Hey, everybody, it's Rishi Agrawal.
Today I want to talk about lobar collapse.
Lobar collapse just means complete deflation of the airspace in a lobe.
And it differs from consolidation because in consolidation,
the air is replaced by another substance like blood, pus, or edema.
In collapse or atelectasis, It's not replaced by anything.
It's just deflated.
Let's take a look at some examples, starting with the right upper lobe.
This is the classic appearance of a right upper lobe collapse.
Remember from anatomy that the minor fissure
is supposed to be about right here, but in this case,
it's displaced superiorly, and it's all the way up here.
Notice also that we lose the contour of the right superior mediastinum
because we have something of the same density, the collapsed lung obscuring it.
In this patient, there's another feature.
Not only do we have lobar collapse, but there's also this slight bulge
centrally here.
So the contour of the minor fissure has this sort of S shape.
This is the S sign of Golden.
You see this sign
when you have lobar collapse and it's mostly in the right upper lobe
but the central bulge represents a mass causing obstruction of the bronchus.
There's one more final sign on this chest radiograph,
and that's this slight contour iregularity of the diaphragm.
This is something called the juxtaphrenic peak sign.
If you remember from anatomy that the visceral and parietal pleura
come together at the hilum.
The extension of that pleural junction is the inferior pulmonary ligament
and it tethers the hilum down to the diaphragm.
When you have volume loss in the upper lobes,
the hilum retract superiorly and it causes tenting of the inferior
pulmonary ligament causing the juxtaphrenic peak.
On the lateral view,
there's this triangular wedge of tissue which represents the collapsed lobe.
The posterior edge here is the major fissure, which is pulled up,
and this horizontal edge is the minor fissure which is also pulled up.
If we look at the CT, you can see that the right upper lobe
stops abruptly, and this is called the bronchial cutoff sign.
And if we narrow the windows, you can make out a mass
that is obstructing that bronchus,
causing collapse of the lobe.
If we look at the mediastinum, you can see that
there are also enlarged lymph nodes which represent metastatic disease.
And here's the coronal
image of the collapsed right upper lobe with this being the minor fissure.
Here's a case of right middle lobe collapse, which in my opinion
is one of the harder lobar collapses to get on X-rays.
Our clues here are that we have this hazy
opacity in the expected location of the right middle lobe.
And if we zoom in
we lose the right heart border
because the collapsed middle lobe abuts the heart border.
We also have this straight edge here in the lung.
When you see a straight edge in the lung.
Usually that means it's a fissure.
The real clue here is on the lateral view.
On the lateral view, you can see that we have this wedge of soft tissue
that's bordered inferiorly by this line here,
which is the major fissure being displaced superiorly.
Superiorly, this is the minor fissure
which is displaced downward.
Here's the patient a few weeks ago,
and this is the major fissure in its normal position.
And this right here is the minor fissure.
Here's the sagittal CT showing the collapsed right middle lobe.
This is the minor fissure and this is the major fissure.
On the coronals, the right middle lobe looks like this triangular or wedge
shaped bit of soft tissue that abuts the right heart border.
So this is right middle lobe collapse.
Here's a patient with right lower lobe collapse.
This patient has COPD and bronchial valves were placed intentionally
in the segmental bronchi of the right lower
lobe to cause the right lower lobe to collapse.
So our clues here are that we have this triangular opacity
that extends from the hilum to the diaphragm
and we have inferior retraction of the right hilum.
If I zoom in
you can see the bronchial valves there
and you can make out partially the right heart border,
but we lose the medial aspect of the right hemi-diaphragm.
Compare that to the pre-op study
where we see the right hemi-diaphragm more clearly.
The lateral view for lower lobe collapse is not super helpful,
but it does show a hazy opacity overlying the spine
in the retro-cardiac clear space Here's the CT.
If we follow this bronchus, this is the bronchus intermedius,
and then it branches into the right lower lobe.
And you can see that these segmental bronchi
contain the bronchial valves.
And this is the major fissure which makes all of this
the collapsed right lower lobe.
