Magnetic Resonance Imaging (MRI) with Contrast:
What is it? Magnetic resonance imaging (MRI) is a noninvasive medical test that uses very strong magnets and pulses of radio waves to manipulate natural magnetic properties in the body to create images of the part of the body being evaluated. Breast MRI requires intravenous injection of gadolinium-based contrast to evaluate the breast tissue (Figure 12), looking at both anatomy and blood flow patterns. Normal tissue, cancers, and benign (noncancerous) findings can enhance on MRI. MRI is recommended for breast screening for high-risk women. It can also be used in “diagnostic” cases to help answer questions that may have been raised by other tests or physical exam.
Figure 12. Breast MRI with Contrast Showing Enhancing Cancer. Axial MRI image of the right breast obtained after contrast injection (and after computer subtraction of non-enhanced images) in this 48-year-old woman shows irregular spiculated enhancing (white) mass (arrow) due to grade 2 invasive ductal carcinoma with DCIS.
How it works: For breast MRI, a patient lies face down on a special table and the breasts are positioned into two openings of a “coil” (the imaging device) (Figure 13 and Figure 14). The MRI scanner makes loud “tapping” noises for several minutes at a time while the exam is taking place. After an initial set of images has been obtained, the contrast agent is injected into a vein in the arm. The usual breast MRI examination takes about 20 to 40 minutes. To reduce normal hormonal changes in the breast, screening MRI is ideally performed from day 7-10 of the menstrual cycle. It is important for the patient to lie very still during the exam as any motion will make the study hard to interpret.
Figure 13 and Figure 14. “Coil” and supports used to image the breasts for MRI. The patient lies face down with her head in the cushioned support and her arms raised. The breasts are placed in the rectangular openings (arrows). The patient is then moved into the tunnel of the scanner for imaging with the head facing out.
Benefits: Breast MRI reveals an average of 10 additional cancers per thousand women screened after mammography, even when both mammography and ultrasound have been performed. The cancer-detection benefit is seen across all breast density categories and similar results have been seen with MRI even in average-risk women.i MRI is very sensitive and is recommended every year for women who are at high risk for breast cancer, including women with a personal history of breast cancer and dense breasts or diagnosis by age 50.ii
Considerations: Breast MRI is a sensitive test and will find more areas of concern than either a mammogram or ultrasound. Some of those “finds” will be cancer, but more than half will not (known as a “false positive”). It is important to have the examination performed at a facility where the radiologist correlates the MRI with the patient’s mammogram and any other breast imaging and prior biopsy results. The facility should also be able to perform an MRI-guided biopsy or formally refer to another facility that can; all facilities accredited in breast MRI by the American College of Radiology should meet these requirements.
MRI cannot be performed in women who have certain metal implants such as pacemakers and is not recommended if the patient is pregnant. Not all patients can tolerate a contrast agent and it may pose a small risk for women with kidney disease. Some women find claustrophobia an issue (as exam time is spent in an enclosed tube). This position can be difficult for some patients with neck problems, obesity or breathing issues. Data are emerging showing there can be accumulation of gadolinium in parts of the brain in patients who have multiple contrast-enhanced MRI studies;iii the importance of this finding is unknown, and this appears to be an issue only with certain types of contrast agents.iv, *
A last consideration for MRI currently is its high cost, which is not always covered by insurance. A lower cost “fast” MRI has been developed which may take less than 10 minutes, but its availability is still quite limited.v, vi ,vii
If MRI screening has been performed, there is no added benefit to ultrasound screening, though ultrasound is sometimes performed to guide biopsy of suspicious masses seen on MRI.
i Kuhl CK, Strobel K, Bieling H, Leutner C, et al. Supplemental Breast MR Imaging Screening of Women with Average Risk of Breast Cancer. Radiology 2017; 283:361-370
ii Monticciolo DL, Newell MS, Moy L, et al. Breast Cancer Screening in Women at Higher-Than-Average Risk: Recommendations From the ACR. J Am Coll Radiol 2018; 15:408-414
iii McDonald RJ, McDonald JS, Kallmes DF, et al.(2015). Intracranial gadolinium deposition after contrast-enhanced MR imaging. Radiology.
iv Radbruch A, Weberling LD, Kieslich PJ, et al. (2015) Gadolinium retention in the dentate nucleus and globus pallidus is dependent on the class of contrast agent. Radiology. pubs.rsna.org/doi/abs/10.1148/radiol.2015150337
v Kuhl CK, Schrading S, Strobel, K, et al. (2014). Abbreviated breast magnetic resonance imaging (MRI): First postcontrast subtracted images and maximum-intensity projection – a novel approach to breast cancer screening with MRI. J Clin Oncol. https://doi.org/10.1200/JCO.2013.52.5386
vi Strahle DA, Pathak DR, Sierra A, et al. (2017). Systematic development of an abbreviated protocol for screening breast magnetic resonance imaging. Breast Cancer Res Treat. https://doi.org/10.1007/s10549-017-4112-0
vii Chen SQ, Huang M, Shen YY, et al. (2017). Application of abbreviated protocol of magnetic resonance cancer screening in dense breast tissue. Acad Radiol. https://doi.org/10.1016/j.acra.2016.10.003
* Early studies suggest that "linear” contrast agents accumulate in the brain whereas “macrocyclic” agents do not, though further study is needed. Linear agents include gadopentetate dimeglumine [Magnevist], gadodiamide [Omniscan], and gadoversetamide [OptiMARK]. Macrocyclic agents include gadoterate meglumine [Dotarem], gadobutrol [Gadavist], and gadoteridol [ProHance].