Chest Imaging

Question 1

On x-ray air appears \_\_1\_\_\_\_
Fat appears \_\_\_2\_\_\_\_\_
Soft tissue and muscle appears \_\_3\_\_\_\_
Bone appears \_\_\_4\_\_
Metal appears \_\_\_\_5\_\_\_

Answer 1

1) black
2) grey
3) grey/ white
4) white
5) bright white

Question 2

On X-ray it is by having _________ that structures are seen

Answer 2

two different densities next to each other

ie you can see the heart because it is surrounded by air but you can’t see the full outline of the liver

Question 3

4 considerations for if an X-ray is technically adequate?

Answer 3

projection, inspiration, rotation, penetration

Question 4

Why are PA x-rays better than AP x-ray?

Answer 4

In AP x-rays the heart is abnormally magnified because it is closer to the scan

Question 5

How do you measure projection of an X-ray?

Answer 5

The CTR is measured on a PA chest x-ray, and is the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura).A normal measurement should be less than 0.5.
CTR should not be measured on AP X-ray.

Question 6

Explain how you can tell if an X-ray is adequately inspired and rotated?

Answer 6

If a CXR is adequately inspired, the anterior ends of at least 6 ribs should be visible

If a CXR is correctly centred, the medial ends of the clavicles should be equidistant from the spinous processes of the upper thoracic vertebrae

Question 7

The left hilum normally lies higher than the right due to _______

Answer 7

the left pulmonary artery sitting higher than the right

Question 8

The left hilum normally lies _____ that the right

Answer 8

higher

Question 9

Describe position of the diaphragms on normal CXR?

Answer 9

On a normal CXR, the right diaphragm lies about 1.5cm above the left diaphragm
Major deviations from this usually indicate disease.(collapse in lower lobe or disease beneath the hemidiaphragm)

Question 10

Why are pathologies talked about in terms of zones not lobes on CXR?

Answer 10

The chest radiograph is a 2D representation of a 3D structure. Since the interfaces between the lobes are orientated obliquely, it is often not possible to determine which lobe pathology is located in or whether it is located anteriorly or posteriorly. Hence, describing the location of pathology using the 3 zones is more accurate.

Question 11

Review areas on a chest x-ray are common areas for missed findings, name the 4 review areas?

Answer 11

lung apices
behind the heart
below the diaphragm
bones and soft tissues

Question 12

Describe why lobar collapse occurs and the process?

Answer 12

This happens when there is obstruction of a lobar bronchus.
Causes of bronchial obstruction include tumours, aspirated foodstuffs, mucus impaction etc.
The lobe supplied by an obstructed bronchus is no longer ventilated and its air gets resorbed. As the affected lobe loses volume it begins to collapse, like a balloon deflating.

Question 13

Describe what is seen on left lower lobe collapse on CXR?

Answer 13

Volume loss on the left with elevation of the hemidiaphragm, left hemithorax looks small
Increased density in left retrocardiac region
Loss of clarity medial aspect left hemidiaphragm
Left hilum displaced downwards

Question 14

Describe what is seen on left upper lobe collapse on CXR?

Answer 14

Volume loss on the left, elevation of the left hemidiaphragm
Loss of clarity of the heart shadow
‘veil like opacity’ diffuse opacification of the left hemithorax

Question 15

Describe what is seen on right upper lobe collapse on CXR?

Answer 15

Volume loss on the right
Loss of clarity of the upper right mediastinum
Density in the right upper zone, elevation of the horizontal fissure

Question 16

Why is isolated right middle or right lower lobe collapse unusual?

Answer 16

The organ of the bronchus for the middle and lower lobe is dual so usually the obstruction occurs at bronchus intermedium causing collapse of both lobes.

Question 17

Describe what is seen on right middle lobe collapse on CXR?

Answer 17

Loss of clarity of the right heart border
Density in the right lower zone,
Right hemidiaphragm preserved

Question 18

Describe what is seen on right lower lobe collapse on CXR?

Answer 18

Volume loss on the right
Loss of clarity of the right hemidiaphragm
Density in the right lower zone, depression of the horizontal fissure

Question 19

Describe what is seen on right middle and lower lobe collapse on CXR?

Answer 19

Volume loss on the right
Loss of clarity of the right hemidiaphragm & right heart border
Density in the right lower zone, depression of the horizontal fissure and oblique fissure
Occurs due to obstruction of both Middle and Lower lobe bronchi due to common origin at bronchus intermedius

Question 20

Consolidation follows the same patterns of lobe collapse in terms of ________________

Answer 20

position/obscuring borders, but without the volume loss

Question 21

Describe what is seen on right middle lobe consolidation?

Answer 21

Increased density in right lower zone

Loss of clarity of the right heart border but preservation of the right hemidiaphragm

Question 22

Describe what is seen on left upper lobe consolidation?

Answer 22

Increased density in left upper zone
Loss of clarity of the left upper mediastinum
Volume preserved

Question 23

On an erect CXR dense pleural fluid from an effusion is seen to collect at ________________

Answer 23

the lung bases and often forms the curved appearance of a ‘meniscus’ at the lung edges, blunting the costophrenic angles

Question 24

In a pneumothorax air tends to accumulate at the ________

Answer 24

lung apex

Question 25

How to look for a small pneumothorax?

Answer 25

look for a dark crescent without lung markings bounded medially by the lung edge. It is often at the lung apex.

Question 26

Signs of heart failure on X-ray?

Answer 26

A - alveolar oedema (bat wing opacities)
B - Kerley B lines
C - cardiomegaly
D - dilated upper lobe vessels
E - pleural effusion

Question 27

Explain normal and malpositioned endotracheal tubes?

Answer 27

normal:
tip 5 cm above carina
width 2/3 tracheal diameter
cuff should not expand the trachea

malposition:
tip may extend past the carina
malposition most commonly seen is the tip in the right main bronchus
May have entered the oesophagus

Question 28

Explain normal and malpositioned nasogastric tubes?

Answer 28

The ideal position should be in the subdiaphragmatic position in the stomach - identified on a plain chest radiograph as overlying the gastric bubble. Ideally, it should be at least 10 cm beyond the gastro-oesophageal junction.
Malpositioning may include tip position:
remaining in the oesophagus
traversing either bronchus or more distally into the lung
coiled in the upper airway
intracranial insertion, possible in both patients with and without skull base trauma or surgery (v rare)

Question 29

How to assess position of central venous catheters?

Answer 29

need to follow lines to basically ensure they go towards the heart

Question 30

Describe pneumoperitoneum and how you would identify that on chest radiograph?

Answer 30

Perforation of a hollow viscus (stomach, duodenum, small or large bowel) results in gas in the peritoneal cavity
A radiograph taken with the patient in the ERECT postion allows the gas to rise up under the diaphragm
It is seen as a thin black line between the diaphragm and subdiaphragmatic structures
Easier to see on the right than the left

Question 31

Radiograph features of scans performed for suspected PE?

Answer 31

X-ray
Chest radiographs are often performed to look for alternative causes for symptoms and to decide on appropriateness of V/Q scan (only if CXR normal)
They are usually either normal or show nonspecific findings - pleural effusion cardiomegaly, atelectasis.
CTAP
CT pulmonary angiogram to look for the clot
V/Q scan
Ventilation perfusion scan to look for the defects caused by the clots