 Hello and welcome to noon conferences hosted by MRI online in response to the changes happening around the world right now in the shutting down of in person events. We have decided to fight free daily noon conferences to all radiologists worldwide. Today we are joined by Dr. Suresh McCurgy. He is a recognized authority and head neck and neuro radiology. He has authored over 400 scientific manuscript and book chapters and written or edited 12 textbooks. He is the consulting editor for both neuro imaging clinics and Magnetic Renaissance sorry clinics of North America. He is devoted educator and has been invited speaker over 400 occasions. Reminded that there will be time at the end of this conference for a Q&A session. Please use the Q&A feature to ask your questions and we'll get to as many as we can before our time is up. That being said, thank you so much for joining us today. Dr. McCurgy, I will let you take it from here. All right. Thank you very much. Can you hear me, Ashley? Yep. You're good to go. Just need you to do a quick screen share. There you go. There we go. Great. Well, thank you again so much for having me. It's a pleasure to be here again at MRI online. I hope everyone is healthy and safe that you, your family and your friends are doing well. And again, I want to credit MRI online for doing this. In times like this, you get, it's strange what makes you happy. When I was younger, other things make me happy. Now that I'm older, what made me happy is yesterday was I was finally able to get a haircut. They opened the salons and barbershops here. So certainly one of those little simple pleasures of life. So what I'm going to go ahead and do then is start with this talk, which is going to be on anatomy and pathology of the oral cavity and oral pharynx. And what I'll be doing is really focusing on the anatomy, because really in head and neck imaging, anatomy is so important. And one of the keys regarding imaging is that imaging is not, at least in head and neck, from a practical standpoint, it's not to do a lot of fancy stuff. If you will, a lot of CTology or MRIology or pathology, but rather it's really to figure out ways to best see the anatomy. And if you don't really understand the anatomy, then it's always going to be a challenging area. So anatomy is really, really key. So the first thing that we'll talk about is, we'll talk about the oral pharynx, and then the first area that we'll talk about is the tongue base. So, you know, when I was a fellow years ago, and unfortunately I trained in the last century, I hate to say that. So I trained back in the old days, if you will. The first day of my fellowship, and I finished my residency at a pretty good place, I just didn't realize that there were different parts of the tongue. So when we talk about the oral pharynx, the first subset of the oral pharynx that we'll talk about is the tongue base. And again, it's all anatomy. When we were back in medical school, we spent whatever time we did on the head and neck. We knew that there was a tongue, and it was separated by this chevron-shaped papilla. You see these papillas right here? These chevron-shaped papillas are called the circumvalid papilla. And right at the apex of the circumvalid papilla is this little area here, which is the foramen cecum. And as we'll see later, the foramen cecum gives rights to the eventual thyroid gland, which eventually descends to the anterior neck. Everything posterior to the tongue base, and I'm going to contour it right there, everything posterior to the circumvalid papilla is the tongue base. So that's that first area is the tongue base. So on the left here is the standard anatomic image, and on the right-hand side is a squamous cell carcinoma involved in the tongue base. And one of the key points that I want to make is that when you look at the schematic illustration, you have some muscles that are going anterior to posterior. This is the combination of the genioglossus and geniohyroid complex. So when we talk about the muscles on the floor of the mouth, and we'll talk about this later, they arise in the geniotubricle. So genioglossus, glossus is Greek for tongue, so that's why it's the genioglossus muscle. So these are the little brown areas here that I'm drawing are the genioglossus-geniohyroid muscle. Now where they attach, they're attaching to these transverse fibers. And essentially, those circumvalid papilla are approximated by where these, if you will, longitudinally oriented fibers attach to the transversely oriented fibers. So when we start looking at imaging, you're going to notice the difference between where the tongue base is and the floor mouth is. And I'm oftentimes asked that question, where does one stop and the other begin? And that little approximation will help you. So these are just two examples of run-of-the-mill squamous cell carcinoma. This talk is not on squamous cell carcinoma specifically. Again, we're going to cover the oral pharynx and the oral cavity and talk about some of the common pathology. But if you see a lesion here that's involving the right lateral, in this case, right lateral aspect of the tongue base, this is how I would contour it. And I want to make that important point that this muscle here is the genioglossus-geniohyroid complex. And notice now it comes into the tongue base. The tongue base typically contains a fair amount of fat. So it's where this transition comes in about where these vertically oriented fibers end and these transverse fibers begin. This area would be the anterior aspect of the tongue base. And on the sagittal images here, a sagittal T1 weighted image just demonstrates a tongue base squamous cell carcinoma. So by far and away, if you're looking at abnormality involving the tongue base and it's a tumor and by far and away, it's going to be squamous cell carcinoma. Now, this is the second most common tumor to involve the tongue base. So here we have this mass right here that's located posterior to the tongue base. And we can see the little epiglottis right here. So this really is situated within the velecula and it does have an attachment to the tongue base. Now, in this image, I like this in particular because we can see the lot of fat right here on the CT scan. That's the normal fat in the tongue base. And this second most common tumor to involve the tongue base, it's not squamous cell carcinoma, but it's lymphoma. Now, are there any specific imaging findings that can help us differentiate between squamous cell carcinoma and the tongue base, excuse me, lymphoma? And the answer really is not. I mean, oftentimes there are overlapping features. In general, if I see a CT scan, I see a very, very bland appearing lesion that is arising in an area that has a high propensity of adenoidal tissue. So for instance, we know that there's adenoidal tissue located at the tongue base. This is what we call the lingual tonsils. If so, if I see a well-marginated, well-defined, very bland, boring appearing lesion in that area, then I will have a higher likelihood to put lymphoma in upper up in my differential diagnosis. But if I was just playing the statistics, squamous cell carcinoma would be number one and lymphoma would be number two. The third most likely tumor to involve the tongue base is going to be minor salivary gland tumors. So a minor salivary gland tumor, again, I'm not the smartest person in the tool shed, but it took me about 30 years to figure out, really understand what a minor salivary gland tumor