Bone suppression imaging improves observer performance for the detection of lung nodules in chest radiographs

S. Schalekamp, B. van Ginneken, L. Bax, M. Imhof-Tas, M. Snoeren, L. Quekel, E. Koedam, N. Karssemeijer and C. Schaefer-Prokop

Annual Meeting of the European Society of Thoracic Imaging 2012.

Objective. To assess observer performance in detecting lung nodules in chest x-rays using bone suppressed imaging. Materials and Methods. Posteroanterior and lateral digital chest radiographs of 108 patients with a solitary CT-proven nodule and 192 controls were read by 5 certified radiologists. Commercially available software (Softview 2.4, Riverain Medical Group, Miamisburg, Ohio) was used to generate bone suppressed images (BSI). We conducted a sequential reader study, in which radiologists marked and scored suspicious regions first on the standard radiographs alone and subsequently with the use BSI. Receiver operating characteristics (ROC) were used for statistical analysis: partial area under the curve (pAUC), based on the specificity normally applied in clinical routine, served as figure of merit (interval 0 - 0.1). Results. Average nodule size was 17.5mm (median 17mm), with a malignancy rate of 83%. Use of BSI significantly improved detection performance compared to chest radiographs alone (pAUC 0.053 vs. pAUC=0.059, p=0.04). Operating at a specificity of 95%, lung nodule detection sensitivity increased from 56.8% to 63.2% with the aid of BSI. For the individual readers, the sensitivities were 51%-56%, 73%-72%, 55%-68%, 49%-56%, and 56%-64%, without and with BSI, respectively. Conclusion. Bone suppression imaging significantly improves the radiologist's performance for the detection of pulmonary nodules in radiographs.