A comparison between the electronic magnification (EM) and true magnification (TM) of breast phantom images using a CDMAM phantom

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.

A review of mammographic lesion localisation and work up imaging in Australia in the digital era

OBJECTIVES

To investigate the use of coned compression with and without magnification in contemporary Australian digital imaging. To describe lesion localisation techniques used for mammographic work up.

KEY FINDINGS

As digital breast tomosynthesis becomes mainstream, the need for coned compression imaging has reduced, however the need for coned compression with fine focus magnification for assessment of microcalcification remains. Adapting film screen lesion localisation techniques to the digital setting is limited by the need for "true size" 1:1 ratio images for ease of measurement. Both the digital ruler and a grid technique can be used as an alternate.

CONCLUSION

Advances in image acquisition has evidenced a change in imaging protocols for suspicions lesions within the breast with breast tomosynthesis superseding the need for non-magnified coned compression views of the breast. Adaptation of the approaches to localising these lesions in the digital setting has also been necessary.

Evaluating clinical implications of 15-mega-sub-pixel liquid-crystal display in phase-contrast mammography

BACKGROUND

Phase-contrast mammography (PCM) systems characteristically yield sharp images with edge enhancement and high-resolution 25-μm/pixel mammograms. However, not all PCM image information can be shown on the display at a resolution of 5-megapixel (5-MP), although 5-MP monitors are recommended for interpretation of digital mammograms. Therefore, we investigated the potential utility of a 15-mega-sub-pixel (15-MsP) display for PCM images.

METHODS

We used a monitor that offered both 5-MP and 15-MsP displays by using a sub-pixel drive (SPD) technique to increase the spatial resolution of the monitor by threefold in the direction of the sub-pixels. Contrast-detail mammography phantom images were evaluated visually by four radiologic technologists. In this study, four display magnification ratios were used and the calculated image quality figures (IQFs) were compared with those of a 5-MP display.

RESULTS

The detection capability of the 15-MsP display was significantly better than that of the 5-MP display at magnification ratios of 49 and 100 %. At other magnification ratios, the detection capability of the 15-MsP display was higher than that of the 5-MP display, but the difference was not significant.

CONCLUSIONS

A 15-MsP display has the potential to provide better detection than that provided by conventional 5-MP displays. A 15-MsP display using SPD technology is suitable for high-resolution digital mammograms, such as those produced by PCM systems.