Chest X-Ray interpretation

Question 1

How would you assess film quality?

Answer 1

RRIPE:

1. Right person
2. Rotation
3. Inspiration
4. Projection and position
5. Exposure

Question 2

How would you assess rotation?

Answer 2

The medial aspect of each clavicle should be equidistant from the spinous processes.

The spinous processes should also be in vertically orientated against the vertebral bodies.

Question 3

How would you assess inspiration?

Answer 3

The 5-6 anterior ribs, lung apices, both costophrenic angles and the lateral rib edges should be visible.

Question 4

How would you assess projection and position?

Answer 4

Note if the film is AP or PA: if there is no label, then assume it’s a PA film (if the scapulae are not projected within the chest, it’s PA).

Question 5

How would you assess exposure?

Answer 5

The left hemidiaphragm should be visible to the spine and the vertebrae should be visible behind the heart.

Question 6

How would you assess the film content?

Answer 6

1. Airway
2. Breathing
3. Cardiac Silhouette
4. Diaphragm
5. Everything else

Question 7

How would you assess the airways?

Answer 7

Comment on:

1. Trachea (deviation; normally slightly to the right)
2. Carina and bronchi
3. Hilar structures.

Question 8

What do you know about the carina and bronchi?

Answer 8

The carina is cartilage situated at the point at which the trachea divides into the left and right main bronchus.

On appropriately exposed chest X-ray, this division should be clearly visible. The carina is an important landmark when assessing nasogastric (NG) tube placement, as the NG tube should bisect the carina if it is correctly placed in the gastrointestinal tract.

The right main bronchus is generally wider, shorter and more vertical than the left main bronchus. As a result of this difference in size and orientation, it is more common for inhaled foreign objects to become lodged in the right main bronchus.

Question 9

What do you know about hilar structures?

Answer 9

The hilar consist of the main pulmonary vasculature and the major bronchi.

Each hilar also has a collection of lymph nodes which aren’t usually visible in healthy individuals.

The left hilum is often positioned slightly higher than the right, but there is a wide degree of variability between individuals.

The hilar are usually the same size, so asymmetry should raise suspicion of pathology.

The hilar point is also a very important landmark; anatomically it is where the descending pulmonary artery intersects the superior pulmonary vein. When this is lost, consider the possibility of a lesion here (e.g. lung tumour or enlarged lymph nodes).

Question 10

What can cause trachea deviation?

Answer 10

Pushing of the trachea: large pleural effusion or tension pneumothorax.

Pulling of the trachea: consolidation with associated lobar collapse.

Question 11

What causes hilar enlargement?

Answer 11

Bilateral symmetrical enlargement is typically associated with sarcoidosis.

Unilateral/asymmetrical enlargement may be due to underlying malignancy.

Question 12

What causes hilar deviation?

Answer 12

Abnormal hilar position can also be due to a range of different pathologies. You should inspect for evidence of the hilar being pushed (e.g. by an enlarging soft tissue mass) or pulled (e.g. lobar collapse).

Question 13

How would you assess breathing?

Answer 13

1. Lungs

2. Pleura

Question 14

What would you say about the lungs?

Answer 14

When interpreting a chest X-ray you should divide each of the lungs into three zones, each occupying one-third of the height of the lung.

These zones do not equate to lung lobes (e.g. the left lung has three zones but only two lobes).

Inspect the lung zones ensuring that lung markings are present throughout.

Compare each zone between lungs, noting any asymmetry (some asymmetry is normal and caused by the presence of various anatomical structures e.g. the heart).

Some lung pathology causes symmetrical changes in the lung fields, which can make it more difficult to recognise, so it’s important to keep this in mind (e.g. pulmonary oedema).

Increased airspace shadowing in a given area of a lung field may indicate pathology (e.g. consolidation/malignant lesion).

The complete absence of lung markings should raise suspicion of a pneumothorax.

Question 15

What would you say about the pleura?

Answer 15

The pleura are not usually visible in healthy individuals. If the pleura are visible it indicates the presence of pleural thickening which is typically associated with mesothelioma.

Inspect the borders of each lung to ensure lung markings extend all the way to the edges of the lung fields (the absence of lung markings is suggestive of pneumothorax).

Fluid (hydrothorax) or blood (haemothorax) can accumulate in the pleural space, resulting in an area of increased opacity on a chest X-ray. In some cases, a combination of air and fluid can accumulate in the pleural space (hydropneumothorax), resulting in a mixed pattern of both increased and decreased opacity within the pleural cavity.

Question 16

How would you assess cardiac silhouette?

Answer 16

1. Heart size

2. Heart borders

Question 17

What would you say about heart size?

Answer 17

In a healthy individual, the heart should occupy no more than 50% of the thoracic width (e.g. a cardiothoracic ratio of less than 0.5).

This rule only applies to PA chest X-rays (as AP films exaggerate heart size), so you should not draw any conclusions about heart size from an AP film.

Cardiomegaly is said to be present if the heart occupies more than 50% of the thoracic width on a PA chest X-ray. Cardiomegaly can develop for a wide variety of reasons including valvular heart disease, cardiomyopathy, pulmonary hypertension and pericardial effusion

Question 18

What would you say about heart borders?

Answer 18

Inspect the borders of the heart which should be well defined in healthy individuals:

The right atrium makes up most of the right heart border.
The left ventricle makes up most of the left heart border.
The heart borders may become difficult to distinguish from the lung fields as a result of pathology which increases the opacity of overlying lung tissue:

Reduced definition of the right heart border is typically associated with right middle lobe consolidation.
Reduced definition of the left heart border is typically associated with lingular consolidation.

