[ROC analysis comparing screen film mammography and digital mammography].

PURPOSE

To compare the diagnosis performances of radiologists on screen film versus digital mammography.

MATERIAL

and methods: Two sets of 123 mammograms, screen film mammography and storage phosphor digital mammography, are studied comparatively with ROC analysis.

RESULTS

Phantom study show that conventional method give better scores for usual tension but the detectability of smaller microcalcification is equivalent. To obtain with digital technic the same conventional score you have to increase the radiation dose. Roc Curves, simulated "detection" mode showed that radiologists performed with higher accuracy with conventional system but this difference is weekly statistically significant. ROC Curves, simulated "diagnostic" mode showed the same results wit no statistically significant difference but when the decision to go to the biopsy is the gold standard, ROC Curves were essentially equivalent for both film screen and digital mammography system. The readers consistently considered the digital mammograms to be less suspicious for cancer findings. The agreement study as proposed by the FDA indicate that probability of a positive digital mammograms given a positive screen film is 75% (threshold value 90%) and the probability of a negative digital mammograms given a negative analog film is 85% (threshold value 85%).

CONCLUSION

Analysis of specific discrepancies indicate that spatial resolution is an essential limiting factor for digital method but high resolution phosphor plate are interesting in imaging treated breast, radioluscent lesion, fatty benign tumor, hamartoma, intramammary lymph node, breast with prosthesis.