is. So we have salivary glands and we have salivary glands, our parotid glands, our sublingual glands, our submandibular glands, et cetera. So what a minor salivary gland is, is that we take the exact same piece of tissue that's in a salivary gland and we put it in an area where it shouldn't be. So instead of it being a salivary gland, we put it in areas that it shouldn't be. And the areas in the head and neck that have a higher predominance of salivary gland tissue, if you will, ectopic tissue include the hard palate, the soft palate, the tongue base, and oftentimes the floor of the mouth. So the reason why I mentioned this is that when we talk about minor salivary gland tumors, the exact same tumors that arise in the parotid gland arise in these ectopic rest of salivary tissue. So for instance, the differential diagnosis, if someone says this is a minor salivary gland that's fine, but we want to take it to the next level and remember what are the most likely tumors that arise in the salivary gland. So this could be the benign types, which could be pleomorphic adenoma. It could be a Wharton's tumor, or it could be the malignant type, which is mucoepidermoid or adenoids to carcinoma. In this particular case, this was a minor salivary gland tumor, and this turned out to be a mucoepidermoid carcinoma. Are there any specific imaging findings that help us separate those two? Unfortunately, the answer is no. We just cannot have any specific imaging findings, except in this one particular case. So this was a case where you can potentially make the diagnosis of a minor salivary gland tumor. So here's a CT scan demonstrating a mass here that's involved in the tongue base. We can see it's pretty bland and we can say, well, maybe it is lymphoma. But when we look at this T2-weighted image, I'm sorry, this is a contrast-enhanced T1-weighted image, we can see that it's homogeneously enhancing. And if you look at the CT of the neck right here, we can actually see a metastatic lymph node. So again, I thought that this was going to be some type of squamous cell carcinoma or lymphoma. But this was an older study, and when I looked at the gradient echo images, we can see it's very, very bright. And if we took this image, and if it was bright on gradient echo or bright on T2, and we stuck it into the parotid gland, then the diagnosis was pleomorphic adenoma. So this was a very unusual case of a minor salivary gland tumor, which was benign, which was a pleomorphic adenoma that arose from the tongue base, and it actually spread into a lymph node. So this was a very unusual case of some will call it metastasizing pleomorphic adenoma. This was still a benign lesion, but the lymphatics are so rich in the tongue base that this small rest of tissue actually ended up extending through the lymphatics into the level 2 lymph node, which is a primary echelon drainage. So one of the things that we're also often asked to determine on imaging is we see a case like this, and this is abnormal soft tissue that's located in the tongue base and in the region of the lingual tonsil. Now one of these is squamous cell carcinoma, and one of these is lingual tonsillitis. And from an imaging standpoint, I can't tell the difference. There's just no way for me to tell the difference, but one of the privileges I have, I work with this group called CENTA here in India, and I get to go in and actually see the patients. And now I've become very familiar with some of the endoscopic findings, especially in lingual tonsillitis. And when you look at patients with lingual tonsillitis, they have heaped up adenoidal tissue involving the lingual tonsils, and clinically, it's very easy for our referring physicians to say this is lingual tonsillitis and this is squamous cell carcinoma. So radiologically, we cannot tell the difference, but remember about 80% of what we see on imaging can be either seen directly at endoscopy, or it can be palpated on clinical examination. So if you see something like this and we know that it's in, if you will, the visceral space or the tongue base, our referring physicians can easily perform endoscopy and they can go in and palpate this, and they can easily make the diagnosis of tonsillitis versus squamous cell carcinoma. So it's completely appropriate to say correlate with endoscopy. Another abnormality that can involve the tongue base is a lingual thyroid. So as I mentioned before, the thyroid gland starts here right at the tongue base, specifically at the level of the circumvallic papilla. And the normal embryology of the thyroid gland is it extends deeply through the floor of the mouth, and whether or not the gland descends or the body arises from it, I think it's up to debate, but there is this relative descent of this thyroid on log with the developing neck. And it has this complex relationship with the hyoid bone, and there's a component of that superior, there's a component of it that's also inferior to it. So that relationship is a little bit variable, but eventually the thyroid gland extends to its natural resting place just anterior to the upper trachea. What a lingual thyroid is, is that a lingual thyroid is when there is thyroid tissue that is solid that somehow has little droplets that are left behind during the natural descent. And on a non-contrast CT, you can see that it's high attenuation here, and that high attenuation, it tells you that the thyroid gland normally concentrates iodide. So on a non-contrast CT, we can see that this is high attenuation. And if we look at the normal location where the thyroid should be, we can so there's no thyroid tissue. So this is just the class of experience of a lingual thyroid. Now another example here of a lingual thyroid densely enhancing tissue, we know the thyroid gland normally is enhancing when we give contrast. So this is just lingual thyroid tissue. On MR, it has a very non-specific appearance. It's a little bit heterogeneous on T2. It is a little bit high signal here, whether that's due to colloid, we just don't know, mid-may or may not be not 100% sure. But again, this is that appearance on sag of limaging. So just based on MR alone, the imaging findings are non-specific. But when we perform CT scan, what we want to do, and I'll just go back to this image is look for the very, very dense tissue in a non-contrast CT, or look for dense enhancement in the expected location of the frame and see them. Now, what's the difference between a lingual thyroid and thyroid-glossal duct cyst? Well, they are cousins. The only difference really is that the lingual thyroid tissue is solid whereas a thyroid-glossal duct cyst contains fluid. So essentially, a thyroid-glossal duct cyst is the water balloon. So if you have a balloon, if you have the balloon and there's no water in it, it's collapsed, you can think of that as a lingual thyroid. But if you blow up the balloon or you put water in it and you expand it, that's the thyroid-glossal duct cyst. So sometimes it can be a little bit confusing, but if you understand that simple concept, you'll always be able to make that diagnosis. So we talked about the oropharynx, and the first thing that we talked about was the tongue base. Now let's move our attention to the tonsil. So when we look at the tonsil, there are actually three components of the tonsils, and our referring physicians are well-versed in this anatomy. The largest component of the tonsil is this area right here, and this is what has different names to it. Remember in