Radiology education
Radiology spotlight
This learning series is intended to help improve the recognition of key imaging features and patterns seen across multiple types of interstitial lung disease (ILD). Each of the short videos will outline how to interpret and report the test results and ensure the appropriate referral pathway for patients.
How to Identify Usual Interstitial Pneumonia/Idiopathic Pulmonary Fibrosis
Michael McInnis:
Hello everyone. My name is Micheal McInnis, and I'm an assistant professor in the Department of Medical Imaging at the University of Toronto. And I'm a thoracic radiologist at the University Health Network.
Over the next few minutes, we will delve into how to identify one of the most common interstitial lung diseases, that is idiopathic pulmonary fibrosis, and how to recognize the characteristic CT pattern of usual interstitial pneumonia associated with that disease.
This program is sponsored by Boehringer Ingelheim for educational purposes, and here are my disclosures. After viewing this video, we would like you to be able to recognize the key imaging features and patterns of usual interstitial pneumonia on CT scans and to understand how to report CT results to ensure appropriate referral of patients.
Idiopathic pulmonary fibrosis, or IPF, is the most common fibrotic interstitial lung disease in Canada, and in fact, there are over 14,000 people estimated to be living with IPF in Canada. IPF is primarily a disease of older men, and many of those have a history of smoking, though it can occur in many patients. It's important for you as a radiologist to be aware of IPF because CT is highly accurate in the diagnosis and really key.
Patients with usual interstitial pneumonia pattern or probable usual interstitial pneumonia pattern on CT can be diagnosed with idiopathic pulmonary fibrosis without further investigation, such as a lung biopsy. Indeed, a UIP or IPF diagnosis is necessary in order for these patients to receive the appropriate treatment and antifibrotic therapy is recommended for patients with IPF. Therefore, you can see that the radiologist plays a key role. If you make a confident diagnosis of IPF or UIP, you can avoid further investigations in the appropriate patient and they can go right to treatment.
Now, let's take a look at a case. This is a 67-year-old man who used to work in construction, and he presented to his primary care provider complaining of shortness of breath on exertion. On physical exam, they found bibasilar crackles, which is a pretty typical finding for pulmonary fibrosis. Therefore, the patient was referred for a CT scan to rule out interstitial lung disease. Now, let's have a look at the CT scan.
Now, I think it's important to note before we get into the fibrosis just some of the technical parameters of a CT scan. When we do a scan for interstitial lung disease, what we do is we perform thin sections, so one millimeter or smaller. We use a lung kernel. You can see how sharp the image is here. And we use contiguous slices, so they're not jumping around. We also perform expiratory imaging and prone imaging, which I don't need to show you in this case but know that we do it. Now, in this CT scan in a patient with IPF or UIP, the lung apices are going to be relatively clear. They may have some emphysema if they're a smoker.
Importantly, as you get to the mid-lung zones, it's very common to start to see the beginning of fibrosis, and here we can see it in the posterior lung and a little bit laterally on the left, in particular, where there's a mild subpleural reticular abnormality. Sometimes it's mild in the mid-lung. And if you're not sure, you can go down towards the bases, and in the basal lung, the reticulation becomes much more evident. I like to look at the costophrenic angles because that's where it's usually easy. Here you can see in both costophrenic angles that there's a diffuse reticular abnormality, and not only is there reticulation, there is traction bronchiectasis.
Have a look here down towards the pleural surface. Have a look here peripherally in the left lower lobe laterally. There are some mildly dilated airways extending to the peripheral lung. Indeed, some of this now is reminiscent of honeycombing. Have a look at the costophrenic angles medially here, anteriorly in the right lung, or in the lingula in the left lung. Now, patients with UIP, or probably UIP pattern of disease, can have some mild ground-glass opacity, and if you look closely, you can see that the fibrotic lung is indeed very mild ground-glass. But more importantly, when you look at the lung that is not fibrotic, you do not see any associated abnormalities, no nodules, no ground-glass capacity, no air trapping.
If you're not sure, a characteristic of IPF is a basal predominant distribution. And here I'm going to show you a coronal reformat. I really like looking at the reformats. And here on the coronal reformat, you can see they have mild fibrosis, and the fibrosis is restricted mostly to the basal lung, and that's a classic feature of UIP or IPF.
We just had a great look at the CT scan, but I want to highlight a few of the key findings for making a diagnosis of IPF or UIP. In panel one, you can see that a key finding is that in the area that is not fibrotic, the lung appears essentially normal. Have a look at the red circle in panel one, and you can see that the lung within appears pretty clear. There are no nodules, consolidation/ground glass, and no evidence of air trapping. Now, patients with UIP or IPF can present with fairly mild disease initially, and in panel two, you can see that the hallmark of IPF or UIP pattern is subpleural reticulation, and that's pretty subtle posteriorly denoted by the red arrows.
In panel three, you can see that when you get into the costophrenic angles, the more classic findings of a UIP pattern, which is basal predominant reticulation, subpleural honeycombing, and traction bronchiectasis, become more evident. And I like to look in the costophrenic angles to make a good diagnosis. Here, you can see the red arrows in panel three point to small areas of honeycombing, but deep in the costophrenic angles, the reticulation is also much more apparent posteriorly.
Now, a key feature of IPF or UIP is the basal predominance, and for this I like to use the coronal or sagittal reformats. In panel one, you can see if you look closely, it's a little small, but at the lung bases in this patient there is a reticular abnormality mostly present in the lower lobes. And if you look towards the lung apices, there's very little abnormality. Now, in all of our patients who present for interstitial lung disease evaluation at baseline, we perform prone imaging. In panel two, you can see how nicely the prone imaging demonstrates subpleural reticulation. It's a mild bronchiectasis, and you even see the honeycombing again in the costophrenic angles there anteriorly.
Which of the following radiologic features is not indicative of usual interstitial pneumonia: mild ground-glass opacities, mid- to upper-lung predominant distribution, honeycombing with or without architectural distortion?
So, in summary, idiopathic pulmonary fibrosis, or IPF, is the most common fibrotic ILD, and you, as a radiologist, will run into it if you're practicing in Canada. A CT is highly accurate in diagnosis of UIP and IPF, so you must be familiar with this. A diagnosis of UIP and IPF is necessary in order for patients to receive appropriate treatment. So, this is really a key place for you as a radiologist to play a role in the diagnosis and management of patients.
I'd like to thank you for your participation. I find that a strong knowledge of interstitial lung disease, and particularly UIP and IPF, is very rewarding because I know if I make a confident diagnosis that I can direct the patient to the appropriate management, and they may get treatment.
The Spectrum of Smoking-Related Interstitial Lung Disease
Michael McInnis:
Hello everyone. My name is Micheal McInnis, and I'm an assistant professor in the Department of Medical Imaging at the University of Toronto, and I'm a thoracic radiologist at the University Health Network. I'm also the radiology QA lead of the University Health Network Lung Cancer Screening Program. Our topic today is indeed smoking-related interstitial lung disease and specifically what to do when fibrotic interstitial lung abnormalities are observed during routine lung cancer screening with low-dose CT. This program is sponsored by Boehringer Ingelheim for educational purposes, and these are my disclosures.
After viewing this video, we would like you to be able to identify imaging features of smoking-related interstitial lung disease, and importantly to recognize fibrosis as an actionable incidental finding in lung cancer screening patients to ensure appropriate referral pathways for the patient.
