Medical Imaging: Lung Pathology Flashcards
How many acini per 2° pulmonary lobule?
3-5
Secondary pulmonary lobule diameter
1.5-2cm
What is the basic lung unit visible on HRCT?
Secondary pulmonary lobule
Which vessels are located centrally vs peripherally in secondary pulmonary lobules?
Central: Artery and bronchiole
Peripheral: Lymphatic and vein
What can cause interstitial opacity on CXR?
- Interstitial thickening
- Filling of intersitium with fluid or cells
What can cause alveolar opacity on CXR?
- Alveoli fill with fluid or cells or extra air
Does lung consolidation refer to alveolar or interstitial opacity? What substances can accumulate in the alveoli/interstitium to cause this?
- Alveolar opactiy
- Can be blood, pus, fluid, tumour cells
What can happen to lung volume during consolidation?
- Increase
- Stays the same
Describe five possible distributions of lung consolidation, and provide one instance in which each of these can occur
- Focal (tumour)
- Multifocal (granulomatous disease)
- Diffuse (bronchopneumonia)
- Lobar (lobar pneumonia)
- Segmental (infarct)
Why are the central airways usually not seen on CXR and CT-chest?
Because they are air-filled, and the lung parenchyma is also air filled; equal density, no visibility
What is the air bronchogram sign? What is its significance?
- 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
What is it called when a pathological process causes two adjacent structures to become indistinguishable on radiological imaging?
Silhouette sign
What signs indicate LLL consolidation on XCR?
- Effacement of left hemidiaphragm
- Opacity behind heart
What signs indicate RLL consolidation on XCR?
- Effacement of right hemidiaphragm
What signs indicate RML consolidation on XCR?
- Right hemidiaphragm visible
- Consolidation over right heart border seen in lateral CXR
Lingula consolidation CXR signs?
- Effacement of left heart border
Which lung lobe is the lingula in?
Left upper lobe
Left upper lobe consolidation CXR signs
- Effacement of left mediastinum (PA film)
- Superior lung consolidation (lateral film)
Describe the CXR findings of bronchopneumonia. Is it as dense as lobar consolidation?
- Diffuse lung consolidation, bilateral
- No, it is not as dense as lobar consolidation
Other than bronchopneumonia, list two other conditions/events that can cause diffuse lung consolidation
- Pulmonary alveolar oedema
- Pulmonary haemorrhage
List two conditions that can cause focal lung consolidation
- Lymphoma
- Pulmonary infarct
Acute CT findings of covid pneumonia
Diffuse patchy areas of ground glass opacity
Miliary nodule size
<2mm
Lung nodule size
<3cm
Lung mass size
> 3cm
List three possible distributions of lung nodules
- Random
- Centrilobular
- Perilymphatic
What is the most common cause of randomly distributed lung nodules?
Haematogenous spread
What is the most common cause of centrilobular nodule distribution within the lungs?
Airway infection
What kinds of infections/conditions cause perilymphatic lung nodules
Infections/conditions that are spread through the lymphatic system
List four kinds of lung collapse (i.e. atalectesis)
- Resorption atalectasis
- Relaxation/passive atalectasis
- Scarring atalectasis
- Adhesive atalectasis
Describe resorption atalectasis
- Blockage of airways
- Air distal to blockage is absorbed, and the distal portion of the lung collapses
What type of substances can cause resorption atalectasis
- Mucous plug
- Tumour (external, pressing on airway)
- Foreign body
- Blood
Describe relaxation pneumothorax
- 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
Describe scarring atalectasis. What can cause it?
- 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
Describe adhesive atalectasis. In which demographic does it most commonly occur, and when?
- Less surfactant production in the lungs promotes volume loss
- Commonly occurs in newborn babies during lung infection/disease
Describe some universal signs of atalectasis
- 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
Describe radiographic findings of lower lung lobe collapse; PA and lateral
PA: elevated diaphragm, inferior displacement of the hilum
Lateral: Oblique fissure is displaced inferiorly
What is sabre-sheathed trachea? What causes it?
- Trachea enlarges in saggital plane and shrinks in coronal plane
- Can be caused by emphysema -> lung hyperinflation
Emphysema vs cysts on lung CT
- Cysts have walls
- Emphysema doesn’t
True or false: all lung interstitium lies between secondary lobules?
- False
- There is also some within the interstitium (since each 2° lobule contains mutiple acini)
- This is called intralobular interstitium
Describe two different patterns of interstitial thickening seen on lung radiology
- Reticular/linear
- Formation of tiny nodules
How to differentiate between acute and chronic interstitial thickening when looking at lung radiology
Acute: Hazy, not distorted
Chronic: Sharp, distorted
What causes kerley B lines during pulmonary oedema?
Distension of lymphatic vessels
Signs of pulmonary oedema
- Engorged veins in upper lung
- Interstitium becomes thickened
- Alveoli fill with fluid (consolidation etc.)
What is the ‘batwing’ appearance on CXR?
- Alveolar congestion bilateral perihilar region