Head and Neck, we take the same piece of anatomy and we give it different names. So this piece of anatomy can be called the fascial tonsil or it can be called the palentine tonsil. Each one of these is completely appropriate. And those of you that have ever had your tonsils resected have had a tonsilectomy. The part of the tonsils that's resected is this tonsil adenoidal tissue located in this tonsilifasa. There's another component of the tonsil which is located anteriorly, and this gets back to the anatomy. So we can see a little ridge right here which is a muscle that goes from the palate to the tongue base. And if we remember our Greek origins, the name of that muscle is the pallidoglossus muscle. This pallidoglossus muscle is referred to as the anterior tonsil pillar. And you can see this. If you look in someone's mouth, that vertical fold of tissue that you first see when you look in someone's mouth on the lateral side is the fold of the anterior tonsil. The fold of the anterior tonsil pillar. Behind that, then we can see the little normal tonsil sticking out. So that's how we can tell the anterior tonsil pillar versus the regular tonsil. Now there's another little muscle right here, and I think I can show it in green. That goes from the palate to the pharynx, and the name of that tissue is the palidofaryngeus muscle. And the other name for the palidofaryngeus muscle is the posterior tonsil pillar. So there's actually three components of the tonsil. There's an anterior pillar. There's a posterior pillar. But the majority of the tonsil is comprised by this tissue, which is referred to as the palentine or the fossil tonsil. And that's where the majority of lesions arise from. So this is an example here of squamous cell carcinoma that's involving the tonsil. So this is what we would see schematically. And this is what we see radiologically. So this is a patient that has a left-sided tonsil carcinoma. Now I mentioned before that about 80% of what we see on imaging can be seen directly or can be palpated on physical exam. So here's a tumor that's involving the left tonsil. Everyone can see that. Now if we just say in our report there's a left tonsil cancer, well our referring physicians again can look in and perform endoscopy and they can see the mass on the left-hand side. We need to take things to the next level. So one of the things that we have to do, because the referring physicians, one option they may have is transoral robotic surgery, as opposed to treating these patients with chemotherapy and radiation therapy. In the U.S., the majority of these patients are going to be HPV positive. If you look across the globe, the incidence of HPV positive tumors really does vary based on geographic location. If you've ever looked at the data, it's quite interesting. The difference in incidence in the U.S. when we see this, it's probably going to be squamous carcinoma. But the key thing here is notice what it's doing to this space that's next to the fairings. That's the paraffaryngeal space. Contrast this patient's right paraffaryngeal space with the left. This tumor is expended deeply and partially effaced the paraffaryngeal space. Similarly, look at this tumor spread anteriorly. Now I'm going to go back one slide, and I'm going to talk a little bit about this anatomy. So there's a muscle right here, which is a superior constrictor muscle. This superior constrictor muscle grows and interdigitates with this muscle, which is the buccanator muscle. Where the superior constrictor muscle interdigitates with the buccanator muscle is called the teregal mandibular refae. The teregal mandibular refae runs from top to bottom. So the point is, is that any time that you have a tonsil or cancer, especially a tumor that involves the anterior tonsil or pillar, they can grow back, jump on the superior constrictor muscle, and grow anteriorly. And this is oftentimes subneucosal spread. Now that you understand the anatomy, take a look at the growth of this tumor and compare it to the normal fascial planes on the opposite side. Notice that this tumor is growing anteriorly along that superior constrictor muscle. So that's important information that cannot be seen clinically. Another example here, here's a tonsil carcinoma. This one's a little bit anteriorly, so this may be arising from the anterior tonsil or pillar. But the key piece of information here is that this tumor is involving a retroferenzia lymph node. Again, information that we cannot see. So those are just a little tidbits on squamous cell carcinoma. But the bottom line is, is that if you see a mass involving the tonsil, the number one diagnosis is going to be squamous cell carcinoma. What do you think number two is going to be? Again, we have this mass here, a very, very large mass here involving the tonsil. Here's a retroferenzia lymph node. Well, the second most likely diagnosis is going to be lymphoma. And unfortunately, there is no way for me to differentiate lymphoma versus squamous cell carcinoma. They look exactly alike. So if I'm dictating out something, I know statistically it's going to be squamous cell carcinoma, but the second most likely diagnosis is going to be lymphoma. Now, similarly to what we talked about, here are two examples of a patient. And I see this every day that one of these patients has a squamous cell carcinoma involving the left tonsil. And the other one has had a tonsillectomy of the right tonsil. So the point is, is that each of these has abnormal tissue here involving the tonsil. Everybody see this here? One of these is squamous cell carcinoma. And one of these, the patients had a tonsillectomy on the right hand side. So the issue is which one is which. Now, I can't tell the difference. There's no way I can tell the difference. And again, maybe with a leap of faith, there's a little bit of more enhancement. And you can say, well, maybe that is the squamous cell carcinoma. In this case, you would be correct. But again, remember what I said, the referring physicians can look in. They can look at the tonsil. They can palpate it. And on the case on your left, this was just a normal add normal tonsil or tissue in a patient that had a right tonsillectomy. And then on your right, this patient had squamous cell carcinoma involving the left tonsil. But again, if you're not sure, it's totally appropriate to just say, Hey, what do you see at endoscopy? Now, these are a couple of nice cute cases that I'll show. This is just a patient that has bilateral tonsillates. The confusing part about this is that if you look at the tonsil, look how bulky and maybe enhancement. And almost, you can almost say it's almost aggressive. But what this is is tonsillates are essentially small little calcified calcifications of a chronically inflamed tonsil. So when you see the calcifications here and you see this thick enhancing tissue circumferentially and symmetrically surrounding it. In most cases, this just turns out to be just chronic inflammation associated with a tonsillate. So tonsillates can be unilateral, they can be bilateral, or in the case on your right hand side, they can be multiple. And these are just by our multiple tonsillates. Now, there's an old saying, I will Rogers, the famous American philosopher said, good judgment comes from experience and experience comes from bad judgment. There's a mass right here that's involving the left tonsil. And I remember this case because I think I read it three times and I called it something different