 Thank you very much for the opportunity to give this talk on lymph nodes of the head and neck what you need to know. We'll be focusing our talk on the lymph nodes of the head and neck and the function of the lymph nodes is to transport lymphatic fluid to filter foreign substances and initiate an immune response. So essentially I consider the lymph nodes as the garbage bag of the body anything that bad comes in eventually gets filtered through the lymph nodes. So the artery in the vein, the orders enter through a highland and the veins exit through the highland. Now the way the lymphatic system works is that the lymphatic vessels that are bringing, if you will, all the junk into the lymph nodes enter through the periphery. They eventually work their way centrally and then eventually leave the lymph node through the central highland. So the way to think about it is when you look at various metastatic deposits they involve the lymph nodes from the periphery so the earliest signs of metastases will be in the periphery. Eventually the lymph nodes become large and oval shaped as we see on the right hand side, but as we'll see in CT scans the earliest areas of low attenuation will be in the periphery of the lymph nodes. So the cervical lymph nodes are classified from groups one through group seven actually including the superclavicular lymph nodes, level ones are below the chin, the submandibular lymph nodes. There are the remainder of the lymph nodes are almost like a string of pearls and the string of pearls essentially are the clasp of a pearl necklaces at the top. The anterior lymph nodes are level three, level four, the back of the pearl necklace that posterior limb is level five and they connect through the superclavicular lymph nodes. So this was the original paper that was written back in 2000 and this is how the various level of the lymph nodes were defined they were defined as basically these schematic illustrations now this is not the way we typically view cross sexual imaging of the head neck. And so as a result, we have to find some consistent landmarks that's going to allow us to evaluate these various levels, and the two landmarks that we should be using are, if we can identify the highway bone and the cryquoid college, then we will always be able to identify the various levels of the lymph nodes of the head neck. So let's start with our journey. The first level is a level one lymph nodes which are located below the chin. They are sometimes referred to as a submental of the submandibular lymph nodes and they extend from the myelohyroid muscle down to the highway bone. Now the difference is that if we draw a line here that connects the back of the submandibular glands, everything anterior to the submandibular glands is level one. And everything posterior to the submandibular gland is going to be in a different lymph node classification. But remember level one lymph nodes are everything anterior to that line that connects the back of the submandibular glands. The level one lymph nodes are divided into two separate groups level one a is located between the anterior belly the digastric muscles. They're referred to as a submental lymph nodes and then level level one be are located posterior lateral to level one a lateral to the anterior belly digastric muscles and these are the level one be lymph nodes. The level two lymph nodes run from the skull base down to the level of the highway bone. And when we draw this line that connects the back of the submandibular gland everything anterior was level one, but everything posterior to this is going to be level two. So level two lymph nodes run from the skull base down to our friend the highway bone. And if we connect this line that connects a submandibular gland everything in this hatched area is going to be in the level two lymph node group. Now the level to lymph nodes are divided into a level to a and to be the this is defined by the presence or absence of a fat plane between the lymph nodes and the internal jugular veins. So in this case we see the level to lymph nodes is compressing the internal jugular vein and there's no fat plane. However, notice there is a large fat plane between this level to lymph node and the internal jugular vein. So that's what separates a to a from a to be a lymph node. So level three lymph nodes run from the base of the highway bone all the way down to the base the cricoid cartilage so there's our other friend the cricoid cartilage. So when we draw our line here there's our line that connects the back of the sternocleidomastoid muscle all of this is a level three lymph node. So here's an example of level three lymph nodes here's a lymph node that's located at the level of the cricoid retinoid joint. This is below the highway bone but above the base the cricoid similar on your left hand side. These are level three lymph nodes. These are below the highway bone again, but again above the cricoid cartilage. The level four lymph nodes run from the base the cricoid cartilage down to the level of the clavicle. So technically the level four lymph nodes run from the sternocleidomastoid muscle anterior to the anterior scaling muscle. So when we look at the top right hand corner it's everything here within the purple area. But for all intents and purposes. If you can remember there's a line that connects the back of the sternocleidomastoid muscle, then you'll be just fine identifying exactly where those level four lymph nodes are located. Here's an example of a level four lymph node we can see it's below the base of the cricoid cartilage. Now the level five lymph nodes are located in the top right hand corner and these are the areas that is located in blue. This is geographically the largest area of the lymph node that runs in the skull base all the way down to the base the clavicles. So when we connect our line here to the back of the sternocleidomastoid muscle everything posteriorly all the way back to this trapezius muscle is going to be