Good evening. I think, or good morning, depending on when you're listening to this, some, webinar. So I'm Valerie Poirier, and I'm gonna talk to you about imaging the cancer, the veterinary cancer patient.
And right now I'm based at the University of Guelph, but actually right now, because of the second lockdown, we actually, stayed home in, Quebec, . And this is, so we basically had a 45 centimetre snowstorm on Monday, and this is the family, just doing some snowshoeing. And just to tell you a little bit about myself, so obviously I'm from Quebec, so I'm a French speaking, Canadian, and this is actually where I am right now on the north of Quebec, but my first, brush with oncology was actually in Wisconsin where I did a medical oncology residency.
And at the time, this was the machine that they had for radiation therapy. I just want to give you like the idea of how far we went as far as cancer treatment in, in the last 20 years. So this was a cobalt machine that was, built in the 1960s, by Canadian actually.
And at the time in America, there was only 3 vet schools that had, or 4 vet schools that had, radiation capability. Now, pretty. Much every vet school does.
And at the time, this was my dog. Her name was Belle Dehane, and, she was from Quebec. So then, from then, I moved into, I went on vacation in, in, Nepal, and that's where I got my second puppy.
So a street dog from Nepal. I would never do that again now, but this is what we did and this was my best friend. So then from there, I moved to Switzerland to do a radiation oncology, residency, and at the time, this was the Linac, that was there.
So obviously it was a Linak, not a cobalt machine, but we didn't have anything fancy, it was just a Linak. And unfortunately, Bell passed away, and then I never understood why I got this dog until I met this man because that's his dog. So this is obviously what I picked up, in Switzerland, he's a nice German boy.
That followed me to Australia, where we set up, where it's my stint in private practise, and this was the Linac that we set up in Australia, so that was the first Linac in the Southern Hemisphere for a veterinary patient. Had a first child, McAlo was still there. Then the poor McAu moved to Canada in Guelph, and that's when the Linac got fancy.
So these are Linak with CTs in them, and this is still the Linac that is in use today. Got the 2nd child. This is us on the north of Quebec, and this is the last time we saw Malu, so MacAoo stayed back in Canada while we moved, back to New Zealand, where I was a medical oncologist at Massey University and also end up, helped set up, the new Line and sash, in Australia, while the radiation oncologist was, still stuck in the states, he came back, probably about 3 months later, I think.
And we move got a new dog, which was kiwi, a nice little, . New Zealand dog and basically right now we're spending the winter on the north shore of Quebec, so beautiful snow. So basically in oncology, we need, we need to answer these 4 questions.
What is it? Where is it, how bad is it, and what can be done. This is pretty much the 4 questions that you need to answer anytime you see a cancer patient.
And obviously, what is it is making the diagnosis. Most of the time you need some kind of tissue diagnosis. So either cytology or biopsy.
Sometimes you're gonna use imaging for this part to make a diagnosis, but most of the time you need to combine it with something else. Where is it is definitely where imaging is gonna be important. And mostly for staging, so we're gonna talk a little bit about the TNM, so the tumour known metastases that are used for solid tumour and for liquid tumour, which is like lymphoma all the round cell tumours, so lymphoma, multiple myeloma or leukaemia or even mass cell tumour.
We're gonna wanna find, do we have local or the extent of the sys systemic disease. How bad is it is the natural history of this particular tumour type and what can be done are basically the treatment option, the prognosis, but always have to take into account the particular of the dog and or the cat or and the owners, obviously. So the role of imaging in oncology, so definitely for diagnosis and staging, also more and more for treatment planning, and more and more for tumour monitoring, and I'm sorry I didn't put a you on the tumour, that's the American version.
So this is obviously here is a dog, with an oral tumour, and you can see that, and this was biopsied as a fibrosarcoma, and you can see that compared to this other side, this is a dorsal view, this is the canine, so this is the, the maxilla. You can see that the tumour has kind of eaten away the bone of the maxilla. So a CT was kind of necessary to determine like, could, could we safely, take 1 to 2 centimetre margins around, this tumour to get clean margins and get a better, basically a good chance for long term control, meaning longer than 3 years.
And this is the dog, 6 months post-surgery. So you can see that definitely the surgeon went in and got the maxilla out. So this is a 3D reconstruction.
This is the endotracheal tube, and this is basically the maxilla and this is a transverse image where you basically see . What what that the surgery could close it with a flap. So obviously, I have to do a disclaimer, I'm not a radiologist, so I work extremely closely with radiologists, but I'm gonna give you this talk from, an oncologist perspective.
So for imaging that is available, there's obviously radiography and ultrasound, CT scan, MRI, and PET CT. So obviously, most practise have, I would say almost all practise have radiography. I would say most practise has some kind of ultrasound.
They don't always have a fancy ultrasound, but they might have enough ultrasound to get a, a point of care to look for, let's say a hemoabdomen. Then the majority of referral practise and even some, smaller practise will have a CT scan and an MRI and really PET CT it's very kind of, there's probably only 2 or, there's probably 3 or 4 now, vet school in North America that has a PET CT. I'm unaware of any.
