Hi, this is Dr. Mahadevan. I’m here with Dr. Kate Stevens, and we are going to go into How to Read a Chest Radiograph, Part 3. And we’re going to start with evaluation of the airway. When we’re talking about the airway, or the ABCs of chest xray evaluation, what are we looking for We’re going to look at the trachea and the right and left mainstem bronchi, as well as the carina. And the questions we have when we’re evaluating the airway are Is the trachea midline And if an endotracheal tube is present,.
Is it in the proper position, meaning the tip ideally is going to be 2 to 5 centimeters above the carina. So here is an xray, and we can see clearly the anatomy that we’re interested in with regards to the airway. You can see the trachea here, outlined in blue, and the right mainstem bronchus here, and the left mainstem bronchus here, and then between them the carina. So let’s take a look at some cases that demonstrate airway abnormalities. So if we’re looking in this patient, we want to make sure that the trachea is midline.
And you can actually see that this trachea is deviated to the right. And the most common cause of this is going to be a lowlying thyroid gland, so retrosternal thyroid. So whenever we see this tracheal deviation, you want to find out what exactly is causing that. Most common cause of this is retrosternal thyroid. And then you can again appreciate the right mainstem and the left mainstem bronchi. Great. And in this patient, the patient is lying on the trauma board. You can recognize the trauma board that the patient is lying on.
7c Chest X ray Case1 Pt3 V2
Patient has an endotracheal tube and the tip should normally be 2 to 5 centimeters above the carina, and the carina is here. And so you can see that this endotracheal tube is actually directed into the right mainstem bronchus. And so obviously that position is not satisfactory and would need to be withdrawn. Fantastic. And this patient again, they told you that the patient has had some major trauma. And again we’re looking at the endotracheal tube, and this time you can actually see that the tube is directed into the left mainstem bronchus.
And again, this is not an ideal position and the tube should be repositioned as quickly as possible. And the carina on this film if we were to look for it The carina is about here on the film. So you can see that this is probably 1 to 2 centimeters distal to the carina. Fantastic. In this patient, you can see the endotracheal tube is deviating to the right, which makes you wonder whether it could be going into the right mainstem bronchus. However, what’s important in this example, you can see that there’s extensive gaseous.
Extension of the stomach. And so this is concerning for an esophageal intubation. So even though sometimes it may look as if it’s in a relatively good position on the chest xray, if you see a telltale sign here you want to make sure that the endotracheal tube is in the right place and not within the esophagus. Great, so with regards to airway we’ve seen the endotracheal tube can be outside of the airway, or it can be too far down, and on occasion, it can be too high up as well.
All of these things can be seen on the xray. The next element in our ABCs are the bones, and what are we looking for. We’re going to look at the structures that we can see on a chest xray, including the ribs, the scapula, and the vertebral bodies, or the vertebrae. And as well as the jaw when it appears, the arm, and the shoulder as well. And our questions when we’re looking at the bones specifically are, do we see a fracture or a dislocation or do we see any other abnormalities,.
Such as lytic lesions. Again, when looking at the bony anatomy, it’s important to identify the first rib, which we can see right here. And then be able to count down two, three, four, five, six, seven in terms of evaluating the expiration or inspiration on film, as well as to ensure that there’s no injury to the bones or any other abnormalities. And again, we want to see down to at least the sixth or seventh rib in the midclavicular line when evaluating the degree of inspiration. And then, Kate, in terms of looking.
At the other bones on the xray So here we can see the clavicle, and this articulates with the scapula. So here we can see the acromion of the scapula here. You can also see the coracoid process which looks like a bent finger so the coracoid process of the scapula. You can also see the articular surface of the scapula, the glenoid, which articulates with the humeral head. And here we can nicely appreciate the body of the scapula. So you want to make sure that the humeral head overlaps.
With the glenoid as in this example. And have you seen fractures of all of these structures on xrays before You may not necessarily see all of them on a chest xray, but certainly I’ve seen different structures. And a lot of them are very readily apparent, that if a patient has major trauma, that you can see at least some of the fractures on the chest xray. All right, so let’s take a look at some examples. So this patient we’re predominately concentrating on the bones. And if you look superiorly you can.
