All right, thank you very much, Sophia, and welcome to everybody. I'm going to start this morning's session, where I'm just going to cover very general imaging of the equine heads, and then my colleagues are going to take you. Through Alison's going to take you through CT imaging of the heads and Justine then is going to talk about more dental related CT imaging, and followed finally by Dave Stack, who's going to take you through imaging of the equine neck and investigation of diseases that occur in the equine neck.

So mine is going to be a little bit more of a a general presentation just to sort of set the scene. So many of you, I'm sure, will be used to working up horses who've got some form of disease process going on within their heads. And as you'll be aware, certainly compared to some of the other species we might be dealing with, such as dogs or cats, the horse has got a much larger heads, and it's got a pretty complex anatomy in there as well.

And to add to that, we've got bony structures, dental structures, soft tissue structures. So there are lots of different disease processes that can occur, and to add into the mix, we've also got the guttural pouch, which obviously, is unique to our aid species compared to other animals that we might be, undertaking veterinary investigations on on a regular basis. In terms of deciding what we're going to do and with regards to imaging of the heads, and it's always important to make sure that we've got a good sort of idea as to what might be going on there and having a good history and performing a thorough clinical examination and looking at that presentation of the horse is really important.

And this can vary quite markedly, as I said, there are lots of different disease processes that can go on in the heads. And that also means that there are lots of different presentations which might point you towards different tests that you might do as a priority. So obviously, a horse that presents with respiratory noise, particularly if it's at rest, you might go off to endoscopy pretty quickly before doing anything else.

And similarly with dysphagium coughing, exercise intolerance will run through some of the diagnostic imaging modalities that you might prioritise there. And then you might have cases that present with a nasal discharge, and obviously the nature of that discharge is really important, whether it's hemorrhagic, pollent material, or whether it contains foods. And obviously making sure that you observe any obvious deformities of the head and make a note of any neurological abnormalities.

So as I've already mentioned, there are lots of options that are available to us, and I'm going to run through all of those sort of more commonly utilised imaging modalities. All of you, I'm sure will be very familiar with these, particularly, endoscopy, ultrasonography, and radiography. Synoscopy and cintigraphy, I'll give a little bit of an overview about, as these may be modalities that some of you may be, less, used to undertaking or working with.

And then the rest of the talks today are going to include quite a lot on computed tomography, and I'll briefly touch upon magnetic resonance imaging. And these are modalities that really have come to the fore in equine in the last sort of 10 years. And as technology has improved, and there's a greater availability of these, partly because the technology is also more affordable, and then these are certainly something that we can utilise to further investigate, what's going on in that horse's head.

So, as I said, the initial assessment is very important. It's, vital so that we can prioritise which are going to be the most useful and, in, in which order we're going to undertake these. So, as I've already mentioned, taking consideration of the presenting complaints.

Getting an accurate history from the owner or the agent, of course, and then making sure that you've thoroughly assessed the horse, to make sure that some subtle abnormalities, which maybe an owner might not have picked up, have been assessed, because again, that may, alter how you prioritise, those, imaging modalities. So I've mentioned some of the clin clinical presentations, but making sure that we've been thorough in assessing the head prior to making our, our decision about imaging is really important. So have a logical approach to this.

It doesn't really matter which sort of order you do these in, I guess as long as you're systematic and thorough. So some of the factors that would be important to consider is particularly if there's been some sort of acute traumatic events, is that sort of horse's level of mentation and whether the horse is showing any neurological abnormalities. It would certainly be horses that you might be very cautious about, sedating and certainly performing general anaesthesia on.

So I've already mentioned respiratory noise at rest again, that does merit, fairly immediate, endoscopic evaluation, because those horses might be at risk of collapse if you can't, if they haven't got a, an open airway, and tracheostomy, might be something that you need to consider, particularly if they're really struggling to breathe. Then running through nasal discharge, checking whether there's nasal airflow down one both nostrils. And there may be an obvious facial deformity, it might be more subtle.

