Welcome to this edition of the Webinar vet entitled Ultrasound Techniques in the Equine. How to get the most out of your machine and hopefully achieve diagnostic images in some difficult cases. I'm Matthew Sinovic.
I'm a surgeon and laman diagnostician at the Lippo Equine Hospital in Hampshire, in the United Kingdom. This webinar will discuss how to get the most out of your ultrasound machine. And we'll look at some advice on tackling some difficult cases and regions.
It will also cover the basics of ultrasound guided injections. So here are the learning objectives for the talk. We'll cover some basic ultrasound physics.
I know that's a very scary topic or potentially a very boring one. We'll try and make that more interesting. How to set up your machine and what sort of functions it has go a little bit into patient prep and how to optimise your image.
And then we'll give a very basic, overview of ultrasound guided injection techniques. So I said, everyone may dread the term ultrasound physics, and wish there was a simple way on how to learn and understand the principles of ultrasound physics. And these are actually very relevant to your clinical practise.
Many of the resources on ultrasound physics that you encounter may seem to be too technical or don't actually relate to clinical use. I totally understand what you're going through, and I've seen countless people just gloss over ultrasound physics because it seemed boring or ir irrelevant. However, if you do spend some time learning these basic physics principles, they're essential.
And if you really want to improve or perfect your skills, you need to do that. Don't worry. We're gonna try and make the ultrasound physics and some of the artefacts as simple, easy and clinically relevant as we can.
So the definition of ultrasound is simply the vibration of sound, with a frequency that is above the threshold of what humans can hear. The frequency of ultrasound is, by definition, any frequency greater than 20,000 hertz. However, ultrasound, which is used in medical practise, is typically about a million hertz, or or one megahertz or greater there or thereabouts.
So the next time you pick up an ultrasound probe or transducer, just notice what frequency the probe is. It's usually a range that's often turn, turn bandwidth and It's usually between two megahertz to 10 megahertz, depending on the probe. You have the machine you have and what you're gonna use the the scanner for.
So, for example, a 2.5 to 3.5 megahertz scanner is generally used for normal abdominal imaging, and then a 5 to 10 megahertz is for more superficial imaging.
And those are usually things that we would use for, like tendon scans and, that sort of functionality. Now let's go over how an ultrasound device uses ultrasonic waves to create pictures on the screen. It traditionally does this by using an effect called the piezoelectric effect, or piezoelectric effect, depending on on where you are in the world.
This is simply the vibration of a piezoelectric crystal at the tip of a transducer that generates a specific ultrasonic frequency to create ultrasound waves. These crystals are easily broken, and they're very, very expensive. So that's why we try never to drop the transducer.
And you can crack little crystals and over time that will, if essentially affect how well your your transducer works. These ultrasonic waves can then penetrate through the body, soft tissue and return to the transducer as ref as reflected sound waves. These returning waves are then converted into an ultrasound image on the screen for you to view, so that is the beauty of the crystal.
Essentially, it uses an electric current to cause vibration. The vibration goes into the body comes back, and that wave of vibration is then converted back into an electrical current, which then creates a picture on your screen. So all of the ultrasound principles are based on the physics of waves.
And if you can understand some basic physics that pertain to waves, you can derive exactly how ultrasound images are formed, why ultrasound artefacts are created and how to use more advanced applications. So many of the newer handheld devices do not have the traditional pazzo electric crystals anymore. They now use silicone chips, but it operates on exactly the same principle.
Here is a very important ultrasound physics table. You can reference this, and basically what it does. It goes over the speed density, acoustic impedance and attenuation of ultrasound relative to specific tissue types.
So you may recognise it from other resources. May have never understood how use it. Don't worry about memorising it.
It really doesn't matter. What we're looking at here is the trends. And this will help you to understand why certain tissues look brighter or more echogenic when compared to others and why ultrasound waves get reflected or refracted and how ultrasound artefacts are formed.
So we'll go over the importance of these findings as we go through the talk. There are a few simple ultrasound physic principles that you'll need to know in order for you to optimise the use of your ultrasound machine and to understand these artefacts. Just invest a little time learning these basic physics concepts, and it will help you tremendously so thinking in terms of waves, an ultrasound device creates images simply by sending short bursts of waves into the body.
Understanding how these waves behave will be helpful in understanding how to optimise your machine and its settings. I'll try and make this as simple as possible and go over a couple of things. I've generally found to be most relevant and be able to use on the ultrasound machine.
Everyone obviously has heard of the term frequency, a lot of it, but and That's usually when we're talking about ultrasound transducers such as high versus low frequency ultrasound probes. What exactly does that mean? OK, let's get some definitions out of the way.
