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Specialty doctors here at Calder Dale. Um The topic for the day is CT neck and uh head and neck surgery. So the uh the breakup of what we're going to discuss today is uh initially a brief introduction of the CT scan and some associated terms. Uh We will talk about briefly about the neck anatomy. Uh We'll talk about spaces of neck, about lymph nodes, deep neck space infections, uh foreign bodies and CT scan, neck trauma and CT scan, neck lumps, malignancies and metastatic lymph nodes. Um Our decisions regarding the choice of imaging, they depend on multiple factors and the clinical clinical picture and presentation is one among them. And of course, the blood investigations also uh CT is one of the uh imaging modalities that we have, but we do also have um other imaging modalities uh in our arm that we can uh use uh according to the appropriate of the situation. So we have x-rays, uh little less used and now uh uh used especially for uh dental related things. We have OPG ultrasound CT Angio Mr Pet. Um and a few other investigations, our CT scan remains one of the uh one of the easily available and very beneficial uh investigation. Um in terms of the types of CT scan we have is uh two basic. One is a non-contrast enhanced CT scan and a contrast enhanced CT scan. We also, we need to perform CT angiogram, especially if we are um uh suspecting a vascular injury with pet CT for malignancies and occasionally CT perfusion imaging. Um However, in in case of the neck uh lesions, most commonly performed investigation is a contrast CT scan that gives us uh a good idea about the bones uh which uh we don't have many there. But uh i it, it does give a good idea about the soft tissue and and delineates the lesions perfectly well. Uh So what is AC T scan? Uh I looked it up the definition of this. Um And it says it's an x-ray imaging procedure basically uh aimed at the patient. And uh the machine is quickly rotated around the body that produces signals that are processed by the machine's computer to generate the cross sectional image. So the, the, the catch point here is a cross sectional images. So it's not like an x-ray that produces a flat turned out image. It's more um like a cross section, it's like a slices through the body. And these slices then can be re stacked together with the computer and basically, we can see them in any way we want, we can look at them in sagittal views. We can look at them in, in coronal views and we can choose basically any, any method and the thickness of the slide just tells us how um how, how much of information we're going to get. So for example, if we're looking at the ear, we need very thin slices. If we're looking um as a stout film in a large lesion, we don't need such thick thin slices. Um And these uh terms I have put it there. So this, these are associated, these are used commonly with CT scans. Like you, you find artifacts, word horns field units, attenuation, um soft tissue density, bone window and pixels. And other terms, I'm not going to go deep on that. However, one important term is the horns field unit. It was named after the inventor um of the same name. Um It basically records the intensity of the brightness of each pixel in the in the CT scan that we see. Um So basically the range is from minus uh 1000 to plus 1000. So if we break this up a little bit more minus 1000 means it's the density of the air and plus 1000 is the density of the bone and anything between these two represent other materials. So they have found out the density of water is zero density of soft is plus 40. So if you, if you are, if you are confused uh while on the computer and trying to identify what this structure is. We can just take our cursor there and measure how much is it. It's HO FI unit. However, most of the time we don't have that luxury. So a rough idea to do that is you imagine air to be charcoal and wound uh to be chalk. So you have chalk and charcoal and then you can differ its intensity according to the amount of each element that we put. So for example, if we get a grayish picture, which grayish white, it would be more of a a bone thing. So its density would be more. But if it's grayish black, it's density will be less. So that this talk and choco concept, it's very helpful in uh guessing what the intensity, what what the density of the material would be. Now, next question is why do we do a CT scan? And when must we do it um uh in, in, in, in any proce in any um situation where we need cross sectional images, it's quite helpful and it's very quick, it's easily available. It gives us a detail about bones and cartilage and also the soft tissues. It, it does give us very good soft tissue evaluation. Um And uh certain times other investigations like Mr scan can be contraindicated, but it's diss come as high radiation. Um Sometimes we have metal arti effects, especially if, if we're working in the head and neck region and they have a lot of dental work. So they, they, they are not very beneficial then and, and of course, there are contrast risks um that we have to do um the kidney function test to, to see whether uh actually giving you contrast is safe in that person. And high radiation in Children can, can be actually carcinogenic. So we have to uh measure our uh benefits and the risks next comes the anatomy. Uh