Now, as you may know, lung cancer screening via low-dose CT is increasingly being performed in Canada and radiologists must be aware of the smoking-related interstitial lung diseases. A couple of these smoking-related interstitial lung diseases are rare, like desquamative interstitial pneumonia or pulmonary Langerhans’ cell histiocytosis. More commonly you'll run into respiratory bronchiolitis. Smoking, importantly, is also a risk factor for the development of idiopathic pulmonary fibrosis. Smokers with idiopathic pulmonary fibrosis, or IPF, may initially present at lung cancer screening, at which point they may be found to have an interstitial lung abnormality or ILA. Now what do these ILAs mean? Interstitial lung abnormalities are frequently found in smokers undergoing lung cancer screening. Some ILAs may mean very little, whereas others may indicate something more serious like a usual interstitial pneumonia or idiopathic pulmonary fibrosis, and patients with this disease require clinical evaluation.
Therefore, radiologists must be aware of concerning interstitial lung abnormalities observed during lung cancer screening by low-dose CT. If you do lung cancer screening out in the community you will run into this and so you need to be aware. Let's take a look at a case. This is a 62-year-old woman, she's retired and she presents to her primary care provider for her annual physical exam. She reveals that she has a 40 pack-year history of smoking, so her primary care provider refers her for a low-dose lung cancer screening CT. That's a pretty typical story. Let's take a moment to look at the CT scan together. Okay, so let's have a look at the CT scan in this lung cancer screening patient. I think the first thing you'll notice is that this patient has emphysema, and this is very common in your lung cancer screening population.
Have a look at the upper lung zones. There is paraseptal emphysema, there is some mild centrilobular emphysema, that's these small lucencies that you're seeing within the lung. Also, you'll find particularly in your active smokers that they have respiratory bronchiolitis. And here this is pretty subtle, but you'll see subtle central ovular ground-glass nodules. Here, we appreciate some in the anterior aspect of the left upper lobe. Both of these findings are not really actionable incidental findings, because they're just so common and signs of having had smoked. Now, more importantly, as we get down towards the lung bases, you can see not only is there emphysema and maybe some respiratory bronchiolitis, but you start to appreciate a reticular abnormality. And what do I mean by that? Have a look at the posterior right lower lobe here at the bottom of the image. You can see that not only is there emphysema, but there also appears to be many little white lines here in the subpleural lung, and these are reticulations.
As we get down towards the lung bases, you can see that the reticular abnormality becomes more striking. Have a look here in the middle lobe laterally, lots of little markings, lots of reticulation. As we get down towards the basal lung, you can start to see that there may even be some bronchiectasis. And what do I mean by that? You can see here in the posterior basal right lower lobe, a couple of dilated airways, the airways are larger than the accompanying vessel. This is traction bronchiectasis. Have a look down here at the costophrenic angles. Not only is there emphysema, not only is there reticulation and bronchiectasis, there may also be some honeycombing. Now this can be difficult to distinguish from emphysema, but I would suspect it's present here as well. In patients with UIP, or probable UIP pattern of pulmonary fibrosis, you can have some ground-glass opacity in the fibrotic lung. There is some here, but if we look at the rest of the lung, I don't see much abnormality.
So, in this kind of patient I would suspect that they have idiopathic pulmonary fibrosis or usual interstitial pneumonia, and this is an important actionable incidental finding in patients with lung cancer screening. You can take a look at the multiplanar reformats here on the sagittal image. You can really see that the fibrosis likes to organize around the costophrenic angles. That'll help you make a diagnosis. In patients where I suspect that they may have idiopathic pulmonary fibrosis or a UIP pattern of disease, not only do I mention the emphysema and respiratory bronchiolitis and the lung cancer screening findings in the report, but I also make sure to highlight that the patient has pulmonary fibrosis. I suggest that they get pulmonary function testing and referral to a specialist for further diagnostic evaluation and management.
Here you play a key role as a radiologist. We just had a great look at the CT scan, but there are a few findings I want to highlight for you. In the top two panels of this slide you can see that there are subtle central ovular ground-glass nodules in the left upper lobe in this patient with history of smoking. This is respiratory bronchiolitis and it's a very common finding in smokers, and is usually not an actionable incidental finding, you'll see it all the time. More importantly though, in the right mid-lung, and these are the bottom two images of the slide, if you look closely at an area of emphysema, you can see that there may be a mild reticular abnormality within. This should have you thinking about the possibility of an interstitial lung abnormality, something more concerning. Indeed, if you do find some reticulation, what I like to do is go down to the lung bases. And you can see in panel one, deep in the costophrenic angle, there are several red arrows pointing to areas of subpleural reticulation in addition to perhaps some very mild bronchiectasis and not much ground-glass opacity.
In panel two, you know that I like to look at coronal or multiplanar reformats. Here's a sagittal image. The red arrow points to the posterior costophrenic angle, and you can see that they're actually fairly extensive reticulation. And this is a patient with a more concerning interstitial lung abnormality, and at this point it's consistent with a probable usual interstitial pneumonia pattern of interstitial lung disease. Now, if you're not comfortable with all these findings of interstitial lung disease you can scan the QR code on the screen, which will take you to the Boehringer Imaging Atlas, and that illustrates more examples of ILD.
In summary, smoking-related interstitial lung disease encompasses several disorders which can coexist in patients. Many of these are rare, but some of them are quite common. Indeed, interstitial lung abnormalities are frequently found in smokers undergoing lung cancer screening, so you'll run into this in your practice. Most importantly though, is that some interstitial lung abnormalities could indicate usual interstitial pneumonia like we saw here, or idiopathic pulmonary fibrosis. In patients where I suspect that they may have UIP or IPF, I recommend to the referring provider that the patient gets pulmonary function tests and referral to a subspecialist so they can get a further diagnostic evaluation. Here you're going to play a key role as a radiologist reading lung cancer screening, and you'll run into this all the time.
I'd like to thank you for your participation in this activity, and I hope you're more confident identifying interstitial lung abnormalities on your lung cancer screening CT after having reviewed this presentation.
Zooming In on Fibrotic Hypersensitivity Pneumonitis
What Are the Key Features of Non-Specific Interstitial Pneumonia?
Jessie Kang:
Hello, everyone. My name is Jessie Kang. I'm a cardiothoracic radiologist at Nova Scotia Health and assistant professor at Dalhousie University. This program is sponsored by Boehringer Ingelheim. These slides are for educational purposes only, and these are my disclosures. Today, we'll be zooming in on hypersensitivity pneumonitis, or HP as I'll refer to it in this presentation, which is a type of interstitial lung disease resulting in an immune-mediated [00:00:30] response. And we'll focus in particular on fibrotic HP.
And after viewing this video, we'd like you to be able to recognize the key imaging features and patterns of fibrotic HP on high-resolution CT scans and understand how to report high-resolution CT results and ensure the appropriate referral of patients.
[00:01:00] So what is hypersensitivity pneumonitis? It is an interstitial lung disease resulting from an immune-mediated response. It occurs in individuals susceptible and sensitized to inhaled antigens, which can be organic, so for example bacterial or fungal, or inorganic, such as low molecular weight chemicals or metals. Serum antibody tests against antigens associated with HP can be performed to detect potential inciting agents [00:01:30] and identifying and removing an inciting agent is normally associated with improved survival for patients.
So here we have a typical case. Lawrence is a 52-year-old male. He lives alone. He presents to his primary care provider complaining of dry cough, which has been getting worse for the past 6 months. He has some weakness and some recent weight loss as well. He's been experiencing some shortness of breath which started when he installed a humidifier in his home, and his physical exam reveals an oxygen saturation of 95% [00:02:00] and bilateral crackles on auscultation. He's been sent for laboratory tests and referred to radiology for a high-resolution CT chest scan.