See that the patient has a comminuted fracture, complex fracture, of the mid clavicle. Any time you see a fracture of the clavicle, you always want to look carefully at the shoulder. And you can also see here that there’s an irregular lucent line going through the scapula. So that’s concerning for a scapula fracture. And again, it’s quite common to get rib fractures associated with that. And you can just see some cortical irregularity along the lateral margin of the fourth rib here. And so the patient also has a fourth rib fracture.
So the clavicle fracture is fairly apparent, and these other ones are more subtle. And you need to look carefully around, and obviously if you do see rib fractures, then you’re going to start to look for subcutaneous emphysema or a pneumothorax. In this patient, again the patient’s intubated, and you can see that the tip of the ET tube is less than 2 centimeters above the carina. The carina is in this area here. You can see a fairly obvious fracture here of the distal clavicle on this side. And again, when you’re looking along the chest wall.
You can see that the patient has subcutaneous emphysema, and the subcutaneous emphysema in this example is extending up into the neck. You can also see some subtle pleural thickening here, which is highly suspicious of rib fractures. So again, you’re seeing some fractures of the ribs here along the lateral chest wall. This patient, again you’re looking around at the chest, the patient’s come in with trauma. Looks relatively good, just checking the clavicles, and yet when you come to the right shoulder, you can suddenly appreciate that here we have the humeral head,.
And that should be articulating with the glenoid. And so the patient has actually got an anterior dislocation of the shoulder. And sometimes the patients have other severe injuries, they’re not going to be able to tell you that they’ve got a painful arm. And so it’s very easy to overlook injuries that are on the peripheral margin of the film when you’re predominantly concentrating on the chest findings. And we’re always told we’re responsible for every abnormality on the xray, not just the ones that we’re interested, ordinarily, in the thoracic cavity.
So this patient, if you look on at the right base, you can see a vague, rounded structure here. And so I’m just going to draw around that. So the patient has a lung mass. And if you look carefully on the left side, you can see this smoothwalled mass along the chest wall. And if you’re just following this rib around, if we’re looking at the anterior margins of the ribs, you can see and anterior margin of the rib coming down now. On this side, as we get down to here,.
You can see that this margin of the rib is lost. And so this patient has an expansile lesion of the rib as a result of the lung cancer, and is forming a large pleural based mass there, so a lung cancer with the metastasis in the anterior end of one of the ribs, with a large pleuralbased mass in this example. This patient is a fairly subtle finding. Patient came in and they were complaining of right shoulder pain. Chest looks fine, but when you look carefully along the left scapula, you can see the margin here.
Very nicely. If we then go and look on the right scapula and we’re drawing down, you can see that there’s actually a step here. And so this patient has a lytic lesion of the scapula, very subtle, with a small pathologic fracture. Again, very easy to overlook. Patient had a history of multiple myeloma. The next step in our ABCs of chest xray evaluation is to look at the cardiac silhouette and the mediastinum. And what are we looking for We’re going to look for the size of the heart,.
As well as specifically looking at the silhouette of the heart, and then move upwards towards the mediastinum. With the following clinical questions is the heart enlarged, meaning is the diameter greater than half the thoracic diameter, or is the mediastinum widened or displaced. So as we can see on this projection, the cardiac silhouette is about half that of the thoracic diameter. Roughly half would be normal, greater than half would be concerning. Again, depending on the type of projection we’re talking about, on the AP film, the heart is generally.
Going to look larger than on the PA projection. And then as we move up and evaluate the mediastinum, the things that we’re going to see are the ascending aorta, the aortic knob, then the descending aorta, and you can also see the left pulmonary artery as well. Alright so let’s take a look at some cases that have us evaluate the cardiac silhouette and the mediastinum. So in this patient you can see that the heart is clearly markedly enlarged. So it’s far greater than 50 of the width of the chest wall.
You can see that the patient has cardiac issues, because they’ve got a pacemaker in place, and you can also see that the hila are markedly enlarged. So there’s prominence of the central pulmonary vasculature on that side, suggesting pulmonary artery hypertension. We’re also looking at the vascularity of the lungs, but the patient does not appear to have any interstitial pulmonary edema or pleural effusions, but certainly a large heart, large pulmonary arteries. This patient, you can see that this is a semierect film, and the patient hasn’t really taken a good inspiration.
