DIGITAL MAMMOGRAPHY - M-CHANNEL QUADRATURE MIRROR FILTERS (QMFS) FOR MICROCALCIFICATION EXTRACTION

Multiresolution methods are reported for feature extraction in breast cancer screening using digital mammography. The initial application is directed at the detection of microcalcification clusters (MCCs). Quad rature mirror filter (QMF) banks, using both two and three channel are proposed for the first time for both multiresolution decomposition an d reconstruction. These filters are specifically tailored for automati c extraction of MCCs. The QMF multiresolution methods are compared to two channel tree structured wavelet transforms (TSWTs) methods previou sly reported. The QMF filters are preceded by an advanced tree structu red nonlinear filter for noise suppression, prior to feature extractio n, in order to minimize the false positive (FP) detection rate in digi tal mammography. The relative performance of these methods were evalua ted using both simulated images and fifteen representative digitized m ammograms containing biopsy proven microcalcification clusters. Simila r high sensitivity (true positive (TP) detection rate (100%) and high specificity (0.6 average false positive (FP) MCC's/image) were observe d, substantially better than more traditional approaches using single scale filters. The three channel QMF method, however, demonstrated bet ter detail preservation of MCC's extracted compared to the two channel method. Detail preservation is important for the characterization of MCC's or individual microcalcifications in cancer screening.