Revision 13 for 'Chest x-ray - an approach (summary)'

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Chest x-ray review (basic)

  • this is a basic article for medical students and non-radiologists

Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals.

Chest radiographs are frequently performed and a fantastic tool for making diagnoses of acute and chronic conditions, as well as acting as a tool for follow up. It is paramount that correct interpretation is performed to ensure that the correct diagnosis is made in a timely fashion.

Procedure

There are many systematic ways to review a chest x-ray. The important thing is to have a system that you use every time you look at a chest x-ray - if you do, you will reduce the risk of missing something.

One of the easiest systems for reviewing a chest x-ray is A, B, C, D, E:

  • A: airways
  • B: breathing (i.e. the lungs)
  • C: cardiac (i.e. cardiomediastinum)
  • D: disability (i.e. fractures or dislocations)
  • E: everything else, e.g. pneumomediastinum, bone mets

Initial review

Who, what, when, why

Whenever you look at any imaging, ask:

  • who does it pertain to? (John Smith 12 Jan 1952)
  • what are you looking at? (PA chest x-ray)
  • when was it performed? (21 Jun 2014)
  • how well has it been performed? (quality)
Quality

Assessment of the quality of a radiograph allows you to make an assessment about what can be diagnosed using the study. If a chest radiograph is under-inspired and rotated, it is of limited diagnostic use.

  • rotation: medial ends of the clavicles equidistant from the spinous processes
  • inspiration: 10 to 11 posterior ribs on left side

A, B, C, D, E

Airways

The airways are often overlooked. Start at the top, in the midline the find the trachea. Follow the trachea down in the midline to the carina and then down the right and left main stem bronchi. The angle between the left and right mainstem bronchi should be between 50 and 100 degrees.

Checklist
  • trachea is straight and midline
  • carina is not widened (less than 100 degrees)
Pathology
  • deviated trachea
  • widened carina
    • mediastinal mass, e.g. subcarinal lymphadenopathy
    • left atrial enlargement
    • cardiomegaly
    • pericardial effusion
    • upper lobe collapse
Breathing (lungs)

There are a large number of pathological process that can result in abnormality in the lungs. This is usually highlighted as a change in the appearance of normally aeration. Broadly speaking, this may be because of increased density (white areas) or increased lucency (black areas).

While the mediastinum isn't central, you should still be able to compare the lungs, ensuring that the apices, upper, middle and lower zones are of similar density and volume.

When looking and comparing the lung parenchyma, check for any focal areas of increased density.

After checking the lung parenchyma, check around the lungs. Start laterally, from the apex down to the costophrenic angle. After checking the costophrenic angle and making sure they are symmetrical, ensure you can trace the hemidiaphragms to the spine. Then, the final check is the 

Checklist
  • both lungs are expanded and similar in volume
  • apices, upper, middle and lower zones are symmetrical
  • normal lateral margins
  • normal CPAs
  • normal hemidiaphragms
  • normal cardiac borders
  • normal lung behind the heart
Pathology

The pathology that affects the lung parenchyma is wide ranging.

  • airspace shadowing
    • consolidation/pneumonia
    • pulmonary edema
  • collapse
    • lung collapse
    • lobar collapse
      • right upper lobe collapse
      • right middle lobe collapse
      • right lower lobe collapse
      • left upper lobe collapse
      • left lower lobe collapse
    • segmental collapse
    • subsegmental collapse
    • lung fibrosis
  • lung lesions
    • solitary pulmonary lesion
    • multiple lung lesions
    • cavitating lung lesion
  • pleural collection
    • pneumonectomy
    • pleural effusion
    • hemothorax
    • empyema
Heart

Assess the heart size and shape on fully inspired PA films

Mediastinum & Hila

Assess the trachea for deviation, narrowing or intraluminal lesions

  • if deviated towards, think volume loss
  • if deviated away, think volume gain

Assess the mediastinal width

  • if widened, think mediastinal mass or vascular abnormality

Check hila position, equal density and normal branching vessels

  • left hilum normally higher than right

Lungs

Look for areas of increased density comparing the left and right upper, middle and lower zones

