1/ To validate a method for simulating microcalcifications in mammography
2/ To evaluate the effect of anatomical background on visibility of (simulated) microcalcifications
Materials and methods:
Microcalcifications were extracted from the raw data of specimen from a stereotactic vacuum needle biopsy. The sizes
of the templates varied from 200 μm to 1350μm and the peak contrast from 1.3% to 24%. Experienced breast imaging
radiologists were asked to blindly evaluate images containing real and simulated lesions. Analysis was done using ROC
The simulated lesions have been used for the creation of composite image datasets: 408 microcalcifications were
simulated into 161 ROI's of 59 digital mammograms, having different anatomical backgrounds. Nine radiologists were
asked to detect and rate them under conditions of free-search. A modified receiver operating characteristic study
(FROC) was applied to find correlations between detectability and anatomical background.
1/ The calculated area under the ROC curve, Az, was 0.52± 0.04. Simulated microcalcifications could not be
distinguished from real ones.
2/ In the anatomical background classified as Category 1 (fatty), the detection fraction is the lowest (0.48), while for
type 2,3,4 there is a gradually decrease (from 0.61 to 0.54) as the glandularity increases. The number of false positives is
the highest for the background Category 1 (24%), compared to the other three types (16%). A 80% detectability is
found for microcalcifications with a diameter > 400μm and a peak contrast >10%. Anatomic noise seems to limit
detectability of large low contrast lesions, having a diameter >700μm.