But good thing is that horses have a left and a right side, so at least you can look to see if there's any asymmetry. And where any swellings are, is going to be important in terms of what might be going on, depending on the local anatomic structures, but also whether those swellings are quite firm, sort of bony in nature, or whether they're fairly soft. Again, that will give you some sort of ideas as to how useful some of the imaging modalities will be.

Wounds are important, taking a careful note of those, and also any discharging sinus tracts. Again, they will give you a clue as to what might be going on beneath the skin, and what sort of disease processes, and imaging modalities that might be useful to further investigate those. And in terms of our clinical examinations, some other factors, some other types of examination that might be useful are intro, and particularly to assess the teeth and the tongue, and, an ophthalmic examination, and I'll run through some cases where, those, each of those would be warranted.

So, the diagnostic test that you're going to choose is obviously going to be based on a number of factors. So what do you think the likely disease process is and where it might be located, and which modality, therefore, will be most likely to be helpful. I've already run through the status of the patients, so identifying those where you might not be wanting to rush into performing a test under general anaesthesia.

And also, which is probably most important, the types of equipment that you have available to you and your expertise or the expertise available to you, not just in acquiring some of the images, but also in interpreting those. So we'll come back to this horse a little bit later on in the presentation, but this was a, an event horse that was out, having a practise session on a cross country course, and, took off, without the rider, and, bizarrely managed to gallop straight into a tree, which, was a bit ridiculous, given it was in a space where there weren't many fixed objects, but the horse successfully ran into that. So obviously, we've got a horse here that's had a quite Blunt, high force, impact the heads, and you can see that there's likely to be some sort of damage to the eye and associated structures.

So we'll come back, to her, further during this presentation. And the other thing I guess I have to mention as well is owner finances. There might be lots of tests that we want to do, but whether an owner is willing or able to afford those may also limit what we're able to do.

So I'm just gonna start with endoscopy of the heads and just run through some aspects of this. I'm not going to go into massive amounts of detail during each of the assessments of the more commonly used modalities, because I suspect that many of you are quite used to using these on a regular basis. But certainly endoscopy is a very widely available imaging modality.

It's minimally invasive and it allows us to see most areas of the heads where some of the important pathologies may occur in the horse. It also gives us some options for treatment. So for example, if we want to remove or penetrate tissues within the upper respiratory tract.

So our main indications would be horses that present with a nasal discharge or some sort of malodorous smell, and you'd certainly want to make sure that you've accurate accurately assessed the nasal passages and to see if you can get some clues as to where that discharge is coming. From. So whether it's coming from the sinus drainage angle here, or the osteo and to the guttural pouches, or potentially if you've got some sort of discharge that's coming from the trachea, which would suggest that you need to investigate the lower airways more.

As I've already mentioned, a horse that's making a respiratory noise, and the endoscopy, of the larynx and pharynx and nasal pastures, is very useful to directly visualise those areas and important in a horse that might be close to collapse, in making sure that you can get a patent airway. And horses with dysphagia, obviously you'd be worried about potential neurologic reasons for this and where you'd want to make sure that you can assess the guttural pouches. So, assessing the nasal passages, pharynx and larynx, it would be difficult or more complex to be able to diagnose many of these conditions by other imaging modalities, and it's great that we're able to directly diagnose and horses, so just some of the more common ones, so an epiglottic entrapment here, a persistent dorsal displacement of the soft parts, a suburb.

Glottic cyst, and this one down at the bottom was a pony that presented with severe dyspnea, perhaps not a surprise, given that you couldn't really see how this pony was managing to breathe. This pony was an aged pony, had a relatively iculated lesion around its laryngeal area, which was confirmed to be a squamous cell carcinoma. As I mentioned, the horse is unique in having guttural pouches, which are really critical structures for us to consider with diseases of the heads and knowing what's normal and what's not, and some of the more common and important diseases.

So obviously we've got a a normal guttural pouch here, with the large, . Medal compartment and the smaller lateral compartments, and also being aware of the the cranial nerves that run through the pouch, but also the vascular structures, which can cause life-threatening disease. So we've got our internal carotid artery here and our external carotid stroke maxillary artery.

