Advancing Equine Health: PET CT Diagnostics and Tarsal Pain Insights

Unlock the future of equine health as we welcome Dr. Pablo Espinosa-Mur to Veterinary Vertex. Pablo shares pioneering research on PET CT and tarsal pain in horses. Experience a revelation in diagnostic technology, as we traverse the findings from Pablo's recent JAVMA article. We discuss correlating complex imaging results with lameness scores, and we unravel the technicalities behind PET CT protocols and showcase the clinical significance of these advanced imaging outcomes.

As we examine the subtleties of tarsal pain, the conversation takes us through the ways cystic lesions and enthesophytes present on PET scans. Pablo, a radiologist with a wealth of experience in equine lameness, guides us through the maze of imaging and clinical signs, offering a nuanced understanding of these findings. Join us for an episode that will not only inform but also inspire the veterinary community to embrace the next wave of diagnostic innovation in equine medicine and surgery.

Full article: https://doi.org/10.2460/javma.23.03.0164

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Transcript

Speaker 1: 0:00

You're listening to Veterinary Vertex, a podcast of the AVMA journals. In this episode we chat about 18F, sodium fluoride, pet and CT for assessment and management of tarsal pain in horses with our guest Pablo Espinoza Moore.

Speaker 2: 0:23

Basically, sarah, we're talking about PET CT in horses again revolutionizing horse medicine for us. So welcome to Veterinary Vertex. I'm editor in chief, lisa Fortier. I'm joined by associate editor Sarah Wright. Today we have Pablo joining us. Pablo, thank you so much for taking time out of your busy clinic schedule to be with us here today.

Speaker 3: 0:44

Hi Pescher, Thanks for having me, guys.

Speaker 1: 0:47

Pablo, we've had a few podcast episodes talking about PET and CT for horses and, as we know, it's a really important topic and we're so happy that you're here today. Can you share with our listeners what they can expect from your JAVMA article?

Speaker 3: 1:02

Yeah, it's a pretty interesting article on main findings in different type of horses on the proximal and tarsal region, which is kind of like a tricky region to evaluate in horses for multiple reasons. So we choose to report main findings in quota horses and population of quota horses, womblets and also I try to remember well, I think it was a couple of thoroughbreds, not a lot, but there is some there. One of the main interests I'm a radiologist working at OVC now but I'm also I was going to say was but I'm still a lameness clinician and a surgeon. So the clinical part for me is very, very important and that's what I try to put forward on that paper, that you know what is the correlation between the abnormal imaging fine and CT, but how do they correlate with lameness course and all that stuff? So personally for me that's kind of the most interesting part of the paper, even if I like imaging, just because we demonstrate some correlation between those and CT grades with lameness of course.

Speaker 1: 2:25

It's always important to include that clinical take home, so we really appreciate you emphasizing that in this article.

Speaker 3: 2:31

Yeah, 100%.

Speaker 1: 2:33

And what are some of the important insights from this article?

Speaker 3: 2:39

I think the main one is that there's multiple but this is kind of like the first paper also that reports where the findings or of that region and forces so so far nothing has been published on it and that CT is kind of a pretty novel and unique image and modality that is becoming like more widely available. But I think there's like four clinics in North America, maybe the entire world where they have it and UC Davis is one of them actually was the pioneer. That's what we start doing. This studies Start with the digital extremity, just because you know, as you know, 80% of lamenesses and forces come from the digital extremity and then we'll move on to more proximal regions, including Darcy. So this is the very first paper of this kind of series of articles on PET CT. This is the very first one on the Tarsus and proximal metatarsal region and one of the you know the reasons. What we do is just to demonstrate that can be done. These horses were anesthetized. We also described the protocol that you can use if you want to do a PET CT on the general anesthesia, the timing as well. You know how long you need to wait between the injection of the tracer and optimal image acquisition. So that's kind of important information just how you perform that PET CT and then you can get diagnostic images in clinical cases. So that's one thing we can like demonstrate is a valuable imaging option.

