Computerized classification of benign and malignant masses on digitized mammograms: A study of robustness

Rationale and Objectives. The purpose of this study was to evaluate the robustness of a computerized method developed for the classification of benign and malignant masses with respect to variations in both case mix and film digitization. Materials and Methods. The classification method included automated segmentation of mass regions, automated feature-extraction, and automated lesion characterization. The method was evaluated independently with a 110-case database consisting of 50 malignant and 60 benign cases. Mammograms were digitized twice with two different digitizers (Konica and Lumisys). Performance of the method in differentiating benign from malignant masses was evaluated with receiver operating characteristic (ROC) analysis. Effects of variations in both case mix and film digitization on performance of the method also were assessed, Results. Categorization of lesions as malignant or benign with an artificial neural network (or a hybrid) classifier achieved an area under the ROC curve, A(z), value of 0.90 (0.94 for the hybrid) on the previous training database in a round-robin evaluation and A(z) values of 0.82 (0.81) and 0.81 (0.82) on the independent database for the Konica and Lumisys formats, respectively, These differences, however, were not statistically significant (P > .10). Conclusion. The computerized method for the classification of lesions on mammograms was robust with respect to variations in case mix and film digitization.