Anteroposterior (AP) chest X-ray of a pediatric patient demonstrating significant pulmonary asymmetry and mediastinal displacement. The left upper lung field shows increased opacity and volume loss, characteristic of a left upper lobe collapse (atelectasis). This is associated with an ipsilateral mediastinal shift, visible by the deviation of the tracheal air column and cardiac silhouette toward the left side of the thoracic cavity. In contrast, the right lung field appears markedly more radiolucent with increased volume, representing compensatory hyperinflation of the contralateral lung. These diagnostic findings are critical for identifying obstructive lung processes, such as follicular bronchiolitis or foreign body aspiration, which lead to differential ventilation and volume loss in the affected segments. The image serves as a clinical example of the secondary effects of focal lung collapse on thoracic anatomy and mediastinal positioning.

This composite medical image presents a clinical comparison of total left lung collapse using two diagnostic modalities: a frontal chest radiograph (A) and an axial thoracic CT scan (B). In image A, the chest X-ray shows complete opacification of the left hemithorax with a notable absence of air-filled lung markings, indicative of massive atelectasis. The right lung remains well-aerated with visible pulmonary vasculature. Medical hardware, including ECG leads and potentially a nasogastric tube, are visible. In image B, the axial CT scan at the level of the main bronchi confirms complete left-sided atelectasis, appearing as a dense, consolidated mass of soft tissue density occupying the posterior hemithorax. The right lung demonstrates compensatory hyperinflation. A key diagnostic feature shown in the CT is the obstruction of the left main bronchus by high-density foreign material (aspirated enteral formula), leading to distal resorption atelectasis. This visual set is essential for teaching the radiographic signs of obstructive lobar/total lung collapse and the clinical complications associated with pulmonary aspiration in patients receiving enteral nutrition.

A comparison image displaying a posterior-anterior chest X-ray (left) and a corresponding axial computed tomography (CT) scan (right) of the same patient. The chest X-ray illustrates a horizontal, linear opacity in the lower lobe of the right lung, highlighted by a cyan contour from an AI diagnostic tool, suggesting localized lung collapse. The right panel shows a high-resolution axial CT scan in a lung window, which definitively characterizes the pathology as discoid atelectasis. Visible features on the CT include a band-like, transverse opacity located in the right lower lobe, parallel to the diaphragm, accompanied by focal volume loss and mild adjacent pleural thickening. This image set demonstrates the diagnostic transition from a projectional screening modality (X-ray) to a cross-sectional confirmatory modality (CT) for identifying plate-like atelectasis and differentiating it from other pulmonary infiltrates or pleural pathologies.