good day and welcome to the lecture on principles of radiographic interpretation as with all your other lectures in the module of radiography i do encourage you to supplement this lecture and the lecture notes with the textbook so why is principles of interpretation of radiographs important firstly it is a legal requirement that all radiographic projections must be accompanied with a written report of the diagnostic findings it also assists in the diagnosis of patients that will eventually link to how you would manage and treat your patient during radiographic interpretation it is important that you have a systematic approach that will evaluate the entire field of view of the radiograph even though you exposed for example a panoramic radiograph to evaluate the impacted third molars it is still your ethical and legal responsibility as a healthcare provider to evaluate the entire radiographic projection the principles of interpretation of radiographs will differ with each radiographic projection it is important that we do it in this manner so that you can detect any incidental findings which may be important in the future management of a patient with radiographic interpretation the clinical information for each patient is very important as it will link to the differential diagnosis that you will apply in your report it is also important that you use a specific professional language and radiographic terms while doing your radiographic report and again i just want to emphasize that knowing your anatomy is extremely important so the principles of interpretation is a clinical skills that needs to be developed this means that even after having listened to this lecture reading up on the textbook it is something that you need to apply in clinical situations to build up your knowledge on how these radiographs are being interpreted that is why in the diagnostic imaging award we encourage you to come for interpretation for each radiographic exposure that you make in the clinic this will then assist in developing this skill just to show you an example of radiographic interpretation is important this patient was seen in our diagnostic imaging award last week and she was referred from service rendering unit for evaluation for full upper and lower dentures so firstly we can see that the patient presents with these types of calcifications in the periphery and these might resemble carotid artery calcifications when confronted with a situation like this it is your legal and ethical responsibility as a health care provider when you see these types of calcifications to refer your patient for cardiovascular assessment also we can see that the patient presented with numerous root rests that might need to be sorted out before they can be supplied with full upper and lower dentures and also importantly the patient presents with a lesion in the anterior mandibular area this lesion needs to be evaluated along with the clinical signs and symptoms and if needed a biopsy be taken to come to a final diagnosis before you can convince with the patient's treatment another example that i would like to share to you is a patient that presented to our ward and the patient had was in a motor vehicle accident and sustained fractures to his jaw after which he was treated with intermaxillary fixation the patient was then sent back to the diagnostic imaging ward a few months later to evaluate the healing of the fracture after the imf has been removed if you look very carefully you will see that the patient presents with a lesion in the right mandibular corpus remus area therefore this lesion needs to be further investigated to identify what it is and biopsied so that this patient can be managed optimally after the lesion was identified on the panoramic radiograph a cvct projection was prescribed to identify the extent of this lesion you can see in the right mandibular corpus ramus area there's a radiolucent lesion that in some areas results in thinning of the cortex just a final example this was a patient that was also referred for extraction of the root rest of the 2 8 area so firstly if you evaluate this radiograph and using the systematic approach that i will teach you during this lecture you will firstly see that the patient presents with mucosal thickening in the left maxillary sinus that can also resemble an antral pseudocyst all of these pathological terms you will learn about in the year to come during your radiology as well as pathology lectures the patient also presented with a radiolucent lesion in the fourth quadrant associated with the canine this could either be a developmental cystic lesion or an inflammatory cystic lesion associated with this canine so therefore it is important that this lesion be evaluated for its clinical history and then managed accordingly also something that we noted on this radiograph is overlying the right maxillary sinus there is this bony area with increased density because on this two-dimensional image it was difficult to evaluate we then decided to subject the patient to a cbct examination the cbct examination confirmed the presence of a bony growth involving the right maxilla it extended also to involve some of the zygomatic bone you can see that it involves all of the floor and as well as the lateral walls of the maxillary sinus therefore even though this patient was unaware of this lesion due to her radiographic examination and of systematic approach in interpreting a radiograph we were able to detect this lesion and therefore manage this patient optimally so in your previous years of study in the subject of radiography we already taught you about how to evaluate curious lesions and bone loss that mainly and pathological entities that mainly affect the teeth and its