19 Introduction to Chest Radiology 2

Question 1

Pattern approach

• Puzzle
• Location
• Pattern

Answer 1

• Puzzle
  
  • History
  • Physical exam,
  • Labs
  • PFT
  • CXR / CT
• Location
  
  • Lung
  • Pleura
  • Mediastinum
  • Chest wall
• Pattern
  
  • Degree of inspiration
  • Lungs too black / white

Question 2

Radoilogic patterns

• Lungs are too white
• Lungs are too black
• Other

Answer 2

• Lungs are too white
  
  • Consolidation
  • Ground glass attenuation
  • Atelectasis
  • Reticular / nodular (interstitial disease)
  • Airspace (acinar)
  • Mixed
• Lungs are too black
  
  • Air trapping – emphysema
  • Bronchiectasis
• Other
  
  • Pulmonary nodule or mass
  • Cyst (multiple): cystic and cavitary disease
  • Pleural effusion
  • Lymphadenopathy
  • Mediastinal widening

Question 3

Air space

Answer 3

• Gas-containing portion of lung parenchyma, to include acini
• Exclude the interstitium and purely conductive portion of lung
• Consolidation: etiology
  
  • Pneumonia
  • Pulmonary edema
  • Aspiration
  • Near drowning
  • Malignancy

Question 4

Air space consolidation

Answer 4

• Air in alveoli is replaced by water, blood, pus, or tumor; results in confluent opacity which obscures broncho-vascular margins
• May be focal, patchy, or diffuse
• Air-bronchogram: radiologic appearance of an air-containing bronchus, surrounded by consolidated lung

Question 5

Air space consolidation: differential

• Edema
• Infectious
• Inhalation
• Neoplasm
• Metabolic
• Other

Answer 5

• Edema
  
  • Fluid overload (heart, renal failure)
• Infectious
  
  • Pneumonia
• Inhalation
  
  • Aspiration, toxic gases, drowning
• Neoplasm
  
  • Adeno CA, lymphoma, mets
• Metabolic
  
  • Alveolar proteinosis
• Other
  
  • Pulmonary hemorrhage
  • Adult respiratory distress syndrome (ARDS)

Question 6

Consolidation: radiologic signs

Answer 6

• Silhouette sign (loss of)
  
  • Loss of normal lung – soft tissue interface
  • Enables anatomic localization
• Air-bronchogram sign
  
  • Air filled bronchi are surrounded by consolidated lung
• Bulging fissure sign
  
  • Lobar consolidation with copious pus causes bulging of the fissure

Question 7

“Loss of the silhouette” sign

Answer 7

• Localize lung pathology
• When air in lung is When air in lung is tissue (pneumonia), the normal interface between lung and heart is lost

Question 8

Consolidation: strep pneumonia RUL

Answer 8

• Silhouette sign
  
  • RUL consolidation obscures normal air – soft tissue interface between lung & heart
• Bulging fissure sign
  
  • Minor fissure bows downward
• Air-bronchogram sign
  
  • Air-filled bronchus is patent
  • Surrounding lung is consolidated

Question 9

Pneumonia LUL

Answer 9

• In lingula
• Lobar
• Lobar on CT
  
  • Dense LUL consolidation
  • Mild posterior bulging of L major fissure
  • Most LUL airways are filled with pus
  • Several air-bronchograms

Question 10

“Round” pneumonia: legionella

Answer 10

• More common finding in kids
• May mimic malignancy

Question 11

Consolidation

• Edema
• Aspiration
• Drowning
• Lung cancer

Answer 11

• Edema
• Aspiration
  
  • Contents in stomach or oro-pharynx are inhaled into trachea and lungs
  • Results in consolidation of dependent portions of lung
• Drowning
  
  • Aspiration of water
  • Consolidation is not always pna
• Lung cancer
  
  • Pneumonic form mimics pneumonia

Question 12

Ground glass opacity

Answer 12

• Hazy increased lung attenuation
• Preserved broncho-vascular markings / margins
• Partial filling of alveoli, interstitial thickening, increased capillary blood flow
• Individual deposits not detectable
• “Smeared chalk” appearance
• Edema, pneumonia
• Pneumocystis pneumonia
  
  • Pink frothy exudate fills airspaces

Question 13

Atelectasis

• Root “ectasia”
  
  • Aortic ectasia
  • Bronchiectasis
• Atelectasis
• Radiologic findings
  
  • Direct
  • Indirect

Answer 13

• Root “ectasia”: dilation, expansion
  
  • Aortic ectasia - mildly dilated aorta
  • Bronchiectasis - bronchial dilatation
• Atelectasis
  
  • Gr. ateles “imperfect” + ektasis “expansion”
  • “Collapse” of lung, volume loss
• Radiologic findings
  
  • Direct
    
    • Displaced fissure
  • Indirect
    
    • Increased attenuation
    • Displaced trachea, hilum, heart, diaphragm
    • Hyperinflation of unaffected lung

Question 14

Atelectasis: definition

Answer 14

• Decreased inflation of a segment, lobe, or lung
• Results in reabsorption of air
• Involved lung has decreased volume, increased opacity
• Due to mucous plug, stricture, tumor, or extrinsic compression of bronchus
• Non-involved lung responds with over

Question 15

Atelectasis

• “Plate-like” atelectasis
• RUL atelectasis
• Lobar atelectasis: RML

Answer 15

• “Plate-like” atelectasis
  
  • Subsegmental
  • Linear
• RUL atelectasis
  
  • Decreased inflation of segment, lobe, or lung
  • Reabsorption of air
  • Decreased volume, increased opacity
  • Mucous plug, stricture, tumor or compression of bronchus
  • Non-involved lung responds with over-inflation
• Lobar atelectasis: RML
  