Wavelength is equal to the length or the distance of a single cycle of a wave. The frequency is the number of sound wave cycles per second. So the equation for frequency is the speed of sound of the sound wave, divided by the wave length so you can see from the equation.
As the wavelength increases, the frequency will decrease and vice versa so short of or more increasing frequency shorter wavelength. This is because the frequency is inversely related to wavelength. So the shorter the wavelength, the higher the frequency, the longer the wavelength, the lower the frequency.
This is why higher frequency ultrasound probes will give you better resolution. Compared to a lower frequency probe. A higher frequency ultrasound probe will emit shorter wavelengths, so the tissues will receive more ultrasound waves per unit of time with a higher frequency probe, which then means that all of these waves reflect back and give you a higher quality picture.
In theory, however, the trade off with a high frequency probe is decreased penetration because the piezoelectric crystals can only send so many sound waves out before the waves dissipate. And that's why a low frequency probe will get better penetration so you'll get a deeper image. But it may not be quite as sharp as the more superficial one.
So here is a graph showing the relationship between the frequency of an ultrasound probe and the resolution versus the penetration it's able to achieve. So here we can see that a phased array probe will give you great penetration and kind of OK resolution. A curvilinear probe will give you good pen penetration and good resolution.
And that's why that kind of is where we we use most of the time and then a linear probe has poor penetration. But great resolution. And that's why we use that for things like tendons, where we're looking for tiny little changes, and so we need great resolution.
They're not very deep in the body, so we don't worry about the penetration quite so much now. The speed of sound is also often referred to with ultrasound. So why is the speed or velocity of sound so important?
Well, the exact speed of sound in specific tissues does not actually mean much to you clinically, however, the change in speed between two different mediums is extremely important. This is the essence of how ultrasound waves reflect and refract and create important ultrasound artefacts. So when you don't need to know the exact speed of sound in certain tissues, you do need to understand how the speed of sound changes between different mediums, like soft tissue and fluid or fluid, and air or air and bone.
The average speed or velocity of sound in all mediums is about 1000 540 centimetres per second. However, depending on what medium the sound waves travel through, it can drastically change the propagation speed of sound as it passes through. So two factors that affect the speed of sound are the stiffness and the density of the material that's travelling through.
So the stiffer the medium, the faster the sound waves will travel. And that's why sound waves travel faster in solids than in liquids or gases. So the ultrasound propagation speed from slowest to fastest is air, then fat, then soft tissue, then bone.
And this happens because stiffer mediums have tighter particles to propagate the sound waves and therefore a greater velocity. Acoustic impedance is the resistance to ultrasound propagation as it passes through a tissue. Acoustic impedance is essentially a resistance and is probably one of the most confusing terms when trying to learn ultrasound physics.
If you're looking at equations of it acoustic impedance. The symbol is Z is usually a physical property of the medium of the tissue. It's dependent on the tissue density and the speed of sound through that tissue, so impedance is equal to density times the propagation speed of sound of the sound wave.
So if the density of tissue increases the impedance or the resistance to the sound, waves will increase as well. The importance of impedance and ultrasound becomes apparent at the interface of two tissues with significantly different impedance values, so ultrasound waves will reflect. When this situation occurs.
The proportion of ultrasound waves reflected back is proportional to the difference in impedance, or the difference in density of the two tissues, so reflection occurs with ultrasound waves when two adjacent tissues have significantly different impedance values. This is why bone and air appear as bright lines on an ultrasound and why you get the reflected lines. When you do a lung ultrasound or a pulmonary ultrasound, there's a great.
There's such a large difference between the impedance of the tissue of the bone or air that they will cause almost all of the sound waves to reflect back. So you get most of the waves back, and that's where you get a very, very bright picture instead of penetrating through. What is interesting is that the impedance values of air, which is extremely low at 0.00004 and bone, which is very high at 12, both cause reflection because of its drastic difference from the impedance of soft tissue, which is approximately 1.6 artefacts that are caused by reflection can be reverberation artefacts, mirror image, artefacts, comic tales and ring down artefacts.
But we'll get into those a little bit later as we go through the talk. Now refraction occurs with ultrasound waves when two adjacent tissues have slightly different impedance values. So when the ultrasound wave travels through tissues and meets another tissue with a slightly different impedance value, the speed changes somewhat, and this causes the ultrasound waves to change in direction.
The change in direction is called refraction. The degree of how much the refraction occurs is dependent on what angle the ultrasound wave encounters the second medium and how much of a change of speed there is in the second medium. This is seen mostly in situations at rounded interfaces between a fluid filled circular structure and the ad adjacent tissue.