level five. So unlike the levels to the levels three the level four the level five is basically one large geographic area. So here's an example of a level five lymph node located here on the patient's left hand side. There's a line that connects the back of the sternocleidomastoid muscle, everything anterior to this in fact this metastatic lymph node here is going to be level three, because we're below the hyoid bone and above the cricoid cartilage, but posteriorly it's in level five. The level six lymph nodes are very interesting group because these are located from the hyoid bone down to the manubrium, but they're actually located between the carotid arteries. So these lymph nodes that are located laterally are going to be level three lymph node, but if we have a lymph node between the carotid arteries this is going to be level six. So this is an example of bilateral metastatic level six lymph nodes note, note, note, notice that they're located between one carotid artery here the other carotid artery here, and we also see some calcifications. So to see these calcifications this is indicative of papillary thyroid carcinoma. So remember thyroid carcinoma has a propensity to involve level six. Here's another example of a level six lymph node. This is what's referred to as a pretracula or pre laryngeal lymph node, and this has been lovingly called the Delphian lymph node in honor of the Oracle of Delphi apparently people used to come to the Oracle from miles and the Oracle had always determined whether or not someone could live or not by palpating their anterior neck so hence this lymph node is referred to as a Delphian lymph node. The level seven lymph node are the mediastinal lymph nodes and they run from the top of the manubrium between between the carotid arteries down to the dominant vein. So really these are mediastinal lymph nodes. I have liked to turf these to the chest radiologist but because I'm a head neck person and the imaging studies go down into the upper mediastinum. We are responsible for these so they are included in the classification for cervical lymph nodes. The top of lymph nodes are the superclavicular lymph nodes so just review here are level one lymph nodes. This is level two this is the class of a pearl necklace. This is level three. This is level four. This was level five and the superclavicular lymph nodes connect the anterior and the posterior red. So on the axial images, this is how I identify the superclavicular lymph nodes if I can see the clavicle any lymph nodes at this group in this region I consider the superclavicular lymph nodes. The majority of lymph nodes that we talk about drain head neck cancers realize that we have an isolated group of lymph nodes in the superclavicular area. We have to think of an arrow upper digestive tract tumor, but also we have to think of tumors that involve below the clavicle so we have to think of breast cancer lung cancer GI cancer, and then also Hodgkin's disease remember lymphoma can involve the superclavicular lymph nodes, as well. The next group of lymph nodes are going to be the retrofarengeal lymph nodes now the retrofarengeal lymph nodes are a lateral and a medial group. So, as you get older the group that becomes more likely to be involved my metastasis are these lateral group of lymph nodes. They are typically located just medial to the carotid artery as a scene on your right hand side here. And typically they're located between two centimeters of the skull base. Now these lymph nodes are our lymph nodes there's no way the referring physicians can palpate these and as a result, we have to look for these in every single study that we perform. So we've talked about the different stage or the different locations of the lymph nodes now let's talk about the importance of staging. If we show that there's a positive lymph node if you the radiologist say that there's a lymph node on the CT scan that's positive or an MR scan, you've reduced that survival by 50%. Now think about it that's an important statement to make 50%. So what is, let's talk a little bit about how we actually look at these lymph nodes. So the lymph nodes are shaped as a kidney bean. Now the lymph nodes have different orientation notice when we look at the level two lymph nodes when we look at the level three lymph nodes and look at the level four lymph nodes and the level five lymph nodes. They have a craniocaudate orientation, but look at the level one lymph nodes and look at the superclavicular lymph nodes, they're the same shape but they're oriented differently. So as a result, there is a issue or problem with just the size criteria and we acknowledge that. But having said that the size criteria that we typically use our 10 millimeters for level one, 15 millimeters for level two, 10 millimeters for level three, 10 millimeters for four, 10 millimeters for five and seven and 10 millimeters for the retroference of lymph nodes. So how do we measure these lymph nodes. Well, we measure these in the transverse plane. Now, as I mentioned before, these lymph nodes are in a different orientation. So, essentially when we look at levels two, three and four, we're measuring the transverse dimension. When we look at level one and level five, we're actually measuring in a different plane. But again, that is one of the weaknesses of the size criteria. But having said that, we have been using this size criteria for 25 years. So if I had to measure the one on the right hand side, this is how I would measure that lymph node. This is different than the way it's done in from the rest of for the rest of the body. Also, when a referring physician palpates a neck, they tend to palpate in the craniocaudate dimension. But having said that this the reason why we do what we do is that this was a perspective study that was done back in the mid 1990s. And therefore we have been using these criteria for years. So these are my standard accepted size criteria that I use for my assessment. Now, having