While the majority of U.S. women have relatively easy geographic access to most breast imaging services, travel times for breast MRI are notably longer.

However, Native Americans and women in rural communities tended to have longer travel times, regardless of the modality, according to a study published online June 2 in the Journal of the American College of Radiology.

Study authors Tracy Onega, MS, PhD, of the Geisel School of Medicine at Dartmouth in Lebanon, N.H., and colleagues assessed geographic access to breast imaging services by conducting a retrospective study of 2004-2008 Medicare claims data for mammography, ultrasound and MRI. ZIP codes in which breast imaging occurred were tracked across the contiguous U.S., and travel times were characterized for more than 92 million women age 30 or older based on 2010 Census data.

Results showed that, overall, 85 percent of women had travel times of 20 minutes or less to the nearest mammography or ultrasound services. Breast MRI access lagged behind, with 70 percent of women having travel times of 20 minutes or less and nearly one-in-five women traveling more than 30 minutes for breast MRI services.

In looking at differences in access for various populations, Onega and colleagues noted that Native American women had median travel times two to three times longer for all modalities compared with women in other racial/ethnic groups. Rural women also had a geographic disadvantage, with median travel four to eight times as long as urban women. Black and Asian women had the shortest median travel times to all three modalities.

“Interestingly, the lowest income quartile had the lowest proportion with >30 minutes travel time, suggesting that geographic access is not a likely barrier to utilization in this group, although transportation and other factors may be,” wrote the authors.

Onega and colleagues explained that they used car-based travel estimates, as is the case in most travel time studies, so other modes of transportation were not incorporated into the estimates.

They added that an understanding of access to additional imaging technologies will become more important as breast density notification laws spread across the U.S. and women with dense breasts are informed they may benefit from supplemental screening.

“Variation in geographic access by race/ethnicity and rurality has potential implications for fully understanding mechanisms underlying disparities in health care utilization and outcomes,” wrote Onega and colleagues. “For example, the approximately 2.5 million women aged ≥30 years who live >30 minutes from the nearest breast imaging facility of any kind may be disadvantaged for early detection of breast cancer.”