Alexander M. Castellino, PhD
August 21, 2014
Is Fast MRI Better Than Mammography?
MRI Screening for Breast Cancer Is Cost Effective for Some
MRI More Sensitive Than Mammography or Ultrasound
An MRI screening protocol for breast cancer that takes just 3 minutes is as good as a regular MRI that takes 21 minutes, and more accurate than digital mammography, according to a proof-of-concept study published in the August 1 issue of the Journal of Clinical Oncology.
The accelerated MRI was as good as regular MRI for detecting 11 invasive breast cancers that had escaped detection on regular mammography, report Christiane A. Kuhl, MD, and colleagues from the University Hospital of Aachen in Bonn, Germany.
“MRI is the technique of the future [for screening]. Ionizing radiation is not involved. Compared with digital mammography, it is highly sensitive, and overdiagnosis is less of a problem, contrary to current notions,” Dr. Kuhl told Medscape Medical News.
Dr. Kuhl’s team “stripped down MRI to the essential part that makes for fast acquisition,” she explained. For the 3-minute protocol, the radiologist reads the first postcontrast subtracted (FAST) and maximum-intensity projection images; for the full diagnostic protocol, all the images are read.
The screening accuracy of the accelerated MRI is similar to that of a full diagnostic MRI, she added.
“A Huge Step Forward”
The accelerated protocol “is a huge step forward in breast cancer screening,” writes Elizabeth A. Morris, MD, chief of breast imaging services at the Memorial Sloan Kettering Cancer Center in New York City, in an accompanying editorial. “Data clearly demonstrate that FAST breast MRI could be the standard for breast cancer screening: it is safe, does not induce cancers, and can find more cancers than mammography,” she explains.
“Although this protocol is likely not appropriate for diagnostic studies, by doing this in the screening setting [the team] achieved a high detection rate without a high false-positive rate, the hallmarks of a quality screening test,” Dr. Morris writes. The negative predictive value was 99.8%.
The Accelerated Protocol
Dr. Kuhl, a radiologist with 20 years of experience, was struck by the fact that early images were best for detection purposes. “The early phase after injection of the contrast agent is best suited to visualize enhancements; other images are used to characterize enhancing structures. That’s why the accelerated protocol is appropriate for screening and not diagnostic purposes,” she noted.
The study consisted of 443 asymptomatic women at mild to moderate risk for breast cancer. They had all undergone digital mammography, and the women with dense or extremely dense breasts had also undergone ultrasound screening, all with negative results.
The women then underwent MRI screening, which identified 11 breast cancers — 7 invasive cancers and 4 ductal carcinoma in situ. The identification of these 11 cancers provided an additional cancer yield of 18.3 per 1000.