We all know about the anatomy of the neck from our medical school. Um a few points which are radiologically important are um this mandible. It's one of the bony landmarks. Second is the hyoid, very important bony landmark, anterior belly Abdi gastric. It's a landmark for differentiating the lymph nodes, sternocleidal mastoid is a landmark for differentiating the level 234 from the level five anterior neck, from the posterior neck. And these Kane muscles uh also are a landmark in differentiating the lymph lymph nodes. Uh The radiologists use these for us as surgeons. We we, we have other final landmark like we can use a nerve as a landmark. We can use um a muscle at a landmark like in, for example, omo, we can use a landmark. But radiology, they, they don't have that luxury. So they depend on these big uh muscles um anatomically. Um This is AC T scan. This one is a contrast and AC T scan. And if you can look at it, uh the, the, the chak and um um charcoal method. You see this is, this is a very hard structure. There is it must be bone, um black air and the rest of that is soft tissue various densities. Um These are other uh saal images through the um through the, through, through, through the neck. And uh basically uh from uh right to left, we can see uh the structures and it, it shows us the vocal cords, epiglottis very clearly. Um These images. Now, if we go on to the next image, uh it gives us a rough idea where the parts of uh the, the nasopharynx, oropharynx and hypopharynx lie. Um No, coming on to describing the neck spaces. So this image um um this image, it, it shows um uh the fascia of the neck. So um in this picture, there's uh if you imagine this uh this, this area here, it's the area of um the superficial fascia which uh encloses the platysma and and close it all around. Then is the deep fascia, deep fascia is divided into three s uh three slips are three layers. One is the superficial layer of the Tiso vial fascia, then is the middle layer of the deep cervico fascia, then is the deep layer of the deeper facia. So the superficial layer, it, it basically encloses um uh underneath uh and closes the strap muscles and closes the sterni, the mastoid and also encloses the trapezius muscle and all around. Uh when we go up in the neck. It also divides into uh into pockets to, to enclose other organs like uh like the like uh the sub mandible gland, uh parotid gland and, and the mass location giving rise space. Uh The, the one in yellow is the middle area of the Yeah, which uh sometimes we call it a uh uh by uh uh ok. Yeah. Uh and the esophagus that pro yearly. So if we go up, uh imagine if we go up uh beyond the level of the larynx, it basically uh um merges into what we call as the ph parapharyngeal uh uh uh uh they're called the pharyngeal mucosal space. Coming back to this picture um on the sides, uh this area and close it between uh superficial layer, middle layer in the deep layer and closes the, the, the vital uh blood vessels and the nerves, uh carotid, internal jugular and the vagus nerve called the uh it's carotid space. Um So that's about the layers of the fascia giving rise to these enclosed spaces and these enclosed spaces um in the neck, we divide um radiologically for our ease, uh these spaces into two parts. One is the infrahyoid and the suprahyoid. Um So, if we look at the infrahyoid, it's basically the same picture I showed before showing the uh spaces. Uh off note here is the retropharyngeal space uh which I missed in the previous one. So if you look at this, right between the uh the the posterior layer of the retropharyngeal of the middle um layer of the deep subcu facial. The deep layer there is a thin layer uh called the LR facia. And in front of that L facia is the retropharyngeal space. It basically connects uh it basically reach from the skull base up to the level of t one uh behind that uh between the LR facia and the um and the deep later of the deep cervical facia, there is the space, what we call is a danger space. Um Anything an infection in this region can track down and go up to the end of the thoracic or perhaps the level of the diaphragm. These two bits are important. Um That's it um coming on to the supra, the suprahyoid uh spaces. Now, as we go up, uh the larynx is gone up, it merges into this pharyngeal mucosal space. Uh And uh the superficial layer also opens up to enclose the masticator space, containing the muscles up all the muscles of mastication and closes the parotid space, carotid space. Um uh And this parapharyngeal space. So, in this slide important uh bit is the parapharyngeal space. It has a, a few um importances. One is it can itself get in infected and uh the infection can get transmitted from any of these spaces in into this space and then lead to uh what we call is a deep neck space infection which can then further connect with the retropharyngeal space, uh uh go up to up the media stum. Uh Another importance is um this uh this area of fat, uh it can get compressed by any tumor or any lesion growing in any of these spaces. And the direction of the tumor uh is suggested by this parapharyngeal fat for um uh uh it's coming from uh say carotid if it's coming from the carotid, uh it uh posteriorly, that's the importance of uh this case uh for infection. OK. Coming on to the next slide. Uh um It's just another space here in