said that, realized that 40% of lymph nodes are less than seven millimeters. And as a result, we cannot detect micro metastasis. So whether we do CT, whether we do MR, whether we do PET or any other type of nanoparticles, etc. We're not going to be able to detect micro metastasis. So therefore the referring physicians need to treat based on the primary drainages as opposed to what we see on imaging. So imaging can help guide treatment, but realize small metastasis we're just not going to be able to see. So what are the diagnostic criteria we use what we talked about size already. So sizes number one. Now the first slide I showed also talked about the drainage of lymphatics notice how there's some small focal areas of low attenuation in the periphery of the lymph nodes. These are small metastatic deposits. So this is what we mean by low attenuation. We also have clumping of lymph nodes. So in this particular case we see multiple lymph nodes on the right side of the neck. The patient had a right sided had neck cancer. Notice there are no lymph nodes on the opposite side. So we can see that there are multiple lymph nodes on the ipsilateral side of the tumor so we would upstage this type of lymph node involvement in indicating that there's likely metastasis. Okay, there is this extra nodal extension. So extra nodal extension is the extension of lymph node metastasis outside the confines of the lymph nodes. Now we'll talk a lot more about this because we can see this radiologically in the updated AJCC staging system. Extra nodal extension really is a clinical diagnosis and not a radiological diagnosis although we can't see it. And we'll have a lot to say about that. And so far as I've talked about the classification of the lymph nodes, we talked about size criteria, and I'm going to spend the rest of my time giving you an approach for evaluating the lymph nodes in the head and neck. So in general, when we perform a CT or an MR scan, we have to look at all parts of the CT or the MR all of the lymph nodes. But what I'm going to do is tell you my approach to help me increase my ability to detect lymph node metastasis. So here's a patient that has an oral tongue cancer, and this is what we see on CT scan. So here's a patient that has a lateralized oral tongue cancer. So which which lymph node metastasis is this cancer likely to go to. Well the studies that have been performed indicate that the lymph node metastasis typically involve the ipsilateral neck, the ipsilateral lymph node, and most commonly level two. Rarely do they involve the contralateral neck when it's an early stage lateralized oral cavity cancer. Another example here floor mouth carcinoma, subtle lesion involving the floor mouth is very well localized. The most likely lymph node involvement is level two on the right with some involvement of the level one lymph nodes. What about the opposite side? Well, not much likelihood of involvement into all. So again, ipsilateral lymph nodes primarily involving level two and level one. Well, here's an example of a tongue based carcinoma. Here's a schematic illustration of a large tongue based carcinoma. Here we see it on CT. So here's a CT demonstrating a very large right sided tongue based carcinoma. So which lymph node metastasis are most likely at risk. Well, ipsilaterally again the ipsilateral neck and there's our level two lymph node. In oral pharynx cancers and specifically in tongue based cancers, you can have the contralateral neck involved. And typically it's involving level two, but still it's more common on the ipsilateral side than the contralateral side. Another example here, tonsillar carcinoma schematically illustrated. Here is a CT scan of a tonsillar carcinoma. Now, knowing what we know already, which neck is most involved ipsilateral or contralateral? Obviously ipsilateral. Which lymph node group do you think is most at risk? Well, as you probably surmised, the ipsilateral level two lymph nodes are at risk. So we're starting to see a pattern. Rarely are the contralateral sides involved, but again most commonly it's the ipsilateral side. Another example here, here's a soft palate carcinoma schematically. Here is one on a non-contrast T1 weighted image. So which lymph node groups are going to be involved? As you probably figured out, ipsilateral level two lymph node, but because it's a soft palate carcinoma, you can have the contralateral group involved. Not as common as the ipsilateral, but again it's level two. Now one thing about soft palate carcinomas, not only are the cervical lymph nodes at risk, but you have to be aware of involvement of the retropharyngeal lymph nodes. So we talked about the retropharyngeal lymph nodes earlier. Just remember soft palate carcinomas can metastasize to those groups. So we have to evaluate those very closely as well. Here's an example of a piriform sinus carcinoma. Now when we look at piriform sinus carcinomas, again ipsilateral lymph nodes level two. And this time we've got the level three lymph nodes. If the piriform sinus carcinoma is well lateralized as it is here, the likelihood of contralateral involvement is low. So just as we've seen in the past, the ipsilateral side is more common. Now one thing when we look at the piriform sinus carcinomas, in this particular case, this piriform sinus carcinoma is located at the cricoritinoid joint. Now we have a talk on the hypofarynx. Anytime this piriform sinus is at the level of the cricoritinoid joint, this is referred to as the apex of the piriform sinus. So anytime you have a tumor involved in the apex of the piriform sinus, this also puts the level six lymph nodes at risk. So we talk about this in great detail in the, in the hypofarynx talk, but just realize that for piriform sinus carcinomas, not only is the level two and level three lymph nodes at risk, but because if it extends into the piriform sinus, we have to look at this level six lymph nodes as well. Well, what about a supraglottic carcinoma? Here's a