Question 19

How would you assess the diaphragm?

Answer 19

The right hemidiaphragm is, in most cases, higher than the left

The diaphragm should be indistinguishable from the underlying liver unless gas is present

In a healthy individual, the costophrenic angles should be clearly visible on a normal chest X-ray as a well defined acute angle.

Question 20

What causes blurry costophrenic angles?

Answer 20

Loss of this acute angle, sometimes referred to as costophrenic blunting, can indicate the presence of fluid or consolidation in the area.

Costophrenic blunting can also develop secondary to lung hyperinflation as a result of diaphragmatic flattening and subsequent loss of the acute angle (e.g. chronic obstructive pulmonary disease).

Question 21

What would you assess in “everything else”?

Answer 21

Mediastinal contours, bones, soft tissues, tubes, valves, pacemakers and review areas.

Question 22

What should you assess about the mediastinal contours?

Answer 22

The mediastinum contains the heart, great vessels, lymphoid tissue and a number of potential spaces where pathology can develop. The exact boundaries of the mediastinum aren’t particularly visible on a chest X-ray, however, there are some important structures that you should assess.

Aortic knuckle
The aortic knuckle is located at the left lateral edge of the aorta as it arches back over the left main bronchus. Reduced definition of the aortic knuckle contours can occur in the context of an aneurysm.

Aortopulmonary window
The aortopulmonary window is a space located between the arch of the aorta and the pulmonary arteries. This space can be lost as a result of mediastinal lymphadenopathy (e.g. malignancy)

Question 23

What should you assess about the bones?

Answer 23

Inspect the visible skeletal structures looking for abnormalities (e.g. fractures, lytic lesions).

Question 24

What should you assess about the soft tissue?

Answer 24

Inspect the soft tissues for obvious abnormalities (e.g. large haematoma).

Question 25

What should you assess about the tubes, valves and pacemakers?

Answer 25

Nasogastric tube placement is something you’ll often be asked to assess on a chest X-ray to confirm safe placement for feeding

Various tubes and cables will be visible as radio-opaque lines on the chest X-ray

Artificial heart valves typically appear as ring-shaped structures on a chest X-ray within the region of the heart

Pacemakers typically appear as a radio-opaque disc or oval in the infraclavicular region connected to pacemaker wires which are positioned within the heart.

Question 26

What is CURB65?

Answer 26

This is a clinical decision support tool focused on stratifying patients with pneumonia into risk categories based on presenting signs and investigation results.

It can inform clinicians on two decisions:

1. Whether to treat as an outpatient or admit for inpatient treatment
2. Where in the hospital may be most suitable, i.e. ward vs HDU/ITU

Question 27

How would you score points on CURB65?

Answer 27

A point is scored for the following:

1. AMTS > 7/10 (confusion)
2. Urea value >7mmol/l
3. RR >30/min
4. SBP <90 or DBP <60
5. Age >65

Question 28

How would you interpret CURB-65 scores?

Answer 28

For total scores 0-1 - outpatient care with oral antibiotics and repeat chest x-ray in 6 weeks is appropriate.

For total scores 2 - inpatient admission is warranted.

For total scores 3 or above - inpatient admission, IV antibiotics, and consideration of HDU/ITU care may be appropriate.

Question 29

What are the management steps for community acquired pneumonia?

Answer 29

1. Oxygen therapy to achieve target SpO2 > 94%
2. Intravenous fluid bolus with a crystalloid solution, with an infusion thereafter for resuscitative purposes
3. Blood for microscopy, culture and sensitivities
4. FBC, CRP, U&ES
   Intravenous antibiotics as per local guidelines for community acquired pneumonia
5. Catheterisation may be appropriate to aid urine output monitoring if patients are particularly unwell and at risk of developing sepsis
6. If blood cultures do grow an organism, antibiotics should be amended in line with the sensitivity results

Question 30

What are typical signs of TB?

Answer 30

Consolidation with ipsilateral hilar enlargement due to lymphadenopathy

Question 31

How would you describe pneumonia?

Answer 31

1. Lobular (upper, middle, lower)

2. Zonal

Question 32

What is Bronchiectasis?

Answer 32

Widening of the bronchi and associated structures, increasing infection risk

Question 33

What patients are at risk of Bronchiectasis?

Answer 33

Cystic fibrosis

Question 34

What is a reliable feature that indicates hyperinflation?

Answer 34

Flattened diaphragm

Also: ribs visible past the mid-clavicular line

Question 35

What are features of pulmonary fibrosis?

Answer 35

Pulmonary fibrosis causes reticular (net-like) shadowing of the lung peripheries which is typically more prominent towards the lung bases

It may cause the contours of the heart to be less distinct or ‘shaggy’

Question 36

How would you spot asbestos on a CXR?

Answer 36

They appear as irregularly-shaped areas of calcific density (as white as bone) and should not be mistaken for areas of consolidation

Question 37

What is pleural effusion?

Answer 37

“Pleural effusion” is commonly used as a catch-all term to describe any abnormal accumulation of fluid in the pleural cavity

Question 38

What are the types of pleural effusion?

Answer 38

1. Transudate (systemic): low protein

2. Exudate (local): high protein

Question 39

What are causes of transudate?

Answer 39

cardiac failure
nephrotic syndrome
cirrhosis

Question 40

What are causes of exudate?

Answer 40

Malignancy
TB
Pneumonia

Question 41

What is consolidation?

Answer 41

Consolidation refers to the alveolar airspaces being filled with fluid (exudate/transudate/blood), cells (inflammatory), tissue, or other material.