Here's what it looks like on the coronal images.
So this is the collapsed lower lobe here.
And notice also that this is the minor fissure
which is displaced, inferiorly as the middle lobe tries
to take up the space that was once occupied by the lower lobe.
This is another patient with right lower lobe collapse.
And again, we see this triangular opacity representing the collapsed lobe
going from the hilum to the diaphragm.
We have elevation of the right hemi-diaphragm indicating volume loss.
We have preservation of the right heart border.
And although we have preservation of the right hemi-diaphragm here,
if we look on the lateral view,
you can see that the posterior aspect of the diaphragm is obscured.
Notice also on the lateral view that the collapsed lobe is not well demarcated.
It just shows up as a hazy opacity overlying the spine.
This patient has
both right middle and lower lobe collapse.
Notice again that we have this triangular opacity
that goes from the high limb to the diaphragm.
And if we zoom in, you'll see that we lose
both the right heart border and the right hemi diaphragm.
This border right here is not the diaphragm.
This is the minor fissure.
If we go to the lateral view
this right here is the collapsed middle lobe on top of the diaphragm.
And notice posteriorly, again,
we have just haziness behind the heart,
but we don't have the posterior aspect of the right hemi-diaphragm.
This is the left hemi-diaphragm.
In this patient, because we have a right middle and lower lobe collapse,
you would guess that the obstruction would have to be in the bronchus intermedius.
And if we go to the CT, what you'll see is that the trachea is patent.
This is the right main bronchus, right upper lobe bronchus.
That's the bronchus intermedius.
And if we continue to scroll down,
you can see that the bronchus intermedius is completely occluded.
And if we continue to scroll,
this is the collapsed right middle lobe.
And this is the collapsed right lower lobe.
On the coronal images, this is the collapse right lower lobe.
Notice that we're posterior here because we can see the spine
which corresponds with this opacity.
And if we scroll forward
this is the collapsed right middle lobe,
which corresponds with this opacity.
All right.
Let's take a look at the left lung.
Here's a patient with left upper lobe collapse.
On first glance, the most striking abnormality
is that you see a diffuse haziness throughout the left hemithorax.
And that actually represents the left upper lobe
that's flattened against the anterior chest wall.
Notice also that the left hilum is elevated
and that we have a very subtle juxtaphrenic peak sign here,
as well as elevation of the left hemi
diaphragm compared to the right.
Another sign is that we lose the left heart border
because remember, the collapsed left upper lobe abuts the left heart.
And then one final clue on the frontal view
is that there's this sort of crescentic lucency adjacent to the aortic arch.
This is something called the Luftsichel sign,
and it represents a bit of the left lower lobe that's interposed
between the collapsed lung and the aortic arch.
The lateral view is much more straightforward.
We see a well-defined opacity along the anterior
aspect of the chest, which represents the collapsed left upper lobe.
And this posterior border here is the major fissure.
On CT, this is the collapsed left upper lobe.
And as we scroll down you could see that there's a little bit of the left
lower lobe that comes between the aortic arch and the collapsed left upper lobe.
And this is what gives us the Luftsichel sign.
Here's what it looks like on the sagittal images.
This is a patient with left lower lobe collapse.
This looks very similar to the right lower lobe collapse.
What we have is a triangular opacity superimposed
over the heart, going from the hilum to the diaphragm.
And we have obscuration of a portion
of the left hemi-diaphragm on the lateral view.
This is the left hemi-diaphragm here.
And you can see again that a portion of it is obscured posteriorly.
Also notice on the lateral view
that the collapsed lobe is not very well demarcated.
All we really see is a hazy opacity behind the heart.
Here's what it looks like on the coronal CT.
It looks very similar to the right lower lobe that I just showed you.
We have a well demarcated and
triangular opacity that represents the collapsed lung.
And this is the major fissure which is depressed inferiorly.
So those were the patterns of lobar collapse.
If you have any questions about this topic or any other thoracic radiology topic,
let me know in the comments below. Thanks.