So, let's take a look at this, his CT chest, and see what imaging findings we may see in this case of fibrotic HP. So, this is a high-resolution CT chest with inspiratory and expiratory views. First and foremost, it's nice to confirm that this is a true expiratory view, as you have the bowing of the trachea here, as you can see at the posterior aspect, [00:02:30] to confirm that this is a true expiratory view. It's a common mistake that learners and residents make by saying that there's no air trapping on expiratory view, but the patient's not even in expiration for a variety of reasons. But here, in this case, we have a true expiratory view.
So in the inspiratory view, you can see that there is background mosaic attenuation of the lungs, with areas of ground-glass opacities, so scattered ground-glass opacities are increased areas of white here on, seen on CT. And there are more lucent [00:03:00] areas as well, for example here. As you get to the lower lobes, you can see more lucent areas that are sharply, uh, demarcated. And if you go to the expiratory view, these remain lucent, confirming areas of air trapping. And you can also see these tiny centrilobular nodules in the upper lobes, which will be pointed out with discrete images later on in the presentation.
And although this is not a dominant feature in this patient, there's evidence of fibrosis here with traction bronchiectasis, particularly in the lingula, [00:03:30] and you can see beading of the bronchi here. It's irregular and beaded in appearance, compatible with fibrosis, so we have irreversible fibrosis in this case, and this is seen to a lesser extent within the right upper lobe as well. There's irregularity of the bronchi. And there's evidence of traction bronchiectasis and bronchiolectasis, and there's some other evidence of fibrosis with subpleural reticulations in the left upper lobe and some mild architectural distortion here as well.
And looking at the overall distribution, this process is upper lung zone-predominant, however [00:04:00] affects all lobes with relative sparing of the lower lobes. And the best way to view this is on the sagittal view, where you can see nicely the sparing of the costophrenic angle and the increased involvement of the upper lobes compared to the lower lobes. And again, there's involvement of all lobes in this case.
So, this imaging finding, or this imaging pattern, is typical for HP. We have ATS criteria from 2020 that should be followed, which will be discussed later on in the presentation. So, the terms [00:04:30] chronic, subacute, or acute HP are outdated terms which we shouldn't be using anymore. So, the distribution of fibrosis relatively spares the lower lobes and the HR CT abnormalities indicate small airways disease, and in this case we have both the ill-defined centrilobular nodules in the upper lobes, the ground-glass opacities, and the mosaic attenuation/air trapping. So, this meets the criteria for typical HP. Please refer to the table on the ATS criteria for this. The other categories [00:05:00] are compatible with HP, indeterminate for HP, but the typical HP pattern is a classic pattern we expect to see with fibrotic HP.
So my impression for this case is that there is a diffuse interstitial process with ground-glass opacities, ill-defined centrilobular nodules, scattered areas of air trapping with relative sparing of the lower lobes, and there is evidence of mild fibrosis with traction bronchiectasis, bronchiolectasis, and subpleural reticulations. And overall, imaging findings are typical for fibrotic HP. [00:05:30] Correlation with any potential exposures, medication history, or connective tissue disorders is recommended, as well as a respirology referral.
So, patients with HP often present with nonspecific symptoms, such as cough, dyspnea, and less commonly, constitutional symptoms, and this highlights the importance of, um, diagnosis via routine CT chests. So you don't need a high-resolution CT chest to diagnose fibrotic HP, although it's helpful for confirmation to have the expiratory view, for example. [00:06:00] If you see imaging findings of mosaic attenuation, upper lung zone-predominance, and relative sparing of the lower lung zones, as well as findings indicative of small airways disease, then you can raise the possibility of fibrotic HP, and the radiologist may be the first physician to diagnose or raise the possibility of HP in a patient so they can get further workup. Thank you for participating in this activity [00:06:30] and watching this video.
Jessie Kang:
Hello, everyone. My name is Jessie Kang. I'm a cardiothoracic radiologist at Nova Scotia Health and an assistant professor at Dalhousie University. This program is being sponsored by Boehringer Ingelheim. These slides are for educational purposes only, and these are my disclosures. Today, our topic is non-specific interstitial pneumonia, as I'll refer to in this presentation as NSIP: What it is, what features it shares with [00:00:30] other types of interstitial lung disease, and how to correctly identify it. After viewing this video, we would like you to be able to recognize the key imaging features and patterns of NSIP on CT scans, understand how to report CT results, and ensure the appropriate referral of patients.
Interstitial lung disease, or ILD, is a group of disorders [00:01:00] affecting the interstitium of the lung. These are characterized by increased inflammation, edema, and/or fibrosis. It is important to note that the fibrosis is not a requisite for ILD, so you don't need to have fibrosis to have interstitial lung disease. You can have an inflammatory process resulting in interstitial lung disease. Some conditions are acute while others are chronic, and NSIP is one of the most common types of interstitial lung disease. These are some details about non-specific interstitial pneumonia.
[00:01:30] So patients with NSIP tend to be younger, with an average age of 40 to 50 years old, than patients with idiopathic pulmonary fibrosis or UIP pattern. NSIP also shows a slight female predominance, and NSIP can be non-fibrotic or cellular NSIP, or fibrotic. These two types represent different stages of the disease. NSIP occurs more commonly in association with other conditions, such as connective tissue disorders, and other potential causes include [00:02:00] drug toxicity, infection, and hypersensitivity pneumonitis.
Let's go over a typical patient case of NSIP. So, this is Emma. She's a 49-year-old teacher. She presents to her primary care physician for her annual physical exam. She mentions experiencing some joint pain, trouble swallowing, and palpitations. She's referred to a rheumatologist, who performs a physical exam and requests an antinuclear antibody test. Emma is diagnosed with systemic sclerosis and is referred to a radiologist and a pulmonologist [00:02:30] to assess for any potential lung involvement.
So let's take a look at her CT and see what imaging findings are typical for NSIP. So right off the bat for this patient, we have a younger female. She is 49 years old with a history of systemic sclerosis. So even without looking at the images and even without a history of systemic sclerosis, we should be considering this patient demographic and be thinking of NSIP. So here, we have a high-resolution CT chest and with inspiratory and supine [00:03:00] images and prone images as well. And you can tell this is prone because the table is down here and the patient's back is facing forward. Expiratory views were not included as they are not routinely done at our institution. We review the patient's history and chest radiograph and any prior imaging before coding high-resolution CT studies, and some other institutions would do an HRCT, inspiratory, prone, supine, as well as expiratory for all their ILD cases. This is institution specific.
[00:03:30] So here we can see the main abnormalities are ground-glass opacities. The distribution is definitely lower lung zone predominant, but we can be more specific than that and say that the ground-glass opacities are also peribronchovascular in distribution. And not only are they lower lung zone predominant, but you can see that the ground-glass opacities surround the bronchia and the vascular, the vasculature as well, so peribronchovascular. This is quite symmetric. You can see that there's relative sharp demarcation of normal and [00:04:00] abnormal lung here. For example, here on the coronal view, you can see that there are areas of ground-glass opacities and right adjacent to it are areas of normal aerated lung.
There's evidence of fibrosis here as well, with traction bronchiectasis, bronchiolectasis. Initially, when you look at them, you might see that these are, you might say that these are cystic changes, but if you follow them along on the CT, these are actually bronchi that are distorted and dilated secondary to fibrosis. [00:04:30] There are areas of relative subpleural sparing. This is best seen on the sagittal view. You can see that there is relative clearing here. For example, there's a sliver of lung here adjacent to the ground-glass opacity that's spared. So, this is called subpleural sparing, which is important for this diagnosis. You can see that on the sagittal view, there's involvement of the costophrenic angle, which is a useful view to look at the distribution of these imaging findings. In this case, the prone view does not add any diagnostic value.