each time. First, I thought it was a tonsil cyst. Then I thought it was a metastatic retropharyngeal lymph node. And then I thought it may be an abscess, even though the patient was asymptomatic. And then one of my really smart fellows at the time who became a great faculty when I was at University of Michigan said, hey, you know, is it possible. This could be a brachial clefsis and low and behold, it was a brachial clefsis. So this was actually a type four second brachial clefsis. So I won't get into too much of the embryology here. But the bottom line is, is that the typical second brachial clefsis we all know is located at the anterior neck. But I want you to realize that there are different types of brachial clefsis. And sometimes if you see these unexplained cystic masses in a patient with no history of cancer, and they have they're not infected at all. We oftentimes say that it's a tonsil or cyst, but you can have type four second brachial clefsis that are isolated to the tonsil and are deep to the plane of the internal and external carotid artery. And I would refer you to Bailey's classic classification of brachial clefsis that was written in the 1930s. I've read that a couple of times and honestly, I have a boring life. I actually like reading those things. It's fascinating how much they knew and part of what we do now is trying to figure out how much people knew before us. Now, this was a patient that has that is febrile. So the image on the middle image right here demonstrates an abscess that's involving the tonsil and this is your classic tonsiler or peri tonsil or abscess. I've seen it called both in the radiology and the e n t literature. And what's on the other hand is another abscess and this abscess is located in the paraphernal geospatial space. So one of the challenges is that what's the difference between this and what's the difference between this and why does it make a difference. What makes a difference because if we say that this abscess is in the tonsil, then this will be drained by our referring physicians through an intraoral drainage. If we say that this is located in the paraphernal geospatial space, then this would be drained through a cervical approach. Now there's only about five or six, maybe maybe a centimeter between here and from the tonsil and to the paraphernal geospatial space, but it makes a big difference. So that's why it's important for us when we localize these to put these in the exact same location in the correct location sorry. So far what we've done is we'll talk about the oral pharynx and we talked the tongue base and the tonsil. Now let's move on to the soft palate. Now, the way that I think about the soft palate because if again I sort of live in the space of head and neck but if you don't, or if you're not there every single day it can be very confusing. So what I think of the soft palate is the following. Here's the superior aspect of the soft palate and we know that this area right here is the uvula. And we've already talked about some of these gray areas. This is the gray ear involved the lingual tonsil. This is tissue involving the palentine or the fascial tonsils. This tissue up at the top here are the adenoids of the nasal pharynx. So this ring of tissue is what's referred to as Waldier's ring. And again it took me about 20 years to figure that out because I would always look for Waldier's ring on axial images. But after a while I realized well Waldier described this before CTs and MRs and he described it when you look in someone's mouth. So right at the top here above the soft palate are the nasal pharyngeal adenoidal tissue. Now when we go back and look at our anatomy one thing I do remember about anatomy is that the palate was always referred to as a palatal arch. It was an arch of palatal tissue. And back in medical school I don't remember much but I do remember the two if you will Italian muscles. They were the levator and the vela, the levator and the tensor veli palatini that tethered the palate all the way up to the skull base. So when I think of the palate I think of a Roman arch and the Roman arch is the following. So the parts of the arch that form the foundation of the arch, these pillars, this is what I remember as the tonsillar pillars. The area that communicates and attaches both tonsillar pillar is the palatal arch. So this is our palatal arch and eventually if I look at here at the skull base, these little bricks right here that tether the palate to the skull base, these are the levator and the veli palatini muscles. So if I can remember that we're dealing the palate is an arch, we can always remember the tonsillar pillars, we can remember the palate, we can remember the skull base, and then we can remember these little muscles right here, which are the tensor and the levator veli palatini muscles. So the palate tends to be a midline structure, there's only essentially one piece of soft tissue. And when we look at tumors involving the palate, unlike tonsill cancer or something else, they tend not to be just unilateral but they tend to be circumferential as it's seen here. So this is just a very, very large squamous cell carcinoma on CT and this is squamous cell carcinoma on MR. So when we talk about a differential diagnosis for the palate, number one is going to be squamous cell carcinoma. And when you are evaluating tumors that involve the palate, make sure that you always perform some type of imaging in the coronal plane. So this is a tumor involving the soft palate on the coronal plane, and this is it on MR, a contrast enhanced T1 weighted image demonstrating squamous cell carcinoma involving the palate. Well, one thing when we are looking at palatal carcinomas, it's important then yes that we look at the palate, this is one of those lateralized squamous cell carcinomas, but realize these squamous cell carcinomas can grow superiorly. So let's go over the anatomy. Remember, the anatomy is absolutely key. So this is the anatomy of the nasopharynx. So this area right here is a torus tubarius. Behind this is the famous fossil Rosenmueller and anterior to it is the opening of the station tube. So this is the normal surface anatomy of the nasopharynx. Once you understand normal, you can understand abnormal. Notice how all of this anatomy on the left hand side is completely in face. So this was an example of squamous cell carcinoma that was growing superiorly along the torus tubarius. And then we look at the skull base. As you get older like myself, I get fatter and a lot of that fat is located within my bone marrow. At least that's what I like to tell myself. So this is normal high signal in the bone marrow. Here is normal high signal in the patient's right petrus apex. And in the left petrus apex, notice how there's replacement of that fat. In fact, in this case, this squamous cell carcinoma grew superiorly extended up into the nasopharynx and then eroded the skull base in the petrus apex. So that is, if you will, taking head neck radiology to the next step. But in order to do that, you have to do what you have to understand the anatomy. I'm just going to take a sip of water. Thank you. So number one is squamous cell carcinoma. Now I don't have the polling system but in your own mind's eye. What do you think the second most likely tumor is going to be of the soft palate. So give a second to to cogitate on that. I'll see if anyone answered on my Q&A. Not yet. That's okay. So, number two is going to be, let's see here, number