Speaker 3: 4:14

On top of that we assess what is the correlation between, as I said before, like PET and CT grades with lemnus scores. And you guys know there's like a subjective way to assess lemnus which is the AP lemnus scale, which is kind of like a pretty all things from the 90s and it's just basically five grades. So we use that scale to assess lameness. But we also use objective lameness analysis which is basically lameness locator. It measures just pelvic acceleration in lame horses. The higher the you know the escorchion of the pelvis, the more significant the lameness is. So we kind of correlate those objectives and subjective lameness values with objective data from the PET scan, which is kind of one of the beauties of PET scan. You can get what we call the standardized uptake values, where you can get like a number of deletion that takes you what is the uptake within that lesion and it's pre accurate. So we kind of correlate those things.

Speaker 3: 5:28

We did it multiple ways and the reason why we did it multiple ways is just because, like we had like different types of forces included, like a quarter horse has nothing to do with a one-lot when it comes to, you know, leachalization, and so that's why we look at like by broad regions you're Tarsicroll, join, proximal, suspensory, distal torsion joints, but for example, in quarter horses we also look at the distal torsion separately and divide it in different regions. So, and you know, these are kind of different ways or different approaches that we use to try to assess that possible correlation between lameness and PET findings. The take on from all those things is that changes, CT and PET scan changes, especially PETs, are the ones that solve the higher this permacorrelation values with lameness but CT also. So the change that affecting the plant heart aspect of the distal torsion joints, either the DIT, the distal torsion joint, or the TNT, the torsion to torsion joint, those changes are the ones that tend to have like the highest correlation with the lameness scores and those are the ones that tend to show highest lameness grades.

Speaker 3: 6:46

It seems that plant heart changes is the one that is just kind of like proximal pain, which is kind of what we care about. You know, ideally in an ideal world, you know it could be awesome to have like a pain tracer. You know what I mean. Like it's like, oh, it's gonna inject this tracer, I'm just gonna look where it's pain and then that's it. It's. I mean, it's very, very difficult, slash, impossible to do it. So that's what we do these things is to see what hurts, which is like, again, what matters to us the most and that's.

Speaker 3: 7:24

I think that's pretty much it it was. Also. We did some correlation, which was this I don't think this is that novel, but we also show that restorative changes on CT. They tend to have the highest standards of take values on PET scan and so they'll try PET scan. S-lerosis tends to be more quiet when it comes to PET scan. That's also in the paper. But I think they made two things that we can do at CT on horses of the parcel and pressure on the parcel region. You get valuable information that can help you know with the diagnosis of pathology and also making decisions. And then the second one is to just plant her changes them to have higher coloration with the mesoscores.

Speaker 2: 8:11

Yeah, I love the idea of the plantar lesions. We don't spend enough time looking back there. We're always looking at dorsal, dorsal medial changes, more OA changes in radiographs, so it's really lovely to have basically a biological marker to give us some more information. As you started by saying that, lameness is tough, you know, they can't point to where it hurts and the blocks aren't perfect, and so thank you and everybody that's doing PET CT to try and put some biology behind it. Pablo, what sparked your research interest in PET CT and then inspired you to write this article?

Speaker 3: 8:47

I always had a strong interest for imaging. That's the question why I go into a second residency program. I did my surgical residency at Davis and I worked since the very beginning. I worked very closely with Dr Esplio, which is one of the radiology professors at UC Davis. I finished the surgical residency and he offered me a fellowship on imaging focus on PET scan. At the very beginning we used different tracer, which is FDG, which is radioactive glucose, and then from there we moved into thionflorae and we had very interesting and promising results using those tracers for the distal extremity. So the natural course of action was to use the same technique in different regions. But it was kind of like a combination of interest in imaging, having the chance to be part of it. It's like extremely unique. And then, yeah, and then Dr Esplio offered me that prestigious and what is great. I'm still grateful for it.

Speaker 2: 9:49

Yeah, he's amazing. You spoke earlier when Sarah asked you what were some. What are the take home messages? But maybe not what was the most the big take home, but what really surprised you in your findings in this article?

