Transcription
Dear colleagues, we are now going to start a new series of lectures on a separate topic, which is chest imaging. Actually, we have finished about nine lectures on the issue of brain imaging. There are still a lot of things to be covered in this particular domain, but actually, I am preparing now some new lectures, and also some lectures are already present, but they will be projected in the sector of pediatric radiology. These topics will include the imaging of hydrocephalus, imaging of neuronal migration disorders, and imaging of cerebrovascular stroke in the pediatric group. Also, imaging of pediatric brain tumors and pediatric intracranial infection.
Now, let's start that sector of chest imaging, and it contains about 11 lectures. We will cover through these lectures most of the issues concerning thoracic pathology. And we start with one of the most important lectures of all in the radiology specialty, which is how to interpret the chest X-ray. This lecture is actually very beneficial for every person who is working in the medical field, including all physicians and even the paramedical staff, and this is essential in their day-to-day practice.
Then, the interpretation of a chest X-ray is a little bit, let us say, it's not that difficult, but it needs some special protocol, or in a simplified way, in order to reach most of the values of this very simple radiographic technique. And as you all know, the chest X-ray is a very simple radiographic technique and is of relative low cost. Meanwhile, it is relatively sensitive, providing excellent resolution and good differential diagnosis for most of the intrathoracic pathologies.
Then, in order to interpret the chest X-ray, we should know the criteria of the optimal chest X-ray. These criteria include accurate patient positioning while being radiographed, and instructing the patient to have full inspiration before taking the X-ray film or exposing the X-ray film. And we select the radiographic factors which are suitable to the size of the human body. Then, how can you know these parameters in detail while you are not attending the technique of chest radiography? Then we should go first for some of the radiographic terminologies. And you all know, especially the radiologists, that the most popular chest X-ray of all is known as the PA view. And the PA view is the posteroanterior view. And most of the radiologists know that the X-ray is named according to the entrance of the X-ray beam through the human body. Then, if the X-ray beam is entering from the back, and this is a posteroanterior, if the patient is facing the X-ray tube, and this is an anteroposterior view.
Then, one may ask, what is the difference between both? And here is the difference. This is in the posteroanterior view, and this is an anteroposterior view. And you know that the cardiac shadow is anteriorly located in the thorax. Then, in the posteroanterior view, the heart is near to the film, no magnification. But in the anteroposterior view, the heart is away from the film. Then you should expect some magnification in the size of the heart. And this is very well demonstrated here. This is the posteroanterior view, and this is the anteroposterior view of the same patient. And you can see here that the normal cardiac transverse diameter, and the heart is relatively increased, or the transverse cardiac diameter appears as if it is increased. But this is because of the magnification of the heart secondary to being far away from the X-ray film.
Then, there are also some differences between the erect position and the chest in the supine position. In the erect position, the patient is able to have full inspiration. Then you can have accurate assessment of the cardiac silhouette. But in the supine position, the diaphragm is relatively high. Then the heart will be flattened, and the transverse diameter will appear as if it is enlarged. And this is the case in the intensive care units and the casualty areas where the patient is usually radiographed in the supine position and in the anteroposterior view. Then, in these conditions, you should assume that the heart will be enlarged, or appear as if it is enlarged, because of the supine position and the anteroposterior projection. And if the cardiac size is of interest, then you should have the lateral view, because in the lateral view, there is no magnification of the cardiac size silhouette.
Then, here this is the lateral view. Whenever you want to have a lateral view, you should specify the side of interest. If the left side is the side of interest, then this side will be close to the film, and this is the left lateral view. And the decision of the lateral view is based usually on the appearance of the chest in the frontal view. Then, if the pathology is in the left lung, you should have left lateral. If the pathology is in the right lung, you should have the right lateral view.
Then, while interpreting the chest X-ray, you should know that there is some difference between the level of the diaphragm on both sides. And this indicates that the right hemidiaphragm is relatively high compared to the left one by a distance ranging from 1 to 3 cm.