tumor involving the right area epiglottic fold. Here's the varucous carcinoma involving the right area epiglottic fold. Well, you probably figured it out. What's most commonly at risk? Ipsilateral lymph nodes level two and level three. Contralateral occasionally, but again, ipsilateral. So we've got this pattern, right? The highest likelihood of nodal metastases are to the ipsilateral lymph nodes, and the majority of lymph node metastases are from level one to level three with most commonly involved level two. So why is this important? It's important because anytime I look at a CT or an MR in a patient with a head and neck cancer, I have to look at everything, but the area that I'm most common, I look at with most scrutiny are the level two lymph nodes on the ipsilateral side. Because that's where the most likelihood of metastasis is going to be. And remember, if we say that there's one positive lymph node metastasis, the survival of the patient is reduced by 50%. So it's really important that we understand this concept. What I've done to you is describe the concept of primary echelon drainage. And if we understand that, we'll be able to make more accurate diagnosis. And having said that, we'll also be able to better understand the staging system. So this is the eighth edition of the AJCC staging system. And I've been on the staging system since basically since the fifth edition. So I've been doing it for a long time. So what does n zero mean? n zero mean that there's no regional lymph node metastasis. n one means we've already gone over this, believe it or not, single ipsilateral lymph node, less than three centimeters. Remember, our size criteria is range from one to 1.5. So basically, you can sort of throw in between one to 1.5 to three centimeters. So that's an n one disease. Now there's two types of n two disease. n two a disease means that this one three centimeter lymph node just got bigger. So it just got a little bigger. That's n two a. And to be is that that one single lymph node recruited its friends on the same side of the neck. So now instead of having single we have multiple ipsilateral lymph nodes all less than six centimeters. So what do you think end to see is well end to see means that now you have disease involving the opposite neck. So whereas end to be was in the ipsilateral side end to see was in the contralateral neck. And then finally we have n three disease. And that is any lymph node metastasis greater than six centimeters. I mentioned I've been on the AJCC staging since the fifth edition. What we did in the eighth edition is that we added this concept and included extra nodal extension. I mentioned extra nodal extension previously that is a lymph node metastasis which extends outside of the confines of lymph nodes. So now all of a sudden, we can see this lymph node metastasis extend outside of the confines of the capsule. Now this is a pathologic diagnosis is not it is not a radiological diagnosis. So specifically radiologically if we see there's extra no extension this has to be confirmed on clinical examination. What we don't want is we don't want you know radiologists that can say well I'm really really good I know there's extra no extension and one lymph node. And all of a sudden I'm going to upstage this to n three be disease so you went from n one to n three be that's not the case. radiologically we can suggest extra node extension but it has to be confirmed on clinical examination in order to pre treat to make a pre treatment staging of n three be disease so extra if it's extra nodal, negative, it's basically the same as staging system has in the past. But if it's extra nodal extension positive. This has to be a clinical diagnosis, and you can have radiological confirmation. And realize this is for all HPV negative disease. Now there is this HPV positive disease which is of oral pharyngeal squamous cell carcinoma in the United States is a very high prevalence of oral pharyngeal carcinoma with HPV disease. The new eighth edition identified this new disease. And the main difference here is that because this is a more disease that's more responsive to treatment the nodal staging is different. And zero means there's no regional lymph nodes was exactly the same. And one is still metastasis to a single lymph node but instead of three centimeters we say it's six centimeters so this indicates again a better prognosis. Contralateral or bilateral disease is n two disease. And again this goes all the way up to six centimeters so again more responsive disease and n three diseases anything over six centimeters. So realize that the next aging differs whether something is HPV negative or HPV positive. The incidence of HPV positive disease and oral pharynx cancers varies across the world in my travels. I know it's high incidence in the United States in South America and in North America, but in places such as the Middle East and in India. The likelihood of oral pharynx cancers being HPV positive is much lower so wherever you are, you still have to test for p 16 to determine whether or not your oral pharynx cancer is going to be HPV positive and your treatment should be based on that specific or molecular biomarker. And then what I've done over the last 30 minutes is we've talked about the radiological landmarks for cervical nodal metastasis. We talked to very about the various lymph node levels. We talked about levels one through four the visceral the retroferential area the super covector the medistinal area. We talked about the classic and the typical size criteria that we used and we also finally talked about primary echelon drainage. It's an important concept, because what this allows you to do is really focus your attention on those lymph nodes that are at greatest risk for metastasis. And by doing so, it can improve the accuracy of your diagnosis, allow you to provide better staging and eventually improve the likelihood for cure for your patients. Thank you very much for your attention.