Type:
Educational Exhibit
Keywords:
Haemorrhage, Normal variants, Localisation, CT, Mediastinum, Lung, Anatomy
Authors:
P. Malkowski; Warszawa/PL
DOI:
10.1594/ecr2012/C-1327
Imaging findings OR Procedure details
Bronchial arteries usually (ca 70% of general population) originate from descending aorta at the level of the 5th and 6th thoracic vertebral body.
They are then referred to as orthotopic.
The orthotopic bronchial artery supply has been divided into four types:
- The most frequent is type I (ca 40% of orthotopic arteries) when two left bronchial arteries derive directly from descending aorta (Fig. 1) and a single right bronchial artery begins as an intercostobronchial trunk ( Fig. 2 ).
- In type II (ca 20% of orthotopic arteries) there is only one left bronchial artery which arise directly from the descending aorta and one right bronchial artery which begins as an intercostobronchial trunk.
- In type III (ca 20% of orthotopic arteries) there are two bronchial arteries on both sides but one of them on the right begins as an intercostobronchial trunk.
- In type IV (ca 10% of orthotopic arteries) there are two right bronchial arteries,
one of them begins as an intercostobronchial trunk,
and one left bronchial artery.
Intercostobronchial trunk is a common vessel for intercostal and right bronchial artery.
Fig. 3
The aforementioned classification covers about 90% of orthotopic bronchial arteries.
In the remaining cases a common trunk of both bronchial arteries or a left intercostobronchial trunk can be found.
If bronchial arteries leave aorta at levels different than the 5th and 6th thoracic vertebral body or arise from lesser arteries,
they are then deemed to be ectopic or aberrant:
- Three quarters of ectopic bronchial arteries leave the concavity of the aorta (usually in the posterior part) ( Fig. 4,
Fig. 5 ).
- 10% of ectopic bronchial arteries arise from subclavian artery,
either on the same side or on the opposite side.
- Less than 10% of ectopic arteries begin from descending aorta at levels other than the 5th or 6th thoracic vertebral body.
Ectopic bronchial arteries can originate also from:
- branches of subclavian arteries (internal thoracic artery,
thyrocervical trunk),
- pericardiophrenic artery,
or
At least one ectopic bronchial artery can be found in more than 30% of patients with haemoptysis and 5% of them have only ectopic arteries ( Fig. 5 ).
The location of ostia of bronchial arteries,
either orthotopic or ectopic,
on the circumference of the aorta is also considerable.
From medial to anteromedial aspect of descending aorta arise:
- all right intercostobronchial trunks ( Fig. 6 ),
- 60% of right direct bronchial arteries ( Fig. 7 ),
- about 25% of left bronchial arteries.
From lateral to anterior wall of aorta derive:
- 40% of right direct bronchial arteries,
- 75% of common trunks of both bronchial arteries,
- 75% of left bronchial arteries ( Fig. 6 ).
Bronchial arteries,
regardless of their origin,
pass through the mediastinum to the hila,
where they follow the course of the main bronchi and their branches.
On the contrary,
nonbronchial systemic arteries do not enter the lung parenchyma through the hila and do not run parallel to the bronchi ( Fig. 8 ).
Their presence can be suspected when there is a 3 mm thickening of pleura and enhancing tortuous arteries in extrapleural fat can be seen.
Nonbronchial systemic arteries usually derive from:
- subclavian arteries (and their branches,
especially internal thoracic artery),
- inferior phrenic arteries,
In normal conditions bronchial arteries are very thin and difficult to identify without using special CT angiographic protocols.
However,
there are certain disorders,
which lead to the dilatation of bronchial arteries (ø>2 mm) and their better picture on CT images.
They are chronic thromboembolic disease,
bronchiectasis and tuberculosis,
among others ( Fig. 9 ).
The dilated bronchial vessels are prone to rupture,
leading to,
sometimes life threatening,
haemoptysis.