I received numerous emails and phone calls about todays article published in Radiology May 14, 2013,
Digital Mammography: Direct Outperforms Computed Radiography by Laurie Barclay, MD.
So what is CR and DR mammography anyhow?
A CR (computed radiography) Mammogram is an offline system using a cassette-based removable detector and an external reading device to generate the digital image.
This means the mammogram image is on a cassette and then the cassette is put in to a “reader” which converts the information from the cassette to digital and then sends it to the computer reading station.
DR (direct radiography) Mammogram is an online system that includes a detector as an integral part of the mammographic unit to allow reading of the digital image in real time.
The images are acquired and stored digitally. These units can also do breast tomograms which are image slices through the breast. That is one reason why they are finding more cancers.
To date there have been few studies that have evaluated the type of detector used in digital mammography.
This study compared the cancer detection rate using data from the Ontario Breast Screening Program in women 50-74 who were screened in 2008-2009.
“CR was 21 percent less effective than DR,” Dr. Chiarelli said in the news release. “This could result in about 10 fewer cancers detected per 10,000 women screened….. There may be several technical reasons reported by others for the lower effectiveness of CR, including loss of spatial resolution, or sharpness, and increased image noise, or granularity.
“The Canadian Institute of Health Research funded the study. They concluded that “Although DR is equivalent to SFM (screen film mammography) for breast screening among women aged 50–74 years, the cancer detection rate was lower for CR,”
“Screening programs should monitor the performance of CR separately and may consider informing women of the potentially lower cancer detection rates.”
I am sure there will be much discussion about this study in the next few weeks. As always if you have any questions or concerns about your recent mammogram, consult with your physician about what is appropriate for you.
From: Medscape Medical News.