Radiology of the Chest Flashcards
Describe how PA and AP CXR are done
- Posterior to anterior (PA) projection is the most common for of CXR
- Involves patient hugging the detector and x-rays to be fired from behind them
- Anterior to posterior (AP) projection used if the patient cannot stand up
- Heart and anterior structures bigger but the lung is more difficult to see
How would you distinguish between PA or AP CXR
To tell if PA or AP, scapula in PA projection more to the side as the patient is grabbing over the detector, thus the scapula is rotated away from the midline
Be able to recognize where the hila, aortic knuckle, bowel gas and costophrenic recess/angle on a CXR
See onenote
Describe how you would evaluate a CXR
- Systematic ABC approach
- Adequacy - rotation (ensure midline), inclusion (includes 1st rib, apex of lungs and hemidiaphragms), penetration (structures visible)
- A= airway - trachea, bronchi (hila)
- B = breathing - lungs, pleural spaces, lung interfaces
- C = circulation - mediastinum - aortic arch, pulmonary vessels (hila), right heart border (middle lobe interface), left heart border (lingula)
- D = diaphragm/dem bones - free gas, nodules, fracture, mass
Describe how a mediastinal shift can occur
- Focus on trachea and cardiac shadow on an adequately centered image
- Mediastinum can be pushed if increase in volume or pressure from the opposite side
- Eg. Pleural effusion or pneumothorax increase pressure on affected side
- Mediastinum can be pushed if decrease in volume or pressure from same side
- Eg. Lobar/lung collapse decreases volume and pulls mediastinum to affected side
Describe the features of pneumothorax on a CXR
- Can be spontaneous (primary) or as a result of an underlying lung disease (secondary)
- Most common cause is trauma, with laceration of the visceral pleural by a fractured rib (closed)
- Tension pneumothorax - mediastinal shift away from the pneumothorax and depressed hemidiaphragm seen
- On percussion - hyper-resonance sound (excessive air in chest)
- No breath sounds on affected side
- Collapsed lung
Describe the features of pleural effusion on a CXR
- Collection of fluid in the pleural space when patient standing up
- Loss of costophrenic angle and hemidiaphragm obscured
- Uniform white area with no airways or vessels seen (as in fluid within pleural space in front of lungs)
- Can cause mediastinal shift from high pressure in pleural space which pushes mediastinum to the opposite side
- On percussion - dull sound
- Reduced breath sounds
Describe how a lobar lung collapse is seen on CXR
- Volume loss within lung lobe
- Elevation of the ipsilateral hemidiaphragm and shift of mediastinum towards affected side
Describe the possible causes of consolidation
- Pus - pneumonia
- Blood - haemorrhage
- Fluid - oedema
- Cells - cancer
Describe the appearance and probably cause of space occupying lesions on CXR
- Nodule if < 3cm and mass if > 3cm
- Can be due to malignancy (primary or metastases), inflammatory, benign mass lesion
- Can lead to lung collapse if tumour obstructs bronchioles
Describe the appearance of pneumonia on CXR
- Consolidation with air bronchogram (air filled bronchus surrounded by fluid filled alveoli)
- Suggests consolidation rather than lung collapse
- Percussion would be dull due to consolidation
- Bronchial breath sounds present
Describe the appearance of TB on a CXR
- Consolidation with ill-defined patching
- Cavitations present - dark spaces due to necrosis
Describe the appearance of COPD on a CXR
- Bilateral flattened diaphragm - due to hyperinflation from emphysema
- Bullae - black circles (air pockets) from emphysema
- Heart stretched due to diaphragm moving down
- On percussion - hyper resonance sound (excessive air in chest)
- Reduced breath sounds, muffled heart sound on auscultation as air between heart and stethoscope
Identify cardiac enlargement on CXR and estimate the cardiac index
Cardio to thoracic ratio should be less than 50% in a PA image