So think an abscess in a lung or something of that sort of effect. This is what gives rise to the edge artefact seen in ultrasound with black lines arising from the edge of a fluid filled structure. So abscesses cysts, vessels in the bladder Attenuation is the loss and absorption of ultrasound energy through a medium.
Attenuation is a fairly easy concept to understand. Compared to impedance, it just describes how rapidly the medium reduces the intensity of an ultrasound wave as it passes through it. Two mediums with the highest amounts of attenuation are actually air and bone.
As you can see, attenuation is not simply dependent on the density of the material like impedance is. This is the reason that ultrasound waves can't pass through a or bone. The ultrasound waves either get reflected back because of the impedance mismatch or get absorbed because of the high attenuation.
Attenuation will account for the shadowing artefact, which you see in the bone. So if you want to speak the language of ultrasound, you'll need to refer to specific structures of an ultrasound image based on its ecogenicity. Ecogenicity essentially refers how bright or echogenic tissue appears on an ultrasound, and those are usually done relative to other tissues, So Anechoic is black.
The term anechoic on ultrasound means that there's no internal echoes are emitted. And there's a completely black appearance. This is most commonly seen with fluid filled structures, since ultrasound waves pass through the fluid without reflecting any echoes back to the ultrasound machine.
So a list of structures that appear anechoic or black on ultrasound un clotted blood, bladder transudate pleural effusions, ascites simple cysts. Hy The term hyperechoic, is bright or white, and so hyper co on an ultrasound means that a specific structure gives off more echoes relative to its surrounding structures, resulting in a brighter or whiter appearance. So here's an example of a plural line, so that's a long line with a very hyper co bright or white line compared to the surrounding tissue hypoechoic, which is darker or grey.
So the time term hypoechoic on ultrasound means that a specific structure gives a fewer echoes relative to its surrounding structures, resulting in a darker or a more grey appearance in the image. Here you see a hypoechoic or darker appearing liver compared to the right kidney. This is a human example.
It just gives you a very good contrast of, materials so you can see hypoechoic and the differences in grey ISO echoic on ultrasound means that a specific structure gives off a very similar echo relative to another structure on the ultrasound SC screen. So basically, those two have fairly similar densities of tissue. Ultrasound artefacts are frequently encountered, and they can be a source of confusion.
When you're trying to interpret things, ultrasound artefacts can essentially be understood with a basic understanding of the ultrasound physics that we've just discussed, and these are pertaining to reflection, refraction and attenuation. The ability to recognise and fix correctable ultrasound artefacts is important for getting quality ultrasound images and also for optimising the care of your patients there's a list here of the basic artefacts, and we'll go through most of those. Some of them are relevant to veterinary.
Some of them are not, but, and particularly with with equine work, but they're always good to go through and have a good idea of what you're looking at. Acoustic shadowing, occurs when ultrasound waves encounter a structure that is a high attenuation coefficient. You'll most commonly encounter this or encounter the acoustic shadowing artefacts with structures when you are scanning bones.
So mostly you think about ribs and or splint bones in the horse posterior Acoustic enhancement is the opposite of acoustic shadowing artefacts, and this occurs when ultrasound waves pass through a structure with significantly low attenuation, so blood or fluid filled structures. And then you will see enhancement. On the back end of this, the most common situation where you will see this sort of acoustic enhancement is if you do get through the bladder, sometimes insists on the opposite side of vessels.
And where you see this quite nicely is if you ever perform ocular ultrasound, and you can see the back of the eye or into the cone behind edge. Artefact on ultrasound occurs because of refraction at the edges. The ultrasound waves are deflected from their original path When they encounter the curved and smooth walled structure, this will usually result in a shadow like line that comes off the edge of these structures, as you can see by the two sort of blue outlined areas over there, which is an edge artefact of an internal carotid artery.
So the most common times you see, these are in round structures. So vessels, abscesses, cysts, reverberation. As we've alluded to before in the lungs is where this happens most commonly, and this in the presence of a highly reflective surface.
So in this case, the echoes reflect back and forth between the reflective surface and the ultrasound probe. This can cause the ultrasound screen to record and display multiple echoes on screen. And then each one gets slightly deeper because of the time it takes to go in, come back, go back in, come back.
And basically they double and then triple and then quadruple on the screen. So this ultrasound artefact is known as a reverberation artefact. And here we use the pleural line, which is a highly reflective surface.
