CXR Interpretation Flashcards
Why are CXRs sometimes hard to read?
Because they are a 2D picture of a 3D structure
Where is the horizontal fissure?
In between the right upper lobe and middle lobe
When can you see the horizontal or oblique fissure in a CXR?
When there’s an issue, e.g. fluid on the fissure
What is the carina of the lungs?
The point where the two main bronchi split
What does a black area below the left lung indicate?
Gas in the stomach
What is the hilar region of the lungs?
Area with lots of vessels, including bronchi and pulmonary arteries and veins
What are the 12 steps to interpreting CXRs?
- Patient’s name
- Date & time of film
- View
- Exposure
- Alignment & expansion
- Attachments
- Bones
- Soft tissues
- Mediastinum
- Hilar region
- Lung fields
- Pleural margins
What are the 2 main ways of taking a CXR?
PA (posteroanterior)
- Most satisfactory
- Standing, arms resting up on top of machine
- Scapulae rotated out of the way
- Normal heart shadow
AP (Anteroposterior)
- Portable (e.g. ICU)
- Magnification of heart
- Scapulae in normal position
- Supine: diaphragm rises, lungs tend to look poorly expanded
What is a less common way of taking a CXR?
Lateral view
- Very rare
- May be used to look for tumours etc
What is the optimal exposure for a CXR?
- Should just be able to make out the IV discs through the heart
- Overexposed = too dark
- Underexposed = to white
- Check exposure when comparing films
What needs to be considered when looking at the alignment of a CXR?
- Angle of clavicles (should be equidistant)
- Relationship of spinous processes & proximal clavicles (should be right behind trachea)
- Symmetry of ribs
What needs to be considered when looking at the expansion of a CXR?
- How low is the diaphragm sitting
- 7th rib anteriorly intersecting diaphragm at mid clavicular line
- Ribs 9-11 posteriorly sitting on diaphragm
- R hemidiaphragm higher than L (due to liver)
What are some of the attachments that may appear on a CXR?
- Endotracheal tube (ETT)
- Central line (CVC)
- Tracheostomy
- Nasogastric tube (NGT)
- Inter-costal catheters (ICC)
- ECG dots
- Pacemaker
- Sternal wires
Where would an endotracheal tube (ETT) appear on a CXR?
- Breathing tube in through mouth into trachea
- Sitting within trachea
- Should terminate 3-5cm above carina
Where would a central line (CVC) appear on a CXR?
- Should terminate just above right atrium
- Internal jugular (neck) or subclavian
Where would a tracheostomy appear on a CXR?
- Tube from trachea to outside
- About width/length of finger, curving around
- Look for circle where trachea is facing camera
Where would a nasogastric (NGT) appear on a CXR?
- Starts at top of XR
- Travels down oesophagus into stomach
- Tip of tube is below diaphragm
- Does not follow the path of the bronchus
- Tube is not coiled anywhere in chest
Where would an intercostal catheter (ICC) appear on a CXR?
- Draining fluid/air from intrapleural space
- Usually connected to UWSD
- Width of finger, extend beyond rib cage, coming out side of chest
What is a pigtail catheter used for & how is it different to an ICC?
- Only used to drain air
- Much narrower than an ICC
Where would a pacemaker, sternal wires and ECG dots appear on a CXR?
Pacemaker
- Lump under skin
- Wires going to heart
Sternal wires
- Around trachea, wires going around in circle/figure 8
- Hold sternum in place while healing
ECG dots
- Clear spots with wires
What does a spring in the lung on a CXR represent?
An external ventilator (ICU patients)
What is flail chest?
- Multiple fractures within same ribs
- One segment starts moving in opposite way to breathing
What should be considered when looking at bones on CXRs?
- Rib fractures/displacements
- Flail chest
- Position of ribs - if horizontal, may be overexpanded/hyperinflated
- Locate border of scapula
- Not rotated away in AP view
What should be considered when looking at soft tissues on CXRs?
- Breast tissue
- Adipose tissue
- Subcutaneous emphysema (air tracking through soft tissues, shows as black outside of lungs, striation of pec major)
What should be considered when looking at the mediastinum on CXRs?
- Trachea: Midline position (relationship to spinous processes)
- Heart: Cardiac diameter should be no more than half the diameter of the lungs
What should be considered when looking at the hilar region on CXRs?
- Proximal main bronchi (L higher than R)
- Proximal pulmonary arteries, draining veins & lymph nodes
- Prominence = enlargement
What are some of the causes of hilar enlargement?
- Infection
- Tumour
- Vascular (aneurysm, stenosis etc)
What should be considered when looking at the lung fields on CXRs?
- Consolidation
- Collapse (atelectasis)
- Pulmonary oedema
What is consolidation?
When alveoli are full of something other than air (e.g. water, pus, blood)
What are the causes of consolidation?
- Infection (e.g. pneumonia, TB)
- Pulmonary haemorrhage
- Aspiration (e.g. gastric contents)
- Infiltration (e.g. lymphoma)
What are the CXR signs of consolidation?
- Areas of increased density (white)
- Air bronchograms: Contrast between dark air in bronchi & surrounding white airless parenchyma (looks like tree branches)
- Silhouette sign: Border of structure is lost because of whiteness
What are some of the causes of atelectasis?
- Mucous plug
- Inhaled foreign body
- Tumour
- Handling of lung tissue (almost always post cardiac surgery)
- Hypoventilation (upper chest breathing)
What are the CXR signs of atelectasis?
Loss of volume resulting in:
- Increased density (whiteness)
- Silhouette signs
- Displacement of fissures
- Elevation of hemidiaphragm
- Displacement of trachea towards side of collapse
- Displacement of hilar
- Crowding of ribs
How does pulmonary oedema appear on a CXR?
- Fluid overload in alveoli
- Increased lung markings throughout (speckles everywhere)
- Wet or fluffy
What needs to be considered when looking at the pleural margins on CXRs?
- Pneumothorax
- Pleural effusion
How does a pneumothorax appear on a CXR?
- Trace border of lung (visceral border)
- Note absence of lung speckles in pneumothorax space (looks unusually dark)
How does a pleural effusion appear on a CXR?
- Fluid appears white
- Flattening of bases (straight lines)
- Curved fluid line (meniscus sign) sometimes visible
How does the positioning of the trachea differ between pleural effusion and atelectasis CXRs?
- Atelectasis: Trachea moves towards side of collapse
- Pleural effusion: Trachea moves away from side of collapse