two is going to be, let's see if I can get this thing to work. Minor salivary gland tumor, exactly right. So the number two thing is going to be minor salivary gland tumor. So when we look at minor salivary gland tumors, these look exactly like squamous cell carcinomas. There's absolutely no difference in there. So there's no way for me to tell. But I just know that if I'm looking at squamous cell carcinoma, excuse me, if I'm looking at a mass involving the soft palate and squamous cell is number one and minor salivary gland is number two. There's no differentiating features from it. Now this one you can make a diagnosis on. So here's a sagittal T1 weighted image. There's no contrast. This is all fat involving the uvula and the soft palate. And this was a lipoma. This was actually a dermoid. It also easily could have been a lipoma, but pathologically this was a dermoid involving the uvula. So what we've done so far is that we've gone through oral pharynx and we talked about the anatomy of the tongue base tonsil and soft palate, and we talked about the differential diagnosis. So in the tongue base, number one is going to be squamous cell carcinoma. Number two is going to be lymphoma. Number three is going to be minor salivary gland tumor. Tonsil, squamous cell is one, lymphoma is two, and soft palate, squamous cell is one, and then minor salivary gland is two. Now we're going to move on to the oral cavity. So the oral cavity, the first area that we'll talk about is the buccal space in the buccal region. So the buccal area is just below between your cheek and your gum. So this is the normal area of the normal buccal region, and this is where a classic buccal carcinoma. So for, you know, I'm from India, so I know one of the things that I do when I go to India is I put a little beetle nut between my cheek and my gum. If you're from the United States, you oftentimes put a little piece of snuff in your cheek and gum. These have often been called snuff dippers cancers. Why? Because whether it's due to some type of direct irritant, whether it's the tobacco, whether it's some aflatoxin, etc., these patients have a propensity to develop squamous cell carcinoma involving the buccal area, but that is the first area that we'll talk about is a buccal cancer. So the number one pathology that you'll see here is a contrast-enhanced T1 weighted MR with contrast with fat suppression nicely demonstrates a buccal cancer. Another example here, this was a patient that had a cancer involving the lip extending into the buccal area. Number one diagnosed the squamous cell carcinoma, and honestly, you can see this across the room. So in this case, especially on the right, there's no magic. Now, some people will go ahead and do the puff cheeks technique. I tend not to have used it, especially about five, six years ago when there was a big emphasis on radiation. But I think in the US, as I've been doing this for a while, more places are trying to do the puff cheek. In general, I tend not to image areas that can be seen clinically. So this buccal cancer can be easily seen clinically, so I tend not to do the puff cheeks. But for those that you want to do it, I think it's totally appropriate. So the number one diagnosis is going to be squamous cell carcinoma. What do you think number two is going to be? Well, it's going to be lymphoma. And in this case, this was lymphoma involving the buccal area. Just contrast this to the opposite side. So squamous cell carcinoma is number one, lymphoma is number two. Now, other things that we have to think about that involve the buccal area are infections and abscesses. So one thing that can involve the buccal area is that if you have an infected tooth and you have erosion of the anterior cortex, well, the pus can actually extend out into the buccal area. So this was actually an abscess involving the buccal region. And when we look at the CT scan, a very, very subtle case, but this is the bone windows for this case. And you can see very, very subtle area, but it was this little area of osteomyelitis that caused the infection to extend into the left buccal area. So if you see something unexplained like this and the patient has a fever, play really close attention to make sure they don't have a little bit of a rotten tooth. The next area, the oral cavity is going to be the oral tongue. And look, life gets easier now, right? Because we've already gone through the anatomy of the tongue. So we talked about the circumvalid papilla. We talked about the frame and cecum. We talked about the tongue base being posterior. And everything anterior to this is referred to as the oral or the mobile tongue. So the oral tongue or the mobile tongue, these are all part of the tongue involving the oral cavity. So on the left-hand side is a schematic illustration of a tumor involving the oral tongue. These are two examples of squamous cell carcinoma involving the oral tongue. Again, very, very run-of-the-mill, very, very bland. There's tumors not on squamous cell carcinoma, the oral cavity. It's specifically just to talk about the anatomy of the oral cavity, specifically the oral tongue, and give a differential diagnosis. So here's an unusual case. And I saw a few years ago this child was born, and we can see a component of fat anteriorly. And on the MR scan, we can see signal loss. Now, what is this signal loss? Is it blood? Is it calcium? Is it melanin? I mean, who knows what that is? I should say, hemosteterin. And when we do a CT scan, this just turns all to be calcification. And at surgery, this patient had a biped tongue, and this was a big teratoma that involved the oral cavity. So this was an oral cavity, teratoma. We can see the fat anteriorly and the calcium posteriorly. And this patient also had a duplicated pituitary gland. So if you do see patients that have teratomas involved in the oral tongue, make sure that you look at the other midline structures. You want to make sure that to look at the pituitary gland, you want to make sure you look at the orbital gyri, you want to make sure that you look at the septic polysum, because there is a higher association of midline anomalies. Here's another example of a child that was born that had a teratoma. The key thing about this teratoma is that there are tiny little calcifications here. The one that I showed before, this turned out to be a benign teratoma. This was a malignant teratoma. And again, there are various ways to classify teratomas. Quite frankly, I let the pathologist figure that out. Various types of classifications, but for me, I just say it's a teratoma and then look at the histology to determine whether it's a benign teratoma, mixed teratoma, de-differentiated, undifferentiated, whatever type of terminology your pathology group likes to use. And this was an unusual case of a very extensive vascular malformation involving the oral tongue. Now let's move on and talk about the floor of the mouth. The floor of the mouth is a very, very important structure. So basically the floor of the mouth is that area that's located below the tongue. Now the last talk that I gave for MR Online, I gave a talk on the spaces, so I called it the sublingual space. Here I'm going to call this the floor of the mouth, because now we're talking about the oral cavity and the oral pharynx. So anything that's located below the tongue is in the sublingual space or in the floor of the mouth. So the normal anatomy here is the mylohyoid muscle. Here's the hyoglossus muscle. The