supporting structures it's important to know that when you do radiographic interpretation as we have taught you you have to follow a specific sequence when reporting of these entities if you remember correctly you report caries and bone loss using the acronym led location extent and diagnosis for example if we look at an example like this the location would be for example the 3 6 distal the extent would be severe because it's more than halfway to the pulp and the diagnosis would be inter-proximal caries there's a specific way in which you need to report on these lesions in the same manner for bone loss please refer to your previous notes just to familiarize yourself with these concepts so after we have taught you already about conditions affecting the teeth and the surrounding structures you will still in the year to come in the modules of radiology and pathology learn about conditions that will affect the periphery the sinuses the tmjs and pathological entities involving the bone so coming to the lecture topic of today we will in this lecture describe how you need to interpret radiographs and an important part of that is using a specific structure as i have already said that follows a systematic approach and also it is very important to have sufficient detail in when you write a radiological report so when you are confronted with a lesion in your field of view of your radiographic project projection it is important to interpret or describe the lesion using the following terms we use the acronym blast to help you remember of all the aspects that you need to discuss when describing a lesion b stands for the borders l for location where is the lesion located e is entity what makes this lesion unique the size and the shape the effect on surrounding structures and the density of the lesion let's start off about talking about the borders of a lesion when describing the borders of the lesion you get borders that are well defined and this means that you can take your finger and trace the lesion so that you know they extend to where the lesion starts and where the lesion stops if you are unsure where the lesion starts and stops and the lesion blends into the surrounding bone we refer to this as poorly demarcated so a well-demarcated lesion you can see the complete extent of the lesion and a poorly demarcated lesion blends into the surrounding bone so you are unsure where the lesion starts and stops a well-defined lesion can either be non-corticated meaning it isn't surrounded by a cortical rim or it can have a nice cortical room as you can see in this middle picture here is an example of a lesion that is well defined meaning you can trace all the borders of this lesion but it loses some demarcation in its anterior dimension because the majority of the lesion is well-demarcated we will describe this lesion as a well-demarcated or well-defined lesion and then we will just add an extra note to say that there is loss of demarcation in its anterior portions the next factor to consider is the location of the lesion this is fairly simple as you just identify the anatomical structures that are involved in the lesion if you think back about the radiograph that we just discussed you would say that the lesion is located in the left ramus and posterior mandibular corpus you can also say that the lesion is associated for example with the apex of specific tooth numbers and remember to include whether it is left or right entity is a concept that says what makes this lesion unique what are some unique features so when we describe radiolucent lesions a radiolucent lesion can have an appearance of either being multilocular in simple terms it's got numerous small locules or bubbles or it can be unilocular meaning one single locule another entity that you can also use to describe unilocular lesions are radiolucent lesions is if a unilocular lesion has got scalloped margins for radiopaid lesions it becomes a little bit more difficult but this you will learn in the subject of pathology when each separate pathological entity is discussed for example in cases where you've got fibrous dysplasia will often refer to the bone as having a ground glass appearance or smoke screen appearance on panoramic radiographs in some conditions such as paget you will then describe the radio opaque lesions as having a cotton wool like appearance the size of the lesions in smaller lesions is easy to determine for example if we look at this radiograph the lesion is approximately 1 to 1.5 centimeters in diameter when it comes to larger lesions it is sometimes difficult to say whether this represents 10 or 15 or 12 centimeters in those instances you can just describe the extent by saying that the lesion will stretch from the 3 8 area to all the way crossing the midline to the 4 2 4 3 area when we talk about the shape some lesions have got round shapes heart shapes and even irregular shapes again this is a concept that you will learn about in your pathology lectures when the different pathological entities are being discussed the effect on surrounding structures very often gives us an idea of the biological behavior of lesions in most instances cystic lesions and benign new plastic lesions will have a slow growth pattern where they will displace structures meaning it can either cause tooth displacement displacement of the sinus displacing the inferior alveolar nerve expanding the cortex those sorts of things when other lesions have got a little bit of a more aggressive biological behavior they often result in destruction of the tissues this can include anything from root resorption cortical destruction infiltration into the soft tissue and so on most of the times infectious and malignant processes will result in a more aggressive