the buckle space um and chose face conversation separately. They, they have shown uh the skull base, it shows the uh the here and the Eustachian tube in this region. OK. Now, the carotid history um this uh contains important vessels uh and, and also sympathetic trunk and the pas can uh can you pick it up? Uh can I find in a space? So, for example, from carotid, we can have aneurys thrombo carotid dissection, thrombo bit and thrombosis, it can be a part of a mo for example, uh the vagus no can present as a s uh uh they can pagan from the chain and straight neck. Um uh And the, now the move in the neck. So what uh how to identify which, what is shown in a particular C scan. So, an easy um uh anything near the mandible is a level one lymph node. So if it's touching the mandible, if it's near the mandible, reaching up to the level of uh say the posterior border of the, the submandibular gland. It's, it's a, it's a level one gland, it's a level one node and the level one and one B nodes are differentiated by the digastric muscle. Um And the, the radiologist use the, I use a digastric muscle as a as a landmark. Um to identify it now comes, second comes the level two nodes. So level two nodes are anything above the lower border of the hyoid will be a level two node posterior to the mandible, of course. And um the level I nodes are further divided into level two A and level two B. Now there's a difference between a surgical level two A and two B and radiological in radiology. They, they take any node which is not, which is uh near to the internal jugular but not touching it. And it posted, they call it a level B node. However, surgically, we say that the spinal axity node di divides these two groups into level A level two A and level two B nodes. Um And this has surgical implications, for example, um A uh assessing the level two B nodes is surgically very difficult and there's always a risk of injury to the spinal X node. So if there, the level two B is radiologically not involved, the surgeon wouldn't uh want to peek into that region to, to cause undue complications. Um then uh the level two, level three and level four nodes, all of them are along uh the internal jugular vein. So I describe it, the level two nodes. Now, level three are um uh found below the lower border of the hyoid bone and above the lower border of the trio uh uh uh cartilage. So if you check those two levels, any, any node in between them would be a level three node. And uh below the level uh of the inferior part of the crack cartilage up to the clavicle is a level four node. Level five nodes are behind the sterno mastoid and uh in front of the trapezius and the level five are also divided into level five A and level five E. Now, there's also difference between the surgical level five A five B and the radiological. So, the omohyoid which comes from the scapula goes up here makes a turn and is uh uh is inserted on the laryngeal uh cartilage network. Uh But uh and that uh radiology, it's very difficult to find the omohyoid. So how they divide it is they make an imaginary line from the sca muscle to the anterior end of the nucular mass, right? So they make an imaginary line and anything outside that line is a level five B and anything in front of that, it, it is a level five A. Now, this level five B and level four nodes because they lie very near to the, to the clavicle. They not only drain the superior part of the neck but the but also can drain the rest of the viscera. So if there's a malignancy in say breast in lungs and liver, they can uh in esophagus, uh they can throw up uh mets in that region. So uh they are also called as ver shows nodes and they, they, they become radiologically very important. Uh When, for example, that's enlarged on a CT scan, the radiologist must look lower down into thorax or ask for further investigations to actually check for those structures. Also. Um The level six nodes are um paratracheal and uh para pre prelaryngeal and paratracheal. So they're right in front. These type of uh nodes are usually getting in, get involved in the um in thyroid diseases and uh are taken out as part of uh central neck dissection. And level seven are the interior media Stal lymph nodes. So that's that there should be a fair idea how to actually find them on AC T scan. Uh these nodes, of course, uh every node has its draining territory. Um For example, uh the level one A one B come from the oral cavity level. The second comes it, it's the most common node that can get an or and it has a very wide draining area from mouth, oral cavity, face and neck. Uh even from the scalp and level three is mostly oropharynx. Uh Even the uh the the thyroid malignancies can throw mets into that region. And like I told you, level five and level four can have met status from the neck as well as from um uh from the, from the rest of the body. Another important bit of uh notes is that retropharyngeal lymph nodes which uh which are located in the retropharyngeal space and can get enlarged in the lesions of nasopharynx and sometimes oropharynx also. So, um for example, if, if I say this is a node here because it's very near to the, to the mandible, I will label it as a level one B node and it's uh outside the region of uh digastric. Um Similarly, this, this is a level two node because it's near to the um to the, to the hyoid. Uh