[00:05:00] We don't need the prone view to diagnose this case or to classify this case, because we know that the ground-glass opacities are real and not secondary to the atelectasis. However, if you suspect some of these ground-glass opacities are areas of atelectasis, you can confirm that with a prone view. In terms of the other findings of fibrotic ILD, there's no honeycombing here, no diffuse centrilobular nodules, and no background mosaic attenuation. And looking at the esophagus and the soft tissue windows, it's not dilated. It appears normal. And this [00:05:30] is a good feature to check for, to support the lung findings and the overall diagnosis of NSIP, and overall, the imaging findings are compatible with fibrotic NSIP. So, my impression for this case is that there are lower lung zone predominant ground-glass opacities that are peribronchovascular in distribution, associated with areas of fibrosis with traction bronchiectasis and bronchiolectasis, with few areas of subpleural sparing.
Overall, findings are compatible with mild fibrotic NSIP, particularly given the patient's demographics and history of systemic sclerosis. [00:06:00] I would not give another differential here. A respirology referral is recommended if not already done in this case. These are key radiologic features of NSIP. In the image on the left, there is evidence of fibrosis with traction bronchiectasis and bronchiolectasis. In the image on the right, peribronchovascular lower lung zone-predominant ground-glass opacities. The radiologic features of NSIP include honeycombing, although it is uncommon. If this is present or a predominant feature, then UIP should be considered over NSIP. [00:06:30] There can be some overlap, uh, uh, but it's not a hard rule. Subpleural sparing is specific to NSIP, and when seen, strongly suggests a diagnosis. And traction bronchiectasis and ground-glass opacities are more peribronchovascular compared to UIP.
To summarize fibrotic NSIP, the clinical context should be [00:07:00] considered when making the diagnosis. A younger woman in her 40s or 50s with a history of connective tissue disease makes NSIP more likely, even though UIP is more common overall. Patient demographics are important. Differentiating, differentiating between fibrotic NSIP and UIP can be difficult, but key features help. Subpleural sparing, minimal or absent honeycombing, and peribronchovascular fibrosis suggest NSIP over UIP. If a history of connective tissue [00:07:30] disease is known, a radiologist can check for ancillary imaging findings, such as a dilated esophagus and scleroderma, which increases the diagnostic certainly for NSIP versus UIP or even HP. Thank you for participating in this activity on fibrotic NSIP.
Questions? Contact the presenter
Screening & Diagnosis: Identifying ILD
[Dr. Cameron Hague]
[Clinical Assistant Professor of Radiology at UBC]
[Dr. Hague] Radiologists, rheumatologists and respirologists all have an important role to play in the diagnosis and management
of patients with fibrotic interstitial lung diseases, also known as fibrotic ILDs.
The obvious first step for every patient is a diagnosis, but with so many different types of
fibrotic ILDs, determining a diagnosis isn't always an easy task.
And while an appropriate diagnosis impacts the immediate course of action,
it also has serious implications for the patient as their condition progresses.
This video will take you through key building blocks for diagnosing fibrotic ILDs and 6
steps for reading HRCTs, ensuring ILD patients get started on the best path for their condition.
After you finish watching the video, you can test what you've learned with the patient case studies also found on this page.
So let's get started.
[Lung Injury Patterns]
[Basic Building Blocks of Lung Injury]
[Dr. Hague] The lung has a limited number of responses to injury.
These seven patterns of injury or “building blocks” are key to the interpretation of
high-resolution computed tomography, abbreviated as HRCT, in the evaluation of fibrotic lung disease.
You are likely familiar with these building block terms from the Fleischner Society Glossary of Terms for Thoracic Imaging,
and they are: Honeycombing, Reticular pattern, Ground glass, Consolidation, Cyst, Micronodule and Heterogenous Lung Attenuation Patterns.
We're going to break down how to identify each of these building blocks and establish their role in the diagnosis of fibrotic interstitial lung disease.
[Building Block 1]
[Honeycombing]
Our first building block is honeycombing and a key step for identifying fibrotic lung disease.
The American Thoracic Society 2018 guideline on idiopathic pulmonary fibrosis, or IPF, defines honeycombing as seen on HRCT as two or more adjacent subpleural cystic air spaces.
In terms of size, each honeycombed cyst could span between 3 and 10 millimetres in diameter,
have walls between 1 and 3 millimetres thick, and are usually located in the subpleural region of the lung.
However, even among experts, the presence or absence of honeycombing can be very challenging to interpret.
Disagreement commonly occurs in the presence of subpleural pathology mimicking honeycombing, such as traction bronchiolectasis or subpleural cysts.
I would err on the side of caution when determining the presence or absence of honeycombing in any given case.
In particular, if you observe paraseptal emphysema, be cautious about your certainty
about the presence or absence of honeycombing.
[Building Block 2]
[Reticular pattern]
Our second building block is reticulation;
it is an essential finding to check for when determining whether you are looking at pulmonary fibrosis or not.
Reticulation is defined by small, linear opacities that represent thickened intralobular or interlobular septa,
which produce an appearance that resembles a net.
It is important to separate the small linear opacities of reticulation from interlobular septal thickening related to
non-fibrotic etiologies such as pulmonary edema and lymphangitic carcinomatosis.
Searching for traction bronchiectasis within areas of intra and interlobular septal thickening can increase
specificity for your determination of reticulation.
Traction bronchiectasis or bronchiolectasis can be defined by irregular bronchial and bronchiolar dilation caused by surrounding retractile pulmonary fibrosis.
To identify traction bronchiectasis, look for sharp, linear lines that are causing fibrotic change adjacent to airways
larger than their associated artery, or too close to a pleural surface, less than 1 centimetre.
Students of HRCT interpretation often ask: How do you separate cases of primary bronchiectasis related
to airway abnormality from cases of traction bronchiectasis and fibrotic lung disease?
Primary airway pathologies such as cystic fibrosis, or Williams-Cambpell will generally have normal appearing interstitium adjacent to bronchiectatic airways.
Take this case of cystic fibrosis as an example: While bronchiectasis is present,
note how the interstitium adjacent to areas of traction bronchiectasis are normal, i.e. no reticulation is present adjacent to the airways.
Remember to look for sharp linear lines adjacent to airways to ensure what you're looking at is traction bronchiectasis.
You can see in this example that the airways appear distorted or pulled apart, and the adjacent interstitium is abnormal.
The secondary pulmonary lobule is a helpful landmark when investigating traction bronchiectasis.
In this illustration of a healthy lobule, you have the artery and airway in the middle,
then the interlobular septa, and veins at all the corners of the polyhedron.
Distortion of the secondary pulmonary lobule is key to ensuring the case is fibrotic.
With fibrosis, the airways get pulled closer to the periphery of the secondary pulmonary lobule and they may dilate.
Through imaging, we see this as traction bronchiectasis.
The result is that the dilated airways appear larger than the adjacent artery.
In this example, we can compare and contrast reticulation with traction bronchiectasis from interlobular septal thickening related to pulmonary edema.
[Building Block 3]
[Ground glass]
The appearance of ground glass is the third building block that aids in our interpretation of interstitial lung disease.
To label ground glass, we'll need to recognize an increased lung attenuation pattern.
