Introduction to Respiratory Radiology

Question 1

What colour (density) is air on a CXR?

Answer 1

Black - least dense

Question 2

What colour (density) is fat on a CXR?

Answer 2

Grey

Question 3

What colour (density) is soft tissue/muscle on a CXR?

Answer 3

Grey/white

Question 4

What colour (density) is bone on a CXR?

Answer 4

White - very dense

Question 5

What colour (density) is metal on a CXR?

Answer 5

Bright white - densest

Question 6

(pic)

Answer 6

Label the different densities from least dense to densest

Question 7

Why is intra-thoracic air not as dense as extra-thoracic air?

Answer 7

Chest wall and blood vessels impair x-ray beams

Question 8

What is the CT density of air?

Answer 8

-1000

Question 9

What is the CT density of lungs?

Answer 9

-500

Question 10

What is the CT density of fat?

Answer 10

-100

Question 11

What is the CT density of water?

Answer 11

0 (all CT densities are given relative to water - anything less dense than water will be negative and anything denser than water will be positive)

Question 12

What is the CT density of muscle?

Answer 12

+50

Question 13

What is the CT density of bone?

Answer 13

+200

Question 14

What is the CT density of metal?

Answer 14

+1000

Question 15

(pic)

What does the tiny nodule on the CXR indicate?

Answer 15

Shade of white-grey denser than adjacent ribs - nodule composed of calcium (granuloma)

Question 16

Are calciferous granulomas worrying?

Answer 16

No, likely to be chronic

Question 17

What modality other than CXR and CT scans can be used for lung imaging?

Answer 17

Ultrasound

Question 18

What is ultrasound?

Answer 18

Uses passage of sound waves which bounce off of structures to create image based on speed of return of sound wave

Question 19

What effect does fluid have on the passage of sound waves?

Answer 19

Allows passage of sound waves - appears black

Question 20

What effect does soft tissue have on the passage of sound waves?

Answer 20

Allows passage of sound waves - appears bright

Question 21

What effect does air have on the passage of sound waves?

Answer 21

Blocks passage of sound waves

Question 22

What complications can fluid in the chest lead to?

Answer 22

Haemothorax - can lead to lung collapse

Fluid - haemothorax
Air - pneumothorax

Question 23

What is the standard CXR technique?

Answer 23

• Patient stands 2m from the x-ray apparatus, facing the digital cassette
  *The shoulders are braced forward so that the scapulae do not obscure the lungs
  *The radiograph is taken at full inspiration.
  “Breathe in and hold your breath”
  *The x-rays pass from Posterior to Anterior producing a ‘PA radiograph’

Question 24

When is ‘AP’ view taken in CXR?

Answer 24

• When patient cannot stand

Question 25

What are 3 reasons that AP x-rays are technically inferior to PA views?

Answer 25

* The heart shadow is magnified so heart size cannot be assessed accurately * The scapulae overlie and partly obscure the lungs * It can be difficult for the patient to take an adequate inspiration

Question 26

What are other CXR techniques, aside from AP and PA view?

Answer 26

Lateral view

Question 27

What are the advantages of lateral view CXR?

Answer 27

Gives additional information - shows structures behind the heart i.e. lung cancer in regions behind heart

Question 28

What are 3 factors that determine whether a CXR is technically adequate?

Answer 28

The 3 '-ations' * Inspiration * Rotation * Penetration (is there enough radiation?)

Question 29

What is the importance of inspiration and rotation in CXR?

Answer 29

A poorly inspired or rotated CXR can simulate pathology when none is there

Question 30

How can you tell if a CXR is adequately inspired?

Answer 30

The anterior ends of at least 6 ribs should be visible

Question 31

How can you tell if a CXR is correctly centred?

Answer 31

The medial ends of the clavicles should be equidistant from the spinous processes of the upper thoracic vertebrae

Question 32

Why would cardiothoracic ratio change in different images of the same patient's chest?

Answer 32

Due to inspiration and expiration

Question 33

What is situs inversus?

Answer 33

Congenital anomaly - large organs are swapped from left to right

Question 34

Name the mediastinal borders labelled 1-9 | pic

Answer 34

1) Aorta 2) Pulmonary artery 3) Left auricle 4) Left ventricle - left heart border 5) Right atrium - right heart border 6) Trachea 7) Hemidiaphragm 8) Horizontal fissure

Question 35

Why is left hemidiaphragm lower than right hemidiaphragm?

Answer 35

Right hemidiaphragm pushed up by liver

Question 36

Are lymph nodes visible on CXR?

Answer 36

Only visible when enlarged

Question 37

What do visible lymph nodes on CXR indicate?

Answer 37

Pathology of the lymph nodes

Question 38

What are 'red flags'?

Answer 38

* Weight loss | * Haemoptysis

Question 39

Label the lateral radiograph of the right lung | pic

Answer 39

1) Oblique fissure 2) Horizontal fissure 3) Posterior costophrenic recess 4) Retrosternal space

Question 40

How can you tell if an abnormality is if left lower lobe or left upper lobe?

Answer 40

Behind oblique fissure - lef blower lobe | In front of fissure - left upper lobe

Question 41

What is the only part of the right lung that touches the right heart border?

Answer 41

The right middle lobe

Question 42

What is the part of the left lung that touches the left heart border?

Answer 42

The lingula

Question 43

Why is patient history important with regards to CXR?

Answer 43

A tumour would look identical to pneumonia - history of fever (infection) would indicate pneumonia, whereas afebrile may indicate cancer

Question 44

What are red flags for lung cancer?

Answer 44

* Weight loss * Loss of appetite * Haemoptysis * Dyspnoea * Cough