Then, if you look to the frontal chest X-ray and you can see some obliteration of the costophrenic angle and you suspect the presence of pleural effusion. And in the lateral view, you also see some obliteration of the posterior costophrenic angle by pleural fluid. One of the ways to confirm this is to put the patient on his side. And in this case, the patient lies on the left side, then the pleural fluid will track into the pleural cavity, and you can confirm the diagnosis. Actually, nowadays, we do not use this projection. Instead, we use the ultrasound, and we put the ultrasound in the region of interest, and you can see minimal fluid between the costophrenic angle. And this is the liver, of course, and here you can see the diaphragm.
Then, the lordotic view is obtained in the anteroposterior projection by tilting the patient about 45 degrees relative to the X-ray beam. And the main value of this lordotic view is to displace the shadow of the clavicle away from the area of the lung apices. Then you can see this is the lordotic view, and the shadow of the clavicle is not covering the apices of the lung. And if there are any infiltrations, minute lesions, calcification, can be clearly visualized. And this is also an example of the normal chest posteroanterior view and the lordotic view, displacing the clavicular shadows away from the field of view in the apices of the lung.
Also, one of the values of the lordotic view is to augment the appearance of middle lobe lesions. And you know here, this is the frontal chest X-ray, and you see an opacity in the middle lobe which is relatively projected anteriorly. In the lateral view, the lordotic view clearly demonstrates the lesion in the middle lobe.
Then, if you look to the chest X-ray and you can easily appreciate if this is a well-exposed film or an overexposed like this, or underexposed like this. Optimal exposure will display the lung fields, the lung markings, the cardiac shadow, the costophrenic angles. Overexposure will project the lung fields very dark, and you can see also the thoracic vertebrae across or through the cardiac shadow. While the underexposed film, you can see the haziness of the higher shadows, also the appearance of the costophrenic angles, which are not clearly projected in this view.
In cases of mastectomies, and you can, if you look to the chest X-ray and you can see that the left breast has been removed, and that's why you can see some translucency, more translucency in the left lung compared to that of the right lung. And you see the shadow of the breast is superimposed on the lung base here on the right side.
Then, in order to know if the patient had full inspiration or not, and you should count the level of the diaphragm relative to the ribs. Then, number one, how to count the ribs? You start first by the biggest one, which is the first rib. This is the first rib, and this is the second rib, and this is the third one behind the clavicle, and this is the fourth one, the fifth, the sixth, the seventh, the eighth, the ninth, and tenth. And if you see that the diaphragmatic dome is at the level of the tenth rib posteriorly, then you assume that the patient had a full inspiration.
What happens if the patient did not have a full inspiration? Then you will see this is an inspiratory film, and this is an expiratory film. In the expiratory film, the diaphragm is high, and the transverse cardiac diameter is apparently increased because of the flattening of the cardiac shape.
In the lateral view, you should notice that the upper dorsal vertebrae are white, while the lower dorsal vertebrae are black. And that's because the upper dorsal vertebrae are superimposed by the shadows of the shoulders of the patient, while the lower dorsal vertebrae are superimposed by the lung bases containing air. Then, if you look to the lateral view and you don't see any difference between the upper dorsal vertebrae and the lower dorsal vertebrae, then you assume that there should be a lung base lesion that has been superimposed on the lower dorsal vertebrae.
Then, if you look to the frontal chest X-ray, and if you look carefully, then you see this opacity behind the heart, and this is left lower lobe consolidation or collapse, which has been projected over the lower dorsal spine, and this is the cause of being similar to the upper dorsal vertebrae.
Then, if you look to the chest X-ray and you want to know if the patient was centralized during radiography or not, then you put your finger on the spinous process of the dorsal vertebrae. Then you measure the distance between the spinous process and the medial edge of the left clavicle, and the same distance to the medial edge of the right clavicle. If the patient is not rotated, then the distance will be equal. But if the patient is rotated, then you put the mark on the spinous process and you look to the medial edges of the clavicle, and you can see the difference because of this rotation. You get one of the lungs is hyperlucent, and one of the lungs is veiled, because one of the lungs is closer to the film than the opposite lung. And before misinterpreting this as empyema or this as pneumonia, you should look carefully for the patient's position.