Increased lung attenuation patterns develop with an increase in the density of lung parenchyma.
The interstitial lung tissues, walls of the alveoli, small airways, and capillaries
contribute to the density as they can increase in both size and by amount.
In HRCT images, pure ground-glass can be visualized as homogeneous haziness of the lung,
in which the vascular and bronchial components are preserved and still clearly seen separately from the increased attenuation when viewed on HRCT
lung windows, and there are no solid components.
It is important to distinguish pure ground glass from ground glass associated with fibrosis.
Pure ground glass opacification is not a typical feature of fibrosis, although it can be associated with numerous fibrotic entities, most commonly in fibrotic HP and NSIP.
Patients with fibrotic lung disease may have the appearance of ground glass opacification that is superimposed on a fine reticular pattern, which represents fibrosis.
As you'll remember, the presence of traction bronchiectasis or
bronchiolectasis is another distinguishing feature of fibrosis.
This image is ground glass associated with fibrosis. It is not considered “pure” ground glass.
Upon observation, you'll note that within the areas of ground glass there is also fine reticulation,
and importantly traction bronchiectasis.
In conjunction with other features of fibrosis such as a coarse reticular pattern and traction bronchiectasis or bronchiolectasis,
notice how the ground glass opacification may take on somewhat of a granular appearance.
There is a caveat to the presence of extensive ground glass in acute exacerbation of interstitial lung disease.
Occasionally, extensive ground glass opacification associated with fibrotic lung disease can represent a superimposed acute process
of viral pneumonitis, pulmonary oedema or, an acute exacerbation of underlying fibrotic lung disease.
The importance of recognizing this in the setting of making a specific fibrotic lung disease diagnosis is discussed in the 6-steps section.
[Watch the 6 Steps video]
[For more information on ground glass and acute exacerbations, click the links below.]
[Acute Exacerbation of Idiopathic Pulmonary Fibrosis]
[Acute Exacerbations of Progressive Fibrosing Interstitial Lung Diseases]
[Building Block 4]
[Consolidation]
Moving on to building block four, we have arrived at consolidation.
Consolidation occurs when the alveolar space has been replaced with something else such as fluid, blood, pus or cells,
rather than the gas, creating a solid appearance on HRCT.
Consolidation appears as a homogenous attenuation that obscures the lung parenchyma,
such as the vessels and airway walls, as viewed on HRCT lung windows.
This image clearly shows the presence of subpleural, peribronchovascular, and perilobular consolidation in a patient with underlying organizing pneumonia.
Note that the “atoll sign” is also present in the anterior segment of the right lower lobe.
Atoll sign demonstrates perilobular consolidation with central, pure ground glass.
[Building Block 5]
[Cysts]
Fifth on our list of building blocks are cysts.
You may be familiar with identifying them as a round space surrounded by an epithelial or fibrous wall,
which have thin, sometimes almost imperceptible margins.
The thinness of the wall is what helps distinguish a cyst from a cavity.
This image clearly shows the presence of cysts in a patient with lymphangioleiomyomatosis.
Notice the normal intervening lung parenchyma.
[Building Block 6]
[Nodules]
We have reached nodules, the sixth building block feature.
Nodules in fibrotic lung disease are not the same nodules that clinicians monitor when concerned about malignancy risk,
but rather relate to an injury patten due to an underlying lung disease that can be seen in a setting
of hypersensitivity pneumonitis, sarcoidosis, or respiratory bronchiolitis.
In this case of sarcoidosis, the nodules are well-defined and are perilymphatic in location.
The nodules are often found along bronchovascular bundles (thin blue arrow) or fissures.
An alternative appearance of nodules associated with fibrotic lung disease is the nodules seen with HP.
Nodules related to HP are poorly defined, usually centrilobular, almost ground glass in appearance
and are generally less than 3 millimetres in size.
[Building Block 7]
[Heterogenous lung attenuation patterns]
We've reached our seventh and final HRCT pattern: heterogenous lung attenuation.
This umbrella term refers to ground glass which we have addressed previously,
as well as mosaic attenuation, mosaic perfusion, and lobular gas trapping.
[Watch the Ground Glass Building Block video]
The first pattern is mosaic attenuation and this is defined as areas of two or more different attenuation on inspiratory CT.
Generally, this presents itself as a region of lung that looks like ground glass and an adjacent section
of lung that looks comparatively more lucent.
On inspiratory imaging, the first step with a mosaic attenuation is to ask yourself:
“Which is the abnormal lung?
Is it the ground glass lung or the more lucent lung?”
To answer these questions, consider the size of the vessels in the areas that look like ground glass
and the more lucent lung.
If the vessels are the same size then you are dealing with true ground glass which we discussed in more detail previously.
[Watch the Ground Glass Building Block video]
If the vessels are smaller in the more lucent lung, you are looking at mosaic perfusion.
Mosaic perfusion occurs when the vessels are too small related to a primary vascular abnormality (such as chronic PE) or
when the vessels are too small secondary to reflex vasoconstriction driven by a primary airway pathology such as asthma, or bronchiolitis obliterans.
Let's move on and take a look at a third heterogenous lung attenuation term with another scan.
This is known as the three-density pattern. This pattern was previously referred to as the “head-cheese sign.”
Unlike pure mosaic perfusion, this pattern is a combination of normal-appearing, high attenuation (such as ground-glass opacity), and lucent lung.
The term three-density pattern comes from the presence of three different lung densities that are sharply demarcated from each other.
In this case of hypersensitivity pneumonitis, a three-density pattern is demonstrated.
It shows ground glass lung, lucent lung (make note of the reduction in the size of vessels in this lucent region compared
to both the ground glass and normal lung), as well as normal lung.
This is a pattern described on inspiratory HRCT. It is not a pattern or finding that requires expiratory imaging.
We'll move on to the fourth term for heterogenous lung attenuation, which is known as air trapping.
Air trapping can be recognized when you see lucent parenchymal areas that lack the normal increase in attenuation
and the volume of reduction compared to normally ventilated lung on expiratory imaging.
Air trapping is not synonymous and not intended to be a term used interchangeably with mosaic attenuation.
Air trapping is a feature that can only be described when viewing expiratory imaging.
Check to see if the posterior wall of the trachea has bowed forward to ensure that your patient has performed expiration appropriately.
This building block is tricky! Differentiating between the patterns of heterogenous lung attenuation
will help you categorize the pattern of lung injury during evaluation of many HRCT scans.
In addition to recognizing the building block features that indicate lung injury patterns,
we should also be aware of their distribution on HRCT.
We've already talked about honeycombing usually being present in a subpleural distribution.
We'll see in the 6-steps section that recognizing a subpleural and basal distribution pattern
will be critical to identifying a UIP pattern on HRCT.
[Watch the 6 Steps video]
Looking for upper-or-mid-lung, note the relative basal sparing denoted by the blue circles in this image,
as well as a peribronchovascular distribution is also important, such as in this case of fibrotic HP.
Highlighted in this image are the three different distribution patterns.
As a reminder, the distribution of HRCT features is not an “all or none" situation
There is some subjectivity and nuance to determining if the feature is predominant in a given region.
In this patient with fibrotic HP, note that the fibrosis and associated traction bronchiectasis extend along bronchovascular structures in the left upper lobe.
In this scan of a patient with fibrotic HP, you'll notice the peribronchovascular distribution of fibrosis in the left lower lobe.
In this video we've reviewed the building blocks and distribution patterns of lung injury.
Now we must be able to accurately assess these building blocks on a HRCT scan
and identify the distribution within the lung to diagnose the pattern of lung injury.
