 Okay. Hi, everyone. It's Mark again. And we're moving on and we're going to talk about a topic here that hope you find helpful. It's really common. So hopefully we'll be useful. We're going to talk about the imaging approach to fibrosis fibrosis part of the diffuse lung disease kind of spectrum. The main objectives to go over the five main morphologic imaging patterns of fibrosis and talk about the importance of honey combing in particular because that one kind of signifies a particular disease. And understand when we start going into this chronic round glass that the presence and extent of fibrosis significantly changes your differential. There are certain things that you wouldn't see in a chronic round glass with a lot of fibrosis or say, as opposed to if there was no fibrosis. So this is a kind of a key. And when you approach a chronic round glass process. So, first of all, let's define what fibrosis has a different than scarring. Well fibrosis refers to the connective tissue deposition and you know it's part of this normal healing. It's usually seen as an organizing pathologic process. It's usually the usual interstitial pneumonitis NSIP, as opposed to scarring, which that's fibrosis to, but that's fibrosis secondary to an injury. Say, residual from a prior necrotizing pneumonia or infarct will leave a scar. It's fibrosis, but it's secondary to a prior injury. So scarring evidence or imaging of fibrosis is five main morphologic appearances chronic round glass opacity, irregular visceral pleura, reticular opacity, traction bronchi axis, and then honey combing. Okay, honey combing by the way, is one of the most difficult. It really is tricky. And it's important. So, the whole basis of fibrosis is when it occurs pathologically and histologically, there is a retraction of volume loss, which then causes a distortion of that parankamal anatomy. So it can manifest as a kind of a chronic ground glass process, but the ground glass really should have other evidence of fibrosis in it. Reticular, which is just means it's a net like kind of thing, lines that crisscross. Okay, reticulation traction bronchi axis is the pulling apart of the airways because of that surrounding parankamal volume loss and retraction, it pulls it apart and makes it wider and it's called traction bronchi axis. Nothing wrong with the airway. It's just the airway lives in a really bad neighborhood. Okay, so it's secondary to that irregular visceral pleura which I find very helpful. Pleur should be nice and smooth, nice and smooth. When it starts looking speculated. That's the again a sign of retraction. And last is the honey combing one of the most important and very difficult these small cysts that are smack up against the ground. So let's look at each of them chronic ground glass. The more imaging evidence of fibrosis within that ground glass tells us that the ground glass actually reflects fibrosis. So this person's got a lot of ground glass but no imaging evidence of fibrosis right this replers good no traction. This is, this isn't fibrosis right this represents alveolar prognosis in this case. This patient's got some ground glass chronic little bit of irregular visceral pleura traction. So it represents some fibrosis here. And then you get into this which is like there's traction bronchi axis irregular visceral pleura see that serrated night serrated appearance. Very diffuse. That's pretty much if you buy up see it's going to be fibrosis in this case fibrotic NSIP. This patient has got ground glass and not a lot of imaging evidence for fibrosis was treated with corticosteroids and a lot of it got improved, but some of it didn't go away. And the areas that didn't go away are these areas of ground glass with evidence of fibrosis within attraction bronchi axis irregular visceral pleura. So the more fibro evidence of fibrosis within the ground glass, the less likely it will improve with therapy. Okay, the irregular visceral pleura one of my favorites. The pleura should be nice and sharp look at this serrated appearance right. Another one here, a little bit of a serrated appearance here scarring. And you can tell when you see this kind of serrated or irregular visceral pleura that the underlying parenchyma has evidence of fibrosis or scarring but fibrosis and it retracts and pulls the pleura and it tugs it in and gives it that kind of little little speculated shape at various points. Okay, that's the distortion. Reticulation is actually just lines right and they're intersecting and it's like a net or web of intersecting lines. We don't tend to see those so-called curly or inter lobular septation thickening normally because of the parenchyma gets so distorted they get distorted too. So you see these crisscrossing lines often in the setting with the irregular visceral pleura and maybe associated traction bronchiectasis. Okay, so this is reticulation another sign morphologic sign of fibrosis. And traction bronchiectasis. Well, this can be seen with any real cause of scarring or fibrosis. This patient has cryptogenic organizing