And if you have a pathology in the lung and you want to locate the pathology in a specific area of the lung, and you know that any radiograph is just a patient facing the physician, and then this is the left side of the patient, and this is the right side of the patient. Then the highest area in the lung is known as the lung apex. And the zone at the level of the hilum is known as the middle lung zone. The zone above it is the upper lung zone, and that is below it is known as the lower lung zone. Then, if you have a lesion here, and you say this is left middle lung zone, or here you say this is right lung apex, or here you say that this is the right lower lung zone lesion. But if you have a lateral view as well, then you should locate the lesion in a lobe, because you know that on the left side, there is a major fissure, on the right side, there is a major and minor fissure. Then, if the lesion is here, and this is left upper lobe. If the lesion is here, and this is the middle lobe. If the lesion is here, and this is the right lower lobe.
And this is a patient with recent cardiac surgery. You look to the sternotomy wires, with right-sided pleural effusion that has extended into the major and the minor fissures. Then you can easily appreciate the region of the upper lobe, the region of the middle lobe, and the region of the lower lobe.
Then we have some terminologies you should know. Number one is what is known as the silhouette sign. And the silhouette sign means that there is an opacity in the lung that has masked the cardiac border. Then, if you look to this opacity in the right lung, and you want to follow the right cardiac border, and you cannot do this through the opacity, then what does this mean? This means that the opacity is adjacent to the heart, and the heart is anteriorly located. Then the opacity is anteriorly located, and the anteriorly located region in the right lung is that of the middle lobe. Then you say that this is the middle lobe opacity without the need to have a lateral view. And in this case, you see an opacity here, and if you want to follow the cardiac border, you can easily do so. Then this opacity is not adjacent to the heart, it should be posteriorly located in the lower lobe.
Then let us make a test. And here is an opacity in the left lower lobe, and you can easily follow the cardiac border on the left side. That means that this opacity is posteriorly located, and this has been confirmed by the CT scan, and this is pneumonic consolidation. This is the fissure, and this is the heart, and this is the diaphragmatic dome, and the dome of the liver on the right side.
The second terminology is known as air bronchogram. And by air bronchogram, we mean that there are there is an opacity in the lung through which multiple linear air translucencies are seen, representing air-filled bronchi. Then, if you see this phenomenon, which is known as air bronchogram, you know that this opacity is of pulmonary origin, and it is of alveolar pathology, and it means that this is consolidation. And of course, pneumonia is one of the causes of consolidation. Pneumonia is one of the causes of consolidation and air bronchogram.
Then there are four other terminologies we want to know. The definition of a pulmonary nodule is a well-defined lesion which is less than 3 cm in diameter. The pulmonary mass is a well-defined lesion that is more than 3 cm in diameter. The pulmonary patch is an ill-defined lesion containing air bronchogram. The pulmonary cavity is a well-defined lesion containing air, whether this air is total or partial. Partial meaning there is some air-fluid level, as we will discuss soon.
Then, by this introduction, we are now able to try to interpret the chest X-ray. What to do? Then, number one, put the chest X-ray on the viewer and ensure optimal quality radiograph. How? The exposure factors, the level of the diaphragm, and the centralization of the patient. Then, number two, being a physician, then you should have the clinical data of the patient, the complaint, the symptoms, laboratory findings. Then, if you have the chance to have the previous films, this will be a good opportunity for you for comparison. And if you cannot reach the diagnosis from the plain films, you should have CT support.
Then, putting the chest X-ray on the viewer, you have to discriminate between two main pathologies. The first one is the focal lung lesion, and the second one is the diffuse lung disease. By focal lung lesion, we mean that we have a lesion or two or three or four, but the rest of the lung fields are clear or is clear. Then diffuse lung pathology means that both lung fields are involved by disease, diffuse involvement by disease.
Then, if you decided that you are dealing with a focal lung lesion, what are the possibilities? There are four: the nodule, the mass, the patch, and the cavity. The nodule is a well-defined lesion less than 3 cm in diameter. The mass is a well-defined lesion more than 3 cm in diameter. The patch is an ill-defined lesion containing air bronchogram. And the cavity is a well-defined lesion totally or partially containing air.
