Visibility of single spiculations in digital breast tomosynthesis

Purpose: To investigate the visibility of single spiculations in digital breast tomosynthesis (DBT). Method: Simulated spheres (6 mm diameter) with single spiculations were added to projection images acquired on a DBT system (MAMMOMAT Inspiration, Siemens). The spiculations had a cylindrical shape and were randomly, diagonally aligned (at four different positions: +/- pi/4 or +/- 3 pi/4) at a plane parallel to the detector. They were assumed to consist of a fibroglandular tissue composition. The length of the spiculations was 5 mm while the diameter varied (0.12 - 0.28 mm). Reconstructed central slices of the lesion, separated by insertion in fatty or dense breasts (100 images in each), were used in 4-alternative forced choice (4AFC) human observer experiments. Three different reconstructions were used: filtered back projection (FBP) with 1 mm thick slices and a statistical artifact reduction reconstruction (SAR) method generating 1 and 2 mm thick slices. Five readers participated and their task was to locate the spiculation in randomly presented images from the whole image set (4 diameters x 100 images). The percent correct (PC) decision was determined in both fat and dense tissue for all spiculation diameters and reconstructions. Results: At a PC level of 95% the required diameter was about 0.17 - 0.22 mm in dense tissue, and 0.18 - 0.26 mm in fatty tissue (depending upon reconstruction). Conclusions: SAR was found to be a promising alternative to FBP. The visibility of single spiculations was determined. The required diameter depends on both tissue composition and reconstruction.