Investigations of Image Depiction Capacity of Hard and Soft Copies of CR Digital Mammograms for Breast Cancer Screening

Abstract

In the present study, we compared the image depiction capacity of hard copies (HC) and soft copies (SC) of CR digital mammograms from 969 cases. Two of 12 Grade A board-certified radiologists recognized by the Central Committee for Quality Control of Mammography Screening in Japan, independently diagnosed each individual case. Then, at least one of the two radiologists who examined either the HC or SC image diagnosed as “Category 2”, however, a different category was also given. We picked up 65 suspicious cases (69 findings including 13 tumors, 39 cases of focal asymmetric density (FAD), 15 calcifications, and 2 architectural distortions). Three senior members among the 12 radiologists re-examined these images paying special attention to differences in depiction capacity between HC and SC. We used the 5M LCD and changed the window level, window width and employing zoom. Thirteen (1 tumor, 6 FAD, 6 calcifications) of the 69 findings showed differences between HC and SC, but 54 findings showed no difference. In 2 cases there were interpretation differences between the radiologists. Calcification was clearly depicted by SC when zoom was used, compared with HC. There was a tendency for FAD in the mammary gland to be enhanced by changing the brightness and contrast, resulting in overdiagnosis. Furthermore, it was difficult to evaluate low-density areas in the extra-mammary gland.
In conclusion, state-of-the-art technology in digital mammography is not yet mature enough to evaluate all suspected lesions, and further improvement of soft copies is required.