Chest X-ray interpretation (DRE) Prof. Mamdouh Mahfouz

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 of the 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. We start with one of the most important lectures at all in the radiology specialty, which is how to interpret the chest X-ray. This lecture actually is 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. As you all know, the chest X-ray is a very simple radiographic technique and is of relatively low cost. Meanwhile, it is relatively sensitive, providing excellent resolution and good differential diagnosis for most of the intrathoracic conditions. Then, in order to interpret the chest X-ray, we should know the criteria of the optimal chest X-ray. This 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. You all know, especially the radiologists, that the most popular chest X-ray at all is known as the PA view, and the PA view is the posteroanterior view. 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, this is a posteroanterior view. If the patient is facing the X-ray tube, this is an anteroposterior view. Then, one may ask, what is the difference between both? Here is the difference: this is the posteroanterior view, and this is an anteroposterior view. You know that the cardiac shadow is anteriorly located in the thorax. Then, in the posteroanterior view, the heart is near to the film, so there is 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. This is very well demonstrated here. This is the posteroanterior view, and this is the anteroposterior view of the same patient. 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 shadow. 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. 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. 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. 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 shadow. Here 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. The decision of the lateral view is usually based on the appearance of the chest in the frontal view. If the pathology is in the left lung, you should have the left lateral. If the pathology is in the right lung, you should have the right lateral view. While interpreting the chest X-ray, you should know that there is some difference between the level of the diaphragm on both sides. This indicates that the right hemidiaphragm is relatively high compared to the left one by a distance ranging from 1 to 3 cm. If you look at 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. 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. Nowadays, we do not use this projection; instead, we use ultrasound. We put the ultrasound in the region of interest and you can see minimal fluid in the costophrenic angle. This is the liver, of course, and here you can see the diaphragm. The lordotic view is obtained in the anteroposterior projection by tilting the patient about 45° relative to the X-ray beam. The main value of this lordotic view is to displace the shadow of the clavicle away from the area of the lung apex. You can see this is the lordotic view, and the shadow of the clavicle is not covering the apex of the lung. If there are any infiltrations, minute lesions, or calcifications, they can be clearly visualized. 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 apex of the lung. One of the values of the lordotic view is to augment the appearance of middle lobe lesions. Here 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. If you look at the chest X-ray, you can easily appreciate if this is a well-exposed film or an overexposed one like this or underexposed like this. Optimal exposure will display the lung fields, the lung markings, the cardiac shadow, and the costophrenic angles. Overexposure will project the lung fields very dark, and you can also see the thoracic vertebrae across or through the cardiac shadow. In the underexposed film, you can see the haziness of the higher shadows and the appearance of the costophrenic angles, which are not clearly projected in this view. In cases of mastectomies, if you look at the chest X-ray, you can see that the left breast has been removed, and that's why you can see more translucency in the left lung compared to that of the right lung. You see the shadow of the breast is superimposed on the lung base here on the right side. In order to know if the patient had full inspiration or not, you should count the level of the diaphragm relative to the ribs. Number one, how to count the ribs: you start first by the biggest one, which is the...

things to be covered in this particular domain but actually I am preparing now some of the new lectures and also some of the lectures are already present but they will be projected in the sector of pediatric radiology and these uh topics

will include the Imaging of hydrus Imaging of neuronal migration disorders and imaging of cerebrovascular stroke in the Pediatric Group also uh Imaging of pediatric brain tumors and pediatric intracranial infection now let start that sector of chest Imaging and it contains about 11

lectures uh we will cover through this uh these lectures most of the issues concerning with the thic pathology and we start with one of the most important lectures at all in the uh Radiology uh speciality which is how to

interpret the chest xray and this lecture actually is very beneficial for every person who is working in the medical field including all physician s and even the paramedical stuff and this is essential in their uh daytoday PRS then uh the interpretation of a CH xray

is a little bit uh uh let us say it's not that difficult but it needs some uh special protocol or in a simplified way in order to reach most of the values of this very simple uh radiographic technique and as you all

know that the chest xray is a very simple radiographic technique and is of relative low cost meanwhile it is uh relatively sensitive providing excellent resolution and good differential diagnosis for most of the intra thcs then in order to interpret the

chest x-ray we should know the criteria of the optimal chest x-ray this criteria include accurate patient positioning while being radiographed and instructing the patient to have full inspiration before taking the uh 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 uh parameters in details while you are not attending the technique of a chest radiography then we should go first for