Then, if you decide that you are dealing with pulmonary nodule or nodules, what are the possibilities? If you open the books, you will see a major list of the differential diagnosis of pulmonary nodules. But actually, here we would like to put our fingers on the most common nodules seen usually in the clinical practice. And you can ask yourself the questions I will ask you during this talk and try to confirm to reach the facts during your clinical practice. The common nodules, which are well-defined lesions less than 3 cm in diameter, include the tuberculoma, the hamartoma, the bronchogenic carcinoma, metastasis, arteriovenous malformation, and the hydatid cyst.
Then, if you see multiple nodules in the lung, then this is the diagnosis of metastasis, even if you don't have the clinical data of the patient. But actually, if you have the clinical data and you know that the patient had the primary malignancy, like breast cancer, for example, renal carcinoma, then you can confirm the diagnosis that these nodules represent metastatic deposits. And the same case, if you see the nodules on CT, and these are multiple variable-sized pulmonary nodules, in the pleural effusion, these nodules should represent metastatic deposits. And metastasis may be large in the form of masses, and may be small in the form of nodules. Then a mixture of both does not exclude the possibility of metastatic disease.
Then, if you see a nodule with a smooth margin containing calcium, then you assume that this is a benign lesion. And on the top of these lesions, the tuberculoma and the hamartoma are in the differential diagnosis. And you see this is the nodule with a smooth margin containing some flecks of calcification. Then you think of a benign lesion, which may represent the hamartoma or tuberculoma. And this is also another nodule in the right lung base. And this nodule contains flecks of calcium with a smooth edge, and you think of a tuberculoma or hamartoma. Actually, the tuberculoma is usually seen in the apices of the lung and may be surrounded by reticular nodular infiltrations of the tuberculous inflammation. While hamartoma is usually located anywhere in the lung, it has a smooth margin and shows calcium. And this calcium sometimes stimulates the popcorn calcification. And this is a classic appearance of hamartoma in the right lung showing the classic popcorn calcification.
And if you see a nodule with a speculated margin, and the speculated margin means that the lesion is spreading through the adjacent lung parenchyma, and this is the bronchogenic carcinoma. Then, if you see a nodule with speculated margin like this, and you think of a bronchogenic carcinoma, whether this is the appearance on the CT scan or the X-ray, and this is the classic appearance of a bronchogenic carcinoma with the speculated margin in the right lung base.
And if you see a nodule which is containing water, and the water content cannot be confirmed unless you have a CT or ultrasound, and the nodule containing water in the lung is nothing but the hydatid cyst. The hydatid cyst is the only nodule or mass containing water in the lung. Then, whenever I say this, many of the attendees say, what about the lung abscess? And this is the difference between the hydatid cyst and the lung abscess. Actually, most of the lung abscesses contain some amount of air, and the wall of the abscess is very thick. It takes contrast enhancement whenever you inject the contrast media, while the wall of the hydatid cyst is relatively thin, and it does not enhance with contrast media. And hydatid cyst does not contain air unless it is ruptured or infected.
Then, if you see a nodule with water content in the lung, and you assume the possibility of hydatid cyst. And sometimes one may say, what about the unilocular pleural effusion in the fissure? It is actually a lesion containing water, but you should know that this is not a nodule, and it is not in the lung. This is an elliptical shaped lesion, and it is in the fissure. And this is the appearance on the chest X-ray of the unilocular effusion in the fissure.
Then, if you see a nodule which is connected to the hilum by two cord-like structures, and these cord-like structures represent the feeding artery and the draining vein, then you know that this nodule should represent an arteriovenous malformation. On the era before CT and MRI, if you see a nodule like this connected to the hilum by two cord-like structures, then the only way to confirm the diagnosis of an arteriovenous malformation is to insert a catheter in the pulmonary artery via the left femoral vein or the right femoral vein, then you inject contrast material into the pulmonary artery, then you are able to see the feeding artery, the AVM, and the draining vein. But nowadays, if you see a lesion like this and you suspect the possibility of an arteriovenous malformation, you have the multi-detector CT, inject contrast media intravenously, and you say to the machine, I would like to do a CT pulmonary angiograph. I will discuss this in the next lecture in detail. Then you see the feeding artery and the arteriovenous malformation as well as the draining vein.
