[Music] [Music] hey guys so welcome to the class today uh we will be taking off from where we left yesterday which is uh hrct approach so today we'll be talking yesterday we did the normal Anatomy how a normal scan will look like what are the structures we have to see what are the planes what is the lymph Nole Anatomy all of that today we'll be uh talking about one the general approach to hrct that we have to have which is the pattern approach a bit of it we have learned on the chest x-ray as well but now we shall be talking about the CT approach happened to my screen and uh then I'll be taking you through ields okay I may uh it is something which is a very very difficult thing uh uh to report it is one of the topics where where you know when you are a Jr it seems easy when you are reading or when somebody's teaching but every scan and every patient is different and you know um not always will you see the characteristic pictures that you see in the textbooks and and what you see in classes so that's why it is very tricky to report but overall this is one of the most important things that we need to know in just Imaging these are the common things which are U very non-specific you know in in general so I will try my best to make it a bit easier for you okay so you can see my screen now okay all right so let's start thank you thank you so much all right okay let's let's start off so Imaging of interstitial lung diseases first I'll be talking about the pattern okay so uh basic approach that all of you need to uh remember here in thoracic Imaging is is the secondary pulmonary pulmonary lobule this is the smallest functional unit for us you know so uh it is not the smallest unit anatomically where we know that you know we have terminal bronchol we have respiratory bronchol we have alv duct which opens into alv Sac right so that is what Anatomy is but radiologically what is our unit for pathologies and radi iology is going to be the secondary pulmonary lobule so what does the pulmonary lobule consist of so what you can see here this is something which is a very nice schematic and something you will see almost everywhere is how a lobule looks like so in the center of the lobu you can see that the artery is entering here this is what we call as the centry lobular artery because it opens in the center and this is where you have the respiratory bronchol dividing into the various acid ducts and the various as so in one lobule we have around 5 to 15 as right on an average they say eight as in one pulmonary lobu and it measures around 1 to 2 cm okay so this is what is the lung unit for all diseases for us okay so while we have this as the smallest unit and we'll discuss more on this we also have the inum what the inum is is the connective tissue through which we have the lymphatics and the veins which are csing this you need to know so any intertial lung disease can have this appearance right either it can involve the lobu yeah which is the centry lobular inum or the intal lobular inum or it can be interlobular interum or it could be along the peribronchovascular bundles so when we talk about fibrosing diseases this is what we will discuss that is there in interstitial thickening which is interlobular intralobular or is it peribronchovascular so this will help you understand that all right this is where the interum is so this is where the fibrosis can happen Okay so this is the basic anatomy that you need to know now let's go back into Basics you know what can happen depending on the anatomy of the pulmonary lobu so in the center we know what all is opening in the center we have one the centry L ular artery and second is the bronchol right so we have the respiratory bronchol which enters here so can I say that anything which is coming by the artery or more importantly the airway will mostly have this sort of a pattern which is called as a centry lobular pattern okay so if I have a nodule which is in the center of the pulmonary lobu and it is not touching the plural surface this is what we call as a centry lobular nodule okay so the hallmar we will study of a central lobular nodu is it will never touch the plural surface did you understand so can you tell me some DDS differentials when you see this centry lobular pathology it has to be either arterial or Airway so out of the airway can you tell me a few differentials of anything which is coming from the airway some somebody who has hyper sensitivity right very good so hyper sensitivity pneumonitis very very typical is going to be into the airway it is going to come along the Sentry lobular nodules what else yes respiratory bronchitis or as a generalization can I say any bronchiolitis for that matter all of the inflammation yeah this is a very big uh you know waste basket sort of a diagnosis that bronchitis anything which is Sentry lobular is going to be bronchitis right so respiratory bronchitis follicular bronchitis infectious bronchitis right so TB TB can also come as centry lobular nodules so basically anything which is inflammation is going to come via the airway right so this is what you need to remember not aspiration aspiration pneumonitis again aspiration is not in the small Airway right it is usually in the big Airways right so that is where all right you may have some wall inflammation in aspiration pneumonitis but usually there'll be like a consolidation that present okay milar spread again you have to understand that this is not milary when we say that milary is hematogenous it