So some of the more common diseases you'll all be familiar with, I'm sure, is guttural patch mycosis. This horse had a haemorrhage. You could see blood emanating from the oste guttural pouch and, endoscopy could confirm the location and the nature of the disease process.

And then we come down to emyema, the guttural pouch, and then, more established chondroids. Endoscopy is a really flexible tool if you think about virtually any orifice a horse has, you can usually get an endoscope into it. So you can look at bladder, you can look at rectum, but also with upper airway things, it's sometimes worth just thinking slightly outside the box.

So this was a case that actually we wrote up fairly recently, was a gelding that presented with a respiratory noise. I'm at rest and the exercise, it's quite marked exercise. And you can see these sort of this sort of bilobes and soft palates.

It was very difficult to work out what was going on. I'll come on to radiography of the larynx, but we can see this caudal border of the soft palate looks a bit abnormal, it looks a little bit sort of blunted and thickened. But by inserting an endoscope in retrogradely, so we did a tracheostomy and inserted the endoscope in so that we could actually visualise that cordal border of the soft palate, and that enabled us to be able to access this with the laser, and confirmed that these were bilateral.

Palatal cysts, so it enabled us to more accurately sort of diagnose what was going on and to establish treatments. So sometimes just taking a slightly different view of things, and there are lots of ways you can do this can be very helpful. Dynamic endoscopy is something that's really revolutionised and the ability to assess what's going on in horses that make a noise at exercise.

And as I'm sure many of you will be, used to either working with this or know of clinics that do have these facilities. And certainly become quite widely available. And the key advantage of this is the ability to actually see what the larynx and pharynx are doing, when the horse is working and when the respiratory noise is also being hurt.

So for example, it might be when a horse is only put into flexion. And is working, or is working at high speeds, such as your racehorse that will only make a noise just as it's becoming, coming to the end of a race. It can be quite difficult to challenge some of these horses, on a non-treadmill situation.

And certainly this, endoscopy exercise used to be something that was done with the horse on the treadmill before the advent of these portable systems. But now most centres would use these in horses as they're sort of exercising off the treadmill. And there are Lots of conditions that can be very nicely assessed, including recurrent laryngeal neuropathy, dorsal displacement of the soft palates, collapse of the area epiglottic or vocal folds, pharyngeal collapse, epiglottic retroversion, and there are several, several more, which I'm not going to go into massive detail at the moment.

OK, so moving on from endoscopy, many of you will be very familiar with taking radiographs of the heads. So again, I'm not going to spend too much time going through this, but just running through some key aspects of this. And traditionally, for assessments of bony or dental structures, this was our gold standards, and for this, obviously, that's been succeeded now by imaging modalities that includes computed tomography.

But the advantages of radiography is that it's an imaging modality that's certainly readily available and it's very easy in the fields, environment to perform many of the standard views. The key disadvantages are that complex anatomy of the equine heads and being able to work out quite accurately what's going on. It will give you a fairly general idea in many instances.

But, it will also only provide you with a, a, a two type two dimensional image, which again, the new cross-sectional imaging modalities that allow you to see things in a 3D, environment, make life much, much easier for us in trying to work out what's going on. So I'm just gonna run through the views for some of you who might not be so familiar with taking radiographs of the horse's heads. So the, the key one, well, the key two really would be the, laterolaterals and the, and the lateral obliques.

And, it's quite difficult to, you can see this horse isn't a quite a perfect lateral lateral. You can see that there isn't quite direct superimposition, but it, again, it allows you to get an overview. Of some of the key anatomic structures.

So we've got the ethno turbinates here, frontal and caudal and rostrum axillary sinuses, you can obviously see the cheek teeth quite nicely. Where you've got anything going on within the cheek teeth, and certainly in the apical regions, this superimposition does make assessment much more difficult. And also, if you have got something that's superimposed, it's difficult to tell whether it's the right or the left side that's affected.

