How Do I Make Sense of Chest X-Rays? Flashcards

1
Q

What is the ideal complete chest x-ray?

A

Erect

Posteroanterior (PA) and lateral

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2
Q

Why is PA preferred to anteroposterior (AP)?

A

AP magnifies heart

In PA see more of lung fields

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3
Q

What is a projection in x-rays?

A

Way an x-ray is taken; eg:

  • PA
  • Lateral
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4
Q

Why is the lateral projection usually left lateral?

A

Places heart closer to film

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5
Q

What does a left lateral projection mean?

A

Left side of patient closest to x-ray film

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6
Q

If a patient is sitting upright, is the x-ray considered erect?

A

Yes

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7
Q

Why are AP chest films usually done?

A

Patient very unwell/unable to stand

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8
Q

What does a frontal projection describe?

A

AP

PA

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9
Q

What is a mobile x-ray?

A

X-ray taken with mobile x-ray machine

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10
Q

Why might a chest x-ray be performed supine?

A

If patient is very unwell

Not possible/unsafe to sit patient upright

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11
Q

What should you check first in a chest x-ray?

A
Name
Date
Other labels
- Mobile
- AP
- Supine
- Side marker = L/R
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12
Q

What do you normally see in lung fields as opaque structures?

A

Pulmonary arteries
Pulmonary veins
Don’t normally see airways

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13
Q

Where are pulmonary vessels larger when seen on an erect chest x-ray?

A

Towards lung bases due to hydrostatic effect

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14
Q

How do you measure heart size?

A

Cardiothoracic ratio <50% on PA film with good inspiration

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15
Q

What is the cardiothoracic ratio?

A

Max cardiac transverse dimension/max transverse lung dimension

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16
Q

When can a normal heart size appear larger on a chest x-ray?

A

AP - 10% larger
Supine - at least 20% larger
Poor inspiration

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17
Q

Why is a chest x-ray taken on inspiration?

A

Doesn’t magnify heart size

Allows clearer view of lung fields

18
Q

What is the effect of a supine film?

A

Heart looks bigger

Lungs look smaller and congested

19
Q

How do you gauge lung volume on a chest x-ray?

A

Count number of anterior ribs visible

Normal = 5-6.5 anterior ribs

20
Q

How does lung volume change on a chest x-ray in COPD?

A

Lung volumes expand in sagittal dimension, and top and bottom

21
Q

What does increased retrosternal lucency mean?

A

Increased area behind sternum

22
Q

What does the diaphragm look like in a chest x-ray with hyperinflated lungs?

23
Q

What creates increased opacity in lung fields?

A
Pleural fluid
Collapse of part/all of lung
Fluid/cells in airspaces
- Oedema
- Infective consolidation
Fluid/cells in lung interstitium
- Oedema
- Inflammatory change
Tumours/other masses in lung
24
Q

What does a pleural effusion typically look like?

A

At base
Meniscus curves up chest wall
Becomes less opaque more superiorly

25
What are some causes of pleural effusion?
Infection Cardiac failure Blood > haemothorax Pus > empyema
26
Are pleural effusions unilateral or bilateral?
Depends on cause
27
What does atelectasis typically look like?
Collapse > loss of volume > increased opacity of affected zone Possible silhouette sign?
28
What is the silhouette sign?
Loss of silhouette that normally occurs when air lies adjacent to soft tissue structure and creates silhouette outline
29
What does fluid or cells in the alveoli typically look like?
Called airspace/alveolar opacity Fluffy +/- bronchograms Often bounded by fissures
30
What are air bronchograms?
Airways appear less opaque because still contain air
31
What does interstitial lung field opacity typically look like?
Lines +/- dots
32
What are the common causes of interstitial lung field opacity?
Pulmonary oedema Atypical infection Pulmonary fibrosis Malignant infiltrate
33
What are Kerley B lines?
Horizontal lines Less than 2 cm long Commonly found in lower zone periphery Thickened oedematous interlobular septa
34
How do you confirm the position of a pathology on a chest x-ray?
Confirm using both frontal and lateral films
35
What do masses typically look like on a chest x-ray?
Usually rounded | May contain gas because of cavitation
36
What are the commonest causes of masses in a chest x-ray?
Cancer | Abscess
37
What are the common causes of lung opacity due to multiple nodules?
Most often due to pulmonary metastases from distant tumour | Occasionally infective causes
38
What are the commonest causes of increased lucency in a lung field?
``` Pneumothorax Bullous emphysema, especially if asymmetrical Others - Lobar collapse - Pulmonary embolism ```
39
When you suspect a pneumothorax, why should you take both an inspiratory and expiratory image?
Expiratory film makes pneumothorax more obvious | - Helpful for detecting small pneumothoraces
40
What does a pneumothorax typically look like on a chest x-ray?
Usually see lung edge Increased lucency Hemidiaphragm depressed on expiratory film
41
Where is bullous emphysema more commonly seen?
Upper zones of lung fields