Medical Imaging: Lung Pathology

Question 1

How many acini per 2° pulmonary lobule?

Answer 1

3-5

Question 2

Secondary pulmonary lobule diameter

Answer 2

1.5-2cm

Question 3

What is the basic lung unit visible on HRCT?

Answer 3

Secondary pulmonary lobule

Question 4

Which vessels are located centrally vs peripherally in secondary pulmonary lobules?

Answer 4

Central: Artery and bronchiole
Peripheral: Lymphatic and vein

Question 5

What can cause interstitial opacity on CXR?

Answer 5

• Interstitial thickening
• Filling of intersitium with fluid or cells

Question 6

What can cause alveolar opacity on CXR?

Answer 6

• Alveoli fill with fluid or cells or extra air

Question 7

Does lung consolidation refer to alveolar or interstitial opacity? What substances can accumulate in the alveoli/interstitium to cause this?

Answer 7

• Alveolar opactiy
• Can be blood, pus, fluid, tumour cells

Question 8

What can happen to lung volume during consolidation?

Answer 8

• Increase
• Stays the same

Question 9

Describe five possible distributions of lung consolidation, and provide one instance in which each of these can occur

Answer 9

• Focal (tumour)
• Multifocal (granulomatous disease)
• Diffuse (bronchopneumonia)
• Lobar (lobar pneumonia)
• Segmental (infarct)

Question 10

Why are the central airways usually not seen on CXR and CT-chest?

Answer 10

Because they are air-filled, and the lung parenchyma is also air filled; equal density, no visibility

Question 11

What is the air bronchogram sign? What is its significance?

Answer 11

• When alveoli become consolidated, central airways become visible, which they usually are not
• If we see this sign, we know the issue must come from the lung parenchyma, and not the pleura or the mediastinum

Question 12

What is it called when a pathological process causes two adjacent structures to become indistinguishable on radiological imaging?

Answer 12

Silhouette sign

Question 13

What signs indicate LLL consolidation on XCR?

Answer 13

• Effacement of left hemidiaphragm
• Opacity behind heart

Question 14

What signs indicate RLL consolidation on XCR?

Answer 14

• Effacement of right hemidiaphragm

Question 15

What signs indicate RML consolidation on XCR?

Answer 15

• Right hemidiaphragm visible
• Consolidation over right heart border seen in lateral CXR

Question 16

Lingula consolidation CXR signs?

Answer 16

• Effacement of left heart border

Question 17

Which lung lobe is the lingula in?

Answer 17

Left upper lobe

Question 18

Left upper lobe consolidation CXR signs

Answer 18

• Effacement of left mediastinum (PA film)
• Superior lung consolidation (lateral film)

Question 19

Describe the CXR findings of bronchopneumonia. Is it as dense as lobar consolidation?

Answer 19

• Diffuse lung consolidation, bilateral
• No, it is not as dense as lobar consolidation

Question 20

Other than bronchopneumonia, list two other conditions/events that can cause diffuse lung consolidation

Answer 20

• Pulmonary alveolar oedema
• Pulmonary haemorrhage

Question 21

List two conditions that can cause focal lung consolidation

Answer 21

• Lymphoma
• Pulmonary infarct

Question 22

Acute CT findings of covid pneumonia

Answer 22

Diffuse patchy areas of ground glass opacity

Question 23

Miliary nodule size

Answer 23

<2mm

Question 24

Lung nodule size

Answer 24

<3cm

Question 25

Lung mass size

Answer 25

>3cm

Question 26

List three possible distributions of lung nodules

Answer 26

- Random - Centrilobular - Perilymphatic

Question 27

What is the most common cause of randomly distributed lung nodules?

Answer 27

Haematogenous spread

Question 28

What is the most common cause of centrilobular nodule distribution within the lungs?

Answer 28

Airway infection

Question 29

What kinds of infections/conditions cause perilymphatic lung nodules

Answer 29

Infections/conditions that are spread through the lymphatic system

Question 30

List four kinds of lung collapse (i.e. atalectesis)

Answer 30

- Resorption atalectasis - Relaxation/passive atalectasis - Scarring atalectasis - Adhesive atalectasis

Question 31

Describe resorption atalectasis

Answer 31

- Blockage of airways - Air distal to blockage is absorbed, and the distal portion of the lung collapses

Question 32

What type of substances can cause resorption atalectasis

Answer 32

- Mucous plug - Tumour (external, pressing on airway) - Foreign body - Blood

Question 33

Describe relaxation pneumothorax

Answer 33

- Gas (pneumothorax) or fluid (pleural effusion) creates extrinsic pressure on the lung - This separates the lung from the negative pressure of the parietal pleura, and so it follows its natural inclination to collapse

Question 34

Describe scarring atalectasis. What can cause it?

Answer 34

- Fibrosis/scarring of lungs means that lung parenchyma loses compliance, cannot expand as much as it should, and hence collapses - Can be caused by factors such as inflammation or infection

Question 35

Describe adhesive atalectasis. In which demographic does it most commonly occur, and when?

Answer 35

- Less surfactant production in the lungs promotes volume loss - Commonly occurs in newborn babies during lung infection/disease

Question 36

Describe some universal signs of atalectasis

Answer 36

- Increased density of lung tissue - Displacement of other lung towards collaped lung - Displacement of trachea towards collapsed lung - Displacement of hilum and trachea upward or downward - Adjacent lobes may hyperinflate

Question 37

Describe radiographic findings of lower lung lobe collapse; PA and lateral

Answer 37

PA: elevated diaphragm, inferior displacement of the hilum Lateral: Oblique fissure is displaced inferiorly

Question 38

What is sabre-sheathed trachea? What causes it?

Answer 38

- Trachea enlarges in saggital plane and shrinks in coronal plane - Can be caused by emphysema -> lung hyperinflation

Question 39

Emphysema vs cysts on lung CT

Answer 39

- Cysts have walls - Emphysema doesn't

Question 40

True or false: all lung interstitium lies between secondary lobules?

Answer 40

- False - There is also some within the interstitium (since each 2° lobule contains mutiple acini) - This is called intralobular interstitium

Question 41

Describe two different patterns of interstitial thickening seen on lung radiology

Answer 41

- Reticular/linear - Formation of tiny nodules

Question 42

How to differentiate between acute and chronic interstitial thickening when looking at lung radiology

Answer 42

Acute: Hazy, not distorted Chronic: Sharp, distorted

Question 43

What causes kerley B lines during pulmonary oedema?

Answer 43

Distension of lymphatic vessels

Question 44

Signs of pulmonary oedema

Answer 44

- Engorged veins in upper lung - Interstitium becomes thickened - Alveoli fill with fluid (consolidation etc.)

Question 45

What is the 'batwing' appearance on CXR?

Answer 45

- Alveolar congestion bilateral perihilar region