Spotlight on breast imaging at RSNA 2019
Breast imaging was a hot topic at the recent 2019 RSNA, including several presentations on the use of MRI as a supplemental imaging modality for breast cancer screening. Initial results from the Dense Tissue and Early Breast Neoplasm Screening (DENSE) trial were included in a session highlighting ‘Best Clinical Trials @ RSNA 2019’.
The DENSE trial was a multicenter, randomized, controlled trial evaluating the use of supplemental MRI to reduce interval breast cancers in women with extremely dense breast tissue. This work presented by Dr. Marije Bakker and Dr. Stéphanie de Lange showed that the interval cancer rate was significantly reduced from 5.0 per 1000 screenings to 2.5 per 1000 screenings (P<0.001) when women with extremely dense breast tissue and a negative mammogram were invited for supplemental imaging with MRI. Of the women invited for MRI screening, 59% (4783/8061 women) accepted the invitation. In these women who actually underwent MRI the interval cancer rate was 0.8 per 1000 screenings. Furthermore, MRI detected 16.5 cancers per 1000 screenings in women with a negative mammogram, with a biopsy rate of 300 per 1000 and a false positive rate of 78 per 1000 screenings.
The DENSE trial is an important addition to current knowledge regarding the use of supplemental MRI for breast cancer screening. However, limited MRI access remains an issue when considering increasing the use of MRI in breast imaging. One way to help deal with this issue is the use of an abbreviated breast MRI protocol, which was the topic presented by Dr. Jean Seely, who is head of the Breast Imaging section at The Ottawa Hospital. Dr. Seely presented outcomes from a 22-month study in 1539 patients comparing an abbreviated protocol (consisting of pre- and two post-contrast T1 and T2 sequences) to a standard breast MRI protocol in a population-based high-risk screening program. The abbreviated protocol was an average of 16.3 minutes, while the standard protocol was an average of 27 minutes, increasing scanner capacity by roughly 50%. Use of the abbreviated protocol was found to lead to fewer false positives and fewer breast biopsies, while still maintaining a similar cancer detection rate (16.7/1000 with the abbreviated protocol versus 17.0/1000 with the standard protocol; p=0.96).
The use of ultrafast breast MRI was presented by Dr. Ritse Mann in a session on Advanced MRI Applications. Ultrafast breast MRI looks at the early inflow of contrast in the first several seconds after injection. Since most breast cancers will enhance earlier and faster than benign lesions, the first lesions to enhance are the most suspicious. Adding to the appeal of using ultrafast sequences in a breast MRI protocol, these sequences can be added without adding to the total acquisition time of the study.
These topics presented at the 2019 RSNA add to a growing body of literature around the use of MRI in breast imaging. The demonstration of a reduction in interval cancers using MRI for supplemental imaging in women with extremely dense breast tissue is an important step, while the use of abbreviated protocols may enable increased access to MRI for breast cancer screening.