So you can probably see maybe three or four anterior ribs. And so that can give you a false impression of the heart being enlarged, but it still really looks a little prominent. The other thing, particularly when a patient is in the supine position and hasn’t taken a good inspiration, you can get widening of the mediastinum. But you can see, in this example, that the superior mediastinum is markedly widened. And the patient went on to have a CT examination, and had sustained a fairly severe aortic dissection which accounted for the widening of the superior mediastinum.
Do you ever use a numerical figure, in terms of evaluating the width of the mediastinum Is there a cut off I don’t use a particular measurement. So it’s really more about the appearance itself looking abnormal, like in this particular patient. And you can see it in this example, the aortic contour is extremely prominent as well. In this next patient, again you can appreciate that this is a supine film, and the patient is on a trauma board. And in this example, again, you can see patient hasn’t taken a bad inspiration, because you.
Can see probably at least five or six ribs. The heart does look a little bit enlarged, but what is interesting in this patient is you can see that the aortic contour here is very illdefined. Normally you can see it much better defined, and then there’s also some opacification in the apex of the lung, concerning for an apical pleural cap or apical pleural fluid. And this patient, on subsequent CT, turned out to have a fairly significant aortic injury with a partial rupture. So the mediastinum is wide, the aortic structures are.
Sort of indistinct, and on top of that you can see that blood tracking up in the left apex as well and the history of trauma. With regard to the diaphragm, we’re looking at or for the diaphragm, the costophrenic and costocardiac margins, and then we’re going to look above the diaphragm, and below it with the following questions. Are the diaphragmatic margins sharp Is there any blunting of the costophrenic margins Is one of the diaphragms elevated are enlarged And then finally, is there free air beneath the diaphragm So let’s take a look at some examples.
So in this patient, again, it’s an AP semierect film. So not very accurate evaluation of the heart, but you can see that the heart does appear somewhat enlarged. We’re looking at the diaphragmatic contour in this case, and it’s not particularly well seen. But sometimes, particularly when the heart is beating fast, you can get pulsation artifact that can make it appear a little indistinct. But you can see that there’s definitely some blunting of the costophrenic angle here. So that’s concerning for a small pleural effusion. And again, you can’t see the costophrenic sulcus here.
Very well. And particularly when they’re semierect sometimes the fluid drains posteriorly and collects posterior so we may not necessarily see it, but we should be able to see a sharp costophrenic margin. So in this patient it’s concerning for small bilateral pleural effusions. And you can also see that there’s some increased density in the retrocardiac lung. So quite likely that the patient also has some consolidation in the lung behind the heart. In this patient, again, the patient is on a trauma board. That’s a supine film. You can see the right hemidiaphragm is.
Nice and clearly defined, and you can see that the left one is quite markedly elevated and irregular. In addition, you can see that the heart shadow so you should normally only be seeing about 13 of the heart to the right of the spine and you can see that the majority of the heart is over here. So there’s obviously mass effect from whatever is causing the elevation of the hemidiaphragm. And you can see here, that they have elevation of the stomach bubble. And this patient had ruptured their diaphragm,.
And so some of the contents of the abdomen are herniating up into the chest. And that is what is responsible for ending up shifting the mediastinum over and causing some collapse of the underlying lung. Another case here, and we look at the endotracheal tube and you can see, in this is example, that the endotracheal tube is very close to the carina. And so that should probably be withdrawn. And again, we can see that there’s elevation of the hemidiaphragm with elevation of the stomach bubble. So again, concerning for a diaphragmatic injury.
In this patient, this was probably a patient presenting with abdominal pain. As you can see it’s an erect chest xray. And so you want to look carefully below the hemidiaphragm in these patients. And you can see that we’ve got gas outlined in the under surface of the diaphragm, and you can see it outlining the underlying structures probably the folds of the stomach here. And so this is compatible with free air, and the patient obviously has something going on in their abdomen that would require more investigation. Another example here, patient with severe abdominal pain.
And here you can see that there’s a lot of free air under the hemidiaphragm. You can actually see it outlining here the dome of the liver. So there’s air interspersed between the liver and the hemidiaphragm. You can see that there’s gas passing underneath the heart shadow here. And again, you can see that there’s free air all the way along here. So it’s fairly substantial pneumoperitoneum. Wonderful. This has been How to Read a Chest Radiograph, Part 3, and we’ve reviewed the airway, bones, cardiac silhouette and mediastinum, and then finally the diaphragm.