European, university I have a PET CT, but but but the most of them have some kind of access to pet to through a human hospital or a research centre. So when do we use conventional radiography? Anything for screening, so I say any dog that's cough should always get a chest X-ray.
Any dogs that's lame should try to figure, have a good orthopaedic exam to figure out where it's painful and then definitely do a radiograph of the painful limb. Chest radiograph, once you have a diagnosis, cancer is to me a mandatory for a metastasis check. Conventional radiography is very good for bone, mostly long bone and, rostral jaw.
So basically the mandible, I would say for the maxilla, nasal cavity, the head, radiography is not good. I mean, it's potentially OK for screening, but it's so non-specific that and, and now that we have CT that does such a better job for the head. I don't necessarily feel that, I feel like, conventional radiography has kind of fallen out, as far as treatment planning and even staging, for, for tumours.
And then for the abdomen, obviously it's mostly an overview. So obviously, if a dog had, was coughing and you got a chest X-ray like this, a bunch of nodular, soft tissue nodules well marginated, throughout the lungs, this, this really cannot be anything else but metastasis pretty much if it's solid like that. .
This is most likely metastasis, so this is what's called a miliary pattern where you have small little nodules that coalesce into larger nodules. Obviously, if you lived in a country where there's a lot of fungal disease or mycobacteria, this could be infectious, but if you, lived in the places where I used to live, so like New Zealand, this, cannot be anything else but metastasis. Primary lung tumours, mostly located, the majority of carcinoma are located in the caudal lung lobe, and they're usually single soft tissue, well marginated, mass, often in the right middle lung lobe, which this one is, is, is more, more often histocytic sarcoma, which there's newer paper that kind of indicate that.
And obviously, to me, for primary lung tumour, a thoracic radiograph, is great to say, well, there's definitely a soft tissue mass there. Could that be an abscess? Yes.
Could that be something else, of course, but most likely on an old dog, that's otherwise well, that's most likely a primary lung tumours. I wouldn't send them to surgery based on that. We've, we've how we now have multiple, study that definitely shows that if you have Lymph node metastasis or other pulmonary metastases for primary lung carcinoma, your prognosis, even with surgery is dismal, meaning like less than a month or a month or two.
So doing a, a thoracic CT is important prior to doing surgery because a thoracotomy is not a benign procedure. So you definitely want to make sure that you give the the information to the owner, prior to deciding that that's what's best for the dog. And a minimum next step for any cancer is preview thoracic radiograph.
And I know that there is and I've heard that, that for hemoabdomen in the UK people say, well, it's an emergency, so we shouldn't do thoracic radiograph and I will show you the data that maybe says that maybe you should, so I, I'm, I'm not, to me, I feel like a thoracic radiograph review is a minimum for anything that has cancer. And the reason why we do 3 view is if you look at those two of your radiographs, so this is basically a right lateral and I believe this is a DV. I personally like DV better for pulmonary metastasis check just because you you see the lungs better over overlying overlying the abdomen, so the liver.
And in those two views here, I don't see anything, that would tell me that this dog has metastasis. But when we had, the other view, all of a sudden you have this little nodule here that's something with the heart, that actually could not be seen, and there is this one here, that is too big to be a blood vessels, towards us because this is in the periphery. And I can almost make out another one here.
So, there's a study proving that with two view thoracic radiograph you can miss up to 10 to 15% of metastasis. So because of that, you should always do a review, thoracic radiograph. Aggressive bone lesions.
So obviously, we do have probably once or twice a year. Remember, that's what I do for a living, so I, I'm an oncologist. We are, we see a dog that had a cruciate and had a TPLO or TTA done and on retrospect, you can see on the original.
Radiographic, they've, sometimes they've not been done or they've been done post-op, and we see a lytic lesion in the tibia or the femur and it was actually an osteosarcoma that was causing the lameness. The dog also had a cruciate, but the lameness was caused by cancer. So we do have that.
So always, always on lame dogs once you determine where they're painful, actually do an X-ray of that region. And obviously, if you have something like that with a sunburst, what we call a sunburst periosteal reaction here, permeative bone lysis, you can see your cortex is, you have a long zone of transition. So this is basically an aggressive bone lesion and this can only be I mean, fungal, you can, if you live in a place where there's fungal disease, but they're not usually located in the metaphysis, otherwise it's a primary bone tumours.
It can also be a secondary bone tumours, or metastasis, but usually they're more in the diaphysis, not necessarily in the metaphysis. So this is a distal, femur lytic lesion, once again, aggressive bone lesion that cannot really be anything else, . But tumour in my book, except the fungal disease once again, and this is a little bit more subtle, but this is also a moth eaten and permeative lysis, that is definitely an aggressive bone lesion.
Other bone lesions that you can see and sometimes you can pick up, especially on chest x-ray on the dorsal spinous process or even in the long bone is those little punch out lesion. That can, that are basically most likely either lymphoma, metastatic carcinoma, isocytic disease, or the most common one is actually multiple myeloma. So it is not super common.
