on the angle of the probe, the blood flow can go towards the probe (appear red) or away from the probe (appear blue).
​
Take a look to the next doppler images of the radial artery (transversal view):
​
PROBES OR TRANSDUCERS
It is the most important part. Since they contain the piezoelectric crystals, they are highly fragile, as well as the cable that connects them to the ultrasound machine. It is mandatory to clean them with products which are allowed by the manufacturer (usually derived from the ammonia, no alcohol allowed), after and before its use, in order to avoid transmission of infections. The probes’ cables are extremely fragile, and they often touch the ground risking being pinched by the ultrasound scanner’s wheels. Please be always carefull!
There are two main characteristics:
-
Fequency: it is a probe’s determining factor. Probes are currently multifrequency and able to work in a certain range (low frequency, from 1 to 3-5 MHz, half frequency from 3 to 6-7 MHz and high frequency from 7 to 20 MHz).
​
REMEMBER
​
HIGH FREQUENCY ïƒ LOW PENETRATION (suitable for superficial structures)
LOW FREQUENCY ïƒ HIGH PENETRATION (suitable for deep structures)
​
-
Footprint:​ can be linear, convex, sectorial (“cardio”), micro convex and endocavitary. The linear ones are flat and, due to the arrangement of the crystals inside, they create a rectangular image on the screen. They are used to study superficial structures. Therefore, they present elevated frequencies. The convex ones create a truncated cone-shaped image on the screen and are used to study more general areas. They usually have a low-medium frequency. The micro convex probes present a conical image and usually have medium frequencies. The sectorial probes are more complex regarding their intern functioning. They create a conical image and are designed to study general areas from a small window (e.g. heart from intercostal spaces). Their frequencies are low-medium.
​
Image 18: Different probes (top) related to their images (bottom). Linear probe with frequency range 5 to 15 MHz (left), conves probe with frequency range 2 to 6 MHz (middle) and sectorial probe with frequency range 1 to 4 MHz (right). On the bottom we can observe lineal shape (left), cone (middle) and narrower cone (right).
It is highly important to take into account the probe’s orientation on the patient, so that we all do it in a similar way in order to enable a fast interpretation of the images. By consensus (except in the case of echocardiography) the monitor mark should be placed on the left of the screen. The probe mark will be placed on the patient’s right side for transversal views and towards the patient’s head in the longitudinal sections.
REMEMBER
The probe will normally be placed in 2 axes of the space:
-
Transverse or axial: probe marker towards patient RIGHT.
-
Longitudinal or sagittal: probe marker towards patient HEAD.
Image 19: Image of the gallblader on a transverse view (left) and longitudinal view (right). The blue dot is the marker in the probe and the screen (always in the left side unless we are performing a cardiac ultrasound).