Okay, if you see a nodule in the lung like this, then you want to answer four questions: What about the edge? Is it smooth or speculated? What about the calcium content? Is it containing calcium or not? What about the density? Is it solid or water-containing? What about the vascularity? Is there any vascularity or not? If you cannot answer the four questions, then you should have the support of CT. And this is the CT scan of the same case, and you can see that the nodule has typical speculated margin, diagnostic of a bronchogenic carcinoma.
Then, look at this nodule in the apex of the right lung, and you may feel that there are some speculations of the margin. Now let us see the CT scan of the same case. Actually, it has a speculated margin and it represents a bronchogenic carcinoma. And this is a third example of an asymptomatic female patient. She is a smoker, and her sister has just been diagnosed with lung cancer. Then the chest X-ray of this asymptomatic female shows a pulmonary nodule in the apex of the lung. One may say this is a smooth-edged lesion in the apex of the lung. It looks like a benign lesion. Let us say it is a tuberculoma. No. Then you should have a CT scan, and you see the irregular margin, diagnostic of bronchogenic carcinoma.
The fourth example, in the vicinity of the hilum, you are not sure about the vascularity, you are not sure about the edge. Then you should have a CT scan, and they see the speculated margin, and this is also a bronchogenic carcinoma.
Then we finish about the nodules. And the question is, ask yourself about, is there any nodule in the lung? You know, in the clinical practice, that is common so as to be seen once per year. Once per year during your clinical practice, if there is any nodule seen once per year in the clinical practice, you consider it common, and you put it into the differential diagnosis. Then you have seven, seven, seven possibilities, and you started to put some criteria for the seventh lesion to be differentiated from the rest of the six possibilities.
Then we came to the masses, and the masses are well-defined lesions that are more than 3 cm in diameter. Actually, the masses in the lung are only three: and these are the bronchogenic carcinoma of large size, the hydatid cyst of large size, and the metastatic deposit which is of large size. Then, if you see a mass like this in the lung, and you want to know one of these possibilities, then you should have a CT scan. If you see water content, then you are dealing with a hydatid cyst. And this is an example. You see a big mass here, and you do a CT scan, and you see water, then this is hydatid cyst. But if you have a mass like this, and you did the CT scan, and you see that the mass is solid, whatever the edge, and the mass is solid, meaning that this mass is one of two: bronchogenic carcinoma or metastatic deposit. Metastatic deposits are diagnosed by the clinical history of a known primary or by multiplicity. If there is no history of a known primary or the lesion is solitary, then you think of a bronchogenic carcinoma.
One may say that this bronchogenic carcinoma contains calcium, and calcium means benign. I say that calcium means benign in the nodule only, but calcium does not have a clinical radiological significance in the diagnosis of bronchogenic carcinoma as a mass. Then, if you see a mass like this, and needed a CT scan, the mass is solid, it contains calcium, does not make a difference, and this is a bronchogenic carcinoma. The mass has a smooth edge, does not make a difference, this is a bronchogenic carcinoma. And if you see a mass in the lung, and you see by CT scan that this mass is solid, then you consider a bronchogenic carcinoma if the patient is adult, because in the pediatric age group, there are other possibilities.
Then you see a mass in the apex of the right lung, and you did a CT scan, and you see that the mass is solid, and you are going to diagnose bronchogenic carcinoma, but you know from the history that the patient had breast carcinoma, then you think of metastatic deposit. And this patient had an osteosarcoma with a big mass containing calcium and breakdown in the right lung, representing metastatic deposit. And if you have a chest X-ray with multiple large lesions like this, you think of metastasis, and you confirm this by CT scan or by the known history of primary malignancy, like this male, 50 years old, with colonic cancer, and you see multiple masses and nodules in both lung fields, diagnostic of metastasis. And these are metastatic deposits in a patient with breast cancer, and these are metastatic deposits in a patient with non-seminomatous tumor of the testis.
