Diffusion-weighted MRI shows potential for finding cancers in patients with dense breasts

Researchers believe diffusion-weighted MRI (DWI) has potential as a “rapid supplemental screening tool,” according to a study published in the American Journal of Roentgenology. Their findings show that DWI can help radiologists see mammographically occult cancers in at-risk women with dense breasts.

Elizabeth S. McDonald, MD, PhD, Perelman School of Medicine at the University of Pennsylvania in Philadelphia, Pa., and colleagues retrospectively reviewed data from more than 1,000 women with dense breasts who underwent screening breast MRI at a single institution from January 2007 to May 2013. The team then divided 48 patients with dense breasts into two groups: one group of 24 patients with mammographically occult cancer detected by MRI and another group of 24 patients with negative MRI findings.

Three “experienced breast imagers,” blinded to health records and contrast-enhanced MRI findings, then studied DWI scans for cancer.

Overall, at least one of the three readers correctly identified breast cancers in 16 of the 24 patients with cancers not visible in mammograms. Eleven of the cancers were identified by two or more readers.

“The results of this study suggest that the addition of a rapid unenhanced MRI examination with DWI to conventional mammography screening could potentially identify a significant number of mammographically occult cancers in women with dense breasts,” the authors wrote.

McDonald and colleagues also examined the cancers none of the three experienced readers identified.

“Eight of the 24 cancers were missed by all readers, including four invasive ductal carcinomas, one invasive lobular carcinoma, and three DCIS lesions,” the authors wrote. “The median size of the missed cancers was 12 mm (range, 6–26 mm); six presented as masses and two as non-masses. Four of the missed cancers were imaged at 3 T and four at 1.5 T.”

McDonald et al. wrote that there is still a significant amount of work to be done as researchers continue to examine the effectiveness of DWI.

“Our study highlights several areas of focus for future work to improve the sensitivity of DWI for detecting mammographically occult cancer in women with dense breasts,” the authors wrote.

Alternative ways to “increase DWI spatial resolution” and “reduce spatial distortions,” they explained, could improve the ability of DWI to detect small lesions. The authors also said new computer-aided technology for assessing the images and updates to specific interpretation algorithms could improve readers’ performance when using DWI.