Thoracic Ultrasound

Question 1

How does ultrasound work?

Answer 1

High frequency sound waves bounced off internal aging of organs and tissues via array of transducers to produce 2D images

Question 2

What are the types of ultrasound probes?

Answer 2

3.5 MHz: lower res, inc depth of view, fanned view

7-12MHz: high res, limited depth, can look at superficial thing

see notes

Question 3

What is an echogenic line?

Answer 3

• Line between visceral and parietal pleura

- Can see gliding pleura sign

Question 4

What are the main artefacts on ultrasounds?

Answer 4

A lines: run parallel to the lung edge, apparently within the lung - if seen lung is normal because full of air

Comet tails: perpendicular to lung edge = interlobular septa (run vertically down)

Question 5

What is m mode ultrasound?

Answer 5

One dimensional display of motion (M) of echo-producing interfaces displayed against time (T) along the second axis

see notes

Question 6

What is the best plane for a thoracic US?

Answer 6

Paracoronal or parasagittal

Eliminates rib artefact

Question 7

What are the functions of thoracic US?

Answer 7

• Detect pleural effusion and guide drainage
• Assessment of respiratory muscle function
• Differentiate sub-pulmonary from sub-phrenic fluid
• Assess tumour invasion of chest wall and pleura
• Guide pleural and lung biopsy
• Identification of pneumothorax

Question 8

What is the colour of fluid on an US?

Answer 8

Black

Question 9

What is the function of the forced inspiration?

Answer 9

Tests function of phrenic nerve
Assess movement of diaphragm
Normal: rapid caudal movement - contracts and moves sharply down towards feet
Abnormal: paradoxical cranial movement

Question 10

How does the diaphragm look on an US?

Answer 10

• Better seen than in XR or CT
• Has echogenic stripe
• Obscured by aerated lung so must be looked at from below