Just mentioning some little tips and tricks that are quite useful with your laterolateral radiographs. If you have got a horse that's got some form of discharging sinus tract or a swelling. it's, you get less distortion compared to the oblique views.

So, having a marker in place does allow you to get a rough idea of what's going on and having some sort of, radio dense, marker, either sort of on the skin or if you use, a metallic probe, for example, if you've got a draining tract, and that gives you very clear evidence if that runs straight to the axes of a particular tooth. Mentioned about imaging of the perinatal sinuses and the dental structures in the head, but don't forget that lateral lateral views of the more caudal parts of the head, will allow you to see the larynx and pharynx and the guttural pouch. So you can see quite nicely here.

You've got the epiglottis, the epiglottic folds sitting on the soft palates, and then you've got your retinoid cartilages and your laryngeal ventricles here. This radiograph, on the right is the case that I showed you with the latetal cyst. This was taken after treatment to monitor response once we're deflated and lasered the inside of those cystic structures.

But I thought I'd include it in here because it does show you quite nicely, that you can also get an idea of what's going on in the guttural pouches and in the, pharyngeal area as well. So this is an example of where, you know, a couple of fairly standard imaging modalities, you don't have to go to anything too technical, too quickly can allow you to quite rapidly work out what's going on. So this was a, mature riding pony that was sent in in acute respiratory distress.

This pony was struggling to breathe, at rest, and we knew that we had to secure the pony's airway quite quickly. So endoscopy again allowed us to see that this pony really didn't have much of an airway, but it also allowed us to see that there's quite a lot of muoid material within the pharynx, and also that there was quite marked sort of deviation of that pharyngeal roof, down into the airway. So obviously, we were concerned that there might be something going on in the guttural pouches.

And in this pony, she became quite distressed, just having an endoscope in place, and it was actually virtually impossible to try and get into the guttural pouches. So, a lateral lateral radiograph, and you can leak these, we can perform that quite quickly and confirm that indeed, and this pony, had, inters material and chondroids within the guttural pouch. So it allowed us to very rapidly, have a discussion with the owner about possible treatment options.

So I've mentioned the lateral lateral views, lateral lateral views, and then the lateral obliques, which are really important to allow you to assess for superimposition. And I've just included these two different radiographs just that to highlight the importance of getting good quality radiographs in attempting to try and work out what's going on. It's difficult enough, particularly with the periaal regions of the teeth, but, you, we have some, you're often looking for some quite subtle changes, such as looking at the sort of the periodontal sort of ligaments and this lamina duodenta.

So if you've got any sight sort of movement blur, then it does make things a little bit more difficult to assess. You can see this red graph beautifully, demonstrates and of course it's got fluid line as well here, but you're able to very nicely assess those apical regions. And then, dorsoventral views, which, if you've got a machine that's powerful enough to be able to take these, again, are very good for assessing the right and the left side of the heads and working out, what side any pathology going on, or confirming it might be bilateral in nature.

So this gives you, again, a slightly different perspective on things you can see, again, in a normal horse, differentiating your rights and your left. And you can see in this source that obviously there's increased radio density within the perinatal sinus structures on the right side, and you can see that there's likely to be material sitting in this ventralcontial sinus, you can see it's abnormal on, on the right side compared to the left. Some other projections, which again, very easy to obtain in sort of fields scenarios would be intraural projections.

Obviously the horse's mouth doesn't open particularly wide, so you only get a very limited view, limited really to the incisor teeth and parts of the scisive bone. But this is a young horse, you can see, it's not, erupted it's permanent teeth yet, but this is a young horse that sustained a, fracture of the mandible and through to dental disease which, which I know that Justine will cover, such as yours and, and trying to assess and treatment options and monitoring. Just going to mention a very useful technique, if you haven't got facilities to undertake CT assessment of teeth, if you want to more further success and certainly the clinical crowns of teeth is a very nice paper, by Say and Paddy Dixon, that demonstrates how you can use an open mouthed, oblique radiograph to further assess those areas.

And other non-standard views, well, anything goes really, so you can take various obliquities of tangential views. So again, some work that was done by Neil Townsend and Sophia Baraka with Joanna Cotton. Demonstrates how you can, further evaluate, the temporalomandibular joints.

