Multidetector computed tomography of spontaneous versus secondary pneumomediastinum in 89 patients: can multidetector computed tomography be used to reliably distinguish between the 2 entities?

PURPOSE: To analyze the multidetector computed tomography (MDCT) findings of spontaneous pneumomediastinum (PM) to determine whether MDCT can reliably differentiate spontaneous from secondary PM.

MATERIALS AND METHODS: A retrospective clinical and chest MDCT analysis of all patients diagnosed with spontaneous PM over an 8-year period was performed. Radiologic comparison was undertaken with patients diagnosed with secondary PM from a central airways defect, esophageal rupture, or recent intervention in the airway or esophagus. The Fisher exact test for independence was used to compare the different MDCT findings between the groups.

RESULTS: A total of 89 patients were analyzed, with 1 secondary PM patient being included in both esophageal and central airways subsets, as the patient had an esophageal balloon-assisted intubation. Thirty-four patients were diagnosed with spontaneous PM. Compared with 28 patients with secondary PM from esophageal pathology, spontaneous PM patients were more likely to have air in the anterior mediastinum (97% vs 61%, P<0.001) and pulmonary interstitial emphysema (57% vs 4%, P<0.001), and less likely to show subdiaphragmatic air (0% vs 32%, P<0.001), pleural effusions (9% vs 61%, P<0.001), and acute pulmonary airspace opacities (14% vs 50%, P=0.003). Similarly, compared with 28 patients with secondary PM from trachea and bronchi pathology, patients with spontaneous PM were more likely to have pulmonary interstitial emphysema (57% vs 25%, P=0.01), and were less likely to show subdiaphragmatic air (0% vs 25%, P=0.002), pleural effusions (9% vs 39%, P=0.005), and acute pulmonary airspace opacities (14% vs 43%, P=0.02).

CONCLUSION: Spontaneous PM is associated with a favorable clinical course, and it is possible to suggest this clinical diagnosis based on typical MDCT findings and clinical presentation.