This one would be labeled as a level three node because it's below the high he but the cry he has not yet finished. So it's a level three node. Um Similarly level five note, it's uh is in the, in, in the same region. It, it, it, it would be a five, a node, likewise the same for it. So the cricoid cartilage uh is not there. It's, it's the, it's the trachea now. So the lymph node here would be a uh a level four node. Um Next bit is, is, is the various pathologies I will quickly go through them. Uh For example, there's a patient coming in with a peritonsillar abscess. Um uh with uh symptoms more severe than a perons abscess. The we, we don't sometimes go in and drain it uh by conservative measures, we sometimes think that it could be uh deep neck space infection. So, so uh ask for it uh for ac scan and cross imaging. And for example, in this one, it's an isolated uh peritonsillar abscess. Um Another is uh another picture that I'm showing here is is a perons abscess which is bilateral. So, CT scan is very helpful uh in uh demining our plan of action, which will definitely be a surgery. And uh in this patient, the airway would be at risk. So we'll be taking our own our precautions. I'll give you an example. It's a patient that we saw. Um it was a peritonsillar abscess that got complicated uh over the course of few days and led to formation of this uh abscess uh going down uh in the peripheral space, tracking in front of into the anterior neck space, right around the um right around the thyroid, uh gland and this patient went into this complication because AC T scan was not performed uh initially. So when initially a tonsillectomy was performed for um for a pitons abscess. Uh a a parapharyngeal abscess was missed. So that presented a few days later as a frank neck abscess. Um Similarly, this one is a ph parapharyngeal abscess and the CT scan will actually diagnose it. And the CT scan will also guide us how deep it is. And if it is accessible or I mean able to uh drainage intraorally or should we, or must we go uh externally uh by a neck incision? So, uh in this case, for example, if this were a patient, it would uh whether we will be able to uh uh whether we should consider doing a uh a a lateral neck approach, which uh which um should be done in this case. For example, um Similarly, this is a parapharyngeal abscess, but it's rather more localized it. So, so uh an intraoral approach could be good in this one, but of course, it will depend on other parameters. Also, another important bit is uh the dental abscesses. Um So sometimes we suspect a neck abscess and uh it's basically not coming. Uh the source is not the neck but just the teeth. So the, the examination is very important in this and the investigation basically changed the mod mode of treatment. So in, in UK, uh these cases are managed by the maxillofacial surgeons. So if uh they, they get admitted in an ent ward, they will definitely be neglected. Uh A Ludwig's Angina uh and an inflammation, infection of the sublingual space is a, is an, is, is a, is a, is an acute emergency in the airway risk that needs to be treated. I uh urgently. And uh uh ac T scan is quite helpful in determining the extent of the infection. Uh And, and if we uh if, if we do it uh in an emergency, um it will, it will guide um our next step which is uh uh a guided drainage of the procedure and uh and protection of the airway. Um The next is the retropharyngeal abscess. Um These abscess usually seen more commonly in um in Children, uh a, a child, uh dehydrated, not eating well, um with high CRP levels uh crying. Uh so such Children um need to be evaluated for a re for retropharyngeal abs. And um this can also be as a separate component of a, of a other deep ne ne space infection. So, in this case, for example, if a child is uh underwent an ultrasound scan and uh they found an uh a abs which was drained, but a retropharyngeal abs was drained and later on after a few days he presented with frank symptoms. So a cross sectional imaging uh is important and it's, it's the surgery. It's the clinician's um uh understanding of the, the patient's picture that he should not. Um, he should not stop himself from ordering a cross surge imaging when, when it's indicated. Uh Another uh in in adults, usually the retropharyngeal abscess is present as a cold abscess, uh the like part spine. So they might have a tuber closes of the spine, uh which presents as a cold abscess. Such patients can uh not seriously be not very symptomatic. They might, they have mild symptoms uh with uh and throwing, uh and, and having temperatures. Uh So suspecting a cold abscess uh is paramount in such patients. Um This is a, this is uh another patient which might have come in as um a sore throat, difficulty swallowing of sudden onset. And it, uh after the CT scan, they identify that it is uh not a surgical disease, but a medical uh one and he has uh basically uh angioedema. So um a conservative approach will be uh done. Now, next is the foreign bodies. So, in, in emergencies, we sometimes have situations where uh an x-ray or the clinical history does not identify uh a foreign body. So there is definitely a history but we don't know what is the situation. For example, in this patient, there was a uh vegetative foreign body that had uh entered into the posterior pharyngeal wall and led to an abscess