We'll explore how to do this in the 6 steps video: “Imaging of Fibrotic Interstitial Lung Disease”
[Click here to watch the 6 Steps video]
[Imaging of Fibrotic Interstitial Lung Disease]
[Learn how to read HRCTs from a Canadian Chest Radiologist]
As you know, HRCT can be difficult to interpret.
These 6 steps provide an easy-to-navigate road map that will increase your chances of correctly identifying the fibrotic lung pattern on an HRCT scan.
[Step 1]
[Boost your odds!]
When I approach a case, the first thing I do to boost my odds of correctly identifying the HRCT pattern is to look at patient
demographics, disease factors and exposure history before evaluating the images.
A selection of patient demographics to consider are age, sex, family history of fibrosis, and smoking history.
Let's walk through how these patient demographics can inform your interpretation of the HRCT pattern.
Knowing the patient's sex and age can be useful.
For example, the likelihood of presenting with a UIP pattern is higher in male patients that are 60 and over.
On the other hand, in younger female patients, typically 45 and under pre-test likelihood argues against UIP.
UIP related to idiopathic pulmonary fibrosis, or IPF, is uncommon in this population, and for that reason, I start to consider NSIP or fibrotic HP as being more likely.
Another risk factor for IPF is a family history of ILD. IPF patients can have biological family members that also present with the disease.
In addition to sex, age and family history, smoking history can be very helpful in setting your pre-test likelihood.
UIP tends to be very uncommon in women who don't smoke or don't have smoke exposure.
Let's look at a quick case history to apply what we've learned so far!
If you have a 65-year-old male smoker, your pre-test likelihood of a UIP pattern should be very high.
You should recognize that since he is over 60 and a smoker, the likelihood of finding a UIP pattern increases.
Being male is another factor that leans towards UIP, but it is not as decisive as age and smoking status.
Underlying disease is also an important factor to consider.
Specifically, looking for connective tissue diseases, like scleroderma, by reviewing your patient's history and checking serologic test results.
The NSIP pattern is more common in patients with an underlying CTD.
An exception is rheumatoid arthritis, where a UIP pattern is more common in this population.
Also, current medication should be considered.
NSIP can be a secondary manifestation of a drug reaction.
It is important to note that NSIP can still be present on HRCT outside of these circumstances, but idiopathic NSIP is felt to be uncommon.
Putting these concepts together, if you have a case with a 60-year-old woman with known scleroderma, the most likely pattern to consider is NSIP.
We should also consider the importance of exposure history.
A frequent or prolonged exposure to common antigens related to HP can be helpful.
However, we should also be aware that up to 60% of cases of HP have no antigen or exposure identified
even after a thorough background search for possible exposures.
For example, let's consider a 63-year-old male farmer who has worked in a hay field for multiple decades.
His daily antigen exposure increases the likelihood of a fibrotic HP pattern, despite his age and sex.
In short, reviewing patient demographics, disease factors and exposure history can help provide an idea of what pattern
you might see when you examine the HRCT scan.
[Step 2]
[Ensure fibrotic lung disease is present]
Once you boost your odds, take a look at the HRCT scan itself to be certain that you are dealing with a case of fibrotic lung disease.
Start by looking for reticulation associated with traction bronchiectasis or bronchiolectasis;
it is the easiest thing to look for when determining whether you are dealing with a case of pulmonary fibrosis or not.
[Watch the Reticular Pattern Building Block video]
Remember that reticulation is defined as small linear areas of thickened intra and interlobular septa.
Without identification of associated traction bronchiectasis in these areas,
you may run the risk of over diagnosing pulmonary fibrosis on HRCT.
[Step 3]
[Assess for features of typical UIP pattern]
In step 1, we gained an idea of what pattern we might see on the HRCT.
Now we'll examine the scan to see if we were correct!
Always use UIP as the default pattern since it is the most common fibrotic interstitial lung pattern.
When considering a UIP pattern, the hallmark pattern of IPF, it is important to know the current terminology used
in the imaging diagnosis of IPF, and that is: Typical UIP, probable UIP, indeterminate for UIP, and an alternative diagnosis is more likely.
In this step, we are considering whether a typical UIP pattern is present or not.
By definition, a typical UIP pattern must have:
Reticulation and honeycombing.
[Watch the Reticular Pattern Building Block Video]
[Watch the Honeycombing Building Block Video]
In addition, the reticulation and honeycombing must be positioned predominantly in the subpleural and basal lungs.
It may help to recall our building blocks.
Next, we look for features that must be absent in a typical UIP pattern, like extensive pure ground glass.
[Watch the Ground Glass Building Block video]
The caveat to this rule is the presence of extensive ground glass in the setting of acute exacerbation of underlying ILD, where that may be exactly what you see.
For this reason, I would not apply these guidelines for an imaging diagnosis of a UIP pattern in an acutely unwell patient.
In such a scenario my impression includes the diagnosis of pulmonary fibrosis, but not a specific pattern, and I suggest follow-up
to better characterize the patient's lung injury when they are appropriately treated, and their clinical condition has stabilized.
Other features that will be absent from typical UIP are diffuse nodules and cysts.
[Watch the Nodules Building Block video]
[Watch the Cysts Building Block video]
We also have to ensure that mosaic attenuation and sharply defined lobular air trapping are absent.
[Watch the Nodules Building Block video]
[Watch the Cysts Building Block video]
[Watch the Heterogenous Lung Attenuation Patterns Building Block Video]
It's important to note that we're specifically looking to exclude lobular air trapping on expiratory imaging.
This is because the fibrotic HP guidelines include lobular gas trapping as a feature of small airways disease
that is a part of the diagnostic criteria for typical or compatible with fibrotic HP patterns.
You may not be able to reliably separate UIP from fibrotic HP without expiratory imaging.
Take note that you only need to perform expiratory imaging when initially trying to identify the fibrotic pattern;
it is not necessary after a diagnosis is established and follow-up scans are being performed to identify disease progression.
[Watch the Heterogenous Lung Attenutation Patterns Building Block video]
Also, if the predominant lung injury pattern is consolidation, this would not be consistent with UIP.
And finally, if the fibrosis is distributed in an upper or mid lung zone predominance and/or
a peribronchovascular predominance, it is not a typical UIP pattern.
To conclude, determining if typical UIP is present requires certain building blocks and distribution patterns to be present and for others to be absent.
[Step 4]
[Assess for features consistent with probable UIP pattern]
The next step is to see if this case could be a probable UIP pattern.
Is honeycombing present? The first step is to ensure there is no honeycombing.
In this example, you don't see any honeycombing on the provided image.
It's important not to stop here though, since the absence of honeycombing does not confirm or exclude a probable UIP pattern.
Similar to typical UIP − in probable UIP, you must also have reticulation in a subpleural,
basal predominant distribution, and the absence of certain building block features, as listed here.
[Step 5]
[Consider an alternative diagnosis]
If any one or more of the 7 building blocks or distribution patterns listed here are present and are deemed an extensive
feature on the scan, we must consider an alternative diagnosis regardless of whether honeycombing is present or not.
In my mind, I consider the alternative diagnosis category not as “I don't think this is UIP”, but moreso as “I really think this is a case of NSIP or fibrotic HP”.
NSIP most frequently appears as basal predominant ground-glass opacities with reticulation,
traction bronchiectasis, or bronchiolectasis, and minimal or no honeycombing.
