Chest X-ray quality

Rotation

If the patient is very rotated and you do not recognise this, certain appearances may become misleading.

Principles of rotation

The spinous processes of the thoracic vertebrae are in the midline at the back of the chest. They should form a vertical line that lies equidistant from the medial ends of the clavicles, which are at the front of the chest. Rotation of the patient will lead to off-setting of the spinous processes so they lie nearer one clavicle than the other.

Key points

  • Check for rotation
  • If there is rotation ask - does it matter?
  • Rotation may lead to misinterpretation of heart contours, tracheal position and lung appearances
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Well centred PA chest X-ray

  • Find the medial ends of the clavicles
  • Find the vertebral spinous processes
  • The spinous processes should lie half way between the medial ends of the clavicles

Does rotation matter ?

If the patient is rotated then interpretation may become difficult. Firstly, it may be difficult to know if the trachea is deviated to one side by a disease process. It also becomes difficult to comment accurately on the heart size. Changes in lung density due to asymmetry of overlying soft-tissue may be incorrectly interpreted as lung disease.

Rotation and heart size

Heart size can be assessed accurately with a well-centred posterior-anterior (PA) chest X-ray. If the patient is rotated to the left the heart may appear enlarged and if rotated to the right its size may be underestimated.

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Well centred patient

  • An accurate assessment can be made
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Rotated patient - Left

  • Heart size is exaggerated
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Rotated patient - Right

  • The true size of the heart may be underestimated
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©Radiology Masterclass 2007 -