Obviously computer tomography now would be perhaps our preferred method for doing that. But again, if you don't have the facilities for that, it's a very nice paper that goes through the technique. This is a pony that's got a, a very classic sort of swelling at the base of the ear that you would consider might be likely to be a dented or cyst, but, quite simple, radiograph, the site will allow you to see just how large that osseous material, dental material is with regards to the temporal bone.

OK, so running on to ultrasonography, again, this is another very widely available imaging modality that I'm sure many of you will use on a, on a regular basis. And as you'll be aware, anything that includes involves bone generally makes it a little bit more tricky in terms of ultrasounding that area. And that does assess a limit assessment of some areas of the head, and particularly obviously within the parainasal sinuses themselves.

But there are some very important uses, again, I'm sure many of you will be aware of its use for assessing, the, actual eye itself and the periorbital regions. You can get, absolutely beautiful, image quality. Allowing you to assess what might be going on in the, parts, certainly if you've got a horse with high femur where you can't see on direct visualisation, what's going on in the, posterior chamber of the eye, allows you very nicely to image those areas and also the retrovulbar and periorbital areas.

But some other important uses would be certainly any soft tissue, swellings that are external to the skull. But also you can, assess the skull bones themselves and, parts of the temporomandibular joints, and, also the larynx. And, some of the images, that I've used in this presentation, the chapter on the heads, it's one that I wrote, are included in some of the next few slides.

So I mentioned the periorbital and retrovulbar region. Again, important to know the anatomy, it's always quite useful when you're imaging the head to have a cadaver, skull handy, to try and work out what's going on. this, is an example of a horse where, certainly, CT would give you, or MRI would give you, the, the best, detail of what's going on behind that eye, but it's just to demonstrate that you can use these more commonly available imaging modalities to get a fairly good idea of what's going on also.

So a horse that presents with exophthalmus, you can use ultrasound to assess the actual eye itself, and this horse has a mass that's sitting in the retrovular area which was confirmed at a postmortem examination. I mentioned the temporomandibular joints, and again, there's some fairly sets sort of windows at which you can assess the actual joints and it's meniscus. You, unfortunately, are limited in terms of the areas that you can actually visualise.

It would be very much limited to the Abaxial portions of the joint, but it still gives you a fairly good idea of what's going on in these regions and any alterations in the meniscus and the bone. So library guns and ducts well, fortunately in the horse, so not too frequently diseased, but if you have got swellings in these areas, it's useful to be able to use the ultrasound if you don't have access to the more advanced imaging modalities, and the salivary glands has got this sort of multilocular sort of lobulate structure. Again, if you've got a normal one side, you can use it to compare the abnorm.

Side, and you can use it to identify any masses within that area. And sometimes if you've got draining tracks, looking for evidence of any foreign bodies that might be associated with salary tissues such as the submandibular and salivary tissue, you can also check out where the where the ducts are in unusual cases where you might get some form of distension of those. The tongue, obviously, on oral examination, you can get a fairly good idea of what's going on in the rostral portion, but the caudal portions of the tongue can be a little bit more tricky, to assess.

And it was just to sort of remind you that you can use the, you can use ultrasound. And to assess, those areas. And it's very helpful to, identify any foreign bodies, especially if they're not metallic, you occasionally get the odd metallic foreign body that gets stuck in, the tissues around and within the tongue and horses.

But it can also be really helpful in looking at those mandibular, submandibular swellings and, and draining tracts. And if you have got a foreign body, you can, fairly accurately get an idea of depth and location to assist surgical planning. And then the larynx is a structure that several publications have cupboards, and I've put two of these in here.

They're really, really nice papers that run through very nicely, and how to obtain images, the larynx, and the key anatomical landmarks, and how you can use this to To diagnose some important conditions that might affect the larynx, such as laryngeal dysplasia, some of these false brachial arch deformity cases, and also how you can use ultrasound to further assess and some cases of recurrent laryngeal neuropathy and dorsal displacement of the soft palates. Slightly more, difficult to interpret some of these images. There are multiple structures in there and it's always useful to have an idea of what's normal, when you're trying to assess what's abnormal.