You're probably gonna see one in your lifetime as a GP, but if you can pick it up like this, this would be actually a good thing. Oral tumours, like I said before, for the mandible, I think it's completely reasonable to do an open mouth x-ray and then you can basically see always compared to both sides. So you have a very nice cortex here, to the mandible and here you have a periosteal reaction.
You have a lysis around this tooth here. Same thing here and here is different. Obviously for oral tumours just based on X-ray, you cannot tell what they are.
And even on cytology, you often cannot also say, the exact, histology type of an oral tumours. So often for oral tumours are always biopsy and especially because melanoma is always one of them that that it can be and often you need special stain to actually make a difference, . I, I usually biopsy, oral tumours.
And, oops, sorry. And these, this was a squamous cell carcinoma. This was a melanoma and this was, an, amyoblastoma, which formerly were called Aantommatous epilus.
So this one is a, been. 9 tumour as it doesn't spread to other part of the body, but it does invade so you still need to take a 1 centimetre of good margins there. A melanoma, obviously if it's more than 2 centimetre, has an 80% chance of metastasis, squamous cell carcinoma.
Metastasis is fairly low, so only about 15%, but you do need, to get 1 to 2 centimetre margins. So the biopsy will definitely tell you how it's gonna behave and, the majority of surgeons I know will want a CT, but I think if you, if you, if the owner is financially concerned and cannot afford a CT and a surgery, then I feel like for a mandible only an X-ray is acceptable. What about ultrasonography, so, .
It's great for abdomen. It's great for diagnosing, point of care like he like if you have a peritoneal effusion or thoracic effusion. It's great if a radiologist or somebody that's very well trained in ultrasound do does an abdominal ultrasound, but it's so operator dependent, that it's basically to me, doing an abdominal ultrasound is like looking in a room with a flashlight.
So if you don't do it systematically and if you, you could miss lesions easily. And and it's still better than CT as far as I'm concerned for round cell tumour like lymphoma and mast cell, because it basically will tell you the architecture of of the, the, the spleen and the liver, and this is an X-ray here of a lymphoma patient. So you can see that the liver is way all the way back here.
So you definitely have a hepatomegaly. You also have a splenomegaly here. And you can kind of guess that there's maybe sublumbar lymph node here, .
So, obviously, if you would ultrasound this, you would probably see very hypoechoic liver and spleen, and you would still need to aspirate to confirm the diagnosis. For the neck, for thyroid or parathyroid, I think ultrasonography is very good and has a very high sensitivity. But remember that you always have to pair it with a cytology or biopsy to actually tell exactly what the patient has.
And this was a dog that was hit by a car and obviously had a hip dysplas hip dislocation, but he also had as an incidental finding an abdominal splenic mass and this is what an ultrasound is splenic mass looks like. So, I would say majority of oncologists are now using more and more CTS as far as staging goes, and the reason for that is probably about 1015 years ago, the paper, the first paper kind of came out that compares CT to thoracic radiograph and this was a paper from from Germany where they looked at pulmonary nodules, or like positive. Metastasis, radiograph versus CT and for canine osteosarcoma, 5% had, metastasis at initial stage, initial diagnosis on radiograph versus 28% on CT.
And that was very interesting to me because when I was a resident, which was like 10 years. Before that, we used to tell owners of osteosarcoma dogs that there was about a 20% that even without with amputation and chemo would have metastasis at the last chemotherapy. And interestingly to me that's pretty much the number that came out in that paper, so I think I think that's probably those, those 20% of the dogs that had gross metastasis by the end of chemo probably had microscopic metastasis, metastasis that would have been picked up on CT at diagnosis.
And when, they did, a study where they compare CT, Radiograph versus CT, only 9% of the pulmonary metastasis that were seen on CT were actually visible on radiograph. For abdominal ultrasound, CT is superior to abdominal ultrasound for the detection of lesion in dogs about 25 kilogrammes. So this was a study out of Australia, and I would say.
I don't think that CT is necessary for everything, as far as the abdomen goes, but it's a little bit like cheating, and I will show you a bunch of examples where you will understand what I mean. So Going back to splenic masses, these are two studies that came out this year. They're pretty much, gonna came out at the same time and interestingly to me, one of them shows, It is from the UK and the other one is from America, and the difference between the two, so the big conclusion in the UK study is that if you have a hemoabdomen, 90% of the dog will have a malignant tumours, versus the conclusion of the American study is that actually if you have a hemoabdomen, a third of the dogs will have benign disease.
And the difference between the two is that in the UK at least in London, where this, this study was conducted, I believe, They are seeing in a hemo abdomen as an emergency, and they actually don't do any staging prior to going in and removing the spleen. And 60% of the dog in that particular study already had metastasis. Versus in America, the majority of patients will go through staging.
So we'll have in this particular study, they had a thoracic radiograph and abdominal ultrasound, so didn't have any signs of metastasis and when they went in, but they had more and they would transfuse the dog. So, so this is the difference of approach. I'm obviously, I'm North American trained and I think, so to me, I feel the difference in prognosis for, a meningiosarcoma with metastasis, which is probably 6 to 8 weeks, survival versus, 6 to 8 months.