Speaker 3: 10:06

I think the surprise and things and again, maybe just because I quite focus on clinically relevant things is that some very severe changes that had like were very, very, very quiet on PET scan. So we had like large cystic lissions on the distal tibia for example. Even I think we had a horse with with assist, right in the center of the third torso bone. So those cystic lissions, which a little bit of peripheral sclerosis, were pretty quiet on PET scan. So that was one of the main things that surprised me.

Speaker 3: 10:51

I was also very, very, very how that's the word? I was not surprised but I was like I got very excited when I saw enthesiophytes on the region of the proximal suspensory that were both active and nonactive like meaning active I'm calling them active when they're like they show a lot of uptake on sodium fluoride. And we found like similar sizes and fusiclites on that proximal suspensory region that were completely quiet on PET scan. So those discrepancies between the same type of lesion, I think that way caught my attention and that's what I was kind of like another reason to try to try further and put more effort in figure out that correlation between the imaging primates and the pain and lunges.

Speaker 1: 11:45

That's fascinating. Do you have any hypotheses for why that may be Not to take away from your reading script, because we still want our readers to read it, obviously, but is that a personal curiosity?

Speaker 3: 11:56

Yes, I don't know, Maybe one of the things that we don't know in some of those horses it was what was them? Because, for example, when the Fissure Fights we don't have a lot. We had a lot of boarded horses, which is great for like, if you want to study that, like small tariff insurance, but we didn't have that many with those in Fissure Fights it was very hard, as life's impossible to make that correlation with lameness for that type of relation. One hypothesis could be like okay, one hurts, the other one doesn't, but again I just cannot answer that question.

Speaker 3: 12:32

And the other potential explanation is like maybe the horse that had active changes or certain frontets can. Maybe that one was kind of like actively training at the time that we performed in scan and the other one had like just maybe like two months off before we did that CT, and that's why the same type of patient needs not quite and there is no like pulling of the whole proximal suspension. That I think is a quite step to why there is not much activity on activity. So yeah, that's just the possible explanation. Again, a limitation for two reasons. Like I said, there's not that many relations like that in the study. And then the second one is like we don't know exactly what these horses did before we did the study of product and scan.

Speaker 1: 13:21

Very cool. Thank you for sharing. And, as you mentioned, you did not one, but two different residencies. How did your advanced training prepare you to write this article?

Speaker 3: 13:34

Oh, I think it was very useful, I mean, and again, my training was it's just like. It's just that my training was perfect for this paper I have. I mean, I'm a Tarsus brick, I love the Tarsus, I love that region, I love illness, I love blocking and I love imaging. So if you combine all those things, I think this paper kind of like comes out somehow. Yeah, I had done a couple of papers on all the type of pathology, focus on the equine Tarsus and, as you guys know, I love imaging.

Speaker 3: 14:11

So, yeah, I think having my clinical background helped me in a way that I knew the questions that I wanted to answer. You know, I mean I knew how tough it is and non specific, all the blocks within this region. You know you can block the deep branch and then, just you know, have like a massive lesion in the Tarsus you could join or they can deal the way around, you know, I mean. So the blocks within this region is not, they're not very specific. So, yeah, I think it's just just a conflation of things that I love. We might start combining this paper.

Speaker 1: 14:49

That's great. Sounds like it's really the perfect fit. Now this next set of questions is really important for our listeners. The first one is going to be about the veterinarian. So what is one piece of information the veterinarian should know before discussing this topic with the client?

Speaker 3: 15:07

I think you have to be upfront and say what I just said. This is a difficult region to assess and I think the client understands that they might be more open to do advanced imaging, which that city is one of them, and that can help answer the question of what's going on. And I think, on the equaling world we usually I mean, depends on what you are but we tend to be a little bit like oh, you've done an X or an X or something. You don't know what's going on. Yeah, of course, like 95% of the times, of course, we don't know what we're doing with. If you know what you're dealing with with just an X or an X, I think you might have to take a step back and do a little bit of continuing education. But yeah, the first one is just, like I said, just recognizing that this is a tricky region and then that's going to help you kind of like open your mind and consider cross-sectional imaging.

