Detectability of the Mediastinal Lines: Comparison of Conventional Film-Screen Radiography and DigitalRadiography

ABSTRACT

PURPOSE: Using dynamic range compression (DRC) processing, this study compared the detectability ofmediastinal lines by conventional film screen rediography (FS) and by storage phosphor digital radiography(DR). MATERIALS AND METHODS: We selected 200 normal consecutive chest radiographs (100 FS, 100 DR) ; dynamic rangecompression was applied to DR processing and moving grids were used in both systems. Seven mediastinal lines (leftfaraspinal, right paraspinal, azygoesophageal, left para-aortic, posterior junctional, anterior junctional andright paratracheal) were scored from 0 point to 3 point(0not visible, 1suspiciously visible, 2visible, but notclear, 3 clearly visible) according to visibility and sharpness, as agreed by a radiologist and a resident. Thedifferences between the two modalities were compared and analyzed by chi-square test. RESULTS: Among the 1400mediastinal lines analyzed, 419 lines by DR(59.9%) and 232 lines by FS(33.1%) were scored more than 2 points. Inall mediastinal lines except the left para-aortic, DR was more detectable and clearer than FS, with statisticalsignificance(P<.01). CONCLUSION: DR processed with DRC visualizes mediastinal lines more frequently and clearlythan conventional FS, and is therefore thought to be useful for the evaluation of mediastinal diseases.