is not the centry lobular artery which carries it it's the main pulmonary vessel which uh carries it and that is what goes into a random fashion okay so this is what one thing you have to remember that even though it is hematogenous milary is random okay so this is about the center then if I say that the interum is invol you will ask me ma'am what is there in the inum so that I can know that what will be thickened so what is there in a normal inum in a normal inum we have the pulmonary veins and we have lymphatics so does that make sense that when either of them are involved I am going to have the septal thickening Casa septal thickening interlobular isn't it between two lobules so this is interlobular if I have fibrosis within the lobule that is what is called as intra lobular septal thickening okay so this is what we will see in FIB bring lung diseases but when there is interlobular sepal thickening then it's either Venus pathology when do veins get congested the classical example being pulmonary edema yeah cardiogenic pulmonary edema what happens there is a lot of backflow of blood from the left atrium into the pulmonary veins and that's why the pulmonary veins are thickened and you will have interlobular sepal thickening or something to do with lymphatics pathologies like sarcoid silicosis lymphangitic carcinomatosis which is spreading via lymphatics all of this is coming to the lympha atics and that's why lymphatics are thicken you'll have intralobular septal thicking so did you understand the concept so on a city normally do I see the lobu no I don't see only when there is a pathology I will see so in this case can you appreciate this is what is our secondary pulmonary lobule something of this sort yeah so now can you understand that how only when there is interlobular septal thickening I start to see all of these hexagonal units which are nothing but my secondary pulmonary lobules yeah are you guys understanding so this is the sepal thickening that we are appreciating yeah I yeah so I is something that we this is what we are going to learn but in baby steps okay one thing after the other we are going to add up and then approach I because as a diagnosis I can't diagnose something to be I that's not my job I have to tell the exact pattern that you cona I just giving a diagnosis of I is as good as not reporting the scan only so this is what we all have to understand okay so everybody understood the pulmonary lobu before I report anything as fibrosis very very important something I touched upon yesterday as well is to rule out MIM and what is the biggest problem fcy is when you take an expiratory scan when it's not an inspiratory scan in an expiratory scan you will see that overall there is a diffus gradient look at the right lung this is what an expiratory scan does gradient and you will feel that g isn't it if I ask you to report this is what a lot of Jrs do especially Junior Jr basil ground glass opacity query nsip pattern is this NSP pattern no it is not even I it is an expiratory scan how do I know it is an expiratory scan I look at the tra here yeah so we know this if the posterior wall of the tracha collapses but not more than 50% if it collapses more than 50% what trach Malaya isn't it so that was tracho Malaya so when there is a posterior wall collapse and this is expiratory scan I can't report this scan as I you know these are because of expiration why I do do an expiratory scan on purpose is when I want to see air trapping so when I don't see a gradient and I see this hyperlucency then I know that it is air trapping so this is the only place where you would want to do a paired expiratory scan but this is one thing you have to make sure special esally in ields that it has to be a very very good inspiratory scan again one more pointer for all of you okay what to report then in expiratory scan you can't report this you will just say that there is a basil density which is there which is likely because of the expiratory scan okay that's all okay right what was I saying yeah so whenever you do a this is something which is very important for all of you who are junior residents never report ilds on lung window yeah you have to do an yeah you will have to repeat the scan in inspiratory if the suspicion of fibrosis is high in an expiratory scan but yeah what was I saying you do not do a scan in lung uh do not report a scan in lung window whenever it's a pulmonary pathology particularly I you have to do a high resolution CT reconstruction right this is not something that you have to do again right very big misconception you need to acquire a scan in high resolution no now any window you have taken basically any sort of a acquisition you've done you can just do a Recon in the lung window right so this will be a high resolution Recon that you do the kernels that you use are sharp right so that's what you use you use a sharper window you just have to take a hrct Recon so this is something which is very important for all of you don't report ields in lung window you have to report them in hrct Recon it can be done done from the console not from your console where you report but from the console where you acquire you can reconstruct anything in a sharp that's called a sharp bone window Recon which is basically your high resolution Recon okay not bone window Recon it's called as bony algorithm basically that's what is the higher kernel reconstruction okay and yes finally something that I also talked about yesterday [Music] [Music]