Translating microcalcification biomarker information into the laboratory: A preliminary assessment utilizing core biopsies obtained from sites of mammographic calcification.

Rationale and objectives: The potential of breast microcalcification chemistry to provide clinically valuable intelligence is being increasingly studied. However, acquisition of crystallographic details has, to date, been limited to high brightness, synchrotron radiation sources. This study, for the first time, evaluates a laboratory-based system that interrogates histological sections containing microcalcifications. The principal objective was to determine the measurement precision of the laboratory system and assess whether this was sufficient to provide potentially clinical valuable information. Materials and methods: Sections from 5 histological specimens from breast core biopsies obtained to evaluate mammographic calcification were examined using a synchrotron source and a laboratory-based instrument. The samples were chosen to represent a significant proportion of the known breast tissue, mineralogical landscape. Data were subsequently analysed using conventional methods and microcalcification characteristics such as crystallographic phase, chemical deviation from ideal stoichiometry and microstructure were determined. Results: The crystallographic phase of each microcalcification (e.g., hydroxyapatite, whitlockite) was easily determined from the laboratory derived data even when a mixed phase was apparent. Lattice parameter values from the laboratory experiments agreed well with the corresponding synchrotron values and, critically, were determined to precisions that were significantly greater than required for potential clinical exploitation. Conclusion: It has been shown that crystallographic characteristics of microcalcifications can be determined in the laboratory with sufficient precision to have potential clinical value. The work will thus enable exploitation acceleration of these latent microcalcification features as current dependence upon access to limited synchrotron resources is minimized.

The Relationship between Mammography Readers' Real-Life Performance and Performance in a Test Set-based Assessment Scheme in a National Breast Screening Program.

Purpose: To compare an individual's Personal Performance in Mammographic Screening (PERFORMS) score with their Breast Screening Information System (BSIS) real-life performance data and determine which parameters in the PERFORMS scheme offer the best reflection of BSIS real-life performance metrics. Materials and Methods: In this retrospective study, the BSIS real-life performance metrics of individual readers (n = 452) in the National Health Service Breast Screening Program (NHSBSP) in England were compared with performance in the test set-based assessment scheme over a 3-year period from 2013 to 2016. Cancer detection rate (CDR), recall rate, and positive predictive value (PPV) were calculated for each reader, for both real-life screening and the PERFORMS test. For each metric, real-life and test set versions were compared using a Pearson correlation. The real-life CDR, recall rate, and PPV of outliers were compared against other readers (nonoutliers) using analysis of variance. Results: BSIS real-life CDRs, recall rates, and PPVs showed positive correlations with the equivalent PERFORMS measures (P < .001, P = .002, and P < .001, respectively). The mean real-life CDR of PERFORMS outliers was 7.2 per 1000 women screened and was significantly lower than other readers (nonoutliers) where the real-life CDR was 7.9 (P = .002). The mean real-life screening PPV of PERFORMS outliers was 0.14% and was significantly lower than the nonoutlier group who had a mean PPV of 0.17% (P = .006). Conclusion: The use of test set-based assessment schemes in a breast screening program has the potential to predict and identify poor performance in real life.© RSNA, 2020Keywords: Breast, ScreeningSee also the commentary by Thigpen and Rapelyea in this issue.