If they don't have metastasis and they get chemo, I feel the owner might make a completely different decision if they knew that their dog, . Had metastasis. So that's why I would always stage.
And interestingly enough, from the same around the same time, so I think that was published just a year before, also from London, they looked at the prevalence of pulmonary nodules, at CT for dogs with malignant neoplasia. So obviously, looking back at dogs, those dogs did undergo staging. And of amenosarcoma, 41% had multiple pulmonary nodules that could be seen on CT.
And what the other thing that's interesting about that study is a single pulmonary nodule at first CT is not necessarily metastasis and that's one of the problem when you start staging is you're gonna find a bunch of things that might be clinically irrelevant. So the more imaging you do, the more disease you're gonna find that. Might or might not be related to the cancer.
So you always have to kind of, we're learning how to deal with that. And I would say as far as I'm concerned, depending on what the owner wants, sometime I actually do offer two dogs with a hemo abdomen or a splenic mass to do a CT thorax in the abdomen for full staging, . If they need to know before making a decision to go to surgery.
Otherwise, I would say a minimum is at least a preview thoracic radiograph and obviously ultrasound. You can probably skip because you're gonna go in anyway with surgery. So I think, I think that's a reasonable thing to skip but not the thoracic radiograph.
Going back to to using more CTs in the human world in the early, so this is exposure to radiation by the public, so the majority of the radiation that we're exposed in our life is actually from the background and only about 15% are actually from medical, but from the early 80s to mid-2005, the There was an enormous increase in the use or the exposure of people to radiation, due to X-ray, and the great majority of this increase was CT scan because basically CT is so superior in staging. That they actually, are, have been a tremendous use increase in those last 25 years. Obviously, in the human world, it is a problem because we know that radiation can predispose to cancer, so if you get, if you're a child that gets cancer and get multiple CTs, you're, that puts you at risk for developing cancer later on due to the radiation exposure you had as a child.
Having said that, in a dog that is at the end of his life because of cancer, I don't necessarily think it's a problem, but I just want to put it out there that when you do a lot of CTs, you will definitely increase radiation exposure for the patient. But since the majority of them are under anaesthesia and there's no human in the, in the room, it's not usually a big consideration at this point. It might change, but at this point it's not a big consideration.
So going to staging now, so the TNM staging system has been around since the 1980s. I don't necessarily use it that frequently, as much as they use it in humans, but I always like to put it out there just to make people and students especially think about where cancer can go. So you basically have the primary tumour.
You have the regional lymph nodes, so that's called local regional, and then you can have a distance metastasis. So this is what the TNM stands for. What about blood work?
It's always a good idea to rule out any concurrent disease, or any perineoplastic syndrome, but like I always say, if I have an owner that has financial, limitation, I would rather give up a pre-op, blood. And then give up histology of, of the tumour or, or the mass that I'm gonna remove. So ideally, of course, everybody wants to have everything, but if you have to make a choice, I think histology is more important than blood work.
Obviously, ideally you would do both. And this is just from the 1980s, the, the World Health organisation TNF classification scheme for tumour and domestic animals and this is for oral tumours, there's different ones for different type of tumours and this is for the primary tumours, it's basically The size and invasion for regional lymph node is size and do we have fixed to the surrounding tissue and is it only the regional lymph node or is it beyond the regional lymph node and then distance metastasis is one organ or more than one organ. So for tumours is size and primary tumours is size is an invasion.
And this is an example. So this was a dog, that had a neural mass. So when he yawned, the owner saw a mass in the caudal maxilla.
The vet had done a biopsy and this was a fibrosarcoma. So oral fibrosarcoma can be extremely invasive and eat everything away and the dog could look completely normal on the outside, or this could just be the tip of the iceberg. So I'm gonna walk you through a CT.
So the beauty of CT is pretty much like radiographs. So the densities are exactly like the radiographs. So the bone is white, the air is black, soft tissue is grey, fat is just a darker shade of grey, and then obviously this is post-contrast because you can see that the blood vessels are basically lighting up.
And this is, we're at the level, so this is the brain. This is the, the, the TMJ and this is the zygomatic arch. So we are gonna go cranially.
So we're going cranially, and, and basically this is the tongue, the E tube. Let's go back. And the way to look at CTs look for symmetry.
So right now, everything looks very symmetrical, but here there is all of a sudden something coming up here that is not on this side. And you can see that the soft palette always picks up contrast, so there's a little bit contrast there. And then as we go forward, this is the eyes, this is we're getting close to what we call the cribiform plate, which is that butterfly, and you can see that there's the mass, so this is the mass that the owner was saying, and you can see that it's not.
Too much invading, at least, at least it's not like sometime they come all the way up here. This one is really kind of respecting that. And here's what we call the cribiform plate.