As an example, the ultrasound waves that return after a single reflection represent the actual pleural line. So the white arrows, on the line and all of the subsequent subsequent echoes the blue, the green and the red arrows will take longer to return to the probe than to the ultrasound will in turn, will interpret those as increased equities equidistantly space linear reflections. These other lines are known as a lines, and basically, they're just, they're just an artefact comet.
Tail artefact is a form of reverberation in the comet tail artefact. The two reflective surfaces are closely spaced together, such as the bevel of a needle. The reflective surfaces are so close that it's difficult to distinguish between each reflected echo.
Comet tail is different from a ring down, and we'll get into that next because the comet tail artefact dissipates with depth and has a triangular and tapering shape. And you can see the image over there, and that's from a needle tip in a cyst. We used to think the ring down artefact was a type of com artefact.
Since both have bright echogenic lines from a specific location. However, the ring down art in that both echoes do not dissipate. As the depth of the image increase.
These ecogen vertical lines will go all the way to the bottom of the screen, regardless of the depth. So this has become known as a ring down artefact, or often referred to as B lines in lung ultrasound. The theory of the ring down artefact is that when you get when fluid is trapped in a tetrahedron of air bubbles, the ultrasound waves reflect infinitely and result in an infinitely long vertical line.
So this is specifically where you have a gas and fluid interface and the gas is trapped up Or is it? Or the fluid is trapped in the B? Right.
Let's move on to, using your machine a bit, and being a real time imaging modality. Ultrasound images are almost always interpreted by the operator at the time of the exam, so obtaining optimal image quality throughout the scan is very essential. In order to maximise your clinical information that can be obtained and help you get to a diagnosis, so we'll go over some of the main control features that are likely to be present on most machines will cover gain depth focal points, as well as some other options that may be available.
Tissue harmonic imaging, speckle reduction. Some of those are only available on very fancy machines, and may not be available on all portable machines. But it's good to know what's out there and what's available.
And we'll try and see if we can go through how they can be optimised to get the best possible image for you. Quality of images is like a lot of things and very dependent on the skill of the operator as well as the available equipment. Whatever the spec of your equipment used, you can frequent manipulation of the controls during any exam is essential to kind of gather as much information as you can.
Manufacturer presets may be available for different anatomical regions as a starting point for an exam. However, the image quality is always subject is always a subjective assessment, and users may have varying preferences, so you may like darker colours or brighter colours or a brighter screen or a darker screen, and these can differ from preset values. Don't be afraid of the buttons and changing the settings.
It will take time, but you will soon learn how to get the best from your machine. So overall gain, the overall gain controls the brightness of the image, similar to the brightness control on a computer monitor or television. The aim here is to have the screen bright enough to see the image clearly, but not so bright that you start to see echogenicity within normally anechoic structures such as urinary bladder.
Reducing the game slightly when scanning fluid filled structures, and increasing it when imaging solid organs may therefore be helpful. Ambient light levels will also influence the optimal gain. So if you're scanning in a bright stable, or outside, then you may need to increase that, so you'll need a higher gain in order to look at, the structures you're imaging.
So here's an example of two of the same structure with the gain turned all the way down, on the top left, and then as soon as it's turned all the way back up, you can see the 10 and the structures there. Time game compensation controls usually consist of a row of parallel slider buttons. These or the aim of these controls is to obtain an even brightness throughout the entire field of view.
This is necessary because of the attenuation of the ultrasound beam as it travels through the tissue, and again, due to reflection, absorption and scattering. This attenuation means that reflections of the sun being from deeper structures are weaker than those from similar tissues from similar tissue interfaces. Position more superficially.
Without time gain compensation, the image would have a light, dark gradient running from the top of the image to the bottom of the image. In the far field, the sliders are typically set in a diagonal fashion from left to right, like so so that the deeper structures are amplified more to compensate for the reduced sound intensity in the far field. The setting of the slider controls is often reflected on the screen by a line paralleling the edge of the image depth.
Every ultrasound machine displays a scale on the screen that marks the image depth. This is usually in centimetres on the side of the screen. The depth control allows the operator to manipulate the display depth, an independent zoom control may also be available to enlarge a selected area of the image.
The depth setting should be changed according to the size of the animal, as well as the structure that you are imaging. For example, if you want to look at a whole kidney, you'll need to have a relatively deep area and a horse. You're talking kind of maybe 15 centimetres.
Whereas looking at a more superficial structures, it may be adequate to include only the first sort of 2 to 3 centimetres of tissue. As a rule of thumb, what you want to do is just adjust the depth of the image until the area of interest fills approximately three quarters of your screen. To maximise the level of detail that you see like that completely filling the screen with the structure of interest is not usually optimal.