pneumonia chronic consolidation and you can see how the airways are being pulled apart. Same here being pulled apart by the reticular capacities being pulled apart traction bronchiectasis a very good sign of underlying fibrosis. Again, it's not the airway problem that is the issue. It's the fact that the airways get pulled apart. Okay, now. Traction bronchiectasis is almost always varicose in appearance because it has different attachments that get pulled apart. Okay. Well, lastly honeycombing one of the most difficult. It's the it's three to 10 millimeter sort of spheres cystic spaces that are thickened walls and they usually are next to one another. Now, the key thing here is that it has to be right up against the plurip. It has to be right up against the plurip that I cannot emphasize that. And it can be single file, or it can be heaped up on one another. As honeycombing progresses, it starts in that subplural right up against the plural area. And when it progresses it progresses centrally so those peripheral the central. So it is conceivable that you will find areas of honeycombing that will be single layer because some people teach that it has to be on top of one another. It's easier if it's on top of one another, but it does not have to be. It represents the advanced end stage lung disease fibrosis and is strongly associated with usual interstitial pneumonitis, which many people call idiopathic pulmonary fibrosis. It's one of the most specific findings for you IP IPF, and that's why it's really important because if you mention it in your report that people are going to assume it's probably you IP and get treatment for that. Even potentially without a biopsy so you want to be careful when looking at it so again look. Are they are right up against blur. Yes, they're heaped up. Yes, there's traction bromgex is a regular visceral plurals peripherally out that's you IP and honeycomb. This one gets a little bit more difficult. Is this honeycombing. Yeah, I think it is. How sure am I. Well, yeah, I'm moderately sure. But you see it's tough. And now from not sure I'm probably not going to come down totally on you IP although that one is you can just tell by the distribution. Okay, what does it look like on the plane film. Well, reticulation and honeycombing looks like little crisscrossing webs of lines, forming these little and size holes. Okay, and that's what you see here again honeycombing. This is cis that are formed these articulations right up against the plurals peripherally. That's honeycombing that's you IP. Okay, and again once you say it. People are going to assume it's you IP. So this patient has fibrosis as well. Right this is cryptogenic organized pneumonia, and you can see the consolidation, but you have that sort of irregular visceral problem. You've got the traction bronchiectasis, and that architectural just is distorted and architectural distortion is a displacement of the normal anatomy of the vessels, and that bronchi, they get distorted and pulled, right is that retraction and you can see that retraction occurring here. And that tells you it's chronic, and that there is evidence of fibrosis or scarring present. Another patient here with sarcoid. It's got that Bronco vascular is lots of nodules but take a look you can see this retraction and architectural distortion here, even on a plane film that tells you that there is stage four sarcoid that yes, there is evidence here of fibrosis. One other very helpful sign of fibrosis or scarring are when the hyalum are pulled up, kind of like old man's pants in Florida right pull up that belt. The highlight get pulled up and not only really kind of occurs in the chronic setting and this patient's got multiple pulmonary nodules, highly retraction scarring, and this in this case was silicosis. So, take a look, is there imaging evidence of fibrosis. Yes, your regular visceral pleura, for sure, reticulations, a little bit of ground glass with some fibrosis, is there also honey combing. You take a look, these look like to write up against the wall. Yeah, I think there's honey combing. What does this patient have, they have usual interstitial pneumonitis or UIP. Is this patient have honey combing because they have reticulation, ground glass, and you see these little kind of cystic areas. But take a close look at them. They are not up against the pleura. They are not up against the pleura. This is not honey combing. This is not honey combing, but it can be easily confused with it. So, these were actually little cysts slash emphysema that were formed. This is honey combing right up against the pleura. Remember, it's got to be against the pleura. So, summary, the five mean morphologic appearances of fibrosis, ground glass opacity, especially with evidence of fibrosis within it. Traction, traction, bronchiectasis pulled apart, honey combing right up against the pleura, and the irregular visceral pleura sign, that little serrated appearance to the pleura. I hope you found that helpful as we move through the chronic ground glass differential. Thanks.