So this is the butterfly, the separation between the nasal cavity and the brain. And you can see that there's still some irregularity here and this is a salivary gland that's picking up contrast very nicely and we did put a gauze in the mouth to basically push the the cheek away so you could really see where the tumour stands. And then as we go forward, This is basically the last molar.
So, for this particular dog, there was definitely a surgical possibility of a cure. So you need 3 centimetre or and one fascia plane, so there's quite a bit of fascia plane that you can get here. And then in the free moving spice, I think you needed to get some bone out of here of, of the mandible, and this dog actually got clean margins.
And this is, so definitely for oral sarcoma, we don't do surgery without CT now. And there's a paper out of Davis probably for about 10 years ago where they compare. Oral, the outcome of oral sarcoma prior to CT scan versus after CT scan, and prior to CT scan, the median time to recurrence or median survival time was about 8 months.
And after CT theendment of CT scan, it was about greater than 3 years, and that was basically because all of a sudden the surgeon could decide who they should cut and not cut, and they could also determine. How to cut them. Before with the X-ray, they just had to go to where it looked like, versus now they can basically have even 3D models done.
This is another case that was a dog that basically had a mass on, on, on his shoulder for a year and then all of a sudden he grew up very quickly and got all ulcerated and pretty. Much the whole skin that crossed on top of it. So this, this was just a giant hole and this is kind of the piece of the mask and this is the other piece of the mask.
And obviously this was going to be a long time to heal and so it was going to be a big deal. So we did do a CT to see was this mass completely invading? Was that surgical?
So you can see this is just a cross section of the CT, the spine, the trachea, these are the blood vessels, so it's post-contrast. This is the opening of the skin, so this is the normal skin here and there you have the opening of the skin. And you can see that this is the mass here and you can see that there's a very nice facial plane all the way around it.
So this was actually a benign tumours that could definitely be removed and they could close it with obviously a closed section drain. The drain was in for like 10 days, it was producing enormous, but the the dog ended up healing well and was fine as far as tumour goes. This was one of those fat leg on a fat Labrador.
I'm sure, I don't know if some of you have seen it, it's like almost a Michelin man. And a lot of those are actually lipomas or infiltrative lipoma. This one had aspirated as a sarcoma.
So the question was, is that a sarcoma that's just in between muscle or is that a sarcoma that's arising from muscle and basically that an amputation is the only possibility or can we do a debulking followed by radiation? And this is what the CT looks like, so this is obviously the stifle. This is all fat, and this is all muscle.
And then as we go caddily. Actually distally on the limb, all of a sudden, you will see this tumour appear here. Contrast enhancing beautifully.
And here it looks like it's arising a little bit from that muscle, but otherwise, it kind of sits on its own and it almost looks like that you could open the skin and scoop it out, which is actually what we did. And then, we gave, this was an older dog that had diabetes, so we gave it palliative radiation and and she went on 2 years without recurrence. So obviously, CT for cases like that are kind of very neat to tell us the extension and the invasion of tumours and determine if we can do surgery or not.
This was a fat dog with a mast cell tumour, and obviously the mast cell tumour is not that interesting. What we found was an incidental finding also of a thyroid tumour. And there's actually two papers out there, ones with ultrasound and one's with CT and incidental thyroid nodules are found in about 10 to 15%, 5 to 15% of dogs, and, one studies say most of the the incident one are benign, the other one says they're malignant.
This particular one was actually malignant, . And the mast cell tumour was removed, this was removed, and the dog ended up developing pulmonary metastasis, but, a year down the road. So obviously, Often when you do more imaging, you might find other things and then it's not, not uncommon at all for a dogs or even a cat to have multiple tumours that are unrelated just because they're old dog and they get, they get tumours.
What about the lymph node? So, lymph node that we feel all the time are the cervical node. The mandibular node, the axillary only if it's big, the inguinal only if it's big, and the puppial lymph node.
But there's way more of them, and depending, this is, there's two different way to look at them is where do they drain, but we know from multiple studies that pretty much the drainage, lymphatic drainage is very dog dependent, so each dog is a little bit different, but this is basically the big gist of it. So what do we know about lymph node? We know that lymph node metastasis is definitely a negative prognostic factor, definitely for osteosarcoma, mast cell tumour, mammary tumours, malignant melanoma, and if the lymph node is positive, the prognosis will be different and the treatment will be different.
So it's kind of important to figure out which lymph node is actually draining that the tumour and to actually get a sample of it. Normal cytology of lymph node, I'm sure you remember that from vet school. So you basically have small majority of small lymphocytes.
You can have plasma cells, so this is a plasma cell with an eccentric nuclei and a nice golgi zone. You can have immature lymphocytes, that's called lymphoblast or large lymphocytes that are usually big like a neutrophils, so there's a neutrophils and you can also have mass cell. In a normal lymph node.
This is a lymph node with these large cells with black pigments in it. So these large cells with pigment, we used to think that they were automatically melanoma metastasis, but actually a lot of them are actually, macrophage are eaten pigment. This particular dog does have melanoma metastasis, so you can see this big tumour, this big round cell here is definitely metastasis.