As useful artefacts such as shadowing or distal acoustic enhancement may be missed. As well as the atomical anatomical relationship to adjacent structures will be more difficult to determine, so reducing the image depth has a small added advantage of increasing the frame rate, and therefore you'll get more temporal resolution, so your image will be a bit sharper, as the machine will not have to wait as long for the echoes to return from deeper structures. Although some machines may have automatic focusing, many have been met with an adjustable focal zone, which is indicated by an arrowhead or other symbol along the the depth scale.
The focal zone setting indicates the point at which the ultrasound beam is na is narrowest widthwise and is therefore the point at which the best lateral resolution so across the image is obtained. The focal zone should be set at or just below the area of interest, within your field of view. So, for example, if you're looking at a loop of small intestine, adjust the focal zone that it lies at this level, it may be possible to set more than one focal zone in an image.
This does come with a trade off of proportionally slowing the frame rate, and this is because the ultrasound machine is now sending out multiple sound beams, each focusing on one of those focal zones. This takes more time and may lead to a slow motion or lag effect on the image for this reason. More than one focal zone is not always recommended for things like cardiac scanning, where structures are moving relatively rapidly.
If a scanner does not show the focal zone with a marker by convention, the focus is around the middle of the image, and it becomes necessary to change the depth to ensure that the structures of interest are central. In what you're looking at. Many transducers will operate at multiple frequencies, and most ultrasound systems come with the option of several interchangeable transducer types.
Increasing the output frequency leads to an increase in the axial resolution, so top to bottom of the image. However, increasing the frequency does come with a trade off of reducing penetration. As we've said, some machines will show the actual frequency in megahertz.
Others don't show the frequency, and they offer you choices of like a resolution. And that may be res of some sorts, which is suitable for superficial imaging, Gen. Or a general, scanning tool for moderate depths and penetration or a pen setting for deeper structures.
The aim is always to use the highest possible frequency setting that allows you to assess the area of interest because that means you're gonna get the best image quality. Linear probe, can be used for tendons. And that's the ideal probe.
Rectal probe is also a linear probe and can be used for tendons. You will, Depending on the quality of it, you will get, good images. And in certain cases, using things like a micro convex probe for suspense ligaments or, tiny past and ligaments is ideal because the small head can be fitted, neat and snugly snugly into the anatomical locations, and get good contact against the skin again.
A 5 to 10 megahertz is the ideal frequency. Most machines it's possible to flip and invert the image. Flipping the image from right to left can be useful either to obtain a conventional image orientation.
So getting like cranial to the left or something if that works better for your brain or depending on O on your operator preference when performing an ultrasound guided procedure. However, the same result can also be achieved by rotating the transducer through 100 and 80 degrees. So, entirely up to you as to how you use that, you can also invert it so inversion such that the area immediately adjacent to the transducer that lies in the far field of the display can also be a selected option.
It's really very helpful in, veterinary, and I don't know anyone that's ever really used it. Dynamic Range is often buried within the menus but can be considered together with the B mode gain and the grey scale map. The higher the dynamic range is set, the greater the spread of echo of echo strengths, so therefore, the more shades of grey you'll get between black and white.
High dynamic range settings, therefore, make the image smoother and less contrasty, as you can see as it goes across the gradient here. If scanning in a light room, it may help to lower the dynamic range to give a higher contrast as our ability reso to resolve. Subtle grey scale differences in bright light is relatively poor, so if you're very, very bright in a very bright outside area, scanning a horse, you might wanna down the range, and that may help you get a better image.
Adjusting the grey map has a very similar effect on the ultrasound images, changing the dynamic range. But the mechanism is slightly different. This is a setting, usually again in the menus of your, machine.
And usually what you should do is just play around and see which suits you. Whilst dynamic range adjusts the number of shades of grey, a grey map determines how brightly each level of grey or white is shown based on the strength of returning ultrasound considering and adjusting the dynamic range and grey scale in conjunction with each other may be the best approach to optimising your image quality. And this generally comes down completely to us, a preference and what you prefer.
What I like in my grey map and my dynamic range may be very different to you. And that is purely just from a case of what you find easier to see and how your resolution works. Power output is a setting that's also usually found in the menus, rather than a direct button on the control panel.
The power setting is basically like turning the volume of the sound up, but in an ultrasound pulse, a stronger, louder pulse will generate stronger echoes, which is generally good. However, higher power settings can lead to an increase in internal reflections, creating more artefacts such as reverberation. But generally this is good for abdomens or things like that, where you're trying to get, a deeper penetration.
