Chest X-ray examination

Chronic obstructive pulmonary diseases

Changes associated with airway obstruction depend on the type and severity of the process.

• Severe diffuse emphysema: On conventional radiographs, the diaphragmatic dome is displaced inferiorly and flattened. In the posteroanterior view, irregular contours may be visible at the sites of diaphragmatic attachment to the ribs (diaphragmatic insertions). The transverse cardiac diameter decreases, forming the so-called «drop-like heart». Depletion of the vascular pattern is noticeable in the lung periphery. In the lateral view, widening of the costophrenic angle and an increase in the retrosternal clear space are characteristic.
• Giant bullous emphysema: Large avascular (devoid of vessels) areas of increased lucency are visualized. Bullae are limited by distinct, thin, curvilinear walls and can occupy significant volumes, for example, in the upper and lower lung zones.
• Mild centrilobular emphysema: Requires the use of HRCT. Multiple small areas of decreased attenuation are identified, distributed throughout the lung parenchyma but grouping predominantly around the centrilobular arteries.

Infectious lesions and immunodeficiencies

In immunocompromised patients or those with congenital disorders, the radiological presentation has several specific features.

1. Cystic fibrosis (Cystic Fibrosis): Radiography shows hyperinflation with bilateral bronchial wall thickening, bronchiectasis, and focal consolidation. CT reveals mucous plugs (mucous plugging) and background mosaic attenuation. During an infectious exacerbation (e.g., Mycobacterium abscessus), cavitary nodules may appear.
2. Pneumocystis pneumonia: The peak incidence occurs at 3–6 months of age, when maternal IgG levels decline. The classic presentation includes hyperinflation with diffuse bilateral interstitial or nodular infiltrates and perihilar granular shadowing. The process can rapidly progress to an ARDS-like pattern with widespread opacification. Important: radiological clearing of the lungs significantly lags behind clinical improvement.
3. Invasive pulmonary aspergillosis: The angioinvasive fungus causes hemorrhagic pulmonary infarctions. CT reveals multifocal areas of triangular or nodular consolidation. Specific features include the «halo» sign (halo sign — a zone of ground-glass opacity surrounding a nodule, reflecting hemorrhage) and the «air crescent» sign (breakdown of the lesion).
4. Lymphoproliferative disorders (LPD): May manifest variably: from massively enlarged mediastinal lymphadenopathy to lymphocytic interstitial pneumonia (diffuse infiltrate of lymphocytes localized predominantly in the perihilar and basilar regions).

Granulomatoses and organizing pneumonia

Assessment of the presence of cavitation and the distribution of infiltrates is critically important for the differential diagnosis of non-infectious lesions.

• Granulomatosis with polyangiitis: Characterized by the presence of multiple large (>2 cm) cavitating nodules with uneven wall thickness. CT shows irregularly shaped areas of consolidation resembling mass lesions. The bronchocentric type of the disease manifests as wall thickening of segmental and subsegmental bronchi.
• Cryptogenic organizing pneumonia (COP): Unlike granulomatosis, cavitation is atypical for COP. All lung zones are affected, more frequently bilaterally. Areas of consolidation tend toward a subpleural or peribronchovascular distribution. The «reverse halo» sign (Atoll sign) — ground-glass opacity surrounded by a dense ring of consolidation — is considered specific. If a large solitary nodule with irregular borders is identified, oncological screening is required.

Trauma and focal diaphragmatic alterations

Diagnosis of diaphragmatic pathologies requires careful contour analysis and the use of multislice CT with reconstructions.

• Focal eventration (Focal Eventration): Visualized as a soft-tissue attenuation shadowing originating from the diaphragm. CT confirms that liver tissue lies beneath the locally elevated area. In large left-sided herniations, loops of the small intestine may fill the hemithorax.
• Diaphragmatic injury: Frequently diagnosed intraoperatively, as associated injuries (lower chest trauma, severe pelvic trauma) require emergency surgery. Without surgery, rupture is easily missed. Post-traumatic images should always be compared with previous archival data.

In the acute phase of trauma, diagnosis is based on bedside ultrasound and radiography (which remains normal in 25% of cases). Attention is drawn to minimal contour changes of the diaphragm, localized opacities, basal atelectasis, and gas shadows in the thoracic cavity. In the latent phase, barium contrast studies, CT, and MRI are used.

Class and exam questions

What else to study on this topic

• Features of multislice CT in occult diaphragmatic ruptures
• Differential diagnosis of cavitary pulmonary nodules
• Reverse halo sign: in what other diseases does it occur?
• Radiological presentation of bacterial and fungal pneumonias: key differences

Other topics in the «Chest Radiology» section

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