And this is just an example of a whole. With an orytenoid chondritis lesion. Again, you'll often be using many of these modalities in combination with each other.

So you may have had an idea on endoscopic examination that erytinoid chondritis was the main problem that you were dealing with. But some other areas, these are some other cases where ultrasound was very useful in diagnosing and accurately sort of assessing how to approach these cases surgically. And this is a horse that presented with a discharging sinus tract sometime after Exedontia, and we broke cheek tooth.

It was all a little bit strange because it Well away from the sites of a previous sinus flap, and this was bizarrely had us a question, just off its facial crest, and ultrasound was very nice. You can see quite subtly, you can see some changes in this area, but ultrasound was very useful in confirming this diagnosis and very accurately localising where that sequestered portion of bone was. And then other soft tissue swellings again, it's quite nice to be able to put the ultrasound probe on, a soft tissue swelling just to get some idea of, sort of, size, and depth.

This is a horse that had a nasal atheroma, but you can see quite nicely, that you can, plan, just how extensive, that, atheroma is if you were, going to surgically remove it. Skull fractures will be something that are covered in the next talk, but, and obviously ultrasound is not going to give you in any shape or form the detail that a 3D a computer tomography reconstruction will give you, or even a radiograph of the head. But it can be quite useful if you're out in the field and you're worried that a horse has a man to be.

A fracture or any other fracture, and you can just run an ultrasound probe very quickly over the surface of the bone to see this discontinuity. Obviously, this gives you very limited information about the configuration. Again, can quite nicely enable you to very accurately localise where the probe is with where that fracture line is.

This is a young horse that was kicked in the field by one of its friends and had a depressed fracture over the frontal bone. And again, radiographs allow you to very nicely confirm that. This was a case before we had access to CT.

Scans, which obviously gives you your, you know, your best, ability to configure, work out what configuration that fracture is. But it was very useful preoperatively, just in terms of deciding how to access this fracture. It's very useful just to run the ultrasound probe over the horse's head just to see, get an idea of sort of size and accurately plan where the surgical incision was going to be made.

So running on to cynoscopy, this again, may be a a a modality that some of you are familiar with, some of you may, may not be. So I'll just briefly run through this, and for those of you who aren't so familiar with it. So it's more invasive technique than routine endoscopy, but it's something that's very easily performed in a horse that's sedated with local anaesthesia.

And it provides you with a means of directly visualising those paranasal sinuses, which you can't do obviously via any other means, to actually directly see what's going on without generating some sort of sinus flap to look in there alternatively. But you can make a a a small enestration into the bone. That allows you to pass, an endoscope into there, and it allows you to, get further information that helps you with your surgical planning, diagnosis of what's going on in there, and also for monitoring, of the sinuses after you've undertaken treatment and ongoing, lavage as well, particularly if you want to target certain areas.

So, knowledge of the normal anatomy is really important before you embark on this, and just make sure that you know where your boundaries for the perinatal sinuses are, so you don't end up taking a look at the horse's brain. It's not a good idea. So make sure you know your landmarks.

And the key sort of structures are areas such as the ethno turbinates and the fronto front maxi nasal maxillary front axillary, sorry, aperture, looking down into the caudal maxillary sinus and the infraorbital canal. There's some very nice book chapters and papers that cover the anatomy of this, but I thought I'd just pull out one paper, which I think is a really important paper that very nicely goes through the, the technique and the rationale behind this. But, sometimes the mistake that people make is by thinking that they've accessed the, frontal, sinus, that they're able to then access and flush all the, compartments of the perinatal sinuses.

And by penetrating, removing part of the maxillary septal bulla, you can, it's only by then, unless you actually create your refine portal over the rostrom axillary sinus, through a frontal approach, you can't access these structures without doing this. So again, have a look at this paper, it goes through this technique very nicely if you're not familiar with it, and also, the anatomy of these structures. Just briefly, I'm going to run through nucleusintigraphy.

