Broncho-arterial ratio

The broncho-arterial (BA) ratio is a descriptive paramater used in thoracic CT imaging. It is defined as the diameter of the bronchial lumen divided by the diameter of its accompanying artery 1. It is usually measured in the segmental to subsegmental artery level.

In healthy humans, the broncho-arterial ratio is usually taken as being around 1:1.

It can increase or decrease in various situations.

Increased broncho-arterial ratio

Some authors term an increased broncho-arterial ratio of >1.5 as bronchiectasis although there are several non pathological conditions that can slightly increase the ratio. These include

  • ageing 2
  • high altitude 3

Pathological conditions that can increase the bronchoarterial ratio includes

Conditions that can reduce pulmonary arterial calibres

Decreased broncho-arterial ratio

Decreased broncho-arterial ratios have been described with

  • normal individual - ratios down to 0.65 have been described as acceptable within normal limits 5
  • conditions that cause bronchoconstriction
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Article Information

rID: 24580
System: Chest
Tag: cases
Synonyms or Alternate Spellings:
  • Bronchoarterial ratio
  • Broncho-arterial diameter ratio
  • Bronchus to artery ratio
  • Artery-bronchus ratio (ABR)
  • Broncho-arterial (BA) ratio
  • Bronchoarterial ratios
  • Broncho-arterial ratios

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