Résumé
BACKGROUND: Generally hernia is diagnosed with simple chest or gastrointestinal x-ray. Sometimes CT or MRI can give lots of information for the diagnosis. However, there was no study for the differentiation with using CT findings between Morgagni hernia and pleuropericardial fat. The aim of this study was to evaluate the useful CT findings for differentiating Morgagni hernia from pleuropericardial fat. MATERIAL AND METHOD: We retrospectively analyzed CT scans of eight patients with Morgagni hernia and 20 patients with abundant pleuropericardial fat without peridiaphragmatic lesions. All CT scans were performed with coverage of the whole diaphragm in the inspiration state. We evaluated 1) the presence of the defect of the anterior diaphragm, 2) the interface between the lung and fat, 3) the angle between the chest wall and fat, 4) the continuity between the extrapleural fat and fat, 5) the presence of the vessels within fat, and 6) the presence of a thin line surrounding fat. RESULT: In all cases with Morgagni hernia, the defect of the anterior diaphragm was seen. The interface was well-defined, smooth, and convex to the lung. The angle with the chest wall was acute. The continuity with the extrapleural fat was not seen. In the cases with abundant pleuropericardial fat, the defect of the anterior diaphragm was seen in three (15%). The interface was usually irregular (n=10) and flat (n=17). The angle with the chest wall was variable. The continuity with the extrapleural fat, that was markedly increased in amount, was usually seen (n=16). The thin line surrounding fat was seen in four cases with Morgagni hernia, however, not seen in all cases with pleuropericardial fat. All of the above findings were statistically significant, however, vessels within fat was not significant to differentiate Morgagni hernia (n=8/8) from pleuropericardial fat (n=14/20). CONCLUSION: The useful CT findings of Morgagni hernia were fatty mass with sharp margin, convexity toward lung, acute angle with chest wall, and thin line surrounding hernia. Branching structure within fatty mass representing omental vessels that has been known as a characteristic finding of Morgagni hernia was not useful for differentiating Morgagni hernia from pleuropericardial fat.