Contrast-enhanced MRI for breast cancer screening

Abstract

Multiple studies in the first decade of the 21^st century have established contrast-enhanced breast MRI as a screening modality for women with a hereditary or familial increased risk for the development of breast cancer. In recent studies, in women with various risk profiles, the sensitivity ranges between 81% and 100%, which is approximately twice as high as the sensitivity of mammography. The specificity increases in follow-up rounds to around 97%, with positive predictive values for biopsy in the same range as for mammography. MRI preferentially detects the more aggressive/invasive types of breast cancer, but has a higher sensitivity than mammography for any type of cancer. This performance implies that in women screened with breast MRI, all other examinations must be regarded as supplemental. Mammography may yield ~5% additional cancers, mostly ductal carcinoma in situ, while slightly decreasing specificity and increasing the costs. Ultrasound has no supplemental value when MRI is used. Evidence is mounting that in other groups of women the performance of MRI is likewise superior to more conventional screening techniques. Particularly in women with a personal history of breast cancer, the gain seems to be high, but also in women with a biopsy history of lobular carcinoma in situ and even women at average risk, similar results are reported. Initial outcome studies show that breast MRI detects cancer earlier, which induces a stage-shift increasing the survival benefit of screening. Cost-effectiveness is still an issue, particularly for women at lower risk. Since costs of the MRI scan itself are a driving factor, efforts to reduce these costs are essential. The use of abbreviated MRI protocols may enable more widespread use of breast MRI for screening. Level of Evidence: 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:377-390.

Keywords: MRI; breast cancer; mammography; screening.

Figure 1

Typical finding of an MRI‐detected breast cancer (arrow). In this case a 9 mm grade 2 invasive ductal carcinoma in a 46‐year‐old women screened because of familial risk. As with most cancers, this tumor is clearly evident on the maximum intensity projection (MIP) image shown (A), which was created from subtraction images of regular high‐resolution T₁‐weighted acquisitions obtained prior to and 90 seconds after contrast injection. Ultrafast examinations may be used to differentiate the cancer from the somewhat nodular parenchymal background enhancement. (B) MIP generated from the ultrafast series (8.6 sec after enhancement of the descending aorta) is provided, showing that the lesion stands out from the other enhancing foci. (C) The corresponding relative enhancement vs. time curve is given (type 2, plateau).