Breast MRI Screening Practice in Canada

Breast MRI offers the highest sensitivity of all breast imaging modalities for the detection of breast cancer. However, the use of MRI for breast cancer screening is limited due to its cost and complexity. There has been a growing interest in the investigation of abbreviated breast MRI protocols, including the recently published EA1141 study, which demonstrated a significantly higher rate of invasive breast cancer detection using a 10 minute breast MRI protocol compared to the use of digital breast tomosynthesis.¹

In June 2020, Bayer surveyed radiology departments across Canada to better understand how MRI is being utilized for breast cancer screening and to look for opportunities for reducing scan times. The survey was sent to 153 MRI sites across the country, which represents 58% of the MRI sites in Canada (according to a 2017 CADTH Canadian Medical Imaging Inventory report, there are 261 sites in Canada with MRI units and a total of 366 MRI units).² Questions asked in the survey included:

• Do you have a breast coil?
• How many breast MRI screening exams are done per week, on average? How many total MRI exams are performed per week?
• What is the average time for a breast MRI screening exam (booking and scan time)?
• Do you have the ability to perform MR-guided biopsy on-site?
• Do you batch breast exams?

There were 98 partial or complete responses to the survey. Of these responses, 48 sites are currently performing breast cancer screening with MRI and within these 48 sites there is a total of 424 breast cancer screening MRI exams being performed per week. Of the sites that perform breast MRI screening and who also responded with the total number of MRI exams per week, the proportion of exams dedicated to breast screening with MRI is 3.4% (318 breast exams out of 9362 total MRI exams per week). Including sites without screening programs, but who still provided the total number of MRIs per week, then the percentage of exams that are for breast screening across the country is 2.0% (318 breast exams out of 15919 total MRI exams per week).

Wide ranges of booking and scan times for breast MRI were reported across the country (Table 1). Histograms illustrating the distribution of these booking and scan times are provided in Figures 1 and 2. This data demonstrates an opportunity for standardization of protocols across the country to shorten breast MRI scan times. While a minority of sites have already introduced abbreviated protocols as short as 10 minutes, 30 of 43 sites that provided a response are still using a scan time of 20 minutes or more.

Table 1. Booking and scan times for breast MRI screening exams in Canada