Pleural empyema

Radiological presentation of pleural empyema

In the development of pleural empyema (empyema pleurae), imaging methods play a crucial role not only in establishing the diagnosis but also in selecting the treatment strategy. Ultrasonography serves as the primary tool here.

On sonograms, the typical picture is a complex multiseptated loculated pleural collection (complex multiseptated loculated pleural effusion). In some cases, the contents may be isoechoic, making visual differentiation between the pathological fluid and the collapsed lung tissue difficult. In such situations, it is critically important to use color Doppler flow imaging (colour flow imaging), which allows for a clear visualization of the vascular pattern of the lung tissue and helps distinguish it from avascular pleural effusion.

Additionally, ultrasound is used for safe navigation during pleural drainage placement. An important concomitant clinical and radiological sign of empyema is antalgic scoliosis (antalgic scoliosis)—a forced spinal curvature that develops as a reaction to pronounced pain syndrome on the affected side.

Foreign body aspiration

In addition to inflammatory processes, special attention in thoracic imaging is paid to aspiration. An episode of foreign body aspiration often goes unnoticed by adults; however, it can manifest either as acute respiratory distress syndrome requiring immediate intervention or as a chronic wheeze with recurrent infections at later stages. If a young child develops unexplained respiratory deterioration in the setting of lung collapse or overinflation, emergency bronchoscopy is indicated.

In non-emergency situations, the method of first choice is a plain radiograph (plain radiograph).

• Key findings: radiopaque objects (however, plastic and nuts are radiolucent), lobar collapse, and areas of air trapping.
• Hypertransradiancy (hypertransradiancy): may be local or diffuse, developing due to a ball-valve mechanism.

To differentiate the causes of altered radiolucency (e.g., distinguishing aspiration from stridor), fast pulse fluoroscopy (fluoroscopy) is used. During airway obstruction, the lung remains overinflated and does not change in volume during the respiratory cycle, while the mediastinum shifts toward the healthy side on expiration.

Organic bodies such as peanuts, which cause severe local inflammation, pose a particular danger. During their removal, fragments can migrate into the distal pathways, provoking consolidation. An even more critical situation is the ingestion of button batteries (button batteries). They frequently get trapped in the gastroesophageal junction. Alkaline products of electrolysis cause deep burns and esophageal wall perforation in just 2 hours. This can lead to tracheoesophageal and aortoesophageal fistulas, as well as vertebral discitis. Emergency removal is required.

Diagnostics in stridor syndrome

Stridor (stridor) in children is most commonly a secondary condition associated with infectious processes. The role of diagnostic imaging varies depending on the suspected cause:

1. Epiglottitis (epiglottitis): lateral neck radiographs reveal pronounced thickening of the epiglottis.
2. Croup (croup): anteroposterior chest radiograph reveals subglottic narrowing and hypopharyngeal overdistension. The epiglottis is not thickened, although imaging is rarely indicated for croup.
3. Tracheomalacia (tracheomalacia): fluoroscopy is used for dynamic visualization of tracheal collapse on expiration.
4. Vascular ring or sling (vascular ring or sling): barium swallow in a true lateral projection with good esophageal distention is used to assess compression. Anomalous vessels cause characteristic indentations in the contrast column.

Currently, thin-section CT (thin-section CT) with multiplanar reconstruction and volume rendering has practically replaced contrast bronchography for vascular anomalies. However, fluoroscopy retains its position for the functional evaluation of intermittent obstruction (including when tailoring non-invasive ventilation parameters), avoiding the excessive radiation dose of repeated dynamic CT scans.

Congenital chest wall anomalies

Congenital anomalies are considered as a single spectrum of developmental disorders. The group of bronchopulmonary foregut malformations includes:

• Tracheobronchial anomalies: congenital malformations of the lower respiratory tract (CPAMs, formerly known as cystic adenomatoid malformations — CCAMs).
• Bronchogenic cysts (bronchogenic cysts).
• Anomalies with abnormal vascular supply: pulmonary sequestration and scimitar syndrome.

Hybrid lesions are not uncommon, such as a cystic malformation receiving systemic arterial blood supply (a combination of CPAM and sequestration features).

The optimal diagnostic method is multidetector computed tomography (MDCT), which details the parenchyma, systemic arterial supply, and venous drainage pathways. In intralobular sequestration, drainage occurs into the pulmonary veins, whereas in extralobular sequestration (ELSs), it drains into the systemic venous system.

Congenital thoracic cysts (congenital thoracic cysts) can be located both in the mediastinum (bronchogenic, pleuropericardial, and esophageal duplication cysts) and in the lung parenchyma (10–15% of cases). Moreover, bronchogenic cysts are localized precisely in the mediastinum in 85% of cases, most frequently in the subcarinal region.

Class and exam questions

What else to study on this topic

• Detailed anatomy and ultrasound semiotics of the pleural cavity
• Classification and CT findings of congenital pulmonary airway malformations (CPAM)
• Principles of differential diagnosis of pulmonary sequestrations (intralobular vs. extralobular)
• Imaging algorithm for scimitar syndrome

Other Topics in "Pediatric Diagnostic Radiology"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.