Harmonic imaging, is a tech is a functionality that helps to reduce artefacts and increase resolution in the image. It achieves this by sending and receiving signals to different ultrasound frequencies, with the returning frequencies being a harmonic of the initial one. So, for example, with harmonics on a probe may emit a fundamental frequency of four megahertz but would only listen for a returning eight megahertz frequency.
A machine capable of harmonic imaging will usually have TH I harm or H I or a similar control in the machine. When it's enabled, it's typically adjusted by the frequency control. If available, try imaging an area with and without the harmonic imaging activated Kind of see the difference in the in the two images here to see if the image improves, as in the near fields of large hum of large patients with a thick body wall, sometimes may have less, application in veterinary patients, but is sometimes good for fatter horses.
Speckle is seen in an ultrasound image as a granular pattern, which is formed from constructive and destructive interface of back scattered ultrasound waves. It lowers the image contrast and generally obscures the detail various imaging techniques based on altering the beam frequency or beam orientation. So spatial compounding and or digital filtering of the image have been applied to try to reduce the speckle and improve the image quality.
Different manufacturers have different speckle reduction techniques, and they all have very different names. Machines that include this feature of varying levels of speckle reduction so you can see speckle reduction on an image there on the left, going to the right so very, very grainy on the left, slightly less in the middle and then quite smooth on the right. The lowest level reduces small amounts of artefact and slightly enhances the tissue, while the strongest can look almost over processed.
Often the mid-level one is the one that you prefer. Brain averaging or persistence is basically a temporal smoothing function in which large multiple image frames are combined or averaged into a single image. The effect is similar to that with spectral reduction in that the image appears smoother with reduced noise coming back from from your, patient compound imaging.
This technique is also named differently by different manufacturers. With names, including cross beam. CR.
I so OCT I beam omni beam. Look in your manual and you'll find out what yours is called if you have it. A compound image basically combines three or more images acquired from different angles and puts that into a single view.
This is achieved through an ultrasound drug user sending signals at multiple angles. That's usually on sort of a phased array type probe, which helps to eliminate the artefact, including speckle and increases the edge detail. Compound images is available only usually on linear and convex transducers, not on sectors.
So auto optimisation may come as a standard feature. And many machines come with a feature that analyses the returning signals from tissue and then automatically optimise the gain and overall contrast. This synonyms for this are also auto tuning or tissue equalisation.
If your machine has this feature, try it. But also try changing things yourself, often setting it up, how you like may be better. And, you'll there's further room for improvement rather off the off the opt off the auto optimisation standard pads are used when you are trying to image structures in linear field.
And this basically improves contact specifically like around the back of the tendons, which are curved surfaces and you're using a linear probe. It's an acoustically neutral pa pad, and it moves the probes about a centimetre away from the skin surface, depending on the, pad that you're using and that allows you to get better detail of structures in the near field, basically for tendons and ligaments. And you can see here the image on the left has no standard of pad, and the image on the right has that centimetre in the near field.
And you can now see nicely the whole, anatomy that you're looking for, as well as see all of the edges nice and clearly incidents. So, basically, you want to scan on incidents most of the time, and in order to do that, you need to be at right angles to tendon fibres in order to get the best reflection. So that is that sort of thing there and then off incident.
When you go at an angle, you will get a reflection like that. However, off incidence images are useful. Particularly when we are scanning dispensaries.
And when we're scanning them on weight bearing, we use this very, very much. Don't be afraid of it. But also don't overinterpret it and know that you need to check the normal on incident scan before you're calling something a lesion.
But you can often get better definition of the thing that you're looking at by looking at it with an off incident scan. So this is kind of the thing we're looking at here on when it's nice on incidents on the left, off incidents on the right. So that is basically what you would call an off incident artefact.
But what you can see here on the off incidence image is that you can see quite a nice edge to it and get quite nice detail of the edge. So don't be afraid to actually use this to your advantage. We used to get very, concerned about being on incidents all the time, but certainly, as techniques are improving and, we are advancing.
We can use these sorts of techniques to get a better overall idea of this thing that we're scanning. Generally off incidence mostly is used in, tendon and ligament scanning area preparation. This is very, very important.
Mostly, we are using clippers to clip the hair off. The reason for that is that air gets trapped between the the hair and that stops the penetration of the ultrasound. So very hairy horses, you won't get an image.
Thoroughbreds often have very fine hair, and you won't need to clip them. What you can do is use a soap to decrease the skin. At the same time, the water will get the hairs to cling together, so that will reduce the air between them.
And then you can wipe with isopropyl alcohol. Isopropyl alcohol is better than other surgical spirits, et cetera. It's less damaging to the probe, so long-term you won't wear out the plastic of your probe and damage those crystals.
