Digital zoom of the full-field digital mammogram versus magnification mammography: a systematic review.

Objectives: To summarise and compare the performance of magnification mammography and digital zoom utilising a full-field digital mammography (FFDM) system in the detection and diagnosis of microcalcifications.

Methods: We ran an extended search in MEDLINE, EMBASE, CINAHL, Engineering Village and Web of Science. Diagnostic test studies, experimental breast phantom studies and a Monte Carlo phantom study were included. A narrative approach was selected to summarise and compare findings regarding the detection of microcalcifications, while a hierarchical model with bivariate analysis was used for the meta-analysis of sensitivity and specificity for diagnosing microcalcifications.

Results: Nine studies were included. Phantom studies suggested that the size of microcalcifications, magnification or zoom factor, exposure factors and detector technology determine whether digital zoom is equivalent to magnification mammography in the detection of microcalcifications. Pooled sensitivity for magnification and zoom calculated from the diagnostic test studies was 0.93 (95% CI 0.84-0.97) and 0.85 (95% CI 0.70-0.94), respectively. Pooled specificity was 0.55 (95% CI 0.51-0.58) and 0.56 (95% CI 0.50-0.62), respectively. The differences between the sensitivities and specificities were not statistically significant.

Conclusions: Digital zoom may be equivalent to magnification mammography. Diagnostic test studies and phantom studies using newer detector technology would contribute additional knowledge on this topic.

Key Points: • The performance of digital zoom is comparable to magnification for detecting microcalcifications when newer detector technology and optimised imaging procedures are utilised. • The accuracy of digital zoom appears equivalent to geometric magnification in diagnosing microcalcifications.