tongue is located up here, and the bottom area here is the hyoid bone. So when I look at this, I always use this analogy of the teacup. So this is the rim of the teacup, which is formed by the mandible. The wall of the teacup is formed by the mylohyoid muscle, and then the inferior aspect of the teacup is formed by the hyoid bone. So basically everything in this teacup is located within the floor of the mouth. And when we look at the normal anatomy, this green structure here is the submandibular duct. This red structure here is the lingual artery, and just lateral to it are the various venous drainages that extend into the floor of the mouth. This structure right here, glandular structure, is a sublingual duct, and excuse me, the sublingual gland. And notice below the mylohyoid is the submandibular gland. So all of these stripes right here, these tiger stripes identify the normal muscular structures involving the floor of the mouth. Well, the most common tumor that you'll see in the floor of the mouth is swamous cell carcinoma, really nothing much to talk about in the context of this lecture. This is the second most common tumor to involve the floor of the mouth. Now is it squamous cell carcinoma? Is it lymphoma? Is it minor salivary gland? Well, in the floor of the mouth it's minor salivary gland. So the second most common tumor to involve the floor of the mouth is going to be minor salivary gland. So when you're building your differential diagnosis up, solid aggressive lesions, number one is squamous cell carcinoma, and number two is going to be minor salivary gland. How about in this case? I think we all see this. Here's a little psialolith involving the floor of the mouth right at the level of the phrenulum. And this is one of these common reasons you'll do CT. Someone presents with a neck mass, and this is not a lymph node. This is just an obstructive submandibular gland. And this is obstructive syladinitis caused by this little stone that's located right at the phrenulum. We can also have floor of mouth abscesses. I think all of us are familiar with this. Before what I showed was a little erosion on the outer cortex. In this particular case, if that infection erodes the inner cortex, the buccal cortex, then patients will present with an abscess involving the floor of the mouth. And it's always important for us to go back and look at the bone algorithms to ensure that to look for this area of bony break and osteomyelitis. So this was osteomyelitis involving the root of the tooth that eroded the lingual cortex extending into the floor of mouth to cause a floor of the mouth abscess. Now, if it gets really, really severe, this is Ludwig's angina. So Ludwig's angina are multiple layers of abscesses, pus pockets located in the floor of the mouth. Remember, the floor of the mouth is like a compartment. So if this abscess gets too extensive, it starts to elevate the tongue base. Eventually it can extend into the larynx. We can see the edema involving the larynx and the surgical treatment is essentially is to do an anterior filet, if you will, of the neck and try to remove all these various septated areas of abscesses. What about cystic lesions involving the floor of the mouth? If it's anterior and midline, this is an epidermoid. They tend to be midline because small pieces of rest of tissue get caught. If you have something that's pyramid line, as is seen here, we have to think of our friend the frog, and this is the ranula. So notice anterior and midline is going to be epidermoid, pyramid line are going to be ranulas. And you can see that the ranula is located medial to the hyoblossus muscle and lateral to the myelohyoid muscle. Remember, ranulas can be unilateral or they can be bilateral. And if the ranula extends deep to the myelohyoid muscle, if it grows deep to the myelohyoid muscle, it can have three names to it. It can be called a plunging ranula. It can be called a complex ranula or it can be called a diving ranula. So again, head and neck, same piece of anatomy, three different names, diving, plunging complex. Again, all different types of ranulas that extend below the myelohyoid muscle. Now we talked about the thyroglossal duct remnants already. Previously what I showed was a thyroglossal duct remnant involving the tongue base, the fremen's cecum. This was just an example of a thyroglossal duct remnant as it's extending inferiorly. Again, it can leave these little droplets of tissue involving the floor of the mouth. And how do we know it's thyroglossal duct remnant is because it's very, very dense on a non-contrast CT. Remember, the thyroid gland tends to concentrate the iodine. Well, the last two areas that we'll talk about is number one is a retromolar trigon. Now, the teeth can be really, really confusing. So I think one important thing to remember about the teeth is how do we name the teeth? So let's name the teeth. If you can name the teeth, the retromolar trigon is easy. This is the central incisor, lateral incisor canine, first premolar, second premolar, first molar, second molar, third molar. And right behind that third molar is this triangular space that's called the retromolar trigon. Now, for those of you that have ever had your wisdom teeth out, congratulations because those 900 participants today that are online, you have the largest retromolar trigones of your group. So you're the best at something and congratulations. I still have mine in, by the way. Now, the number one tumor that we'll see is squamous cell carcinoma. Now, of all the tumors that I see, the retromolar trigon is probably the most understage and one of the most complex. This is what our referring physician sees because the retromolar trigon is tucked behind this area behind the molar. So it's right behind the maxillary tuberosity. And realize in this case of a retromolar trigon carcinoma, notice how there is early erosion of the anterior ramus of the mandible. So unlike a tumor being in the oral cavity and the tongue where it can grow and grow and grow, it doesn't bump into anything. These things tend to bump into bone pretty early. So when you do have a tumor in this area, there's a high likelihood of bone erosion. So I always try to recommend now only getting a CT but an MR. But the key thing about that retromolar trigon is just remember the names of the tooth and just remember the third name, the third molar is the same as your wisdom teeth. And if you have your wisdom teeth taken out, this expands your retromolar trigon. And the last thing we're home free now is the hard palate. So when we look at the hard palate, we've got a few structures that comprise the palate. We've got this very, very large plate here, which is the Palatine process of the maxillary bone of the maxilla. And then when we look posteriorly, this is actually part of the Palatine bone. So the palate actually comprised of several bones. You've got this process here, which part of the maxillary bone. And then you've got this process back here with the Palatine bone. And then you have your greater lateral and medial teraboid plates. And if you look real closely, have foramen right here, that's a greater Palatine foramen. That's the lesser Palatine foramen. So remember, it's all anatomy. What's the name of this tooth back here? That is the third molar, also known as a wisdom tooth. So your retromolar trigon is going to be back here. And you can imagine trying to look on someone's mouth, these are very difficult places to evaluate just based on