some of the uh uh let us say radiographic terminologies and the you all know especially the radiologist that the most popular chest x-ray at all is known as the ba view and the ba view is the postero anterior 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 an poster anterior if it if the patient is facing the X-ray

tube and this is an anop posterior view then one may ask what is the difference between both and here is the difference this is in the poster anterior View and this is an Antro posterior View and you know that the cardiac Shadow is

anteriorly located in the thorax then in the post anterior view the heart is near to the film no magnification but in the anop posterior view the heart is away from the film then you should expect a some of magnification in the size of the

heart and this is very well demonstrated here this is the post anterior View and this is the anop posterior view of the same patient and can see here that 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 uh x-ray F then uh there are also some differences between the erect position

and the chest in the soine position and direct position the patient is able to have full in insiration then you can uh you can have accurate assessment of the cardiac shut but in the spine 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 uh intensive care units and the casuality areas where the patient is usually radiographed in the suine position and

in the anop posterior view then in these conditions you should assume that the heart will be will be enlarged or appear as if it is enlarged because of the sub position and the anro posterior 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 uh size Shadow 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 uh the side of Interest then this side will be close to the F 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 xray

you should know that there is some difference between the level of the diaphragm on both sides and this indicates that the right cabula is relatively High compared to the left one by a distance ranging from 1 to 3

cm then um if if you look to the frontal chest xray and you can see some obliteration of the costophrenic angle and you suspect the presence of plural fusion and in the lateral view you also see some obliteration of the posterior

costophrenic angle by plural fluid uh 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 plural fluid will track into the plural uh cavity and you can

confirm the diagnose actually nowadays we do not use this projection instead we use the ultrasound and we put the ultrasound in in the region of interest and you can see minimal fluid between the in the costophrenic angle and this is the liver

of course and here you can see the diaphragm then uh the lordotic view is obtained in the Antro posterior projection is tilting the patient about 45° 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 AIC then you can see this is the lordotic view and in the shadow of the clavicle is not covering the AIC of the lung and if

there is any infiltrations minute lesions calcification can be clearly visual visualized and this is also an example of the normal chest poster anterior View and the lordotic view displacing the clavicular Shadows away from the field of view in the AIC of the

lung also one of the values of the lordotic view is to augment the appearance of middle Lo Legions and you know here this is the frontal chest xray and you see an opacity in the middle L which is relatively projected anteriorly

in the lateral view the lordotic view clearly demonstrates the lesion in the middle Loop then if you look to the chest xray and you can easily appreciate if this is a well exposed film or an over exposed like this or underexposed

like this optimal exposure will display the lung Fields the lung markings the cardia Shadow the costophrenic angles overexposure will uh will project the lung feels very dark and you can see also the thoracic vertebrae across or through the cardiac CH while the

underexposed film you can see the haziness of the uh of the higher Shadows also the uh the appearance of the costophrenic angles which are not clearly projected in this view in the uh in cases of mastectomies and you can if you look to the chest

xray and you can see that the uh 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 uh in order to know if the patient had full inspiration or not and you should uh 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 10th the and if you see that the diaphragmatic Cula is at the level of the 10 three posteriorly then you assume that the patient had a full inpiration 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 di is apparently increased because of the

flattening of the cardiac shap in the lat 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 door C verteb and the lower door C verteb then you assume that there

should be a lung based leion that has been superimposed on the lower dorsal vertebrae then if you look to the uh frontal chest xray and if you look carefully then you see this opacity behind the heart and this is lift lower

Lop consolidation collapse which has been projected over the lower dorsal spine and this is the the cause of being similar to the Upp dorsal vertebrae then if you look to the chest xray and you want to know if the patient

was centralized during radiography or not then you put your finger on the spinus process of the dorsal vertebrae then you measure the distance between the spinal proces and the medial edge of the LIF clavicle and the same distance

to the medial edge of the right clav if the patient is not rotated then the distance will be uh at both distances will be equal but if the patient is rotated then you put the uh mark on the

spinus process and you look to the medial edges of the clavicle and you can see the difference because of this rotation you got one of the lungs is hyper translucent and one of the lungs is veiled because one of the lungs is

closer to the fil than the opposite lung and before misinterpreting this as empyema or this as pneumonia you should look carefully for the patient 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 aex and the zone at the level of theum 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 AIX or here you say that this is the right lower lung Zone