[Watch the Ground Glass Building Block video]
[Watch the Honeycombing Building Block video]
A key indicator to help you determine a NSIP pattern is the presence of basal predominant fibrosis with subpleural sparing.
Note that while a very useful finding, subpleural sparing is only seen in 1/3 of NSIP cases.
So, the absence of this finding does not allow exclusion of NSIP, but its presence is a very useful differentiator between UIP and NSIP.
Recall, NSIP may be seen in the setting of connective tissue disease and/or drug-induced lung injury, and it is rarely observed as an idiopathic entity.
Let's take a closer look at another NSIP case.
[Watch the Ground Glass Building Block video]
In this HRCT scan, we see that the ground glass with reticulation is basally predominant.
We can also see there is relative subpleural sparing.
Again, this is a case of NSIP.
Now let's look at fibrotic HP.
Fibrotic HP can be divided into three categories based on imaging findings: typical, compatible and indeterminate.
While the distribution of fibrosis is important when making an imaging diagnosis of fHP it is really
the features of small airways disease which allow separation of UIP from fHP by current guidelines.
In order to be considered typical or compatible with fibrotic HP by the 2020 ATS guidelines, one or more features of small airways disease must be present.
These small airways features are ill-defined, centrilobular nodules and/or ground glass opacities, mosaic attenuation, three-density pattern, and air trapping, which is often in a lobular distribution.
At this point we've considered typical and probable UIP, as well as the alternative diagnosis with NSIP and fibrotic HP patterns.
But what if we still have no clear indication of the pattern on HRCT?
[Step 6]
[Determine if HRCT pattern is indeterminate for UIP]
If you have completed the first 5 steps and are saying to yourself, “I still have no idea what this is!” or the burden of fibrosis is minimal
and it is hard to determine the exact pattern, it's time to consider that you may be looking at an indeterminate pattern.
Although it isn't well-defined in the literature, you should consider an indeterminate pattern when the distribution of fibrosis is variable or diffuse.
I would describe it as not basal predominant.
We also consider an indeterminate pattern when one or more of the 7 building blocks
or distribution patterns that help to exclude typical or probable UIP are present, but the extent of these features is minor or inconspicuous.
[Watch the Building Blocks video to learn more]
Indeterminate patterns also come up when fibrosis is present, but the burden is minimal.
An example is when the HRCT pattern seems to be consistent with probable UIP, but the fibrosis burden is minimal.
If you diagnosed the HRCT as probable UIP, you may have labelled the patient with a very poor prognosis without sufficient evidence that this is indeed probable UIP.
Follow-up can be very helpful in such cases.
If you hit an impasse, consider reaching out to your colleagues for a multi-disciplinary discussion
to support your diagnostic decision making with indeterminate patterns.
Diagnosing based on HRCT imaging can be very challenging, so it is crucial to use the
building blocks and follow these 6 steps to arrive at a most favoured diagnosis.
[Watch the Building Blocks video to learn more]
[Check your understanding with these interactive case studies]
[Darlene]
[Mark]
[Helen]
[Chris]
[Darlene, 72] [Helen, 68] [Mark, 50] [Chris, 48]
[Click a selection to watch]
[ILD]
[CASE STUDY 1] [ Meet Darlene]
After reviewing the Building Blocks and 6-step sections, let’s put your knowledge to the test with Darlene’s case.
Darlene is a 72-year-old grandmother.
She can’t pinpoint exactly when it started, but she’s had a consistent cough for a while now.
Her GP thought it was COPD, but after trials with different inhalers, her cough persisted.
She was referred to a respirologist to further investigate the cause of her cough.
A family history of pulmonary fibrosis was discovered by the respirologist, leading them to suspect ILD, so an HRCT was ordered.
[Step 1] [Boost your odds]
Before looking at Darlene’s HRCT, you can make an educated guess about what you might find by looking on her requisition form.
Consider that Darlene is 72 years of age, a smoker and has a family history of pulmonary fibrosis.
Her serological work-up was negative and she has no known exposures.
Based on what you know about Darlene, which diagram shows the most likely HRCT pattern classification you will find on her scans?
[Choose one:
a) UIP is more likely
b) fHP is more likely
c) NSIP is more likely
d) They are all equally likely]
[Correct]
That’s right!
Darlene’s gender may dissuade you from assuming she has UIP, but other factors such as: age over 60,
positive smoking history and having a family history of pulmonary fibrosis all increase the pretest likelihood that she has UIP.
With this in mind, you can now take a look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Did you consider Darlene’s age, smoking status and family history?
Take another look at Darlene’s chart and try again.
[Try again]
[Review instructions for step 1 on how to "Boost your odds" again]
[Correct]
That's right!
Darlene’s gender may dissuade you from assuming she has UIP, but other factors such as: age over 60,
positive smoking history and having a family history of pulmonary fibrosis all increase the pretest likelihood that she has UIP.
With this in mind, you can now take a look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let’s look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let’s look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Did you consider Darlene’s age, smoking status and family history?
Take another look at Darlene’s chart and try again.
[Try again]
[Review instructions for step 1 on how to "Boost your odds" again]
[Correct]
That’s right!
Darlene’s gender may dissuade you from assuming she has UIP, but other factors such as: age over 60,
positive smoking history and having a family history of pulmonary fibrosis all increase the pretest likelihood that she has UIP.
With this in mind, let’s look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let’s look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let’s look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Did you consider Darlene’s age, smoking status and family history?
Take another look at Darlene’s chart and try again.
[Try again]
[Review instructions for step 1 on how to "Boost your odds" again]
[Correct]
That’s right!
Darlene’s gender may dissuade you from assuming she has UIP, but other factors such as: age over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, you can now take a look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let's look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Incorrect]
Not quite.
Although Darlene is female, you’ll want to weigh other factors such as her increased age, over 60,
her smoking status and the fact that she has a family history of pulmonary fibrosis, which all make it more likely that she has a form of UIP.
With this in mind, let's look at Darlene’s HRCT scan.
[Look at Darlene's HRCT scan]
[Review instructions for step 1 on how to "Boost your odds" again]
[Step 2]
[Ensure fibrotic lung disease is present]
First look at Darlene’s scans to ensure fibrotic lung disease is present.
Based on this closer view of Darlene’s HRCT scan, choose one feature that best confirms the presence of fibrotic lung disease.
What features from this scan help to confirm fibrotic lung disease?
[Choose one:
a) Pure ground glass
b) Reticulation associated with traction bronchiectasis
c) Mosaic attenuation
d) Consolidation]
[Correct]
That’s right!
We see dilated airways associated with reticulation.
This is reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
Take another look and try again.
[Try again]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Correct]
That’s right!
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
Take another look and try again.
[Try again]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Correct]
That’s right!
We see dilated airways associated with reticulation.
This is reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
Take another look and try again.
[Try again]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Correct]
That’s right!
We see dilated airways associated with reticulation.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Incorrect]
Not quite.
We see dilated airways with reticulation associated with traction bronchiectasis, which confirms that fibrotic lung disease is present.
[Continue]
[Review instructions for step 2 to evaluate the presence of fibrosis again]
[Step 3]
[Assess for features of a typical UIP pattern]
Now that you’ve determined that Darlene does in fact have fibrotic lung disease, it’s time to assess for features of a typical UIP pattern.
Upon a closer look, what proof do you see that this is not a typical UIP pattern?
[Choose one:
a) Presence of pure ground glass
b) Upper lobe predominance
c) Presence of cysts
d) Absence of honeycombing]
[Correct]
That’s right!
Here we see extensive subpleural, basal predominant reticulation.