radiological appearance although this is the majority of the case there is always some exceptions to the rules when we talk about density you get lesions that are radiolucent you get lesions that are of soft tissue density and then you get lesions that are radio opaque it's very important to know that the description of a lesion will always link to the differential diagnosis that you supply for example if you describe a ameloblastoma which is typically known to cause bone destruction amyloblastomas will not be a radiopaid lesion they will present as being radiolucent when it comes to mixed lesions it becomes a little bit more difficult you can get a mixed lesion and if we describe this in more detail it would be radio pegs surrounded by radiolucent rim this will be a typical mixed lesion where you will have radio opaque as well as radiolucent areas in this instance a mixed lesion surrounded by radiolucent rim and here we have a radiolucent lesion with internal calcifications as i said earlier this will become more clear to you once you discuss the separate entities in your pathology lectures so now that we have discussed how to describe lesions let's now go through each individual radiographic projection on its own to discuss how to approach the interpretation of these radiographs for intra-oral radiographs you need to start by orientating yourself and identify the projection and the field of view so if we look at this first radiographic projection this is a periapical radiograph of the 1 6 and the 1 7 because we don't see any teeth surrounding it this could might as well just be 1 8 and a 1 7 as well all right so it is important to have a systematic approach for example when you evaluate any radiographic projection especially intra-oral you have to start off by going from the first quadrant to the second to the third and then the fourth so we will follow that sequence so the 1 7 presents with calculus distal and it presents with mild horizontal bone loss on the one wall and moderate to mild vertical bone loss on the other bony wall on the distal aspect easily it presents with secondary carries as well as mild to moderate horizontal bone loss the 1 6 distal has a sharp demarcation so this might represent either a lost restoration or severe distal interproximal carries the 1 6 also contains a pulp stone and bone loss at the distal aspect which is mild to moderate and on the medial mesial aspect again mild horizontal bone mass this represents the coronoid process this is why it is important to understand your anatomy as to not mistake this for a bony projection or lesion if we look at the radiograph at the bottom this is a periapical radiograph in which we can see the 1 3 to the 1 1. 1 3 is sound but the 1 2 presents with severe interproximal carries on the mesial aspect it also contains a dense invaginatus it has internal root resorption it has got external root resorption the one one has advanced interproximal carries distal it has severe interproximal caries mesial and it's got external root resorption now we are going to start describing this lesion we start off by saying that there is a lesion at the apex of the one two and the one one the lesion is well defined but not corticated it is at the apex of the one one two and one one as i already mentioned it is uni locular and it's radio loosened the size of approximately 1.5 centimeter in diameter the shape is round the effect on surrounding tissue is the external root resorption and also we can then mention that it is unilocular radiolucent so that is how you would approach the interpretation of an intraoral radiograph it is important to note you must mention all the curious lesions faulty restorations or root canal treatments any bone loss any eruption disturbances such as infections ankylosis over-eruption it is important to mention pop stones as this might influence the endodontic treatment of certain teeth calculus in cases where the patient has got bone loss to know where to go root plane and scale and polish the periodontal status is the widening of the periodontal ligament space is there loss of laminar dura are there unification lesions and then any pathological entities you need to describe using the acronym bliss and then provide a differential diagnosis a differential diagnosis is a list of two to three or more possibilities of what the lesion can present as you will then use special investigations such as further clinical examination pulp testing biopsies and so on to then come to a final diagnosis let's evaluate how we should interpret a panoramic radiograph a good way to remember is that you always start from the outside going inwards so you first start with evaluating the periphery more information on evaluating the periphery will be done in your pathology and radiography lectures specifically also the radiography lecture on soft tissue classifications after you've evaluated the periphery you will then evaluate the tmj complex further lecturing will be conducted in pathology and your radiography modules same as with the sinuses after we have gone from periphery tmjs to sinuses then we can start with interpreting the teeth you will note if there are any missing teeth any impacted teeth carries calculus pulp stones all of those entities that we have already discussed dental anomalies should always be included in that list as well it's also then important to evaluate the bone bone includes the evaluation of bone levels whether there's bone loss and then any pathological entities so let's as an example do a radiographic interpretation of this panoramic radiograph firstly when i evaluate the periphery i can see that there's a soft tissue calcification in the left periphery that is below the left magnibular angle due to