This will be something that you'll be very aware of. It's used to investigate orthopaedic disease in the horse, and it's fairly infrequently used for diseases of the head. And I'd say now with the advent of CT and MRI, much less so, but there are occasional indications for this.

And as with any imaging modality, knowing what's normal versus what's abnormal is really critical. So that interpretation, not just acquisition of the images. And this modality, rather than giving you anatomic detail, gives you details about this of the physiologic activity of the tissues at that site.

And, again, there's book chapters that cover this technique if you want some more detail, but there's also a couple of articles that were published from here a few years ago now, that run through the normal and some of the more common diseases of the horse's head. The horse, pictured here, is actually a horse that had an adenocarcinoma of the skull, you can see quite marked increase in radiopharmaceutical uptake, in the overlying bones. Again, this would have been a disease that would have been picked up on, on radiographs and other cynoscopy, that just shows you some of the, uses that you can have in certain circumstances.

So you can obtain sort of vascular phase images and then the more sort of commonly used bone phase images. And it's important to note that you need to take a variety of views, so dorsal and ventral, right lateral and left lateral, and then you can focus on, some of the more Caudal corally located and parts of the heads. Again, running through some of the critical areas and that you'd be looking at and temporal mandibular joint, and then the actual bone that surrounds the aps of the teeth.

You don't actually get much uptake in some of the other parts of the skull. So in terms of indications, well, there aren't that many, but it is very useful to try and work out if any changes that you do see radiographically or perhaps on computer tomography are actually physiologically active and the areas that seem to be where it's most useful. Assessing the periaal regions, the temporal mandibular joints, and also, you may be able to identify a disease process before you actually see over changes certainly on radiographs, you might be able to pick up those more subtle signs more easily in the advanced imaging modalities such as CT.

And again, a very nice paper. I'm here for those of you who are interested in that, and just an example of a horse that's got a periodical infection, showing this quite intense and marked focal uptake of increased radiopharmaceutical uptake in the apical in the bones surrounding the apuses of the affected tooth here. So for the last part of my talk, and it's really an introduction into the talks that are going to be given, certainly by the next two speakers with regards to the heads, is how some of these more advanced imaging modalities can help us to image and see what's going on in that horse's head.

And major advances in this have happened, particularly over the last 10 years, making MRI and certainly CT more mainstream. And has allowed us to visualise structures that we might have been very nicely able to see in the postmortem room, obviously not much help to our patients and the owner. But now we can visualise these areas of the heads in different cross sections, allowing us to broaden our knowledge of diseases and treatments and monitoring of these, and have become the gold standard for assessing many areas of the head.

And I've just picked out this book, as I mentioned, the head's got very complex anatomy, but this is a, a beautiful book that runs through CT and MRI images and in the various different cross sections. So you can, more accurately work out what structures you're assessing. So, Alison's going to cover this in much more detail, sorry, CT in much more detail in the, in the next image, but we're not going to cover MRI, in, these, talks.

This is a, a technique that is available in some centres that have the available facilities in the UK. There are only a couple of centres that are able to do this. This does require general anaesthesia for the horse.

And one of the sort of the downsides of it is just in acquisition time. Alison's going to show you some images of CT scans being obtained to the horse's head, which is significantly less than some of the scan times that it would take to image the horse's heads in one paper that the mean scan time was 53 minutes. And this just shows you some of the equipment and and positioning for obtaining MRI images.

But what MRI does is give you an absolutely exceptional anatomic detail to include the soft tissues, including the central nervous system in, in the head, particularly around the brain, and some of the other soft tissue structures such as the base of the tongue and around the larynx and pharynx. And it's much more sensitive than CT to physiologic processes that may be going on in these areas. But the main indications would be imaging of the the horse's brain, looking at the oral and nasal cavities, and particularly if you're worried about some sort of neoplastic disease process going on, and that might be within the soft tissues or potentially even within the bone, and non-dental, sinus disease.