clinical examination alone. So the most common tumor to involve the palate is going to be squamous cell carcinoma. So how do we evaluate this? So if you look at the normal mucosa overlying the palate, it should only be about two or three millimeters. That should be the normal thickness. But this was an example of squamous cell carcinoma, the most common tumor to involve the heart palate. And you can see it's too thick. And when we look at the bone algorithms, it's completely intact. So if we tell our referring physician that this tumor is only involving the soft tissue, tissue and not the bone, then they can perform a wide local excision. But you have to give them information they can't see. So in this particular case, notice how this tumor has eroded the heart palate. Now think how the surgeons think they're just looking at this mucosal layer. They cannot see deeply to it. So if we say that bone is eroded, then the type of surgery that needs to be performed is this. This was a max elective. And this type of aggressive form of surgery is really determined on the information that we provide on imaging. You know, we talked about the value added of imaging, that's value added. So yes, we can confirm what our referring physician see, but more important, we need to provide information they can't see. So that's squamous cell carcinoma is the number one tumor, the most likely tumor to involve the heart palate. And this is number two. So what is it? What are the options? Is it lymphoma or is it minor salivary gland tumor? Well, if you listen to what I said, hopefully somebody was. We know that there are these minor salivary gland rest, right? So minor salivary gland is tissue that should be in a salivary gland that ends up in the wrong place. And one of the areas that has the highest likelihood or highest density of minor salivary gland tissue is the heart palate. So this, in fact, was minor salivary gland tissue. So here's an example of the contrast enhanced T1 weighted image demonstrating a pyramid line, minor salivary gland tissue rising from the heart palate. This was an aggressive minor salivary gland tissue. This one on the left hand side was adenoid cystic. And this one that completely eroded the heart palate was a mucoepidermoid carcinoma. Now, when we look at the minor salivary gland tumors, one thing that can tip us off is the following. What I want to do here, and I think this is my last slide or second to last slide is talk about the normal anatomy. We're now specifically talking about the heart palate. So we're talking about the heart palate, which is located here. Minor salivary gland tumors can extend from the heart palate and extend posteriorly. Once it gets posterior to the heart palate, we're in this little fossa. And this fossa is located between the pteragoid plates in the palentine bone. It's called the pteragopalentine fossa. Minor salivary gland tumors have a propensity to grow along the nerve. Once it gets into the pteragopalentine fossa, we can see these branches of the sphenopalentine ganglion. These tumors can jump superiorly along these nerves, have aggressive perineural spread, involve the ganglion, and eventually jump on this nerve right here, which is V2. Once it jumps on V2 and it's in the pteragopalentine fossa, the tumor can grow anteriorly. But what we also have to worry about is this. We have to worry about this posterior spread. And this was an adenoid cystic carcinoma growing along the second division of the fifth cranial nerve back into the cavernous sinus. So clinically, the referring physicians may know that V2 is involved, but they don't know how far back it extends. So part of that value add for radiology is to determine how far it extends posteriorly. And if you see this, in most institutions, patients will not be treated by surgery, but by combined chemotherapy and radiation therapy. So just remember, the two most common tumors with a hard palate are going to be squamous carcinoma. And number two is going to be minor salivary gland tumor. And when you see that, we always have to be aware of this perineural spread. So in summary, what I've tried to do over the last 15 minutes or so is that we talked about the anatomy of the oral pharynx and the oral cavity. Remember, we talked about the tongue base. So remember the circumvallic papilla. We talked about the three parts of the tonsil, right? There was the anterior tonsil pillar, the posterior tonsil pillar, and then the palentine or the fascial tonsil. And then we talked about soft palate. And remember the soft palate, we use the palentine arch, the Roman arches. The oral cavity, we talked about the buccal area. And remember the buccal area, I'll do it with my finger right here. You put it between your cheek and your gum. That's the snuff dippers, or if you like beetle nut, that's where it ends up. The oral tongue, if you stick your tongue out at someone, my kids always use to stick their tongue out at me. I never really took it personally. I just figured they liked head-neck radiology, and they were just showing me their oral tongue. Remember the floor of the mouth? I was doing it myself. It's a space that's below your tongue. So the other name for it is a sublingual space, but that's the floor of the mouth. The retromolar trigone, how do we remember this? The retromolar trigone is right behind your wisdom teeth. And if you've had your wisdom teeth removed, you've got the largest retromolar trigones. And then finally, we talked about the heart palate. And the heart palate, we always have to worry about perineural spread. So with that, I'll go ahead and stop. Thank you very much for your attention. And I'm happy to answer questions of which it seems like there's several. Thank you very much. Ashley? Perfect. Before I move into that Q&A, I do see you have quite a few questions in there. I just wanted to thank everyone for participating in this noon conference. And remind you that it will be made available on demand on MRIOnline.com in addition to all previous noon conferences. And join us tomorrow. We'll be joined by Dr. Prachi Agarwal for a noon conference on unrepaired congenital heart disease, a case-based review. And we'll be back with another server that and all others on MRIOnline.com. All right. If you don't mind opening that Q&A feature, I do see some questions there for you. Yeah, sure. The first question was, will diffusion help differentiate between lymphoma and squamous cell carcinoma? It's a great question. Honestly, in my experience, I haven't found it. I haven't found it very helpful at all. I think, and I know there has been a fair amount of data, or papers written on it. I haven't found it very helpful at all. The next question is a great question. Can you help explain and differentiate paraffarin gel from tonsil or abscess? I think that's great. So let me do this. Hold on for a second there. There we go. This is what I wanted to do. What did I do, Ashley? Just screen share again and you can hit whiteboard and you can draw on a screen there. There we go. Thank you so much. Of course. Ashley, you're always the guardian angel in this thing. She's my tech guru. So I think it was right in this area of one second there. It was under tonsil, I believe. There it is right there. Yeah. So it's a great question. The key thing here is that let me go back to the screen share here. A, and I'll go down there. If this abscess was located right here in the tonsil, this is a tonsil or abscess. But because that's a