9/8- Chest Imaging in Lung Disease

Question 1

What is the reference substance for x-ray?

Answer 1

Water

Question 2

Describe relative absorption of x-rays by different tissues:

• Bone
• Tissue (fluid, muscle)
• Air

Answer 2

• Bone: high absorption (white)
• Tissue (fluid, muscle): grey
• Air: low absorption (black)

Question 3

What is silhouette sign in x-ray?

Answer 3

Tissues or structures with similar density, adjacent to each other, cannot be differentiated (e.g. blood filled heart) If fluid is obscuring heart/aorta, it’s in the same plane as what is no longer seen

(B- see aorta outline but not heart; in plane of heart. C- see heart border but not aorta; in plan of aorta)

Question 4

Under what position/conditions is a CXR taken?

Answer 4

• Upright
• Full inspiration
• 72” from x-ray source
• Plate in front of patient

Question 5

Characteristics of a normal CXR (postero-anterior)?

• Stomach
• Scapula
• Clavicles
• Vertebral bodies
• Lung lobes

Answer 5

Postero-anterior film

• Air in stomach
• Scapulae at edge of thorax
• Well centered – clavicles equidistant from spinous processes
• Lower vertebral bodies barely visible
• LLL visible (behind heart

Question 6

What is different in antero-posterior view as opposed to postero-anterior?

Answer 6

• Opposite
• Anterior structure magnified: heart, mediastinum
• Scapula in thorax

Question 7

Features of lateral CXR?

Answer 7

Question 8

What is abnormal?

Answer 8

Elevated diaphragm

Question 9

What can cause an elevated diaphragm?

Answer 9

• Collapse/ volume loss of lung
• Subpulmonic effusion
• Subphrenic abscess
• Herniation/eventration

Question 10

What are diseases of increased radiographic density?

Answer 10

• Alveolar filling (blood, fluid, cellular components in pneumonia)
• Atelectasis/Volume loss
• Interstitial infiltrates
• Masses

Question 11

What is seen here?

Answer 11

Silhouette Sign: RML pneumonia

• We are missing the right heart border

Question 12

What is seen here?

Answer 12

Infiltrate in upper lobe

• Opacity above minor fissure (separating upper lobe from middle lobe)
• Possibly additional infiltrate in left lower lobe

Question 13

Which lobes correspond to:

• Right heart border
• Left heart border

Answer 13

- Right heart border: right lower lobe

- Left heart border: left lingula

Question 14

What is seen here?

Answer 14

Uremic lung disease (not a specific finding)

• Diffuse increase in density; bilateral

Question 15

What is seen here?

Answer 15

Collapsed left lung (due to tumor)

• Ipsilateral pulling of midline structures due to collapse
• Heart, diaphragm, aorta/midline structures are all silhouetted out

Question 16

What is seen here?

Answer 16

Pulmonary vascular congestion (turns out he had mitral stenosis)

• Predominant upper lobe density
• Bilateral

Question 17

What does the meniscus sign suggest?

Answer 17

Presence of pleural fluid

Question 18

What is seen here?

Answer 18

Tumor causing obstruction of right main bronchus

• Trachea and heart deviated to the right
• Right lung is smaller and more opaque

Question 19

What are diseases of decreased radiographic density?

Answer 19

• Air trapping: asthma, emphysema, foreign body
• Pneumothorax
• Cysts/bullae
• Loss of soft tissue (e.g. mastectomy pts)

Question 20

What is seen here

Answer 20

Overinflation- severe bullous emphysema

• Diaphragm low and flat
• Streaks are due to upper lung tissue being pulled down (bullae); crowding of lung markings in lower thorax; absence of lung markings (upper)
• Hilum has been pushed down (below aortic knob)

Question 21

What is seen here?

Answer 21

Overinflation- severe bullous emphysema

• Increased retrosternal air space
• Flat diaphragms

Question 22

What is seen here?

Answer 22

Pneumothorax- compression atalectasis of the lung

• Right apex might be considered normal (no markings, but mostly collapsed/compressed lung
• See pneumonic infiltrates on right

Question 23

What is seen here?

Answer 23

Pneumothorax

• Can see pleura line on the lower right with effusion just external

Question 24

What is seen here?

Answer 24

Cavitation of the lung (lucency within density)

• Commonly from infection (also, sometimes from cancers)

Question 25

What is seen here?

Answer 25

Cavity with development of air-fluid level... this is an ABSCESS

Question 26

When would you want decubitus film?

Answer 26

- Demonstrate pleural effusion fluid layers/air rises - Sub-pulmonic effusion - Air/fluid levels - Subtle pneumothorax

Question 27

If there is a pleural effusion on the right, which side do you want down?

Answer 27

Want pneumothorax side DOWN

Question 28

When would inspiratory/expiratory films be helpful?

Answer 28

- Small/subtle pneumothorax - Unilateral air trapping

Question 29

CT is test of choice for what?

Answer 29

- Pulmonary embolism - Vascular malformations Also: - Evaluation of hilar and mediastinal structures: LNs, tumors, central airways - Radiologic diagnosis of bronchiectasis

Question 30

What is seen here?

Answer 30

- "Generous" hilum

Question 31

What is seen here?

Answer 31

Large homogeneous density of a mass/LN

Question 32

Angiography of the chest shows what vessels?

Answer 32

Contrast studies help diagnose vascular diseases such as pulmonary embolism - Pulmonary - Bronchial

Question 33

- A 41 yo presents with dyspnea for 3 weeks- - On physical exam there are decreased breath sound, decreased tactile fremitus, and dullness to percussion on the right lower lung field - Chest x-ray show increased radiographic density and obliterated costophrenic angle. - You suspect pleural effusion. - What radiographic test would you order next to confirm the diagnosis?

Answer 33

Pleural diseases, pneumothorax and pleural effusion are better assessed by decubitus films - For a pneumothorax: air rises when lying on unaffected side, fluid layers when lying on the affected side

Question 34

How does pneumothorax affect absorption of X-ray photons and what is the resulting effect on the X ray density on the affected side?

Answer 34

Air rises when lying on unaffected side, fluid layers when lying on the affected side

Question 35

Name 3 respiratory conditions associated with increased and 3 associated with decreased radiographic density.

Answer 35

**Increased radiographic density:** - Alveolar filling - Atalectasis/volume loss - Interstitial infiltrates - Masses **Decreased radiographic density:** - Air trapping: asthma, emphysema, foreign body - Pneumothorax - Cysts/bullae - Loss of soft tissue