Legion but if if you have a lateral view as well then you should locate the Legion in a lob because you know that on the left side there is a major Fisher on the right side there is a major and

minor Fisher then if the legion is here and this is left upper L if the legion is here and this is the middle L if the legion is here and this is the right lower L and this is a patient with

recent cardiac surgery you look to the stomy wire switchers with right sided plural infusion that has extended into the major and the minor fishion then you can easily appreciate the region of the upper Loop the region of the middle Loop

and the region of the lower loop then we have some terminologies you should know number one is what is known as the silhouette sign and the silouette 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 means 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 L then you say that this is the middle L 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 loop then let us make a test and

here is an opacity in the left lower long Loop 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 C scan and this is pneumonic

consolidation this is the fissure and this is the heart and this is the diaphragmatic copula and the do 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 translucens is are seen representing airfill brona then if you see this phenomena which is known as air bronchogram you know that this opacity is of pulmonary origin and it is of alv

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 of consolidation and air bronchogram then there are four other terminologies we want to know the

definition of a pulmonary nodule is the well defined Legion Which is less than 3 cm in diameter the pulmonary mass is a well defined Legion that is more than 3 cm in diameter the pulmonary badge is an ill defined Legion containing air

bronchogram the pulmonary cavity is a well find Legion containing air whether this air is uh 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 xray what to do then number one put the chest xray on the viewer and ensure optimal quality radiograph how the exposure factors the level of the diaphragm and the 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 Blain films you should have the CT support then putting the chest xray on the viewer you have to discriminate between two main pathologies the first one is the focal

lung leion and the second one is the diffused lung disease by focal lung leion we means that we have a lesion or two or three or four but the rest of the lung fields are clear or is clear the then diffus lung pathology

means that both lung fields are involved by disease diffus involvement by disease then if you decided that you are dealing with the focal lung Legion what are the possibilities there are four the ndule the mass the batch and the cavity the

nodule is a well defined region Less Than 3 cm in diameter the mass is a well defined Legion more than and 3 cm in diameter the badge is an IL defined Legion containing air bronchogram and the cavity is a well defined Legion

totally or partially containing air then if you decide that you are dealing with pulmonary nodule or nules what are the possibilities if you open the books you will see a measure list of the differential diagnosis of pulmonary no

but but actually here we would like to put our fingers on the most common uh nodules seen usually in the clinical practice and you can ask yourself the questions I will ask you during this talk and try to conf to to reach the the

facts during your clinical practice the common nodules which are well defined Legion Less Than 3 cm in diameter include the tuberculoma the Homa the bronchogenic carcinoma metastasis arterial venous malformation and the hydrated syst then if you see multiple nules 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 Reen carcinoma

then you can confirm M diagnoses that these nules represent metastatic the and the same case if you see the nules on CT and these are multiple variable size pulmonary nodules in the plural Fusion these nodules should represent metastatic deposits and

metastasis may be large in the form of masses and may be small in the form of no then a mixture of both does not uh does not uh I mean cannot exclude the possibility of metastatic disase then if you see a Nole

with a smooth margin containing calcium then you assume that this is the Bine Legion and in on the top of these Legions the tuberculoma and the hamoma are in the differential diagnosis and you see this is the Nole with a smooth

margin containing some Flex of calcification then you think of a benign Legion which may represent the Boma or hamon and this is also another ndule in the light in the right lung base and this nodule contains fi of calcium with

a smooth edge and you think of a tuoma or hmer actually the tuoma is usually seen in the ABCs of the lung and may be surrounded by reticular nodular infiltrations of the tuberculous inflammation while hamoma is usually is

is located anywhere in the lung it has a smooth margin and shows calcium and this calcium sometimes stimulate the popcorn calcification and this is a classic appearance ofoma in the right lung showing the classic popcorn calcification and if you see an f with

the speculated margin and the speculated margin means that the legion is is spreading through the adjacent lung binka and this is the bronchogenic carcinome then if you see anule 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 L base and if you see a module which is containing water and the water content

cannot be confirmed unless you have a CT or ultrasound and the Nole containing water in the lung is nothing but the hydrated cyst the hydrated cyst is the only Nole or mass containing water in the lung then whenever I say this many of the

attend uh the candidate say what about the lung abs and this is the difference between the hydrated cist and the lung ABS actually the lung most of the lung abses contain some amount of air and the W of