If you have epithelial tissue, this is metastasis, that's not allowed to be in the lymph node. And then mass cell are allowed, but they're not allowed to be clustered together. They're not allowed to be that big, and they're probably not allowed to attract all those little in the fields.
But the plot ticking, so we thought until about 2-3 years ago that we were doing quite well with cytology until a paper from Davis came out that told us that actually we had false negative cytology for about 30% of mast cell tumours and about 15% of soft tissue sarcoma. And another study, definitely proved to us that we have a very poor correlation between histology and cytology for melanoma. So actually, we had to go back to our drawing boards and we should actually get histology of those lymph nodes.
The problem is, which is the sentinel lymph nodes. So which, which one of those lymph nodes is, is the tumour draining too. And the sentinel lymph node, concept comes from the human world and comes from women with breast cancer, because, up until probably 2025 years ago, women would get a complete mastectomy and they would get all of the axillary lymph node to see if they had metastasis, and that would Cause a lot of lymphedema, especially if they got radiation therapy afterwards and it was very uncomfortable for quality of life.
So they basically came up with the idea of the sentinel lymph node, which is the primary lymph node, the primary tumour is injected either with a marker. Which is often Michelin blue or radioactive, thing, and this is actually from a paper from Colorado. And basically, the Michelin blue is gonna go into the first lymph node and you basically once that surgery, you're gonna basically take the lymph nodes that are blue or the lymph node that are gonna pick up the radiation.
And if that lymph node is negative, then you can assume that the regional lymph nodes, the rest of them is negative and that the dog would Not benefit from . Major lymphadenectomy versus if the lymph node is positive, then there might be some, some, for some tumour type that it would be reasonable to go and get more of those lymph nodes. So imaging of the sentinel lymph node, this is from a paper from Zurich where they basically inject contrast, so IOXL around the, the, the, the tumour and then they basically follow the lymphatic to see where is that, what is the draining lymph node.
This is, another example from an oral tumours and you can see that this is pre-contrast, this is post-contrast, and this is a lymphangiogram. So you can see that the, the contrast is going to the lymphatic to mandibular lymph node, but it's also coming up to that little lymph node here that I'm not sure we would have gone after. So what about if we cannot map it?
So from a study in Colorado, we know that for mast cell tumours, 8 of the 20 for 8 of the 20 mast cell tumour, the sentinel lymph node was not the closest lymph node. In a study that's from Florida of oral melanoma, of the 13 dogs with oral melanoma, 4 showed metastasis to our 4 lymph node centres, so that means mandibular and retrophal lymph node. And in a study for anal sac tumours, I think there's more, more than 1 now, .
It could go to the sacral, to the internal iliac, or the medial iliac lymph node, and it could go anywhere. It could go obsilateral, it could go contralateral, it could jump lymph node, so, because of that, We tend to do CT to actually try to find which, which is the draining lymph node. So, what about, what can you do for you?
Like if you're in practise and you have an or you know in digit melanoma that you're removing, I would say you should probably take the regional lymph node too. And you, it's, it's good. Cytology is a good, a good first step, because if it's positive, then you know that the lymph node is definitely metastatic and you can tell that to the owner and you can prognosticate the tumour based on that.
But if it's not, then histology should be performed. On multiple regional lymph node, if, if it's possible, or at least the most easy one to take, so definitely for digit, you would take for the front limb, the pre-scab, for the back limb, definitely the pupal, you can do sentinel lymph node only if it's well imaged, obviously. So for metastasis, if distance metastases are present, prognosis is worse in the majority of tumours and the prognosis is a median survival time of 1 to 4 months is basically what it is.
Obviously, as, oncology treatment gets better and better, it's possible that eventually we will get a much better prognosis for that, than that, but at this point, I think, for the majority of tumours, that's still in the range of what we're talking about. Couple, so let's look at a couple of CTs because we talked about before how CT is way more sensitive to So here's A CT of the thorax. So these are the lungs, the heart, and basically, normally you should have already seen a couple of metastases kind of pop through.
And to me, I totally see them, but I, I realised when I show it to my students that they don't necessarily see them. So here's one. And the difference between a blood vessel and a pulmonary metastasis is that the pulmonary metastases will have a beginning and an end.
Versus if you come back here, so this is pulmonary metastasis down here, but this is blood vessels because if you go back and forth, you can actually see them. So this is a mat here, this is a met here. So let's play it again, so you guys can see them again.
Thoracic, another thoracic CT just so you get your eyes used to it a little bit. And there's gonna be a couple of mats. Oh, so you saw them.
So obviously on CT you can pick up metastasis from about 1 to 2 millimetre versus on a radiograph, a good radiologist probably 5 millimetre, somebody like me, they have to be at least a centimetre for me to pick them up, so. And then cats are very different, so, pulmonary metastasis in cats can look like anything, interstitial, bronchial, and this is a CAT CT so you can see that here. Here.
So you basically have metastasis. It's way more, they're not as nodular, they're. So it's way harder to diagnose metastasis in a cat, especially since the cat have all the asthma and all the other inflammatory disease of, of the lungs that they can get, but CT can help for that.