And if you look to this case, and you see two lesions in the lung, and you are going to diagnose metastasis, and the patient had the CT scan, and both lesions contain water, then you are dealing with hydatid cyst. Then hydatid cysts can be multiple, and metastasis can be multiple. But whenever you think of which is common, hydatid cysts as multiple lesions in the lung, or metastasis, actually, you will know that metastasis are far common than hydatid cysts as multiple lesions in the lung. And if you see multiple lesions in the lung, you think of metastasis until proved otherwise.
Then we came to the patch, and the patch is an ill-defined lesion containing air bronchogram. And there are two possibilities: the pneumonia and the infarction. And actually, the differential diagnosis between pneumonia and infarction depends mainly on the clinical history, because both lesions will have an opacity in the lung associated with pleural effusion. But the history is different. Pneumonia will present by fever, cough, and expectoration. Infarction will present by acute chest pain and hemoptysis. And you can easily identify the source of the thrombus in the leg of the patient, for example.
Then you remember that in obesity with air bronchogram means consolidation, and pneumonia is one of the causes of consolidation. In the lung, there are five causes, it depends on the material replacing air inside the alveoli. Actually, if you remove air and you put fluids, then you are diagnosing alveolar edema. If you remove air and put exudate, and this is the pneumonia. You put blood, and this is hemorrhagic lung disorders. And you put tumor cells, and this is alveolar cell carcinoma. And you put proteins, and this is alveolar proteinosis. Actually, most of these lesions occur in the diffuse pattern, and they will be discussed in full detail in the topic of diffuse lung disease. But here, we are discussing the difference between pneumonia and infarction, the focal patch in the lung. If you see a patch like this with air bronchogram, then you think of pneumonia. If you don't have the full history, because pneumonia is much, much more common than infarction.
And this is the case of a patient with fever and expectoration. There is some opacity in the right lung base, confirmed by CT scan as pneumonia. And the follow-up CT after antibiotic therapy showed resolution of the lesion. Actually, for the diagnosis of pneumonia, you don't need the help of CT in most of the cases. And this is the patient with a patch in the left lung base, and this patch is projected posteriorly over the spine, meaning that it is in the lower lobe. After antibiotic therapy, a 1-month follow-up X-ray showed total resolution of the lesion. And this is the lesion in the left lung base. And by the silhouette sign, you are sure that this lesion is in the lower lobe, posteriorly located. And this has been confirmed by the lateral view, and you see the lesion is posteriorly located, and this is pneumonia of the lower lobe.
Then this is pneumonia of the right upper lobe, the lesion with air bronchogram inside, and this is diagnostic of pneumonia. But if you see a lesion which is wedge-shaped and pleural-based and in the right lung base, and is associated with ipsilateral pleural effusion, don't diagnose this as an infarction unless you have the clinical history of an infarction, because most of these lesions will be due to pneumonic consolidation.
When to diagnose this as an infarction? If you have the CT scan, and you can see the filling defect within the pulmonary artery as a filling defect, and also you can appreciate that the pleural effusion, which is an associated finding. And in this case, you see here a 43-year-old patient with acute chest pain and hemoptysis, suggestive of pulmonary embolism. The CT scan showed a filling defect in the left main pulmonary artery with three patchy opacities in the left lung, and these are multiple infarcts with ipsilateral pleural effusion.
And finally, we came to the possibility of the cavity. The cavity is a well-defined lesion which is partially or totally containing air. Then the cavity may have a thick wall, or the wall may contain air only, air-fluid level, or air and mass. What are the diagnostic possibilities of each of these? We start first by the cavity which is containing air. And the cavity containing air, the differential diagnosis depends on the thickness of the wall. If the wall is thick, you have two possibilities. If the wall is thin, you have two other possibilities. The thick wall cavity containing air in the lung is diagnostic of a chronic lung abscess. And the abscess starts with a lot of pus, few air loculi, then air will increase, and pus will decrease until you are left with a cavity totally filled with air, which is diagnostic of the chronic lung abscess.