formation. So you can see the foreign bodies in this region, this hypodense region uh and going down along the spine with the with straightening of the spine to spasm of the anterior uh of the of the neck muscles. Um So ac T scan um would have guided in this situation uh to not go for any conservative ma management but take the patient into the into the theater and actually explore the posterior financial law to identify the foreign body. Uh which is iso dense uh with, with the soft tissue. Um In this case, there's a foreign body uh in the esophagus and it's stuck in the esophagus uh horizontally. Uh It, it wouldn't have been identifiable by other measures. You, you can't do an MRI scan for an x-ray will not be helpful. So the, the CT scan uh is, is a guiding uh investigation in this and the surgeon will take precautions uh to actually look and see whether there's any immediate stites involved and how he will approach um the removal of this as a high risk case because uh it's a longstanding foreign body within the esophagus and a sharp one horizontally. Another one, there's a foreign body in it and it has basically gone into the tissues and it's very near to the carotid space. So this one also uh needs a very specialized care if, if someone wants to remove the swollen body. Um Another picture uh I have shown as a patient having swallowed a spoon. It it it's quite rare to happen, but it you you do come across such strange uh situations. We recently had a patient uh who presented as a neck, uh hematoma. And when we did the CT scan, the CT scan identified that there is an iso dense where around almost 11 centimeter foreign body going through the pyriform fossa into the lateral neck. And uh when we identified further, went into the details of the patient, uh ask the patient, uh who, uh who unfortunately was not able to give much history. We found out that uh the, the patient had psychiatric uh history and, um, and uh they had uh swallowed a wooden twig. Um, and that, that was, uh, that was being raised by the radiologist and there is something there, but he can't identify it. The problem with wood is that it's almost ISOS with the soft tissue. Um So, uh the CT scan helped in that situation uh in identifying a foreign body, which was managed further. Now comes the role of AC T scan in trauma, neck. Um For any penetrating trauma, we just divide the uh zone neck in three zones. Uh Historically, it has been known that the level of the zone one and zone three are quite difficult in terms of vascular access. Uh However, most of the neck injuries happen in the zone too, um which are rather easier to manage but not, not definitely uh something that uh a surgeon would want to face every day. Uh So, in this situation, um it's, it's a blunt trauma neck that has presented as a, as a s as a hematoma around the thyroid gland. Um The right one and the left one is, is, is also hematoma that presented in a patient uh following exertion after surgical thyroid hemi thyroidectomy. Um This is AAA hematoma. Uh the the trivial trauma and the bleeding diathesis. Um So, you can see it's almost iso dense with the soft tissues with the rim of hyperdense area. So that shows that it has been there for quite some time. And um it this is walled off. Uh However, the center is uh still uh ISOS with a muscle. So it's not an abscess and it's not a solid mass. So the differential diagnosis is a, is a bleed. Um Another one is um is an app is, is, is, is, is a, is a collection around the carotid that had developed post FN A. So that was in uh a hematoma that had uh happened because of an FNC in that region uh hitting the carotid artery and uh giving us that uh the hematoma within the carotid space. That one another uh important um uh uh patient uh category is is of the neck of the blunt neck trauma. So, in these situations, our treatment depends a lot on the CT scan. For example, there's a classification called Schaffler's classification which describes um presence of hematoma, presence of uh of fractures. And uh if it's a, if it's there is no fracture, uh then you would go for a conservative management. But if there is a fracture, you must uh go for a surgical uh approach in most cases. So if there is no CT scan, we wouldn't be able to identify them. For example, in this patient, you can see that the cryo cartilage is shattered uh by a blank trauma. Uh Another one is uh a several fracture um of the, of the thyroid cartilage. You see, there's a depressed, depressed fracture of the thyroid cartilage. So, this patient is not amenable for uh, uh for conservative management and they should, uh, go for surgical correction of this, uh and this pathology, this uh deformity there. Um And these patients can also be associated with, uh, with voice, um, voice change injury to the recurrent laryngeal nerves and and the risk of uh hematoma forming within the airway uh which can complicate the picture. Um similar thyroid fracture. Uh This is a new fancy um AC T scan that is mostly used it by the orthopedics. But sometimes we use in uh we can use an ent also for identifying the uh the thyroid lamina at the uh uh the laryngeal fractures. Another similar example of uh fracture of the car of the uh thyroid lamina uh other trauma um case uh is the presence of a of a sharp penetrating injuries. So, in this case, there is a, there's a sharp