There's varying feelings on ultrasound coupling gel. Certainly when you are starting out, I would say always use lots and lots of coupling gel and my best hint and tip is to apply the coupling gel. Let it sit for a little while while you're setting up your machine.
Or if you have someone to help you, then let them clip, scrub the skin and apply the, coupling gel liberally. Let that soak in for a while because that's gonna help your image. And always do both limbs Or, if you can If you're, doing something else, try and prep both areas so that you have, a normal comparison as well as an abnormal getting on to some guys for for difficult patients.
If you work in the UK, you'll see over there on Gypsy, then or on Gypsy Cub. They are often a nightmare to scan. Other things that are very, very difficult to scan are often grey horses.
That's because of the high content of melon in their skin. In these cases, clipping is essential. Make sure that you're scrubbing well, S apply gel lots of gel and give it lots of time to soak in.
If you aren't getting an image, what you may need to do is almost to put the gel in under a bandage and let that soak in overnight, or over a couple of hours, If you're on a yard and doing some other things that you can always prep the leg first, put it, under some cling film with a stable wrap on over the top, Let that gel really, really soak into the skin, which is gonna help your coupling and help your, get you get you some images, go up and do your vaccines. Do your dentals whatever else it is, and then come back to it and scan it as a last thing. Make sure that you play with the game and your focus points and always try to reduce the frequency as much as possible so as higher frequency as possible in order to get the best resolution you can.
And unfortunately, with these sorts of things, it is often a game of, of try and see. In some instances, I will use a mixture of gel and alcohol so I will gel the skin, let it soak in over some time and then apply isopropyl alcohol liberally again. And that sometimes gives you good contact, and it means that you can get a decent and diagnostic image, right?
Ultrasound, guided injections. So we're gonna practise. You need to practise the basic techniques in order to perform successful ultrasound guided injections.
And mostly you have to, master two basic skills here. So the most important thing and I cannot stress this enough is needle to ultrasound beam alignment. And what we mean by that is staying in plane.
And that basically means that your ultrasound needle is parallel to your transducer at all times. And we'll go into this a little bit as as we go through. My mainstay is down the side of most transducers, and you will have a little line where the two sides of the transducer are clicked together.
And I try to make sure that my needle is always, always parallel and in line with that line, which means that I can always see my needle in the image. And the other point is to pre or the other tip basic seal to mask. That is accurate positioning of the needle tip, and that comes with practise.
So a good comprehension of the anatomy, and its variations are very very important in the groundwork of your ultrasound guided injections. And you need some good hand eye coordinations, which is an ex, an essential skill for safe needle placement. Visualisation of the moving needle is important, to perform a rapid and uneventful injection.
And essentially, you need extensive practise, in order to learn to align the needle and the ultrasound beam precisely. But, frequently you'll hear me in the next couple of slides talking about staying in plane, and that is really, really the most important thing. Here we have in the picture here, an injection of a back facet joint.
And in this image over here, you can see at the top, right? The needle coming in. You want to be able to visualise it all the time to be sure that your needle is where you want it?
If it's not working, you need to stop. Reset yourself and be sure that you can see the needle come in and that you can follow it. Tracking things to be aware of here, are the position of your hand in space the problem with many of or many techniques when you're doing?
Ultrasound guided injections is that you are looking over your shoulder or moving, and as you move, you get micro movements in the probe. So what you really wanna be sure of is that your probe stays still and that your needle orientation is always the same. And as as long as it's there, you will see your needle, and you will be able to guide it where you want it to go.
The most common mistakes for novices are not viewing the needle and just assuming that it's where it is and failing to visualise the needle before you advance it. So just get it into the skin. And if you need to bleb the skin in order to facilitate this, that that's a very, very good idea.
Get your transducer in position. See the anatomy that you wanna see create a blip on the side where you want the needle to come in. Pop the needle just through the skin in plain parallel to your probe, straight through the skin right on the edge of the transducer.
You'll see the tip of the needle, and then you can advance it, and the other most common mistake as we said before is frequent unintentional probe probe movements. And that's usually because you're too busy focusing on too many things to get your probe stuck and still, and your probe moves just off plane and then you can't see your needle. Ultrasound guides are very useful, and the needle guidance device has been designed to allow a bit of visualisation of the needle.
Essentially, what this does is it takes one factor out. So if you have these when you're starting out, it's exceptionally useful. This is one which is adjustable, so it has two angles, of penetration, one for going in slightly deeper and one for going in slightly more superficial.
And what this does is basically is it just keeps the needle completely parallel to the transducer at all times. A recent study showed that the use of the needle needle guide device, improved needle visualisation, reduced procedure time and increased user satisfaction scores. However, the needle G device used in the plane approach does allow the user to see the needle at least 60% of the time.
