[Comparison between electronic zoom and geometric magnification of clusters of microcalcifications on digital mammography].

Purpose: With the advent of digital mammography with electronic zoom capabilities, we have sought to determine the need for geometric magnification for the evaluation of clusters of microcalcifications.

Patients And Methods: Eighty-eight clusters of microcalcifications were reviewed by two experienced radiologists using electronic zoom (ZOOM) and geometric magnification (MAG). The following criteria were evaluated: image quality, shape and number of microcalcifications, size and shape of the clusters. The clusters were classified based on malignancy risk using the BI-RADS criteria. Histological results from macrobiopsy or surgery as well as 2 year follow-up were used as reference for statistical analysis.

Results: Sensitivity (100% for MAG and 90% for ZOOM), specificity (52% versus 39%), positive predictive value (51% versus 44%) and negative predictive value (100% versus 88%) were superior for geometric magnification compared to electronic zoom irrespective of the reviewer but without reaching statistical significance. However, image quality was significantly superior with geometric magnification (p<<0.05). In addition, reviewers were more confident in their interpretation of geometric magnification images.

Conclusion: Geometric magnification remains necessary in routine clinical practice for the characterization of microcalcifications and BI-RADS classification.