Sabine Peters1, Martin Hellmich, Alexander Stork, Jörn Kemper, Olga Grinstein, Michael Püsken, Leandra Stahlhut, Sonja Kinner, David Maintz, Kathrin Barbara Krug. 1. From the *Prüfstelle für Strahlenschutz GmbH, Wennigsen; †Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen; ‡Institute of Medical Statistics, Informatics and Epidemiology, University of Cologne, Cologne; §Radiological Institute Düsseldorf, Düsseldorf; ∥Clinical Radiology, University Witten/Herdecke, Witten; and ¶Department of Diagnostical and Interventional Radiology, University Hospital of Cologne, Cologne, Germany.
Abstract
OBJECTIVE: The aim of this study was to compare the microcalcification detectability in an anthropomorphic phantom model regarding number, size, and shape in full-field digital mammography (FFDM), synthetically reconstructed 2-dimensional (Synthetic-2D) images, and digital breast tomosynthesis (DBT) performed with 2 different x-ray mammography systems. MATERIALS AND METHODS: Simulated microcalcifications of different numbers (0 to >39), sizes (diameter, 100-800 μm), and shapes (round vs heterogeneous) were scattered by random distribution on 50 film phantoms each divided in 4 quadrants. The FFDM and DBT x-rays were taken from each of these 50 films with both x-ray mammography systems (SenoClaire; GE Healthcare, Selenia Dimensions, Hologic) using an anthropomorphic scattering body and automatic exposure control. The resulting exposure factors were similar to a clinical setting. The synthetically reconstructed 2D images were generated automatically on both systems. All FFDM, Synthetic-2D, and DBT images were interpreted in randomized order and independently of each other by 6 radiologists using a structured questionnaire. RESULTS: The number categories of simulated microcalcifications were correctly evaluated in 55.3% of instances (quadrant by reader) in FFDM, 50.9% in the Synthetic-2D views, and 59.5% in DBT, summarized for 200 quadrants per reader for each Device A and B, respectively. Full-field digital mammography was superior to Synthetic-2D (mean difference, 4%; 95% confidence interval [CI], 2%-7%; P < 0.001), and DBT was superior to both FFDM (mean difference, 4%; 95% CI, 2%-7%; P = 0.002) and Synthetic-2D (mean difference, 9%; 95% CI, 6%-11%; P < 0.001). This trend was consistent in all subgroup analyses. The number of the smallest microcalcifications (100-399 μm) was correctly evaluated in 25.2% of the FFDM, in 14.2% for Synthetic-2D, and in 28.3% of the DBT images. Underestimations of the number of simulated microcalcifications were more common than overestimations. Regarding the size categories of simulated microcalcifications, the rates of correct assessments were in 45.4% of instances in FFDM, 39.9% in the Synthetic-2D views, and 43.6% in DBT, summarized for 200 quadrants per reader and both imaging devices. CONCLUSIONS: In the presented in vitro environment using an anthropomorphic phantom model, standard full-field digital x-ray mammography was superior to synthetically reconstructed 2-dimensional images in the detection of simulated microcalcifications. In view of these results, it is questionable whether Synthetic-2D images can replace FFDM in clinical examinations at the present time. Further investigations are needed to assess the clinical impact of the in vitro results.
OBJECTIVE: The aim of this study was to compare the microcalcification detectability in an anthropomorphic phantom model regarding number, size, and shape in full-field digital mammography (FFDM), synthetically reconstructed 2-dimensional (Synthetic-2D) images, and digital breast tomosynthesis (DBT) performed with 2 different x-ray mammography systems. MATERIALS AND METHODS: Simulated microcalcifications of different numbers (0 to >39), sizes (diameter, 100-800 μm), and shapes (round vs heterogeneous) were scattered by random distribution on 50 film phantoms each divided in 4 quadrants. The FFDM and DBT x-rays were taken from each of these 50 films with both x-ray mammography systems (SenoClaire; GE Healthcare, Selenia Dimensions, Hologic) using an anthropomorphic scattering body and automatic exposure control. The resulting exposure factors were similar to a clinical setting. The synthetically reconstructed 2D images were generated automatically on both systems. All FFDM, Synthetic-2D, and DBT images were interpreted in randomized order and independently of each other by 6 radiologists using a structured questionnaire. RESULTS: The number categories of simulated microcalcifications were correctly evaluated in 55.3% of instances (quadrant by reader) in FFDM, 50.9% in the Synthetic-2D views, and 59.5% in DBT, summarized for 200 quadrants per reader for each Device A and B, respectively. Full-field digital mammography was superior to Synthetic-2D (mean difference, 4%; 95% confidence interval [CI], 2%-7%; P < 0.001), and DBT was superior to both FFDM (mean difference, 4%; 95% CI, 2%-7%; P = 0.002) and Synthetic-2D (mean difference, 9%; 95% CI, 6%-11%; P < 0.001). This trend was consistent in all subgroup analyses. The number of the smallest microcalcifications (100-399 μm) was correctly evaluated in 25.2% of the FFDM, in 14.2% for Synthetic-2D, and in 28.3% of the DBT images. Underestimations of the number of simulated microcalcifications were more common than overestimations. Regarding the size categories of simulated microcalcifications, the rates of correct assessments were in 45.4% of instances in FFDM, 39.9% in the Synthetic-2D views, and 43.6% in DBT, summarized for 200 quadrants per reader and both imaging devices. CONCLUSIONS: In the presented in vitro environment using an anthropomorphic phantom model, standard full-field digital x-ray mammography was superior to synthetically reconstructed 2-dimensional images in the detection of simulated microcalcifications. In view of these results, it is questionable whether Synthetic-2D images can replace FFDM in clinical examinations at the present time. Further investigations are needed to assess the clinical impact of the in vitro results.
Authors: Andreas E Petropoulos; Spyros G Skiadopoulos; Anna N Karahaliou; Gerasimos A T Messaris; Nikolaos S Arikidis; Lena I Costaridou Journal: Med Biol Eng Comput Date: 2019-12-07 Impact factor: 2.602