the approximate location and the manner in which the calcification presents it will most likely be a submandibular sciatic also in the periphery we see a small specular calcification also in the left periphery near the angle of the mandible and this can represent anything from a tonsillitis or a calcification in a lymph node after i have reported on the periphery and i've also provided differential diagnoses i can move on to the tmj the tmj on both sides appear symmetrical no overt erosions or cortical distraction is noted no overt asymmetry in the size or the shape and therefore i can say that the tmj complex is normal same with the sinuses importantly when evaluating the sinuses you must be able to trace the cortical outline of the posterior floor and medial wall of both your left and your right maxillary sinus there's no over pathological entities noted in the sinuses and therefore i can state that the auxiliary sinuses are clear then you will go on to note any missing teeth curious lesions bone loss calculus pulp stones last restorations tooth wear and so on and so forth i'm just going to jump to discussing the pathological entity as i know at this stage you are competent in describing caries and bone loss lesions so firstly we can see by the 2 7 area the reason i'm not calling this a 2 6 as you can see that they are some distance between the two 5 and this tooth which means that this tooth had some form of mesial drifting the two seven presents with a pulp stone as well as widening of the apical periodontal ligament space and in the bone there is a relatively well defined periphical radiolucency the first thing you would do as a clinician is assess whether this tooth is vital you will do periodontal probing to determine that that this is not a periodontal bony defect and then you will provide differential diagnosis of for example a perio endo lesion or a chronic apical periodontitis which is also referred to as a peripheral granuloma then if we go to the right mandible we see a well-defined corticated unilocular radiolucent lesion that is associated with the distal aspect of the full five it is round and roughly one centimeter in diameter as a clinician you will establish if this tooth is vital or not if the tooth is non-vital you can provide a differential diagnosis of a natural variant of a ridiculous cyst or if the tooth is vital even a lateral periodontal cyst or an antigenic carotisist then in the right mandibular posterior corpus ramus complex you have a large lesion that is well defined with a cortical rim the lesion appears to be unilocular with a scalloped margin although the radio opacity there might mean that the lesion can be multilocular the lesion size goes from approximately the four seven area up to the ramus approximately one centimeter below the sigmoid notch the lesion has areas of cortical thinning cortical distraction as well as displacement of the inferior alveolar canal in an inferior dimension the differential diagnosis for this you can include something like aniodontogenic keratosis these types of pathological entities as i have mentioned earlier will be discussed and assessed in the module of pathology for radiology it is for us just important to be able to describe the pathological entities moving on to how to interpret a lateral cephalogram lateral cephalogram is normally a radiographic projection that is taken in conjunction with a panoramic radiograph to get a second view so how to interpret a natural cephalogram it all depends on the referral and the indication why the radiograph was exposed for example if a lateral cephalogram was requested for orthodontic analysis your radiological interpretation will be based around that referral if we look at this case as an example this patient was referred for natural cephalogram to evaluate the joules for orthodontic analysis so from this view already we can have a brief estimate of where our sna and asmb is so we can say that this patient is an angry skeletal angle class 3 because the snb point is more anterior compared to our sna also what we can then mention is the patient presents with an anterior crossbite where the lower incisors occlude anteriorly as compared to the upper incisors you can mention not in this case but in other examples the proclamation of teeth the position of teeth as well as then if any teeth are impacted in some instances we can use a lateral cephalogram to evaluate the adenoids in this instance you can see there's your adenoid gland and you can see that it's also swollen to a point where there's reduction in your nasopharyngeal and oropharyngeal air space we sometimes also request natural cephalograms if a patient has had trauma in particular when a patient presents with a nasal bone fracture so if this is the reason for the radiographic request we will then construct our report based around why the radiograph was taken so here we can see that the patient presented with a nasal bone fracture it's also a good image modality to view any pathological entities involving the swenoid sinus the same with skull views skull views are mainly requested in conjunction with a panoramic radio gulf to have a second view of the patient's condition and therefore your radiographic interpretation will again depend on the referral and the reason for radiographic requests if a skull view was requested for trauma you will evaluate the trauma on the panoramic radiograph to determine the horizontal favorability of fractures skull views for example a pa will then be used to establish the vertical favorability of a fracture and how the fracture is then displaced these sorts of interpretations will then link to how the referring clinician will treat this patient skull views can sometimes be used for