  • Silhouette sign
  • Displaced fissures

Question 16

Atelectasis

• Left lung
• Endobronchial lesions

Answer 16

• Left lung
  
  • Heart displaced to left
  • R lung is over-inflated
• Endobronchial lesions
  
  • Mucus plugs
  • Malpositioned ET tube
  • Foreign bodies
  • Neoplasms
  • Strictures / stenoses

Question 17

Secondary atelectasis

Answer 17

• Compressive
  
  • Pleural effusion or PTX
  • Huge R effusion
  • R lung atelectasis
• Pneumothorax

Question 18

Interstitium

Answer 18

• Continuum of loose supporting connective tissue in the lung
  
  • Broncho-arterial
  • Acinar - between alveoli and capillaries
  • Subpleural - continuous with interlobar septa
• When diseased, tissues surrounding the air spaces & airways are thickened, with preservation of alveolar air

Question 19

Interstitium

• Pulmonary edema
• Pulmonary lobule

Answer 19

• Pulmonary edema
• Pulmonary lobule
  
  • Intralobular septa
  • Reticulations

Question 20

Alveolar ducts and pulmonary acinus

• Microscopic anatomy
• Fibrosing alveolitis

Answer 20

• Microscopic anatomy
  
  • Terminal airways
  • Alveolar ducts
  • Acini
• Fibrosing alveolitis
  
  • Alveolar collapse
  • UIP / IPF

Question 21

Reticulo-nodular pattern

• Reticulo-nodular pattern
  
  • Reticular
  • Nodular
  • Reticulo-nodular
  • Honeycomb
• Nodular pattern

Answer 21

• Reticulo-nodular pattern (sarcoid)
  
  • Reticular: interlacing network of fine linear markings that form a mesh & contain air
  • Nodular: discrete, punctate, round 1 - 5 mm deposits
  • Reticulo-nodular: mixture of interstitial linear thickening & nodular deposits
  • Honeycomb: air-containing cystic spaces (5-10 mm) surrounded by thick fibrous walls
• Nodular pattern
  
  • Miliary TB

Question 22

Reticular pattern: differential

Answer 22

• Infectious - viruses, PCP
• Immune - scleroderma, hypersensitivity
• Edema
• Inhalational - asbestosis
• Airways - COPD with increased markings, cystic fibrosis (bronchiectasis)
• Drug-induced lung disease
• Pulmonary fibrosis

Question 23

Nodular pattern: differential

Answer 23

• Infectious - miliary TB, fungi, CMV
• Non-infectious granulomatous - sarcoid
• Neoplastic - lymphangetic mets, lymphoma
• Inhalational - silicosis

Question 24

Lungs are too black (and too big)

• General
• Emphysema
• Centrilobular emphysema (CLE)
• Centri- and pan-lobular COPD

Answer 24

• Retention of excess gas in all or part of lung, especially during expiration
• Oligemia - reduced pulmonary blood flow
  
  • Cardiac: pulmonic stenosis or atresia
  • Pulmonary artery HTN
  • Large pulmonary embolism
• Over-inflation, air-trapping
  
  • Emphysema
    
    • Abnormally expanded air spaces distal to terminal bronchiole, with destruction of walls of involved air spaces
  • Centrilobular emphysema (CLE)
    
    • Punched out black holes
    • No perceptible wall
    • Pulmonary artery (dot) in center
  • Centri- and pan-lobular COPD
  • Central airway obstruction
  • Small airway diseases

Question 25

Air trapping * General * Panlobular emphysema * Bronchiectasis

Answer 25

* General * Too big and black * Retention of excess gas in all or part of lung, especially during expiration * Due to partial airway obstruction or abnormal pulmonary compliance * Emphysema: abnormally expanded air spaces distal to terminal bronchiole, with destruction of walls of involved air spaces * Panlobular emphysema * Large bulla * Bronchiectasis * Dilation * Mixed pattern

Question 26

Cancer * Lung transplant * Lung cancer * Metastatic sarcoma * Pulmonary nodule, mass

Answer 26

* Lung transplant * We can live on one lung * Lung cancer * Metastatic sarcoma * Nodules, masses, consolidation * Pulmonary nodule, mass * Marble, baseball * Discrete, circular opacity \< 3 cm (T1) * Arises in lung * Mass: \> 3 cm (T2) * Solitary vs multiple * May cavitate

Question 27

Pulmonary nodule or mass: differential

Answer 27

* Developmental - AVM, bronchial cyst * Infectious - TB, fungal (granuloma) * Neoplastic * Benign: hamartoma * Malignant: lung CA, lymphoma, met * Traumatic - hematoma * Immunologic - rheumatoid, Wegener's

Question 28

Normal tracheo-bronchial tree

Answer 28

Question 29

Problems * PET: radioactive glucose * Cavitary septic emboli (infected)

Answer 29

* PET: radioactive glucose * Cavitary septic emboli (infected)

Question 30

Secondary pulmonary lobule

Answer 30

* Building block of the lung * Unit of lung structure, consists of \< 12 acini * Irregular polyhedral, ~ 1.23 cm * Marginated by interlobular septa * Pulmonary veins & lymphatics * Lobular core * Pulmonary arteriole & bronchiole

Question 31

Lymph node enlargement: differential

Answer 31

* Infectious - TB, fungal * Non-infectious granulomatous - sarcoid * Neoplasm - lung CA, lymphoma, mets * Inhalational - silicosis, berylliosis * Metabolic - amyloidosis * Reactive