the absis is very thick it takes contrast enhancement whenever you inject the contrast media while the wall of the hydrated Cy is is relatively thin and it does not enhance with contrast media and hyst does not contain air unless it is

ruptured or infected then if you see a Nole with water content in the lung and you assume the possibility of vated cyst and sometimes one may say what about the insisted plural effusion in the fishion it actually a lesion containing water

but you should know that this is not an odule and it is not in the lung this is an elliptical shaped leion and it is in the fissure and this is the appearance of the BL exray of the insisted

diffusion in the fish then if you see anule 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 nulle should represent an

arterial venus malformation on the uh era before CT and MRI if you see a nule like this connected to the Highland by two cord like structures then the only way to confirm the diagnosis of an arter Venus 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 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 arterovenous malformation you have the multi- detector City inject to 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 to in details then you see the feeding artery and the arenus malformation as as well as the draining vein okay if you see a module 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 contain what about the vascular bicin is there any vascular

bical 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 carcinome then look at this nodule in the aex of the right lung and you may feel that there is some speculations of the Marg now let us see the CT scan of the same case actually the has a speculated margin and it

represents a bronchogenic carcinome and this is a a third example of asymptomatic female patient she is a smoker and her sister has just been diagnosed with Lan then the chest exray of this asymtomatic female show pulmonary nul in the a of the lung one

may say this is the smooth edge Legion in the abic of the lung it looks like a bile Legion let us say it is a tuberculoma no then you should have a city scan and you see The Irregular

margin diagnostic of the bronchogenic carcinome the fourth example in near the Highland you are not sure about the vascular bical you are not sure about the edge then you should have the C scan and they see the speculated margin and

this is also a bronchogenic carcinome then we finish about the nudes and the question is ask yourself about is there any nle in the lung you know in the clinical PRS that is common so as to be seen once per year once per year during

your clinical practice if there any Nole 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 uh uh seven possibilities and you started to uh uh

put some criteria for the seventh Legion to be uh differentiated from the rest of the six props then we came to the masses and the masses are well defined Legions that are more than 3 cm in diameter actually the

masses in the lung are only three and these are the BR ogenic carcinoma of large size the hyd Cy 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 city scan if you see water content then you are dealing with a hydrated CST and this is an example you see a big

Mass here and you do a city scan and you see water then this is Hy syst but if you have a the 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 depos metastatic deposits are diagnosed by the clinical history of a know primary or by multiplicity if there is no history of a non primary or delion

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 a radiological significance in

the diagnosis of bronchogenic carcinoma as a mass then if you see a mass like this and needed a it is SC the mass is solid it contains calcium does not make a difference and this is a bronchogenic carcinome the mass has a smooth edge

does not make a difference this is a bronchogenic carcinome 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 posits then you see a mass in the abex of the right lung and you did a c 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 that re carcinome then you think of metastatic the bosle and this patient had an osteosarcoma with a big Mass containing calcium and break down in the right lung representing

metastatic deposit and if you have a chest xray with multiple large lesions like this you think of metastasis and you confirm this by C scan or by the known history of primary malignancy like this male 50 years old

with colonic cancer and you see multiple masses Andes in post lung field diagnostic of metastasis and these are metastatic deposits in a patient with breast cancer and these are metastatic deposits in a patient with nonseminomatous tumor of the tests 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 Legions contain water then you are dealing with hydrated Cy then hyst can be multiple and metastasis can be

multiple but whenever you think of which is common hydrated cists as multiple lesions in the lung or metastasis actually you will know that metastasis are far common than hydr cyst 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 batch and the batch is an IL defined Legion 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 Legions will have an opacity in the lung associated with plural Fusion but the is different pneumonia will present by fever cuff and exporation infarction will present by acute chest pain and

hopsis and you can easily identify the source of Uli 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 rep placing air inside the Alvi actually if you remove air and you put fluids then you are uh diagnosing alular edema if you remove air and put exate and this is the pneumonia you put blood

and this is hemorragic lung disorders and you you put tumor cells and this is alular cell carinoma and you put proteins and this is alol proteinosis actually most of these Le occur in the diffuse pattern and they will be

discussed in full details in the topic of diffus lung disease but here we are discussing the difference between pneumonia and inection the focal bon in the lung if you see a batch 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 infection and this is the case of of a patient with fever and exporation there is some obesity in the right lung base confirmed by CTS

pneumonia and the followup 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 batch in the left lung