Ensure the heart borders and domes of diaphragm are clearly defined

  • if not, think consolidation +/- collapse
  • localize:  right heart border = RML, left heart border = LUL, right diaphragm dome = RLL, left diaphragm dome = LLL

Assess the vascular markings

  • vessels should taper and be almost invisible at the peripheries
  • lower lobe vessels are larger than upper lobe on erect films
Pleura

Assess the horizontal fissure for fluid or displacement

  • if displaced upwards, think volume loss of RUL
  • if displaced downwards, think volume loss of RLL

Check the costophrenic and cardiophenic angles

  • if costophrenic angle is blunted, think pleural effusion

Diaphragm

Assess shape, position and below for free air

  • right hemidiaphragm should be higher than the left (1-3cm)
  • if flattened, think hyperinflation
  • if free air, think pneumoperitoneum
Thoracic wall & soft tissue

Scan the ribs, clavicles, scapulae and spine for fractures and bony destruction.

Scan the soft tissues for breast shadows, surgical emphysema and foreign bodies.

Review areas

Double-check the apices (masses, pneumothorax), hila (masses, lymphadenopathy), retrocardiac zone (lobar collapse, hiatus hernia) and below the diaphragm (tubes and free air).

Finally, always compare to old films.

Common pathology

Pneumonia
  • most common cause of death due to infectious diseases
  • higher incidence at the extremes of age
  • streptococcus pneumoniae - most common organism
  • homogenous opacification in lobar pattern
  • characteristic air bronchograms and volume loss
  • more: lobar pneumonia
Lobar collapse
  • due to obstruction; luminal (aspiration, mucous plugging), mural (cancer) or extrinsic (mass compression)
  • RUL: right upper medial opacification, elevated horizontal fissure and right hilum
  • LUL: left hemithorax ‘veil-like’ opacity, elevated left hilum
  • RML: horizontal fissure not visible, ill-defined right heart border
  • RLL: right medial basal triangular opacification, depressed right hilum
  • LLL: left retrocardiac triangular opacification, double cardiac contour, depressed left hilum, loss of descending aortic and left medial hemidiaphragmatic outline
  • secondary signs: elevated hemidiaphragm, crowding of ribs and mediastinal shift towards affected side
  • more: lobar collapse
Pneumothorax
  • air in pleural space
  • categorized as primary spontaneous, secondary spontaneous (underlying lung disease) or iatrogenic/traumatic
  • simple: clearly defined visceral pleural edge paralleling chest wall, peripheral lucency with absent lung markings
  • tension: overexpanded hemithorax, depressed hemidiaphragm, contralateral mediastinal shift
  • more: pneumothorax
Congestive cardiac failure
  • commonly due to left ventricular failure
  • stage 1: redistribution (upper lobe diversion, cardiomegaly)
  • stage 2: interstitial edema (Kerley B lines, peribronchial cuffing, hazy hilar vessels)
  • stage 3: alveolar edema (consolidation, air bronchogram, cottonwool appearance, pleural effusion)
  • more: congestive cardiac failure
Pleural effusions
  • collection of fluid within pleural cavity
  • most commonly due to cardiac failure (transudate) or malignancy (exudate)
  • >200ml fluid required for meniscus at costophrenic angle on erect CXR
  • opaque hemithorax and contralateral mediastinal shift in large volume effusions
  • hydropneumothorax - no meniscus visible
  • more: pleural effusion
Lung carcinoma
  • leading cause of cancer mortality worldwide
  • divided into non-small cell and small cell carcinomas
  • adenocarcinoma most common histological subtype
  • may present as a peripheral rounded or spiculated mass, hilar/perihilar mass, mediastinal widening, lobar collapse or pleural effusion
  • more: lung carcinoma
Pulmonary metastases
  • metastatic spread to lungs via blood or lymphatics
  • most common primaries include breast cancer, colorectal cancer and renal cell cancer
  • peripheral, rounded nodules scattered throughout lungs
  • more: pulmonary metastases
Pneumoperitoneum

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