However, there are no stacked or adjacent subpleural cysts typical of honeycombing.
[Continue]
[Review instructions for step 3 about probably UIP assessment again]
[Incorrect]
Not quite.
We don’t actually see extensive pure ground glass or cysts in this scan.
Take another look and try again.
[Try again]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Correct]
That’s right!
Here we see extensive subpleural, basal predominant reticulation.
However, there are no stacked or adjacent subpleural cysts typical of honeycombing.
[Continue]
[Review instructions for step 3 about probably UIP assessment again]
[Incorrect]
Not quite.
Honeycombing, extensive pure ground glass and cysts aren’t actually present here.
We do, however, see extensive subpleural, basal predominant reticulation.
Because there is no honeycombing, this cannot be typical UIP.
Also, note the absence of upper/mid zone predominance, peribronchovascular predominance, consolidation, mosaic attenuation with lobular air trapping, and nodules.
[Continue]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Incorrect]
Not quite.
Take another look at the image just below the carina. Darlene’s fibrosis is lower lobe predominant.
[Try again]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Correct]
That’s right!
Here we see extensive subpleural, basal predominant reticulation.
However, there are no stacked or adjacent subpleural cysts typical of honeycombing.
[Continue]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Incorrect]
Not quite.
Honeycombing, extensive pure ground glass and cysts aren’t actually present here.
We do, however, see extensive subpleural, basal predominant reticulation.
Because there is no honeycombing, this cannot be typical UIP.
Also, note the absence of upper/mid zone predominance, peribronchovascular predominance, consolidation, mosaic attenuation with lobular air trapping, and nodules.
[Continue]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Incorrect]
Not quite.
Honeycombing, extensive pure ground glass and cysts aren’t actually present here.
We do, however, see extensive subpleural, basal predominant reticulation.
Because there is no honeycombing, this cannot be typical UIP.
Also, note the absence of upper/mid zone predominance, peribronchovascular predominance, consolidation, mosaic attenuation with lobular air trapping, and nodules.
[Continue]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Incorrect]
Not quite.
We don’t actually see extensive pure ground glass or cysts in this scan.
Take another look and try again.
[Try again]
[Review instructions for step 3 on assessing a typical UIP pattern again]
[Step 4]
[Assess for features consistent with a probable UIP pattern]
So now that we have excluded a typical UIP pattern due to the lack of honeycombing,
we want to assess if this could be a probable UIP pattern.
… but what imaging features must be present in order for this case to be probable UIP?
Think back to our Building Blocks of lung injury section.
Select the response that best describes probable UIP.
[Which of the following is consistent with a probable UIP pattern?
Choose one:
a) Presence of reticulation
b) Absence of honeycombing
c) Absence of ALL the features of lung injury that indicate an alternative diagnosis
d) All of the above are consistent with a probable UIP pattern]
[Correct]
That’s right!
Reticulation must be present, while the absence of honeycombing is required.
Additionally, the features of lung injury indicating an alternative diagnosis must be absent for a case to be considered probable UIP.
[Continue]
[Incorrect]
Not quite.
While reticulation must be present, there are more requirements for this case to be considered probable UIP.
[Try again]
[Review instructions for step 4 about probable UIP assessment again]
Let’s go back and take another look.
[Correct]
That’s right!
Reticulation must be present, while the absence of honeycombing is required.
Additionally, the features of lung injury indicating an alternative diagnosis must be absent for a case to be considered probable UIP.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
To diagnose probable UIP we need to meet all three of the listed criteria.
Reticulation must be present; honeycombing must be absent, as well as the absence of the features that are indicative of an alternative diagnosis.
You can review instructions for this step again or proceed.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
To diagnose probable UIP we need to meet all three of the listed criteria.
Reticulation must be present; honeycombing must be absent, as well as the absence of the features that are indicative of an alternative diagnosis.
You can review instructions for this step again or proceed.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
While it is true that the absence of honeycombing is a criterion of probable UIP,
what else is required to make a more comprehensive assessment.
Let’s go back and take another look.
[Try again]
[Review instructions for step 4 about probable UIP assessment again]
[Correct]
That’s right!
Reticulation must be present, while the absence of honeycombing is required.
Additionally, the features of lung injury indicating an alternative diagnosis must be absent for a case to be considered probable UIP.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
To diagnose probable UIP we need to meet all three of the listed criteria.
Reticulation must be present; honeycombing must be absent, as well as the absence of the features that are indicative of an alternative diagnosis.
You can review instructions for this step again or proceed.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
To diagnose probable UIP we need to meet all three of the listed criteria.
Reticulation must be present; honeycombing must be absent, as well as the absence of the features that are indicative of an alternative diagnosis.
You can review instructions for this step again or proceed.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Incorrect]
Not quite.
To diagnose probable UIP we need to meet all three of the listed criteria.
Reticulation must be present; honeycombing must be absent, as well as the absence of the features that are indicative of an alternative diagnosis.
You can review instructions for this step again or proceed.
[Continue]
[Review instructions for step 4 about probable UIP assessment again]
[Step 5]
[Consider an alternative diagnosis]
Before you draw your final conclusion, take one last look.
Do you think you should suggest an alternative diagnosis, or have you reached a conclusion?
Based on your prior work, you have concluded this case has reticulation with a basal and subpleural predominance and no
honeycombing, as well as an absence of any of the other features that would indicate an alternative diagnosis.
[Correct]
That’s right!
This is a case of probable UIP.
With a correct diagnosis, Darlene’s respirologist can make an informed decision about the next step in the management of her disease.
[Check out the other case studies]
[Mark] [Helen] [Chris]
[Incorrect]
Not quite.
In step three we determined that there was no clear honeycombing.
Let’s go back and take another look.
[Try again]
[Review instructions for step 5 covering the alternative diagnosis again]
[Correct]
That’s right!
This is a case of probable UIP.
With a correct diagnosis, Darlene’s respirologist can make an informed decision about the next step in the management of her disease.
[Check out the other case studies]
[Mark] [Helen] [Chris]
[Review instructions for step 5 covering the alternative diagnosis again]
[Incorrect]
Not quite.
Since there was no, clear honeycombing, this case cannot be categorized as typical UIP.
It is actually a case of probable UIP.
[Check out the other case studies]
[Mark] [Helen] [Chris]
[Review instructions for step 5 covering the alternative diagnosis again]
[Incorrect]
Not quite.
The features described to indicate an alternative diagnosis are absent in this case.
Let’s go back and take another look.
[Try again]
[Review instructions for step 5 covering the alternative diagnosis again]
[Correct]
That’s right!
This is a case of probable UIP.
With a correct diagnosis, Darlene’s respirologist can make an informed decision about the next step in the management of her disease.
[Check out the other case studies]
[Mark] [Helen] [Chris]
[Review instructions for step 5 covering the alternative diagnosis again]
[Incorrect]
Not quite.
Since there was no, clear honeycombing, this case cannot be categorized as typical UIP.
It is actually a case of probable UIP.
[Check out the other case studies]
[Mark] [Helen] [Chris]
[Review instructions for step 5 covering the alternative diagnosis again]
Reading HRCTs with Dr. Hague
Learning objectives:
Review the basic building blocks and key steps of identifying fibrotic ILDs using HRCT
Test your understanding through interactive case studies
Questions? Contact the presenter
The presenters are solely responsible for developing the content of this presentation and maintaining scientific accuracy, objectivity, and balance. Any discussions of clinical practice or treatment represent the opinions of the presenter alone. This video is made available for attendees, registrants, and individuals requesting further information on this learning program.
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