Chest X-ray Quality
Rotation

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

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.

Well-aligned PA chest X-ray

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Well-aligned 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-aligned posterior-anterior (PA) chest X-ray. If the patient is rotated to their left, then the heart may appear enlarged. If the patient is rotated to their right, then heart size may be underestimated.

Well-aligned patient

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Well-aligned patient

  • An accurate assessment can be made

Rotated patient - Left

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Rotated patient - Left

  • Heart size is exaggerated

Rotated patient - Right

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Rotated patient - Right

  • The true size of the heart may be underestimated

Rotation and the lungs

Thickness of soft tissues of the chest, such as breast tissue, is altered by rotation. This may give the misleading impression of pathology in the lungs.

Pseudo-blunting of the costophrenic angle

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Pseudo-blunting of the costophrenic angle

  • At first glance the left costophrenic angle appears blunt
  • The patient is rotated which results in greater thickness of breast tissue overlying the costophrenic angle on the left compared with the right
  • You may be misled into thinking there is a pleural effusion or other pathology causing costophrenic angle blunting

Page author: Salisbury NHS Foundation Trust UK (Read bio)

Last reviewed: February 2020