3. Chest Radiography Interpretation

Question 1

What is the most frequently requested radiological examination?

Answer 1

chest radiography

Question 2

What is the role of chest radiography?

Answer 2

to exclude or confirm lung pathology

• visualize inserted lines/tubes (deep venous lines, tracheal tube, gastric tube)
• visualize the heart and its vessels
• examine the mediastinum (ie. lymphadenopathy)
• diagnose pathologies related to ribs/vertbrae and soft tissues (subcutaneous emphysema)

Question 3

What are the types of chest radiography?

Answer 3

• conventional two-view radiograph: postero-anterior (PA) + lateral views
• portable antero-posterior radiograph: AP view

Question 4

When is AP chest radiograph used?

Answer 4

when the patient cannot be safely mobilized, so the film is placed under their back (in supine position) with the X-ray source coming from above

Question 5

Which is the preferred type of chest radiography and why?

Answer 5

• PA view is preferred because there is less magnification and distortion, since the chest is closer to the film
• AP view should only be used in ICU, because it magnifies the heart and widens the mediastinum

Question 6

Why is the lateral view useful in chest radiography?

Answer 6

• fluid levels equal to or above 50-100mL can be visible on lateral view
• whereas, on PA view, fluid levels need to reach 200-300mL to be visible

Question 7

What is the use of lateral decubitus view?

Answer 7

• lateral decubitus view is when the patient is laying on their side, the film is in front of the chest and the X-ray source comes from behind
• it is helpful to visualize pleural effusion
• differentiate between mobile or loculated pleural effusion

Question 8

How to check for technical adequacy in chest radiography?

Answer 8

• the thoracic spine should be visible through the heart shadow, suggesting good penetration
• patient should be examined in full inspiration (except PTX)
• diaphragm at the level of 10th-11th rib suggests excellent inspiration
• symmetrical clavicles suggest no rotation
• no angulation of X-ray (the clavicles shouldn’t project at or above the first rib)

Question 9

How to analyze a chest X-ray?

Answer 9

1. check age, sex, anamnesis, and older films
2. use a spiral method: outside to center (extrathoracic structures, diaphragm, sinuses, lung parenchyma, hilus, mediastinum)

Question 10

Which areas need special attention of chest radiography?

Answer 10

areas in which the pathology can be easily overlooked

• apical zones
• hilar zones
• retrocardial zone
• zone below the diaphragmatic dome

Question 11

What is the cardiothoracic index?

Answer 11

ratio of the maximal horizontal cardiac diameter to maximal horizontal thoracic diameter

• ratio greater than 50% suggest cardiomegaly
• should NOT be measured in AP view!!

Question 12

What is the meniscus sign on chest radiograph?

Answer 12

• costodiaphragmatic angle cannot be seen
• pleural fluid (at least 200-300mL) results in radio-opacity of the lung
• fluid filling is in the shape of a meniscus

Question 13

How are small amounts of pleural fluid detected?

Answer 13

• CT and US
• US is useful in guiding the removal of pleural fluid
• CT is useful to evaluate underlying disease

Question 14

What is a white lung on chest radiograph?

Answer 14

• white lung can be atelectasis (collapse or incomplete filling of lung) or pulmonectomy
• there is a pulling of the mediastinum, so it is no longer on the midline
• large effusion can push the mediastinum away
• in case of pneumonia, there is no mediastinal shift

Question 15

What are the signs of pneumothorax?

Answer 15

• on chest X-ray the visceral pleura is visible (separates from the parietal pleura)
• small pneumothorax can only be diagnosed by CT but lung windowing is necessary for air detection

Question 16

Signs of lobar pneumonia

Answer 16

• consolidation
• aerobronchogram
• visible fissure

if no resolution after antibiotics, there is suspicion of bronchoalveolar carcinoma

Question 17

What is the basket sign in chest x-ray?

Answer 17

• classic sign of lung abscess in radiography
• pyogenic abscesses can be caused by staphylococcus/klebsiella infection
• cavitating mass can also be due to tuberculosis, fungal infection, squamous cell carcinoma

Question 18

Chest radiography in case of interstitial pulmonary disease/edema

Answer 18

• causes: viral pneumonia, sarcoidosis, fibrosis, pneumoconiosis
• “batwing” or “butterfly” sign: bilateral perihilar opacities due to lung edema
• in case of worsening conditions, there is perihilar consolidations
• cephalization: pulmonary veins in the superior zone are dilated

Question 19

Chest radiography of severe (alveolar) lung edema

Answer 19

• causes: bacterial pneumonia, ARDS (acute resp. distress syndrome), IRDS (infant resp. distress syndrome), bronchioalveolar carcinoma, pulmonary hemorrhage
• aerobronchogram: air filled bronchi with opacified alveoli (collapsed alveoli)
• pathological airspace: something other than air fills the alveoli

Question 20

What are the stages of pulmonary edema?

Answer 20

1. cephalization
2. pulmonary interstitial edema
3. pulmonary alveolar edema

Question 21

What are the radiological signs of heart failure?

Answer 21

• fluid in lung fissures
• Kerley B lines
• prominent upper lobe arteries
• fluid in the lung interstitium
• pleural effusion

Question 22

What are the types of diseases affecting lung parenchyma?

Answer 22

1. airspace (alveolar) disease
2. interstitial (infiltrative) disease

Question 23

What causes pathological airspaces?

Answer 23

something other than air filling the alveoli, appearing as fluffy, hazy, cloudlike/poorly marginated airbronchogram

• transudate: alveolar pulmonary edema
• blood: pulmonary hemorrhage
• gastric juice: aspiration
• inflammatory exudate: pneumonia
• water: near-drowning

Question 24

What are examples of interstitial lung diseases?

Answer 24

can be focal or diffuse, appearing with sharp/discrete margins and no airbronchogram

1. interstitial pulmonary edema
2. interstitial pneumonia
3. lymphangitic carcinoma
4. fibrosis
5. pneumoconiosis

Question 25

How are interstitial pulmonary alterations best visualized?

Answer 25

determined by high resolution non-contrast CT

Question 26

How does COVID 19-pneumonia look on chest radiography?

Answer 26

• decreased transparency leading to a ground glass opacity on chest X-ray, with bilateral/perihilar involvement
• decreased transparency on CT imaging too

Question 27

Chest radiography of solitary pulmonary nodule

Answer 27

• causes: granuloma, neoplasm, hamartoma, round pneumonia, AVM (arteriovenous malformation)
• criteria for benignity: lack of growth over 2 years, benign calcification
• malignant nodules/masses are characterized using contrast-enhanced CT

Question 28

Radiography of pulmonary mass

Answer 28

• pulmonary mass can be a suspicious of lung cancer
• if there is suspicion of lung tumor, CT should include the adrenal glands because 50% of lung tumors metastasize to the adrenal glands
• site of preference for multiple lung metastasis is the base of the lung due to higher perfusion