Detection of small pulmonary nodules on chest radiographs: efficacy of dual-energy subtraction technique using flat-panel detector chest radiography

AIM: To investigate the effect of a double-exposure dual-energy subtraction (DES) technique on the diagnostic performance of radiologists detecting small pulmonary nodules on flat-panel detector (FPD) chest radiographs. MATERIALS AND METHODS: Using FPD radiography 41 sets of chest radiographs were obtained from 26 patients with pulmonary nodules measuring <= 20 mm and from 15 normal participants. Each dataset included standard and corresponding DES images. There were six non-solid, 10 part-solid, and 10 solid nodules. The mean size of the 26 nodules was 15 +/- 4.8 mm. Receiver operating characteristic (ROC) analysis was performed to compare the performance of the eight board-certified radiologists. RESULTS: For the eight radiologists, the mean value of the area under the ROC curve (AUC) without and with DES images was 0.62 +/- 0.05 and 0.68 +/- 0.05, respectively; the difference was statistically significant (p = 0.02). For part-solid nodules, the difference of the mean AUC value was statistically significant (AUC = 0.61 +/- 0.07 versus 0.69 +/- 0.05; p < 0.01): for non-solid nodules it was not (AUC = 0.62 +/- 0.1 versus 0.61 +/- 0.09; p = 0.73), and for solid nodules it was not (AUC = 0.75 +/- 0.1 versus 0.78 +/- 0.08: p = 0.23). For nodules with overlapping bone shadows, the difference of the mean AUC value was statistically significant (p = 0.03), for nodules without overlapping, it was not (p = 0.26). CONCLUSION: Use of a double-exposure DES technique at FPD chest radiography significantly improved the diagnostic performance of radiologists to detect small pulmonary nodules. (C) 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.