But what it does do is that it won't allow needle replacement, so If you're heading off in the wrong direction, then you're buggered. You have to pull the needle out, reposition and, go again. It also prevents free, transducer movement.
So it limits those two things. But it does mean that you are stuck where you have decided to inject. So tips prepare and get comfortable.
Check your setup and make sure that you are could see your needle. So what I do to try and stop the transducer from moving where possible is to anchor my hand and my elbow to incr increase stability of that. And you can do this by utilising your elbow or your wrist or whatever.
So anchor your hand on your patient. And then, as you can see there in image three, you can see the short end of the ultrasound probe. It's got a little groove down it, and you wanna keep your needle in line there.
Horses are often quite big, and when we're doing these things, they're often, sacre axial backs. So make sure that you have the appropriate height, so you use a step or a positioning tool or something to ensure prior to injection that you are stood comfortably next to your patient, and that the region you're trying to inject is close to you. Ensure that the ultrasound screen is in the same field of view as the body part that you're injecting.
So don't have it over your shoulder, because then you're gonna rotate or twist, and that's gonna move your probe. Aim to maintain continuous real time visualisation of the needle, tip all the time in relation to the target and to the surrounding structures, and then prevent movement of the transducer relative to the needle trajectory by anchoring your hand and holding the transducer. Transducer control can be improved by supporting the elbow forearm on your patient, as we said, and then make sure to visualise the short end of the transducer so that the needle is easily seen.
When it's inserted. You can always if you're on a stool, take a bird's eye view of the transducer with the needle in plane of the transducer to make sure the needles advance along the entire footprint of the transducer. And this will help minimise what we call crosscut artefact.
So some specific techniques now, the bottom one there. Using sterile gel as a standoff is a human technique but is very useful in, superficial things. So if you're injecting a tendon and we'll get on to that a little in in a bit.
But some of the things techniques to talk about here, fish tailing. So to make sure that the entire needle is visible before advancing the needle further, keep the transducer still, while the needle is visible and intimately rotate the other end of the probe from left to right. Stop when the entire needle is completely visualised.
So by fish tailing your rope, you'll get the needle in plane, and then you can advance it heel to toe. With a steep needle trajectory. Consider improving the angle by pushing one end of the transducer.
So the part of the transducer that's furthest away from the needle into the soft tissue in order for the transducer to be more parallel to the needle and that improves your visualisation as you go. And then, as you said, using a standoff or using, ultrasound gel so sterile gel, as a standoff can be helped to visualise the needle trajectory even before entering the skin. Sometimes sometimes that's very superficial.
So if you're trying to, like, aim into a core lesion in a superficial digital flex attendant, something like that that's quite useful. But it is. This is not a basic principle.
This is something to, try a little bit, when you've got a little bit more, practise and you're a little bit more confident with the whole thing. When injecting, it's possible to get a more parallel needle position by inserting a needle at a distance away from the probe. But in playing with the probe, so that's this is injecting away from the probe.
This makes it possible to inject deeper located structures with good with good needle visualisation. And this is like when we're doing sacro iliac injections. You do, however, need to ensure that you understand the anatomy adjacent to the probe so that you know how to get the needle through the tissue.
And then you'll see it as it's visualised on the ultrasound. OK, so that I think is AAA whistle stop tour through, how to all of the the physics of your machine, how to optimise your image, how to deal with some difficult patients and the basics of your ultrasound guided injections. Key points I hope you take away from this are maximising your image.
Quality is critical even with lower end equipment. Understanding and manipulating the available settings you have will help you get the best image you can and that that sets you up to succeed when scanning as you move between different regions or different depths, always think about the display depth and the gain, including your time. Gain compensation and adjust these to optimise the image for your area of interest.
Think about what you're aiming to look at and set your machine accordingly. Always select the highest possible frequency setting that allows you to see the depth of the structure of interest. If the focal point can be manually set, move it level two or just deep to your area of interest within your displayed image.
And then, as you said, there are many other I or image settings available. Look at your user interface or your keyboard and your menus, and you use a manual for these and don't be afraid to play them. Play with them, try them even if it's on yourself or get your dog at some point and scan.
Scan them and and just play around with your machine till you know how to get the best out of it. And, get the best image you can and set yourself up for success. Be patient.
Have good patient preparation and prepare for yourself. Practise a lot. Practise, practise, practise.
Use your ultrasound for every single thing you can, and I promise you'll be great at it. Thank you very much for your time, and I hope that was very informative, hope to see you again soon.
