Evaluating wavelet compression in microcalcification detection in mammography

The aim of this study is to evaluate the performance of a wavelet-based image compression algorithm in mammography. As microcalcifications detection is selected as diagnostic task, the algorithm is evaluated with respect to its visually lossless threshold at low compression ratios and not its supra-threshold performance. The threshold is determined by means of observer performance using a set of digitized mammograms from the Digital Database for Screening Mammography and by means of an image quality study, related to transfer characteristics of the compression algorithm, using computer-generated test images. The image quality parameters used are input/output response, noise, high contrast response and low contrast-detail response. The computer-generated test images mimic mammographic image and microcalcification characteristics. Receiver operating characteristics analysis of pooled data for microcalcification detection in mammograms indicated a threshold at compression ratio 40:1. Image quality parameters assessment, with respect to low contrast-detail patterns, indicated a threshold at compression ratio 35:1. The two approaches provided comparable thresholds, indicating the potential use of image quality parameters.