Pneumothorax Diagnosis and Evaluation

The standard chest X-ray (CXR) is the primary imaging modality for diagnosing a pneumothorax.

• Visceral Pleural Line: The hallmark finding on a chest X-ray is the visualization of the visceral pleural line. This appears as a thin, sharp white line separated from the chest wall by a radiolucent (dark) space devoid of lung markings.
• Lung Collapse: The lung tissue peripheral to this line is absent, and the collapsed lung is seen retracted toward the hilum.
• Upright vs. Supine: In an upright patient, air collects at the apex (top) of the lung. In a supine patient (e.g., a trauma victim), air collects anteriorly and inferiorly, creating the “deep sulcus sign,” in which the costophrenic angle appears abnormally deep and lucent.
• Expiratory Films: Historically, X-rays taken during expiration were thought to accentuate the pneumothorax by reducing lung volume while the pleural air volume remains constant. However, standard inspiratory films are generally sufficient for diagnosis.