A subsequent retrospective study compared accuracy for cancer diagnosis of separate digital mammography manufacturers with screen-film mammography.3 This study found that there was no significant difference in accuracy of cancer diagnosis for soft-copy digital and screen-film mammography for the three digital manufacturers investigated. The authors did not intend to compare one digital manufacturer’s equipment to another but to compare digital with screen-film mammography for each digital manufacturer. Since different women were imaged on different digital systems it would not have been possible to perform a paired comparison between different manufacturers.