So what do you think the prognosis is? So I told you before, if you have pulmonary mets, prognosis is 1 to 4 months. So this was November 2015.
February 2016, yeah, they're bigger, but they're not that bad. No, May 2016. And this was a year later.
So this was pulmonary mets from thyroid carcinoma. So there's a couple of tumours where the pulmonary mets don't grow that fast. And so thyroid carcinoma, some of the anal sac, multilobular osteochondrosarcoma.
So it's very important that, yes, if you have pulmonary mets, most likely prognosis is very bad, but sometimes it's important to know what the primary tumour is, because some of the some of the dogs with metastasis actually live a long time with them. Abdominal CT, so this is a caudal tie, and we're gonna go forward. So this is obviously a female dog, anal sac, rectum.
This is the urethra. We're going towards the bladder here. And here you're gonna have those lymph nodes.
These are GI tract. So small intestine. This is the spleen and it's not it's not rare to have those multiple little nodules in the spleen, .
But they shouldn't be bulging out. This is a kidney. This is the adrenal gland on that, that side of the, so here's the adrenal gland.
This is the other kidney. The other adrenal gland that's way closer to the vena cava, so that's why a right adrenal gland invades into the vena cava way faster than the left, obviously. Here's the stomach.
Spleen again, this is the liver. And this is the pancreas. So actually, I always think on ultrasound, the pancreas looks like nothing to me, but this here is the pancreas.
So it looks like it's a real organ, stomach with nice contrast in the mucosa, and this is basically the liver. And this is the gallbladder here. And there's a couple of cysts in the liver.
OK. So sometime, this was a dog that presented because of caudal abdominal mass. The friend that had done, an ultrasound and thought that it was a bladder mass, but when I palpated the dog, I was like, well, usually they would have way more straining if the, the mass, the bladder was that big.
So we decided to do a CT. Because on the ultrasound, you could just see a big mass and this is what it looks like. So we're starting at the level of the kidney.
This is contrast in the ureters and, and this is the spleen. And as we go caudally, you can actually follow the ureter that's a bit dilated. Here's the bladder with contrast into it, and here's the mass.
So the mass is actually located between the bladder and the rectum, and this is obviously a female dog. So this is actually a uterine stump mass. And it was a sarcoma.
And you can see that here's the, the ureter that was passing just on top of the mass here. And then the other thing you could say, see from the CT is you had those multiple little nodules that were basically seeding of of the mass throughout throughout the abdomen. So obviously, even doing surgery would only be really palliative for that dog because we had seeding of metastasis.
So the owner actually elected not to, just to take her home and enjoy her. Liver metastasis, so this was a dog on ultrasound that had a coarse liver. So obviously a coarse liver on ultrasound to me always warrant aspart.
In this particular case when to CT scan because they, the dog was hypoglycemic, so they were expecting . A pancreatic mass that is not necessarily visible on, on ultrasound, the majority of them are not. And when they did the three-phase contrast on the second phase, they actually saw in the liver multiple.
Metastasis, so you see the liver is pretty much like cottage cheese. And this was aspirated as a carcinoma. So the dog didn't have an insulinoma, it did have a liver, a liver carcinoma metastasis that were causing the hypoglycemia.
Primary lung tumours, like we talked before, usually you do a CT to make sure that there's nothing else in the other lung lobe and that the tracheobronchial lymph node looked normal. So this is obviously an arterial phase, a delayed phase, and that particular t was unlucky. We did thoracic and abdominal CT for staging.
And we did find a little mass in his stomach, and that was actually in his cardia and also a little mass on his spleen that you can see, so this is their to phase, this is the venous phase, and this is the delayed the portal vein portal phase and this is the venous phase and you can see that . The different phase in the stomach and then I ended up aspirating all masses to see if they were related. And this was a little leiomyoma.
This was a benign EMH so extramedullary metoposis, and this was actually a benign lung tumour. I think it's the only one I've ever seen. So this dog was actually cured from his tree masses.
This was a medicine case, so I don't necessarily think that I would have CT the dog, but obviously, when you can, you do. So this is obviously an intact and this was a 3 year old dog that presented with bicavitary effusion. So intact male, it was 3, and you can see that it probably has, you can see the fluid here, so fluid is, is more like urine in the way that it looks on CT.
So if we go forward, rectum, this is peritoneal effusion, huge prostate. Bladder here and then this all here is all peritoneal effusion. This is mesenteric fat and you can see that lining.
The peritoneum here, there's all those little nodules and this is actually carcinomatosis. So if you were in your clinic, you could have done an ultrasound, found the the fusion, aspirated, send it send it to the, the pathologist, and you would have probably got your carcinomatosis diagnosis and this is the pleural effusion here, so obviously, Most of the time, if you have effusion into cavitary, it's usually not a good news. I think they didn't believe it because it was a trail dog, but definitely, that's what it is.
What about this one? So this was another dog with a primary lung tumours that we CT. So you can see here it's cavitated, so they can be cavitated once in a while.
