Abstract :

Aim: The shape and physical properties of the anterior mediastinum can be easily affected by inflammatory lung diseases, tuberculosis, empyema, radiotherapy, chronic fibrotic lung diseases, previous surgery, and after steroid therapy. We planned to compare the properties of anterior mediastinal fat (AMF) in 3 different groups: patients with idiopathic pulmonary fibrosis (IPF), patients with chronic hypersensitivity pneumonia (cHP), and in the healthy control group. We investigate the AMF shape, dimensions, and AMF area properties on the images of high-resolution computed tomography (HRCT) and to find any difference between IPF and cHP patients in terms of AMF. Material and Method: The study comprises a total of 80 cases in the three groups. The first group comprises 26 cases diagnosed as IPF. The second group comprises 19 cases diagnosed as cHP. The third group comprises 35 control patients. The clinical, demographical, and AMF characteristics on HRCT were retrospectively evaluated. The AMF shape and area characteristics were compared between the three groups. Results: There was no statistical difference between the mean ages of cases, BMIs, and smoking status in IPF, cHP, and control groups. Gender distribution was found statistically significant between the 3 groups (p=0.001). A statistically significant difference was observed between the IPF and cHP groups in terms of FVC levels (2.67±0.59, 2.14±0.80, respectively; p=0.024). Also, a statistically significant difference was observed between the IPF and cHP groups in terms of DLCO levels (57.42±17.21; 77.31±35.21; respectively; p=0.016). In the evaluation of AMF shape properties between two groups (cHP and IPF), the concave figure was significantly more frequent in cHP group (p=0.014). The AMF area analyses revealed that the IPF group’s areas were significantly greater than the cHP and control group’s. The AP dimension of AMF analyses revealed that only the cHP group’s dimensions were significantly smaller than the control group’s (p=0.037). In the analysis of the transverse dimension of AMF, the IPF group’s dimensions were significantly greater than the cHP and control group’s (p<0.0001 and p=0.007; respectively) and also the cHP group’s dimensions were significantly greater than the control group’s (p<0.0001). Conclusion: The transverse length, total AMF area, and shape characteristics of AMF can be evaluated as a radiological marker for differential diagnosis of IPF and cHP, whose differential diagnosis may be difficult. Both the transverse length and AMF area can take greater values in the IPF group than in the cHP group.

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