pen penetrating object, uh object uh uh lying just behind the mandible. It's an, it's a level, it's a zone three injury uh uh in, in these situations. Uh It's a master for perform a, a CT angiogram. Also to identify whether there is a, there is a uh there, there's a breach of the uh of the, of the carotid space or, and any vessels there. Um We recently saw a patient with uh with a, with a sharp stab in the, in the anterior neck. And the and the knife had gone between the internal and external carotid arteries and the CT scan uh showed uh mild uh breach uh which needed uh repaired then. Uh otherwise, he was very asymptomatic. Uh Another sharp foreign body is injury with the glass. So the glass objects are presenting as high potent uh objects in uh within the visceral uh visceral neck space. So this patient uh definitely needs exploration. Uh Next is neck lumps. So, if a patient presents with a neck lump, usually our first investigation, ultrasound and FNE however, not always uh beneficial. Sometimes we need a cross section imaging in our uh we have a choice between an MRI scan and an uh and AC T scan. And um in uh in certain cases, we do go ahead with a CT scan. For example, this is a, this is a carotid body tumor. Uh and on a contrast CT scan, it's showing very high contrast buildup. Um It doesn't look like a malignancy. There is uh no other differential diagnosis in this. It's just it's pathognomic for, for a carotid body tumor which needs specialist uh surgical removal. If we further investigate such a lesion, we would identify, we can identify them by uh by performing the uh the CT angiograms like this patient, for example, had a rightsided a left-sided um uh lesion with a small uh right carotid body tumor also present. Um Another one is a, is, is a, is a, is a benign looking lesion with a cystic cystic center, like a hypodense center in the rim around it. So, uh they would take it as a brachial cyst and go and uh do a conservative approach. However, for example, in this case, when they removed the cyst and send it for, for a biopsy, it came back as malignant. Um Next is a, is a case uh of a in this uh th this is a a CT scan, but the, these people had done a uh a CT scan without contrast and that had shown this pa region in the lateral, in the lateral neck and around the carotid space area. And they performed MRI scan which identified as a Anoma. So uh it's not a malignant lesion. However, if it's causing symptoms, it needs uh removal. Um AC T scan is also helpful in case of vascular and lymphatic malformations. Um the ultrasound will be able to identify the cystic spaces. However, it will identify how, how deep are the space and what's the extent of them, whether they are amenable to surgical treatment or whether we can give other modalities of treatment like cle therapy or the conservative measures and also identify whether the airway is at risk. So this patient has isolated pockets of high um A DS. Uh So it looks like a child. So um this is uh uh this is a lymphatic uh uh malformation, cystic hygroma. Another one is for example, Coronal image in a patient with a submandibular region swelling and identified it's actually uh um uh a plunging granula coming down to the to the mylohyoid muscle and presenting uh under the under the chin. Uh Another example is a, is a typical uh swelling present in the, in the level two region right across the high I um in, in, in, in a, in a young uh male, in a young person uh with the typical features of hypodense uh fluids and a very um and a very uh irregular borders. So it's um um it's pathognomic for a, a brachial cleft cyst. However, uh you can see this is the internal carotid and external carotid and the slip of it passes, you can see the high poten area going right uh into it. Uh That's another pathognomic feature of it being a branchial cleft cyst because of having this uh weak sign. Uh a third brachial cleft cyst is usually rare. But if it's behind the sterno mass and lower down, uh at a around uh say uh below the level of the hyoid, it would be labeled as a third brachial cleft cyst. Um This is an infected thyroglossal cyst. It shows a, a wall of uh high, high uh hyperdense areas with a cystic uh center uh in the, it's right in front of the thyroid, uh thyroid lamina. So that, that is uh in that region, uh one of the most common uh diagnosis uh would be a thyroglossal duct cyst. Similarly, for example, uh an ectopic thyroid that could have been missed by other investigations. If we, if we don't do a cross sectional imaging and the CT scan is uh is good at picking such lesions. Um Next is talk about um malignancies. So in case of malignancy, doing an imaging, uh the choice of imaging is very important. Uh So the role of imaging imaging is first detection or an exclusion of a tumor. For example, you can identify if, whether it's a tumor, it uh or, or it's any of the other um neck lumps, uh the benign uh benign lesions. Uh If it is there, it, it will be able to identify the size and uh what's the extent of this uh tumor. It can even characterize the tumor, whether it's an aggressive tumor or whether um it's uh it, it, it does not have aggressive features can also tell us uh which structures are involved. So by telling us the size extension and, and which structures involved, we, we are able to give a staging to the tumor. And uh and