Chest Imaging

Question 1

How do different structures appear on x-ray?

Answer 1

Air = black
Soft tissue = grey/white 
Fat = grey
Bone = white
Metal = bright white

Question 2

What type of x-ray view is used to measure the cardiothoracic ratio?

Answer 2

PA CXR = shouldn’t use AP CXR because it makes the heart seem artificially large

Question 3

What is the cardiothoracic ratio?

Answer 3

The ration of the maximal horizontal cardiac diameter to the maximal horizontal thoracic diameter = normal is <0.5

Question 4

What should be visible if a CXR is suitably inspired?

Answer 4

The anterior ends of at least 6 ribs

Question 5

What should be visible if a CXR is correctly centred?

Answer 5

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

Question 6

What is the position of the left lung hilum in relation to the right lung hilum?

Answer 6

The left hilum is usually higher than the right

Question 7

What is the position of the right diaphragm on a normal CXR?

Answer 7

Right diaphragm lies about 1.5cm above the left diaphragm

Question 8

What are review areas?

Answer 8

Common areas for missed findings = lung apices, behind heart, below diaphragm, bones and soft tissue

Question 9

What causes lobar collapse?

Answer 9

Happens when there is obstruction of the lobar bronchus = caused by tumours, mucus impaction or aspirated foodstuffs

Question 10

What does lobar collapse cause on a CXR?

Answer 10

Causes adjacent major fissure to be displaced, with increased density and loss of clarity

Question 11

What does infection of the lingular segments of the left upper lobe cause on CXR?

Answer 11

Obscures left heart border

Question 12

What does pleural effusion cause on a CXR?

Answer 12

Blunting of the costophrenic angles

Question 13

How does a small pneumothorax appear on a CXR?

Answer 13

Dark crescents without lung markings bounded medially by lung edge

Question 14

What are the radiological signs of pulmonary oedema?

Answer 14

Dilatation of upper lobe vessels/cardiomegaly
Interstitial opacities = peribronchovascular cuffing
Airspace opacification = perihilar if severe, air bronchograms
Pleural effusions

Question 15

What causes air bronchograms?

Answer 15

Air filled bronchi running through fluid filled alveoli

Question 16

What are the features of heart failure on a CXR?

Answer 16

Alveolar oedema = bat wing opacities
Kerley B lines and cardiomegaly
Dilated upper lobe vessels and pleural effusion

Question 17

What is the correct placement for an endotracheal tube?

Answer 17

Tip 5cm above carina
Width 2/3 of tracheal diameter
Cuff shouldn’t expand trachea

Question 18

What are some examples of endotracheal tube malposition?

Answer 18

Tip may extend past carina
Tip most commonly seen in right main bronchus
May have entered oesophagus

Question 19

What is the correct placement for a nasogastric tube?

Answer 19

Subdiaphragmatic position in stomach

At least 10cm beyond gastro-oesophageal junction

Question 20

What are some examples of nasogastric tube tip malposition?

Answer 20

Remaining in oesophagus
Traversing either bronchus or more distally into lung
Coiled in upper airway or intracranial insertion

Question 21

Where are central venous catheters inserted via?

Answer 21

Internal jugular or subclavian veins

Question 22

Where should the tip of red, blue and purple venous catheters be positioned?

Answer 22

Tip should be at cavoatrial junction

Question 23

What are some examples of red, blue and purple venous catheter line malpositions?

Answer 23

Tip in proximal SVC = increased thrombus risk
Tip in distal right atrium/ventricle = increased arrhythmia
Coiled or displaced in another vein

Question 24

Where should the tip of yellow venous lines be positioned?

Answer 24

At cavoatrial junction or subclavian vein

Question 25

What are some examples of malposition of yellow venous line tip?

Answer 25

Superficial upper limb vein or azygous vein
Distal right atrium/ventricle
Right internal jugular vein

Question 26

What are the different sizes of pulmonary nodules and masses?

Answer 26

Miliary nodule = <2mm
Pulmonary micronodule = 2-7mm
Pulmonary nodule = 7-30mm
Pulmonary mass = >30mm

Question 27

What are the different morphologies of pulmonary nodules?

Answer 27

Solid (calcified), partly solid or ground glass

Question 28

What are the distributions of pulmonary nodules?

Answer 28

Perilymphatic (perifissural), centrilobular or random

Question 29

How is contrast CT used to assess lung cancer?

Answer 29

Assesses tumour size, shows metastases and can guide biopsy of peripheral lesions

Question 30

What does FDG-PET CT visualise in lung cancer?

Answer 30

Nodal metastases and distal metastases (not brain)

Delineating tumour in area of collapse

Question 31

What is pneumoperitoneum?

Answer 31

Gas in the peritoneal cavity = radiograph taken with patient in erect position

Question 32

How does pneumoperitoneum appear on CXR?

Answer 32

Thin black line between diaphragm and subdiaphragmatic structures = easier to see on right

Question 33

What does a CXR of a pulmonary embolism show?

Answer 33

Usually normal or shows non-specific findings like cardiomegaly

Question 34

What are some investigations used for pulmonary embolisms?

Answer 34

CT pulmonary angiogram = used to look for clot

V/Q scan = looks for defects caused by clot