Evaluation of the effect of zoom function on lesion detection by soft-copy reading of screening mammograms

INTRODUCTION

This study aims to evaluate the effectiveness of zooming in improving screen-reader performance in reporting digital mammograms.

METHOD

Two experiments were conducted. In the first experiment, 5 readers were asked to report 59 two-view bilateral mammograms retrospectively with zooming function turned off. The second session was similar to the first one except that zooming was enabled. The task of readers was to assess if the mammograms were normal or abnormal and rate the confidence levels for each of the lesion they detected. The reader performances were evaluated via case sensitivity, lesion sensitivity, specificity, receiver operating characteristics (ROC) area under the curve (AUC) and jackknife free-response receiver operating characteristics (JAFROC) figure of merit (FOM).

RESULTS

There was no significant improvement in overall reader performance in detecting abnormalities in zooming condition compared with no zooming in terms of case sensitivity (96% and 87%, P = 0.285) or lesion sensitivity (88% and 81%, P = 0.224). However, differences in ROC AUC and JAFROC FOM (P ≤ 0.05) were found in two readers when they performed the test set with zooming function.

CONCLUSION

The results suggested that the use of the zooming function did improve the performance of some readers in detecting abnormal cases.

The adverse implications of the transition from film to digital mammography for performing surveillance in patients with a history of breast cancer or significant risk factors for the disease

AIM

The transition from screen-film to digital mammography at Peter MacCallum Cancer Centre was investigated, considering the impact on patient management and resource utilization.

METHODS

A retrospective comparison of the imaging outcomes of the last year of screen-film and the first year of digital mammography was performed. The study group of 692 patients, all with a history or a significant risk factor of breast cancer, underwent a surveillance mammogram in both periods, enabling serial comparison of imaging outcomes on the same patient.

RESULTS

Overall 92 patients required a total of 125 further investigations after their film mammogram due to a mammographic abnormality while 130 underwent a total of 202 additional investigations after their digital mammogram. This is a significant increase in the number of patients further investigated (Fisher's exact test P = 0.005). However, the positive predictive value of further investigation finding a tumor after digital mammography was not significantly higher than that of film mammography (7.4 vs 6.5%, Fisher's exact test P = 0.57). There was a 44% increase in the cost of additional investigations during the first year of digital mammography compared to the previous year and an associated increase in hospital visits for patients.

CONCLUSION

For patients undergoing annual surveillance mammography at Peter MacCallum Cancer Centre, the transition from film to digital mammography was found to be associated with an increase in both the number of additional investigations performed and in the number of hospital visits. The findings of this study should be considered when conversions from film to digital mammography are planned, specifically in terms of cost allocations and the burden on patient services in radiology and outpatient departments.

Digital mammography: more microcalcifications, more columnar cell lesions without atypia

The incidence of columnar cell lesions in breast core needle biopsies since full-field digital mammography in comparison with screen-filmed mammography was analyzed. As tiny microcalcifications characterize columnar cell lesions at mammography, we hypothesized that more columnar cell lesions are diagnosed since full-field digital mammography due to its higher sensitivity for microcalcifications. In all, 3437 breast core needle biopsies performed in three hospitals and resulting from in total 55 159 mammographies were revised: 1424 taken in the screen-filmed mammography and 2013 in the full-field digital mammography period. Between the screen-filmed mammography and full-field digital mammography periods, we compared the proportion of mammographies that led to core needle biopsies, the mammographic indication for core needle biopsies (density, microcalcifications, or both) and the proportion of columnar cell lesions with or without atypia. The columnar cell lesions were graded according to Schnitt, and we included atypical ductal hyperplasia arising in the context of columnar cell lesions. Proportions were compared using χ(2) tests and prevalence ratios were adjusted for age and hospital. We found that more core needle biopsies per mammogram were taken in the full-field digital mammography period (7.6%) compared with the screen-filmed mammography period (5.0%, P<0.0001). Microcalcifications were more often diagnosed with full-field digital mammography than with screen-filmed mammography (adjusted prevalence ratio: 1.14, confidence interval 95%: 1.01-1.28). Core needle biopsies from the full-field digital mammography era showed more columnar cell lesions (10.8%) than those from the screen-filmed mammography era (4.9%; adjusted prevalence ratio: 1.93, confidence interval 95%: 1.48-2.51), particularly due to more columnar cell lesions without atypia (8.2% respectively 2.8%) while the proportion of columnar cell lesions with atypia remained nearly constant (2.0 vs 2.6%). In conclusion, since the implementation of full-field digital mammography, more microcalcifications are seen at mammography, more often resulting in core needle biopsies, which especially yields more columnar cell lesions without atypia.