on the basis of staging, um uh we devise our treatment uh for example, uh at a tumor of stage stage uh of uh TT one and N zero has different treatment uh than for example, say T three and uh N two tumor. So, uh imaging um uh uh of, of the tumors is, is, is, is very, very important. Um Also uh another uh role for AC T scan is that if we identify, for example, a neck tumor, we won't exclude whether there's any other tumor present. So we go on to a scout imaging of, of the chest uh as well as abdomen most of the times uh between the CT scan and an MRI scan. Uh uh There are certain situations in which a CT scan is more helpful than, than the MRI scan. However, as a rule, mostly MRI scans are done for, for, for, for the tumors as a second line investigation, once they have been picked up by um by the, by the CT scan, but there are still certain situation in which AC T scan is helpful. I would be able to explain that in the next few slides. Um further in, in the management of AAA uh a tumor, we might need to say imageguided biopsies. Um We after say giving you treatment, for example, radiotherapy would want to reevaluate them and the CT S are are helpful. Uh Here is a patient uh with uh with a known malignancy and uh it shows um a malignant looking lesion in the right pyriform fossa lesion. So it shows that it's asymmetrical, the mucosa is thickened and you can see some high potent areas which shows that there is necrosis. It's not a, it's not a picture of a normal looking tissue. And um if you look in the next slide, this one looks like a node and it, it, it, it must be a level three node in that region uh which shows uh rounded contours with hypodense area in, in between. So it becomes a pathognomic that there's a mali, there's a, there's a patho, there is a malignant looking lesion inside in the pyro four and there's a lymph node outside. Um So um such a lesion um will definitely be highlighted as a malignant and uh ask and they will ask the surgeon to take a biopsy um of the lesion in the pyro fun courses and maybe form an FN ac of uh of this A A US C guided FN ac of this lymph node to actually get the, get the type of the, get the cancer typed and uh then uh do the staging for further treatment. Um If we look at this CT scan, um this is where a CT scan is more helpful than say, for example, an MRI scan, you see there's a, there's a lesion right underneath uh the right inside the jaw which is showing a break in the inner table of the jaw. So uh this is a at four lesion in in this situation and the treatment will be totally different. For example, if we did an MRI scan in this patient that will definitely not be able to differentiate uh or identify the loss of this inner table. It might. But the that the CT scan is more helpful uh in this situation. Um This is uh uh a, a tongue base tumor basically uh showing is a large hyperdense uh area in this region with uh typical lymph nodes in the level two region, level three region. Um Another example of a of a tumor of a slightly different picture um in the pyriform fossa. So pyro thrombosis is uh one of the uh notorious uh region of uh malignancy within the hypopharynx. Most common hypopharynx malignancies come from the, from the pyriform fossa and then they throw mats and they mostly are not amenable to surgical resection, especially if say, for example, the apex after the um after the para coa is involved. Another similar example of uh a hyperdense uh swelling in the level uh two region. This is level two because it's near to the mandible, the level two region and then the level three region. So they look large and uh necrotic center. So they must be malignant. Um Another um important uh benefit from uh AC T IC T scan A A across imaging is identification of trans cancers. These cancers will not be identifiable by simple examination uh by surgeon even under general anesthetic. So, transglottic is a is, is a cancer which which has risen in, in one of those locations and it just passed on to the next location. Like for instance, agt lesion has gone down into the, into the glottis. A alot lesion has gone down into the, into the subglottis. So it's involving more than 11 subset. So such cancers definitely have a, have a poor prognosis and CT scans done beforehand will be able to identify such patients. So their treatment becomes curtailed according to the situation. Um Another one is uh AC T scan is very helpful in identifying the breach of uh of the cartilage. For example, if there is a clotting malignancy with a breach in the, in the in the thyroid cartilage, it's not pick it up so easily on an MRI scan. However, ac T scan easily picks it up. So once a tumor is within the, within the cartilage network is labeled at T two, but once it treats the cartilage lab is T three and that, that changes the treatment altogether. So any tre lesion is not amenable to con conservative, a surgical approach uh or a limited surgical approach, uh the whole of the larynx must be taken out. Um Similarly, uh if, if a lesion is present um uh and going into the prey space and involves a pret space, it, it is picked up nicely on AC T scan and involvement of the of the pret epiglottic space, puts the tumor as A as a T as A T three rather than A T two and that changes the whole uh uh management. So they need aggressive treatment uh including a late laryngectomy. Um