true tonsil or abscess, but if the tonsil was involving the fat here in the paraffarin gel space, the triangular fat in the paraffarin gel space as this is, this is a paraffarin gel space abscess. So if I go one up, this abscess is in the tonsil and you see the paraffarin gel space laterally, that abscess is in the paraffarin gel space. So subtle difference, but it makes a big difference because that's how it makes a big difference in how these patients are treated. Do you have experience on DCE to differentiate squamous cell carcinoma from lymphoma? No. You know, a lot of people have studied that. I think in general you can. The only thing that I caution of is that I'm always leery over time to use some type of molecular biological imaging for something that can be easily biopsied. So from an academic standpoint, there have been some studies that have shown some perfusion changes. But in general, none of what's been written really has been sustained into clinical practice. Can thyroid glossal duct cysts have tumors within absolutely 100%? I didn't really have time to get into that, but yes, the most common tumor tumors about I think one or 2% of thyroid glossal duct cysts can have papillary thyroid carcinomas within them. So and you would you have to do is look for a little bit of enhancement on the CT or the MR. How do you differentiate necrotic tons or tumor from tons or abscess? I think that's a great question. Part of it is just based on history. Anyone that has a very bad tons or abscess is going to have a severe infection. So they're going to be very, very infected. They're going to have obvious clinical signs of infection. So from an imaging standpoint, it can be hard, but really we always have to default through clinical examination. Here's a great question. Basically it says HPV cancer versus brachial cleft cyst. That's a great question. So how do I, how do you separate that? And I assume it's relating to the lymph nodes. So here's the way I look at number one, if you have a purely cystic lesion involving the anterior neck anterior to the sternocleidomastoid muscle that has an imperceptible wall in a child, then it's probably going to be a brachial cleft cyst. In an adult, if I see something that has a little bit similar that has a necrotic appearance to a cystic lesion that looks like it's an lymph node that has a thick shaggy wall, especially in a smoker or an adult. I will 99% of the time default to calling that a metastatic lymph node because we know that to have a brachial cleft cyst present as an adult, it's very, very rare. So in general, the necrotic HPV lymph nodes can be cystic absolutely, but they have a thicker wall that wall can enhance, especially on MR. And then if you look at the inner margin of that wall, that inner margin, the wall tends to be thick and irregular because that's where that necrosis is. So great question. Hope I answered that clearly. And I think it's one more, maybe just one more, because I think it's one o'clock and I want to be respectful of everyone's time. Let's see. Someone said, can I differentiate again, wall dires ring. So Ashley, if it's okay, I'll just do that one real quick. Yeah, absolutely. And if you want to say on another 15 or so, we can allow that if you want to answer some more questions up to you about your schedules. Yeah, sure. So this is the wall dires ring. So when we look at wall dires ring, here is all this soft tissue here in the axial plane. So this is all soft tissue involved in the lingual tonsil. This is the Palantine tonsil and this is a nasopharyngeal adenoid tissue. So how does this transfer translate into axial images? So let me go back to this one. So this is good here. Actually, this is good. So all of this adenoidal tissue here on the axial plane, this is the inferior portion of wall dires ring because this is the lingual tonsils. When I go to this image here, this is all tonsil or tissue involving the right tonsil. So this is the Palantine tonsil. So this is the lateral aspect of wall dires ring. And then the superior aspect of wall dires ring is going to be within the nasal, it's going to be within the nasal pharynx. Sorry about that. Good. We've got another question. Yeah, someone asked, can I please explain about the complex ranula and the complex ranula and regular ranula. So let me see if I explain that again. I think it's down here. Yeah, right there. Perfect. So if we have a ranula that is located, if we have, if this is our mylohyoid muscle here, this little green right here and this structure right here is a sublingual gland. So this sublingual gland becomes obstructed and this is what forms our ranula, which is located between the mylohyoid muscle and the hyoglossus muscle. If this ranula stays in this compartment, and what I mean by the compartment is that if it stays between the mylohyoid muscle and the hyoglossus muscle, then, and it stays especially above the mylohyoid muscle, then this is a simple ranula. But if the ranula extends below the mylohyoid muscle and then extends deeply and eventually into the submandibular space and directly in butts the submandibular gland, that is called a plunging diving or complex. Now, how it does that, it's debatable. Some people think it gets too big and it thinks the muscle. Other people feel that there's some natural defects within the mylohyoid muscle and the ranula kind of eventually squeezes its way through that defect into the sublingual space. Let's see. Someone said, can I explain the T cup again? Sure. Let's see. So the way, again, it's all anatomy. So here's the mylohyoid muscle here. Here's the hyoglossus muscle. Here is the mandible. And if I look at this image right here, this is our hyoid bone. This is our mandible and this is the mylohyoid muscle that comes around. So when I look at the T cup concept is that this is the ramus of the mandible. This is the mylohyoid muscle and then at the base of the mylohyoid muscle is the hyoid bone. So everything that's in the T cup is located between the mylohyoid muscle here, a hyoid bone and the rim of the T cup which is formed the mandible. So everything that's in the T is located here and that's in the sublingual space. And I think I got time for one more. Let's see here. So many good questions. Oh, for all you guys, you can friend me on Facebook or something or follow me on Twitter if you ever want to chat. Yes, here's a good question. Is a retromolar trigon only in relation to the maxillary molar or the mandibular as well too? So the retromolar trigon is that triangular space behind both the third molar at the maxillary tuberosity and the mandibular tuberosity. So it's both of them. So it's a fairly extensive space cranial caudad. And again, it's right behind that moment. So Ashley, why don't I stop there? Thank you very much for everything. And you can probably email me questions on Facebook or maybe send to Ashley or something. And then I'll be happy to try to try to answer them. So thank you very much. Perfect. Does it bring this to a close? I want to thank you, Dr. McCrudger for your time today. We appreciate you coming back for another noon conference. And thank you to all of you for participating in this conference today. A reminder again that it will be made available on demand at MRI online.com complimentary in addition to all previous new conferences. Please join us tomorrow. We'll be joined by Dr. Prachi Agarwal. We look forward to seeing with you again and thanks and have a wonderful day. Thank you.