Rapid MRI Tops 3D Mammo for Dense Breast Screening

A 10-minute MRI for breast cancer screening in women with dense breasts was associated with improved cancer detection compared with digital breast tomosynthesis (DBT), a cross-sectional study found.

Among the more than 1,400 average-risk women in the study, the rate of invasive cancer detection was 11.8 per 1,000 women with abbreviated breast MRI, as compared with 4.8 per 1,000 with DBT, also known as 3D mammography (P=0.002), Christiane Kuhl, MD, PhD, of the University Hospital Aachen in Germany, and colleagues reported.

Abbreviated MRI had a sensitivity of 95.7% and specificity of 86.7% for detecting cases of either invasive cancer or ductal carcinoma in situ (DCIS), compared to sensitivity and specificity rates of 39.1% and 97.4%, respectively, for 3D mammography.

“The significantly higher sensitivity of abbreviated breast MRI was associated with a reduced specificity, but with a PPV [positive predictive value] that was not significantly different from that of DBT,” the group wrote in JAMA.

In the MRI arm, 7.5% received recommendations for additional imaging based on positive findings versus 10.1% for the DBT arm (P=0.02). Notably, PPV values were still relatively low with both modalities: at 19.6% in the MRI arm and 31.0% with DBT (P=0.15).

“Women and referring physicians should be aware that having a screening abbreviated breast MRI, especially a baseline examination, may lead to additional benign biopsy findings, 6-month follow-up recommendations, or both,” wrote Kuhl and coauthors. “On the other hand, DBT, but not abbreviated breast MRI, may require further imaging after initial screen-detected abnormalities.”

In an accompanying editorial, Anna Tosteson, ScD, of Dartmouth College and Norris Cotton Cancer Center in Lebanon, New Hampshire, noted that “the promise” of abbreviated MRI — it takes less than 10 minutes — is the improved cancer detection minus the cost and time constraints associated with conventional MRI.

“However, abbreviated breast MRI still requires the contrast-enhancing agent used in full-protocol breast MRI and thus carries the same gadolinium-associated risks,” she said.

Tosteson pointed out that the improved detection rate with abbreviated MRI — seven additional cancers per 1,000 women screened — compares favorably to results of a recent trial that randomized women with dense breasts and a negative mammogram to supplemental ultrasound or DBT imaging. There, adding ultrasound yielded an additional two detected cancers per 1,000 women screened over DBT.

But in the current trial, the so-called EA1141 study, accelerated MRI also introduced more biopsies (107) to reach that goal compared with 3D mammography (29).

“Overall, the cascade of care ensuing from an abbreviated breast MRI callback would likely also be more costly because of the more involved and expensive types of additional imaging and procedures,” said Tosteson.

Writing in an editorial in JAMA Surgery, Lisa Newman, MD, MPH, and Cheng-Har Yip, MBBS(Mal), wrote that, compared with conventional MRI, the shorter patient time with abbreviated MRI and reduced reading time from the radiologist could be potential cost-savers, but also highlighted the additional biopsies in the accelerated MRI arm.

“All of these findings would be expected to have cost implications,” Newman and Yip wrote.

From December 2016 to November 2018, Kuhl and colleagues randomized 1,444 women ages 40 to 75 to first undergo accelerated MRI followed by DBT, or vice versa, at 47 centers in the U.S. and one in Germany. All women included in the trial had an average risk of breast cancer and had dense breasts on their most recent mammogram. In, all 77% had heterogeneously dense breasts and 15% had extremely dense breasts.

Screening detected 19 invasive breast tumors in 17 women. Abbreviated MRI cancer in all 17 of the women while DBT detected cancer in seven. When including cases of DCIS, these numbers were 22 and 9, respectively.

One serious limitation of accelerated MRI for breast cancer screening, the study authors noted, is the lack of available MRI units to regularly screen such a large population (over 40% of U.S. women have dense breasts).

“Although abbreviated breast MRI does not require specific additional equipment beyond what is used for regular breast MRI, given the current limited availability of breast MRI in general for screening the relatively small number of women at high risk of breast cancer, the ability of centers to offer abbreviated breast MRI may be limited until more MRI units are added,” they wrote.