So we have been seeing a few lymph nodes up in uh in the slides till now. However, let me just uh give a a short brief uh outline of what a malignant lymph node looks like. So they say any lymph node that's large is a, is a malignant lymph node on this bone otherwise. So by and large, it doesn't mean that you have to actually go about and measure these. Anything that looks larger should be suspicious. Uh Some people do measure them, especially if we need to stage a tumor. For example, uh in case of uh a neck malignancies, uh If the tumor is more than three, less than six, it will be an N two. If a, if a node is more than six, it will be an N three lesion. Um So the size is important, however, um solely identify uh so solely um fixating on the size is, is, is, is not worthwhile. Then shape is also important. The normal um uh lymph nodes are more like jelly beans uh with uh with a high limb. Uh But uh once it, it is, it's malignant uh or has it has metastases inside it, it becomes, it becomes circular and shows up uh as a ball. Um and it has heterogeneous enhancing pattern. It doesn't have that uh that soft look anymore. Um It can, can have eccentric cortical hypertrophy. It may have hypodense centers showing necrosis within the nodes. Uh these nodes may be mass massed up together. So any cluster of three or more uh even if they are borderline node size nodes, they are considered suspicious and their margins can be ill defined. Now, another important um criteria for malignant node is uh extranodal extension. That means that the state that the disease has uh gone beyond the borders of uh of the node. And it's, it's visible on ac T scan by having indistinct margins, having an irregularly enhanced capsule. So that means it is kind of breached through the capsule. And uh if there is a muscle and fat infiltration on in, in the surrounding areas, that's definitely um a a metastatic lymph. For, for example, if you see in this first picture on the left side, it looks like a big node. It's not, it doesn't look very smooth, there's infiltration, it is going into the muscle. So it's definitely an externo extension. This node, it looks uh with a necrotic center, not so big, but uh it's heterogenous. So you would label it as a suspicious malignant node. Similarly on this uh node, it probably shows a breech in this area because the capsule is not intact. Uh Similarly on this node, it's uh it it's enlarged uh quite irregularly and has a hyper uh irregularly en irregular enhancement. Um uh The further few slides are just examples. So this is a level two metastasis because the mandible is nearby. So it's at the level two metastasis show shown as a bright red spot on a pet scan. Um Level two level three lymph nodes, we already discussed this uh in an image up a level four lymph node. Uh you see this is the thyroid gland. This is the tria, the cricoid has already gone, finished. So a lymph node in this territory would be a level four lymph node. And this is the interocular uh vein. So it's a level four lymph node. So they had i it's, it's one of it can be worse. They have, they have to be suspicious about uh me about medicine from other regions. Um A level five lymph node, this is a 55 a lymph node because it's up near the level of the thyroid cartilage right in the posterior triangle behind an imaginary line drawn between the scales and the mast and the, and the sterni mastoid like this. So if we draw a line between this, it's behind that. It's a level five B lymph node. Uh five A uh if I be lymph node, I'm not really sure exactly which one. But um I think it's a five, a lymph node. Yes. Uh uh Still uh being CT is very much informed, but sometimes the lesions can be very deceptive and it needs a very keen eye from a radiologist. Uh And occasionally they, they need further investigations to actually describe what a lesion is. And then they will be able to um uh give some uh further information to the surgeon. For example, if you look at this lesion, it, they look pretty similar to each other. Um hypodense area with uh with a smooth outline in the level. Uh two region here, just uh at the level of the, of the, of the vale, same one here. However, they have two different pathologies. Uh One is a brachial cleft cyst which is a smooth outline looks uh the non-malignant. However, the other one is uh is a malignant papillary thyroid carcinoma and how the, the, the radio is would identify because of this uh these irregularities in the borders and, and high densities there. Um That's it. Thank you. Thank you so much for that missing. That was very, um a very detailed, I think. I, yeah. Um at the moment I felt like no one is listening because I cut off from the network. Yeah, we all just turned into silence. Very, very absorbed into your presentation. OK. Thank you so much. Um Guys, is there any questions before we cut off if you just type it onto the um chat box and I can read it out if there's any questions? No. Um Well, in that case, thank you very much for your time, Azim. And um when you sign off, um you guys, there is a feedback form So if you sign that, you fill that out, sorry, you'll get a certificate automatically to your inbox. Um If you need a speaker certificate as well, same thing, it should appear on to your medical. Well, thank you. Brilliant. Thank you. Hope you all have a lovely evening.