Grid-Less Imaging with Anti-scatter Correction Software in 2D Mammography: A JAFROC Study Using Simulated Lesions

Purpose: To perform a virtual clinical trial study to assess the justification of the grid-less mammography acquisition mode with scatter correction software, as developed by Siemens Healthcare (PRIME mode). Materials and methods: The study was performed on a Siemens mammography unit using the conventional acquisition mode (system 1) and a second system used PRIME. Mean glandular doses (MGD) were compared from data of 5981 images. A paired t-test for all thickness groups (<29 mm, 30–49 mm, 50–70 mm, >69 mm) separately and combined had shown a significantly higher average MGD for system 1 (NON-PRIME) when compared to system 2 (PRIME), with an overall decrease of 11.7 %. The next phase in justification focused on detectability performance, in particular for screening applications. A dataset mimicking an enriched screened population was created by simulating previously developed anthropomorphic mass models and microcalcification clusters in 60 out of 100 normal mammograms of system 1 (NON-PRIME). The same physical lesions were then simulated into 60 out of 100 PRIME, normal mammograms. Care was taken to simulate each lesion model in matched mammograms PRIME-NON PRIME in terms of BI-RADS score, in a region with the same background glandularity (obtained after analysis with Volpara) and in a breast of the same thickness group. All images were visualized with ViewDEX software and four radiologists performed the free search detectability study. A JAFROC analysis was executed and detectability was quantified by means of the AUC. Results: Present approach allowed the realization of paired virtual clinical data sets starting from 200 normal mammograms. The results of all readers separately as well as combined showed approximately the same AUC for PRIME and NON-PRIME (0.57 vs 0.60), and the ANOVA analysis showed no statistical significant difference in detectability of the lesions between PRIME and NON-PRIME (p-value 0.36). The same result was found if the dataset was subdivided for both types of lesions: masses (p-value 0.88) and microcalcification clusters (p-value 0.33). Conclusion: Results state that the MGD is significantly lower in PRIME mode than with the conventional acquisition while lesion detectability remained constant for all four radiologists.