And funny enough, the dog also had What at the beginning we thought was a kidney, but you're gonna see the kidney appears here. So this is the kidney, so this is not a kidney. This is actually an hepatocellular carcinoma coming off the liver.
So this dog also had, two tumours that it could be cured of. So always remember that it's not unusual to find two tumours in a dog. They're not always metastas they're not always related.
Medtinal mass, so sometime we do CT just to make sure that they're surgical and that they're not too invasive and too here. So this was a thymoma. So obviously, just a big cyst that is surgical.
Sometimes it can be incidental, so on thoracic radiograph, we in retrospect, we could see it, but you know, because of the thora sometimes the thoracic limb with the, with the, the muscle that kind of at the back, you don't always see the cranial mediastinum very well, but this was an incident of finding on the dog that had a sarcoma so we staged just for that and then we found this very cute, . Cute little thymoma. Starting at the bottom, a good physical exam, especially in the UK, you guys have so many anal psych carcinoma, dogs, in the, in New Zealand, they imported dog from Britain and I've never seen so many as there.
Obviously, like we talked before, I tend to do CTs for these guys to figure out which lymph node it goes to. And the reason I started doing that was this dog. So this dog had an abdominal ultrasound that looked normal.
On rectal, you could see the primary tumours that was very big, but you couldn't feel anything else. And when we did the CT, for the surgeon to plan the surgery, we, we actually found this sacral node here. That my finger was not long enough to feel and the surgeon's finger also was not long enough to feel.
So we did that to plan the surgery because the tumour was quite big at the back, and on ultrasound, they couldn't go far enough in the pelvis to actually see it. So, this was, I was like, oh, after I saw that, I was like, well, maybe we should CC them all the time because I had been burned. It's not the first one I've been burned with, but it's the first one I could determine that I've been burned with.
And since then, there's a study that, that, proved that you identified only, all the metastatic lymph node in 30% of dogs compared to CT. And this is just another example. Kidney had big adrenals, so this dog had Cushing, kidney, spleen, all the GI tract, and then you're gonna see some lymph node pop.
So there's one here that shouldn't be there. He shouldn't be there. There's a big one there.
There's still one here. There's another one here, that's what we used to call the hypogastric one. And then there's Nothing else.
And then the vet had removed the primary tumour. So the primary tumour was removed, but then he had all of those lymph nodes in. So the conclusion is not all cancer behave the same.
Each patient and its owners are different and there's not really a cookbook approach, but there's a systematic approach on how you approach cancers. You just have to answer those four questions is what it is, where it is, how bad it is, and what can we do about it, . Treatment monitoring, obviously x-rays for something, a cap with a thymoma before and after radiation.
It's always fine, then you can follow with X-ray. This was an old, so that's during my residency, a dog that had an atomato syphilis, that's the dog 10 years later where you could see he got radiation and this is basically we followed him with a radiograph, . Now in the Linac, we have those conde CT which are not as good quality CT but to follow up, it's way cheaper than a real CT.
And it still does the job, so this is at at treatment, 3 months, 6 months, 9 months, 19 months. So you can definitely follow them. And because it's cheaper, owners do come back and when it regrow or it gets bigger, you can either retreat or you can use systemic therapy.
So there's the reason why we monitor is that there's something else we can do once it progresses. And this is, we haven't talked about MRI at all, but obviously MRI is good for neural tissue. This was an example of a brain tumours that we radiated.
This was at the 6 month recheck. This was at a 1 year recheck, so it was starting to grow back and I was like, well, she said I would accept toxicity. I just cannot let the tumour grow again, so I treated it again.
And this is 6 months later, it pretty much disappeared and the dog ended up dying 2 years post radiation from metastacheangosarcoma, and they did an autopsy and there was some radiation side effects, but the tumour was in complete response, which was very surprising to me. And sometimes it's the only way we get an answer, kind of. So this is once again, peritoneal effusion.
This was a medicine case too. Obviously, you can see that compared to all the other CT we look, there's way more contrast in those intestine. And there is way more contrast in.
The liver, the liver is huge and super contrasted. And then if you go back up, if you look here, the vena cava is way bigger than the aorta. So this would tell me that this is a right-sided, right-sided occlusion, and you would, it's called Bud Kiri syndrome, but normally this would be caused by some kind of thrombosis, but we don't see any thrombosis anywhere.
And when we get to the heart, We actually see a mass into the heart that was blocking. So this was an intracardiac tumour. That's the only one I've ever seen, so that was kind of cool.
Obviously, it would have been picked up on echo, but because they were concentrated on the abdomen and they were thinking that there was gonna be a venous thrombosis somewhere, they were not thinking that it was gonna be this. And the future of imaging of cancer might be PET CT which is a functional as well as a positioning. And you basically can combine, so this is from a study from David Vaile, where they look at the lymphoma patient and how when they go into remission, the PET CT signal kind of disappears and in the human world, PET CT is pretty much the standard of care now for staging, lymphoma patients because CT is not that great for round cell tumour.
And that's the end. Thank you very much. Only koala I've ever treated.