Then this is the chronic lung abscess with thick wall and containing air, both in the plain film and in the CT scan. What is the second possibility of a thick wall lesion containing air? And this is the cavitating bronchogenic carcinoma or the tumor with central breakdown. And this is the bronchogenic carcinoma that has developed central necrosis, and the patient has coughed the tumor shreds, then you are left with a cavity with thick margin and containing air. What is the difference between lung abscess and the breakdown in tumor? It is the inner wall of the lesion. The inner wall of the tumor is extremely irregular, while the inner wall of the abscess is smooth, and this is the difference. This is the abscess with a smooth inner margin, and this is the bronchogenic carcinoma with irregular inner margin. And this is the sequence of events concerning lung abscess: the acute phase, little amount of air, a lot amount of pus, then air will increase and pus will decrease until you are left with the chronic lung abscess, totally filled with air, with thick margin and smooth inner wall.
If the wall is thin, and you have two other possibilities, which are the hydatid cyst if the lesion is located in the center of the lung, and the atelectasis bulla if the lesion is located against the chest wall or pleural base. Then, if the wall is thin, the lesion is in the center of the lung, this is the hydatid cyst, peripherally located. And this is atelectasis bulla. And this is a good example of emphysema in the apex of the right lung. And this is what we call chronic obstructive pulmonary airway disease with hyperinflated chest, low flat diaphragm, re-shaped heart, enlargement of the hilar shadows, peripheral attenuation of the vascular markings. And I will discuss this in full detail in the topic of diffuse lung disease. Then, this chronic obstructive airway disease may be associated with emphysematous bullae or not. And you see here gross multiple emphysematous bullae in both lung fields, both in the lateral and the frontal view.
Then, if you have a cavity with air-fluid level, this is the abscess, provided that the fluid level is straight. And if you see a cavity with a straight air-fluid level, and you think of an abscess, but if the air-fluid level is wavy or not straight like this one, what we call the water lily sign, and this is the hydatid cyst which has been ruptured, because the daughter cyst of the hydatid cyst will try to float on the surface of the fluid level, and so the surface of the fluid level will not be straight. And this is the classic appearance of a ruptured hydatid cyst with the wavy air-fluid level, diagnostic of ruptured hydatid cyst. And this is the classic appearance of a lung abscess with a straight air-fluid level in the right lung.
Then, if you see a cavity with a mass inside, and this is the fungus, and what we call the fungal ball, the mycetoma, or the aspergilloma. And actually, this aspergilloma will arise on top of a chronic pre-existing cavitary lesion in the lung, usually of tuberculous etiology, and it is usually located in the apex of the lung, as you can see here in this example by CT scan of a cavity with a ball inside, representing mycetoma, aspergilloma, or fungal ball.
So, if you look carefully to this cavity, and you see that this cavity has a thick margin with an irregular wall, then you think of malignancy. And that diagnosis will not change if there is a ball inside the cavity, because this ball can be easily explained on the basis of the shreds of the tumor before being expectorated. Then, if you see a cavity in the lung fulfilling the criteria of malignancy, which are thick margin and irregular inner wall, whatever the content of this cavity, you should diagnose malignancy, if the cavity is containing air or a ball or a fluid level. Then you think of malignancy, provided you have these two criteria, which are thickness of the margin, regularity of the inner wall.
The rest of the differential diagnosis of a cavity containing a ball are the ruptured hydatid cyst and the blood clots. Actually, you cannot reach the diagnosis of blood clots from the films unless you have the MRI examination, sometimes it provides some signal which is specific for blood. And the hydatid cyst, whenever it ruptured, it ruptured in two ways: the slow rupture will result in collapse of the daughter cyst into the original cavity, forming a ball, and this is rarely seen in the clinical practice. But acute rupture will result in air-fluid level which is wavy in appearance.
Then, if you see a lesion like this, a cavity with air-fluid level in the plain film, actually most of the cavities in the lung containing air-fluid level are secondary to abscesses, and abscess is far, far common compared to a cavitating bronchogenic carcinoma with a fluid level. But if you have a feeling of suspicion against the wall of the lesion and the irregularity of the inner margin, and you should confirm this by the CT scan, and don't jump for the diagnosis of cavitating bronchogenic carcinoma from the plain film unless you are sure about the age and the irregularity of the inner margin.
And I thank you very much.