base and this patch is projected posteriorly over the spine meaning that it is in the lower after antibiotic therapy a 1 month follow up xray show total resolution of the leion and this is the leion in the left lank base and by the silhouette

sign you are sure that this lesion is in the lower Lop posteriorly located and this has been confirmed by the lateral View and you see the legion is posteriorly located and this is pneumonia of the lower loop then this is

pneumonia of the right upper Loop Lo the region with air bronchogram inside and this is diagnostic of pneumonia but if you see Aion which is wedge shaped and plural based and in the right lung base and is associated with Epsy lateral

plural diffusion don't diagnose this as an infarction unless you have the clinical history of an inection because most of these lesions will uh be due to pneumonic consolidation when to diagnose this as an infarction if you have the CT scan

and you can see the implus within the pulmonary artery as a faing defect and also you can appreciate that the plural Fusion which is an an Associated finding and in this case you see here A M 43 years old patient with acute chest

pain and hemoptisis suggest itive of pulmonary embolism the C scan showed and feeling defect in the left main pulmonary artery with three baty opties in the left lung and these are multiple infections with its lateral plural diffusion and finally we came to the

possibility of the cavity the cavity is a well defined Legion which is partially or totally containing air then the cavity may have thick wall or 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

whole if the wall is thin you have two other the thick uh wall cavity containing air in the lung is diagnostic of a chronic lung absis and the absis starts with a lot of bus few air loculi then air will increase and bus will

decrease until you are lift with a cavity totally filled with air which is diagnostic of The Chronic lung absis then this is The Chronic lung absis with thick wall and containing air both in the Blain film and in the CD

scan what is the second possibility of a thick wall Legion 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 cuffed the

tumor shreds then you are left with a cavity with thick margin and uh containing air what is the difference between lung absis and the breakdown in tumor it is the inner wall of the Legion the inner wall of the tumor is extremely

irregular while the inner wall of the absis is smooth and this is the difference this is the absis with a smooth inner margin and this is the bronchogenic carcinoma with ir regular inner margin and this is the sequence of

events concerning lung absis the acute phase little amount of air a lot amount of bus then air will increase and bus will decrease until you are left with the chronic lung absis totally filed with air with thick margin and dis smoth

inner wall if the wall is thin and you have two other possibilities which are the lato seal if the legion is located in the center of the lung and the aysus baa if the legion is located against the

chest wall or plural BAS then if the wall is thin the lesion is in the center of the lung this is the Neato peripherally located and this is Inus bua and this is a good example of enimine in the AIC of the right lung and

this is what we call chronic obstructive pulmonary airway disease with hyperinflated chest low flat diaphragm Reon shaped heart enlargement of the higher Shadows peripheral attenuation of the vascular markings and I will discuss this in full details in the topic of

diffused lung disease then uh this uh chronic obstructive airway disease may be associated with infmus bully or not and you see here gross multiple infmus bully 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 absis provided that the fluid l is straight and if you see a cavity with a straight air fluid level and you think of an AIS but if the air fluid level is wavy or uh uh not straight like this one

what we call the water lily sign and this is the hydrated cyst which has been ruptured because the doter cyst of the hydrated cist 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 rupture di that assist with the wavy air fluid level diagnostic of rupture di system and this is the classic appearance of a lung absis 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 motoma or the Asom and uh actually this asula will arise on top of a chronic pre-existing cavitary

Legion in the lung usually of tuberculous itology and it is usually located in the aex of the lung as you can see here in this example by CT scan of a cavity with a bowl inside representing motoma asula or fungal bone

so if you look carefully to this cavity and you see that this cavity has a thick march with in our irregular wall then you think of malignancy and that diagnosis will not change if there is a bowl inside the cavity because this poow

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 IR regular inner wall whatever the content

of this cavity you should diagnose malignancy if the cavity is containing air or a bowl 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 rupture died cist and the blood clots actually you cannot reach the diagnosis of blood clots from the FMS unless you have the uh Mr examination

sometimes it provides some signal which is specific for blood and the hydrated cyst whenever it ruptured it ruptured in two ways the slow rupture will result in collapse of the ocy into the original cavity forming a bowl 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 Blain fil actually most of the cavities in the lung containing air

fluid level are secondary to abses and absis is far far common compared to a cavitating bronchogenic carcinoma with a fluid level but if you have a feeling of Suspicion against this wall of the Legion 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 Blain film unless you are sure about the age and the irregularity of the uh inner margin and

I thank you very much