Imaging of the Lung 2 Flashcards
On CXR, how can you tell the difference between an airspace problem (alveoli) or interstitial problem?
Airspace problems are foggy and homogenous with an ill-defined border. Interstitial processes show up as dots and dashes.
Which one has a problem w/ airspace and which one has an interstitial problem?
The one on the left is an airspace problem (homogenous) and the one on the right is an interstitial problem (dots and dashes).
Explain this slide
In interstitial problems, you get kerley B lines. The picture on the top shows you how the interstitium is very linear with the airspace in between. This is why in airspace issues, you get a diffuse homogenous haze but with interstitial issues, you get dots and streaks. The Kerley B lines are extending out to the border of the chest wall and show that there is a lymphatic issue (classic finding of pulmonary edema).
Explain the progression of pulmonary edema (with increased wedge pressure) through CXR
You begin with pulmonary vascular congestion, you then get lymphatics and veins becoming distended (interstitial appearance), then you get fluid into the alveolar airspaces (homogenous appearance).
A to B to C
Airspace disease (homogenous haze appearance in CXR) can be caused by both acute and chronic processes. Name 3 acute and 2 chronic
Acute:
Blood, puss (infection), water (pulmonary edema)
Chronic:
Cells (tumor), protein (organizing pneumonia)
What is the ABCDE system?
Airway (including lungs and pulmonary vessels)
Bones
Cardiac (heart and mediastinum)
Diaphragm (and pleural surfaces)
Everything else (lines, tubes, upper abdomen, chest wall, neck)
What’s this?
Right lower lobe pneumonia.
The right cardiac border is clear.
What’s going on here?
Left upper lobe pneumonia.
There is a loss of the left cardiac border. You can see the homogenous haze with bronchi shadows in it which shows that this is an airspace problem.
What’s going on here?
Loss of right cardiac border. Homogenous in appearance. On the lateral view, you can see that it is localized anteriorally.
This is a right middle lobe pneumonia.
What’s going on here?
Bilateral diffuse opacity. Homogenous haze and air bronchogram indicate airspace disease.
This is ARDS. Systemic process that is resulting in diffuse bilateral process (in contrast to pneumonia which is local)
What’s going on here?
Left lower lobe pneumonia.
In this case, the PA image doesn’t help much because the posterior end of the lower lobe is blocked by the diaphragm. However, in the lateral view, you can see both the spine sign and silhouette sign. The vertebral bodies should stay the same in opacity or get darker (because there is less soft tissue blocking as you move down), but you can see that the vertebrae start to look more white. This is the pneumonia in the posterior side of the lower left lobe. There is also the silhouette sign where you can see one side of the diaphragm border clearly but the other side (left side) is lost.
What’s the spine sign?
The vertebral bodies should stay the same or get darker as you go down the spine because there is less soft tissue obstructing the view. However, with the spine sign, you can see that the vertebral bodies start to look more dense (white) as they go through the part of the lower lobe that has blood/puss/whatever.
What’s going on here?
This is a right middle lobe pneumonia.
You can see that the right heart border is lost and on the lateral view you can see below the middle lobe is a fissue. This shows that the pneumonia is localized to the middle lobe and not the lower lobe.
Explain the reliability of physical exam findings vs. age when diagnosing patients with pneumonia.
With patients less than 40 years old, negative physical exam findings for pneumonia mean that the patients have a very low likelihood of having pneumonia. So, with patients less than 40 y/o, you would reserve CXRs for patients that have positive physical exam findings.
With patients greater than 40 years old, physical exam findings are less reliable. So, you may still take CXR even with negative physical exam findings.
