Variation in mammographic appearance between projections of small breast cancers compared with radial scars.

Aims: The study aims to assess variation in appearance between mammographic projections (conspicuity variation) for invasive breast cancers (IBCs) compared with radial scars (RS). Conspicuity variation has been previously described as characteristic of RS. The lesions were also compared with respect to breast density and the proportion of cases detected by one of two readers and required a third (consensus) read. Material(s) and Method(s): The study was approved by the BreastScreen Victoria research committee. Mammograms of 75 randomly selected invasive breast cancers, with histological diameter =10mm (IBC), were mixed with 67 consecutively detected RS, all from a double-reading population-based breast cancer screening programme. On blinded review, these 142 lesions were classified for mammographic findings and assessed for marked or minor conspicuity variation between views. We assessed the associations between lesion type, lesion spicules and centres, breast density, conspicuity variation and proportion detected by one reader only. Result(s): Marked conspicuity variation was common, but not statistically different for IBC and RS (64% vs. 66%, xi2=0.8, P=0.04). Conspicuity variation did not correlate with spiculation type (long, fine or short, broad based) or lesion centres (lucent or dense) (rho<0.05, P=0.5), and showed no significant change with increasing Breast Imaging Reporting and Data System breast density (IBC, xi2=2.3, P=0.5; RS, xi2=0.95, P=0.6). Density did not vary by lesion type. In the screening programme, 29% of IBC (125 of 431) versus 43% of RS (32 of 75) had been detected by one of two readers (xi2=2.7, P=0.098). Conclusion(s): Two-thirds of small IBCs displayed marked conspicuity variation, similar to RS. Therefore, conspicuity variation does not discriminate between IBC and RS. © 2010 The Royal Australian and New Zealand College of Radiologists.