And for those of you who are interested, there's a number of papers that have come out as people have started utilising. Head MRI to assess horses, certainly for assessment of neurological disease, where you suspect there may be a lesion going on within the brain itself, some very nice descriptions and separate group written up by Caroline Tazia and Co went through some of the indications and features of cynonasal disorders in, in horses, for example, assessment of ethmoid hematomas and sinus cysts. And I've just pulled out some other case reports that might be useful if you ever do see a similar case in practise.

And again, knowing the sort of the normal anatomy is really important and some more, sort of detailed information about the anatomy of the horse's head and how these correlate with what we're seeing on these advanced imaging modalities is also being published and is available in the literature. So I'm gonna then run on to computer tomography of the head, because this is what our next two speakers are going to focus on in much more detail. And this has certainly become the gold standards for cross-sectional imaging, and to assess the bony and dental structures within the equine heads.

And there are multiple indications for this, which Justine and Alison are going to cover in the rest of this webinar session. One of the key sort of abilities or benefits of having CT images is being able to reconstruct the images into different planes, such as the frontal and sagittal planes, and being able to get three dimensional, . Images, which is particularly useful for, working out, for example, surgical approaches to managing a disease process going on in the heads.

So you can see here this course 3D images show you very nicely the configuration of this rather nasty, skull fracture. But also just being able to work out through all the different planes, work out which actual sections of the head are affected and, and get you much more detail about where these are and, and, and how you're going to approach them if you're aiming to surgically manage them. Alison's going to run through, in a much more detail about the CT systems, but these are certainly increased in their availability in equine hospitals across the world, and there are lots of systems that are available.

In practical terms, the most critical aspects to to consider whether you've got a system that requires general anaesthesia for a horse's head to be imaged, which obviously has implications in terms of any risk to that horse, and particularly a horse that might have neurologic disease or sustained some sort of trauma to the head where you might be worried about its mentation and therefore its ability to recover following a general anaesthetic. But also systems that have been, designed to assess the horse's head under standing sedation. And this is something that, Alastair Nelson, in the UK, Rainbow Equine Clinic was absolutely, crucial to the development of and, rapidly and enabled multiple, hospitals in the UK, to get systems set up where we were able to do this quite quickly and easily, with horses under standing sedation.

Alison's going to run through this in much more detail. So I said, the advantages of being able to image the horse's head standing is avoiding the risks of general anaesthesia, so that you can stabilise your patients prior to surgery, whilst being able to undertake pre-surgical planning to work out what's going on. So we gonna come back to our little horse who decided to go galloping into a tree.

And you can see that CTs demonstrated the quite severe nature of the fractures that she sustained to multiple parts of the, the skull, including the actual orbital rim. So this was really helpful in, planning our surgical approach, but at the same time, stabilising this force just to make sure that she was a suitable candidate for general anaesthesia. If you're lucky enough to have that a choice between whether a horse goes for MRI or CT, that's absolutely great.

And I said, for many of us, it's a bit constrained by the availability of equipment, but the key factors would be considering which tissues you're interested in. And certainly for soft tissues, MRI would be optimal, particularly if you want to assess the brain, and certainly for bone and dental structures, CT would be your modality of choice. And I said, there are various risks and benefits that you might need to, to weigh up in how practically you're going to.

Achieve those images. And there's a a nice paper that was published, a couple of years ago, that goes through comparing some of the, the images that you obtain and, and can help you decide which would be best in a in a particular case if you do have that option between the two. Alison will run through imaging of the heads and the non-dental structures in, in much more detail in her next talk.

But just to show you that for where you've got a suspected soft tissue structure of the head, CT can still give you very useful information, particularly where you've got contrast enhanced images. But this is the course that I presented earlier with . Ophthalus and where ultrasounds and was able to quite accurately identify that the horse had a retrobulb of mass, but you can see on the CT images that again, you're able to see this mass and again, and get some sort of three dimensional, reconstructions to work out and its size if you were, planning on doing anything surgically.

OK, so that's a bit of a a run through all the imaging modalities that we have to look at diseases of the equine heads.