Lesley Cockmartin, Presenter: Nothing to Disclose

Gwen Aerts, Abstract Co-Author: Nothing to Disclose

Federica Zanca PhD, Abstract Co-Author: Nothing to Disclose

Nicholas Marshall, Abstract Co-Author: Nothing to Disclose

Eman Shaheen, Abstract Co-Author: Nothing to Disclose

David Dance PhD, Abstract Co-Author: Nothing to Disclose

Kenneth C. Young PhD, Abstract Co-Author: Nothing to Disclose

Hilde Bosmans PhD, Abstract Co-Author: Co-founder, Qaelum NV Research Grant, Siemens AG

To compare the detectability of microcalcifications in patient images for digital mammography (2D) and breast tomosynthesis (BT) using a hybrid technical-clinical method.

Spherical microcalcifications (CaCO3), in groups of 5 in the Voxmam phantom (Leeds Test Objects, UK), were imaged in 2D and BT mode. Templates of microcalcifications embedded in different thicknesses of polymethyl methacrylate (PMMA), were created for 2D and BT projections by dividing exposures of the Voxmam phantom containing microcalcifications in PMMA by images of homogeneous PMMA. The templates were multiplied into projection images of patients with equivalent breast thicknesses and then processed/reconstructed. Four groups of microcalcification diameters were used: 354-224, 283-180, 226-150 and 177-106 µm. All microcalcifications were imaged at 2 different heights (z-positions) above the detector. For the detection study, 511 2D images and 511 BT series were viewed: 355 with microcalcifications and 156 without. Seven observers scored the presence or absence of the microcalcification group in the center of a highlighted area via a 5 point confidence rating scale and counted how many microcalcifications were visible. Detection performance of 2D and BT was compared via ROC analysis with sub-analyses for microcalcification size, breast thickness and z-position.

Peak contrast in the projections ranged from 1.3% to 16% for 2D and from 0.8% to 11% for BT templates. Preliminary ROC results showed a better detection of microcalcifications in 2D compared to BT (p<0.0001) with an area under the curve (AUC) of 0.95 compared to 0.85. A statistically significant difference was found for the two intermediate size groups only. The AUC in 2D and BT were significantly different only for higher breast thicknesses (>5cm). Higher z-positions (>3cm) showed higher significant differences between 2D and BT. Finally, the Wilcoxon matched pairs test indicated a significant difference (p<0.0001) between the counts for 2D and BT.

Detection performance of 2D and BT for all microcalcification sizes depends on breast thickness and z-position, suggesting the need for further optimization of acquisition and reconstruction in BT for thicker breast and higher z-positions.

This hybrid method can quantify detectability differences between 2D and BT and allows investigation of influential parameters using real clinical backgrounds.

Cockmartin, L, Aerts, G, Zanca, F, Marshall, N, Shaheen, E, Dance, D, Young, K, Bosmans, H, Comparison of Microcalcification Detection in Digital Mammography and Breast Tomosynthesis Using a Hybrid Technical-clinical Test Method.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13022568.html