Speaker 1: 16:11

Even with cross-sectional images like pet CT sometimes is hard, thank, you and then on the other side of the relationship, what is one thing that the client should know about? Pet and CT for assessment and management of tarsal pain in horses.

Speaker 3: 16:28

I think, maybe a more simple message in a way that is like a technology that is now available to them. In some places, especially if they are California, florida and Kentucky, we can do that and there are places there where that's an option. I'm not saying that this is the only type of imaging. There is high-fill MRI, which is extremely good and sensitive. So we don't know if there are relations that we will not be able to pick up with pet CT that might be present on MRI and vice versa. So that's another dimension of the study. We don't have MRI to compare, but MRI, if I put it, as another kind of cross-sectional imaging mobility. It's also like a possibility for this region. So, yeah, you could just say that pet CT is an option If not MRI, and they are complementary. You can do either one. We don't know more so far.

Speaker 2: 17:29

Yeah, thank you, Pablo. I think pet CT I truly believe is going to revolutionize horse injury, horse lameness, and I love what you just said. Open your mind, it's just a game changer. The concept that assists with sclerosis around it is not biologically active is fascinating and it's going to take a whole new education. So, thank you, you clearly need to do multiple residencies and live in the OVC. Have resilience, determination, grit. Where do you think your determination came from?

Speaker 3: 18:09

My determination, I think, is passion Whenever I start a research project. I've done multiple research projects. I've done research that I like, I've done research that I don't like, and the ones that I like like this project. It's just so straightforward you want to just keep learning more and reading more. So I think it's just passion for what I like to do and I just kind of do it. And I just got a master's student that's going to start with me in the next couple of weeks and we're just talking about like a new kind of type of the opera that we can apply, and I told her, like we can do like so many things. But I told her, like my experience, you know, the easiest thing to do is to do what you like. You know what I mean. So we'll have all these things, but what kind of motivates you most? There's something that you like. I mean everything is going to be way easier. So I think you know, just doing what I like makes things very, very easy.

Speaker 2: 19:11

Very well said. I was just at a conference over in Newmarket at the British Equine Veterinary Association and people were talking about those little spikes that you're talking about in the proximal metacarpus and metatarsus, especially the metatarsus, and some people think that the bone then leads to the suspensory problem, that it's the, the thesis on the bone that starts. So it would be. Actually, if you have this Doppler, it would be fascinating to see, like perhaps the PET CT is hot for lack of a better word it goes cold and now you've got a suspensory problem, like if you could, possibly, but you need a bunch of warm bloods. As you said, the coronal issues don't really get that problem 100%.

Speaker 3: 19:53

That's a great idea. But, yeah, like complementary complementation of different imaging modalities, I think is. I think it's also great, like because ultrasound, like you said, it's just like something that more people can do and then, so far that's it. It's just like, I think, for hospitals in North America. Yeah, that's something that's great.

Speaker 2: 20:13

Fascinating. As we wind down, we ask a little bit more of a personal question. So for you, the question would be what is the oldest or the most interesting item in your desk drawer?

Speaker 3: 20:28

The most interesting is a drawer that my son made where I am with him and there's like a little part. So every time I sit it kind of melts my heart, and when it's kind of like 5pm and I want to keep doing things, I said, no, I have to live this year and go, just because I have to spend time with him. Yeah, so that's the best part, just like a drawing from my 4-year-old.

Speaker 1: 20:57

That's adorable. Sometimes it is hard to turn off the work brain. There's always so much more you could do. I'm sorry. Yeah, yeah, yeah, definitely understand that. Well, thank you so much for being here today with us, pablo. We really appreciate it.

Speaker 3: 21:11

Thanks for having me, guys.

Speaker 1: 21:13

And to our listeners. You can read Pablo's manuscript in print jama and on our journals website. And Sarah Wright with Lisa 40a. You want to thank each of you for joining us on this episode of the veterinary vertex podcast. We love sharing cutting edge veterinary research with you and we want to hear from you, and I hope you enjoyed this episode of the veterinary vertex podcast.