Principle and technique
Since normal lung tissue and airways merge on a radiograph, artificial contrasting is necessary for a detailed study of the bronchial structure. In classical bronchography, iodolipol is used for this purpose — an agent that effectively absorbs X-rays.
The procedure requires strict preparation. First, preliminary local anesthesia of the patient's airways is performed. Then, the contrast agent is injected into the bronchial lumen, after which a series of X-ray images is taken. The resulting radiograph forms a clear, contrast-enhanced cast of the bronchial tree.
Main indications and findings
Historically, the method played a key role in X-ray bronchological diagnostics. It was used by doctors to detect:
- Bronchiectasis (pathological dilations of the bronchi).
- Abscesses and cavities in the lung tissue (to assess their connection with draining bronchi).
- Tumor processes leading to narrowing of the bronchial tree lumen.
The study demonstrates the highest informativity when analyzing the lower lobes of the lungs (pathologies are particularly frequently detected on the left), where changes are localized predominantly at the level of the 4th–6th order bronchi.
Radiological presentation of bronchiectasis
Acquired bronchiectasis most commonly develops via the classic obstructive-infectious mechanism. On a contrast bronchogram, it manifests as marked deformation and dilation of the bronchial tubes.
The most specific and recognizable radiological sign is the «stubbed broom» sign. It occurs because the contrast agent freely fills the pathologically dilated areas, but fails completely to penetrate the distal branches of the bronchi located below this zone. On the image, this appears as an abrupt cutoff of the bronchial pattern.
Role of the method in modern medicine
Today, traditional contrast bronchography is used extremely rarely. In modern clinical practice, it has been almost completely replaced by high-resolution computed tomography (HRCT) and thin-section CT (thin-section CT).
HRCT has a number of absolute advantages:
- It is completely non-invasive (does not require anesthesia or instillation of contrast into the lungs).
- It details wall thickening and the absence of normal bronchial tapering toward the periphery.
- It demonstrates specific «tram track» and «signet ring» signs on cross-sections.
- It allows evaluation of concomitant parenchymal lesions: areas of consolidation, mosaic perfusion, and differentiates obstructive bronchiectasis from traction bronchiectasis (arising from severe pulmonary fibrosis and the «honeycomb lung» sign).
Additionally, thin-section CT with volume rendering and multiplanar reconstruction has completely replaced bronchography in the diagnosis of vascular rings and congenital bronchopulmonary malformations.
Alternative instrumental examinations
In addition to tomography, other imaging and endoscopic methods are used for a comprehensive assessment of the respiratory system:
- Plain chest radiography (plain radiograph): the method of choice for detecting cavities, infiltrates, areas of atelectasis, and loss of lung lobe volume.
- Fluoroscopy (fluoroscopy): allows real-time assessment of lung field transparency, mediastinal shift, detection of foreign bodies, presence of fluid/air in the pleural cavity, and coarse adhesions.
- Bronchoscopy: an endoscopic method which, unlike imaging methods, makes it possible to visually assess the mucous membrane from the inside and confirm the presence of catarrhal-suppurative or purulent inflammation (endobronchitis).
To easily memorize the classic sign of bronchiectasis, imagine an old, worn broom: the contrast (iodolipol) easily and abundantly fills the large, pathologically dilated bronchi, but does not flow any further into the fine distal branches. On the radiograph, the bronchial tree ends abruptly, forming the characteristic «stubbed broom» sign.
Class and exam questions
What agent is used for bronchial contrasting?
In classical bronchography, iodolipol is used — an oily substance that absorbs X-rays. It is injected into the airways strictly after preliminary local anesthesia.
At what level are acquired bronchiectasis typically detected?
Pathological changes, deformation, and luminal dilation are predominantly localized in the lower lobes of the lungs (especially on the left), usually at the level of the 4th–6th order bronchi.
Why is bronchography considered an outdated method?
The method involves invasive intervention and radiation exposure. It has now been replaced by HRCT, which demonstrates bronchial dilation, «tram track» and «signet ring» signs, as well as the state of the surrounding lung parenchyma in a completely non-invasive manner.
What else to study on this topic
- Radiological diagnostics of foreign body aspiration: local hyperlucency and air trapping
- Radiological signs of stridor: differentiating croup from epiglottitis
- Differential diagnosis of a collapsed lung and loculated pleural empyema via ultrasound
- Foregut bronchopulmonary malformations: cysts, sequestration, and CPAMs
- Differentiating obstructive-infectious from traction bronchiectasis in pulmonary fibrosis
- Barium fluoroscopy in suspected vascular ring or sling
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