Effect of soft-copy display supported by CAD on mammography screening performance

Abstract

Diagnostic performance and reading speed for conventional mammography film reading is compared to reading digitized mammograms on a dedicated workstation. A series of mammograms judged negative at screening and corresponding priors were collected. Half were diagnosed as cancer at the next screening, or earlier for interval cancers. The others were normal. Original films were read by fifteen experienced screening radiologists. The readers annotated potential abnormalities and estimated their likelihood of malignancy. More than 1 year later, five radiologists reread a subset of 271 cases (88 cancer cases having visible signs in retrospect and 183 normals) on a mammography workstation after film digitization. Markers from a computer-aided detection (CAD) system for microcalcifications were available to the readers. Performance was evaluated by comparison of A(z)-scores based on ROC and multiple-Reader multiple-case (MRMC) analysis, and localized receiver operating characteristic (LROC) analysis for the 271 cases. Reading speed was also determined. No significant difference in diagnostic performance was observed between conventional and soft-copy reading. Average A(z)-scores were 0.83 and 0.84 respectively. Soft-copy reading was only slightly slower than conventional reading. Using a mammography workstation including CAD for detection of microcalcifications, soft-copy reading is possible without loss of quality or efficiency.

Increase in perceived case suspiciousness due to local contrast optimisation in digital screening mammography

“…All previous mammograms had been routinely digitised using an Array 2,905 Laser Film Digitizer (Array Corporation Europe, Roden, the Netherlands) at a resolution of 100 μm, because an earlier study had shown this to be sufficient for comparison of previous mammograms [15]. For views consisting of multiple images (mosaics) only the image containing the largest part of the breast was digitised.…”

Current state of digital mammography

“…Both hard and software of mammography review work-stations has improved significantly over the last few years. Dedicated mammography review work-stations now allow to switch almost instantaneously between different image layouts including a sequential magnified quadrant zoom, with soft-copy reading speed approaching [30,31]. However, depending on detector area and pixel size, digital mammograms may have an image matrix of up to 4,800 9 6,000 pixels with a file size of more than 50 MB.…”

Digital mammography: what do we and what don’t we know?

“…Both hard-and software of mammography review stations has improved significantly over the last few years. Dedicated mammography review stations now allow to switch almost instantaneously between different image layouts including a sequential magnified quadrant zoom, with softcopy reading speed approaching or even surpassing that of batch film reading [56,57]. Viewing the entire image piece by piece in full resolution may be tedious, but necessary to ensure that no microcalcifications are overlooked.…”