pathological entities as well for example a waters radiograph is a good projection to evaluate the sinuses the maxillary sinuses in particular and therefore can be used to evaluate pathological entities involving these structures let's talk about analyzing a cvct scan the lectures on cdct will still follow and after those lectures you'll have a better understanding of how a cbct unit works and how to analyze the radiographs for now it's just important to know that when a cvct is projected you have coronal sagittal sagittal and axial slices as well as a 3d reconstruction whichever one you decide to start off with first it is just important that you scan through all of these three different views from start to finish to analyze the whole scan volume for all instances you need to analyze the entire field of view of the cbct scan if only the tmj as an example is projected in the field of view you need to analyze them in extensive detail when doing a radiological interpretation or report on a cbct scan you need to have a good understanding of the anatomy and anatomical structures in most instances we follow the same sequence as we do for panoramic radial growth analysis using a systematic approach you will evaluate the periphery tmj's sinuses teeth and bone if these structures are not in the field of view then you can't analyze them due to some inherent limitations of cbct scans it's not a good radiographic projection to evaluate for curious lesions this will be explained in the lectures on cbct that is still to come let's look at the one slice of cbct projection that we have in front of us firstly i need to orientate myself to know what i'm looking at i am looking at a coronal slice and the slice is taken from relatively anterior as i can still see the eyes and eyelids as well as my frontal sinuses these teeth resemble premolar teeth so to analyze the cvct scan firstly you will see that there is very very slight mucosal thickening on the floor and lateral wall of the right maxillary sinus you can see that the left maxillary sinus is completely opacified being filled with tissue of soft tissue density similarly you can see that the left frontal sinus is also a pacified and filled with soft tissue we can see from this projection that the right inferior nasal conquer has got mucosal thickening we also can use different radiographic projections in combination to analyze a specific structure for example in a panoramic radiograph we can see a well-defined radio opaque one centimeter structure that is located in the left mandibular corpus apical to roughly the 3 8 area and also it is close to the inferior border of the mandible so when only looking at a panoramic radiograph you can have various differential diagnoses but now that we expose the patient to a cbct projection we can see that this structure is completely separated from the bone therefore ruling out any bony pathos and therefore your differential diagnosis will then change to a submandibular silence [Music] let's look at this cbctr placement to use as an example to practice our radiological interpretation firstly i need to orientate myself to know what i'm looking at this is a coronal slice an axial slice a three-dimensional reconstruction as well as a panoramic reconstruction from the cbct data set from the coronal slice i can see that there is a lesion that involves the right maxillary sinus the lesion is of soft tissue density and relatively poorly defined it is poorly defined mainly because cbct has got a limitation of having poor soft tissue contrast if this lesion will be viewed on another image modality such as an mri it may be well demarcated but from this projection we cannot see the start the extent of this lesion but what we can see is the effect of surrounding tissue this lesion results in destruction of the lateral wall the floor and the medial wall of the maxillary sinus it also causes destruction of the floor of the orbit it infiltrates into the nasal cavity involving the inferior and middle conquer on the right and it also causes destruction of the floor of the nasal cavity and part of the hard palate on the axial slice we can see the same lesion resulting also an additional destruction of the posterior wall of the maxillary sinus the anterior wall involving some of the zygoma and here we can see the extent of infiltration into the nasal cavity this is why it is important to have a good understanding of anatomy because basically we are describing the structures that are missing in this area because they are being destroyed by the lesion so you need to have a good understanding of your anatomy to know what structures are being destroyed just some key points before we end the lecture it is important to know your radiographic principles know all the physics of the projections and know their limitations for example if you see a area that is blurry on a panoramic radiograph you need to consider the fact that it might be a positioning error placing that area of the bone outside of the focal trough it is important to know that cbct has got poor soft tissue contrast therefore the borders and extent of soft tissue lesions cannot be clearly identified it is important to know your anatomy to know that the location of lesions will assist in your differential diagnosis you need to have a good understanding of what is normal to be able to diagnose and identify abnormal conditions you need to know your pathology you need to know the pathological entities that can present in the head and neck area and after knowing all of this you need to integrate your knowledge into practice when you are confronted with a clinical situation thank you for attending this lecture today if you've got any questions please feel free to email me