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Breast MRI

Health consumers information

Authors: Dr Donna Taylor *
                            A/Prof Liz Wylie *

What are the prerequisites for having a breast MRI done?

Ideally MRI should be scheduled for days 6-12 of the menstrual cycle unless there is a clinical urgency to have the procedure performed as soon as possible (e.g. known breast cancer awaiting treatment).

Ideally, breast MRI should not be performed in women who are taking hormone replacement therapy (HRT) as this may cause hormonal related parenchymal contrast enhancement which can obscure pathological changes and make study interpretation difficult. If the indication for the study is not urgent, then cessation of HRT for 4-6 weeks prior to the study is suggested.

MRI is best avoided during pregnancy unless the clinical indications outweigh the small (currently unknown) risks involved. If there is a possibility the patient could be pregnant then a pregnancy test is suggested prior to the scan, or alternatively the procedure could be rescheduled until after the next menstrual period starts.

MRI can be performed on lactating women, however image interpretation may be more difficult due to the hormonal stimulation of the breast.

Excretion of gadolinium contrast agent into breast milk has been shown to be minimal (0.01%) and very little (less than 1%) of the drug is absorbed by the baby when taken in this way which is far less than the dose of gadolinium given to a baby having an MRI. If the patient is breastfeeding it is quite safe to continue this after the examination as studies have shown that only a very tiny amount of the contrast material is absorbed by the baby from the milk.

Claustrophobia: 1-4% of women suffer from claustrophobia and some will not be able to tolerate being in the MRI machine. Some of these women may be able to tolerate the examination if they are given anxiolytic premedication. Please discuss this issue with your patient and the personnel at the MRI facility at the time of booking the procedure.

A safety screening questionnaire should be completed by every patient prior to MRI. This asks questions regarding the presence of ferromagnetic objects, implants and pacemakers and is designed to ensure that no contraindications are present to exposure of the patient to high magnetic fields.

Patients with impaired renal function are at risk of developing Nephrogenic Systemic Sclerosis.

Biochemical screening for impaired renal function is not thought to be warranted in the absence of relevant history or symptoms. If there is any reason to suspect the presence of renal impairment, estimation of GFR should be performed prior to gadolinium administration.

What are the absolute contraindications for a breast MRI?

Patients with known allergy to gadolinium contrast agents should not undergo contrast enhanced breast MRI. Breast MRI to detect presence of breast implant complications does not require injection of contrast and can be safely performed in this setting.

Patients with ferrous aneurysm clips, known metallic foreign bodies in the eye, bionic ear implants, cardiac pacemakers, vascular filters (AAA-Zenith stent) and tissue expanders should not have MRI.

Patients with severely impaired renal function (GFR<30ml/min/1.73m2) should not have a breast MRI examination with IV contrast due risk of developing NSF (nephrogenic systemic sclerosis).

What are the relative contraindications for a breast MRI?

Patients with a history of allergy to iodinated contrast, other allergies and a history of asthma are at increased risk of an adverse reaction to gadolinium.

Patients with mild-moderate renal impairment (eGFR between 30 and 60 ml/min/1.73m2) should not undergo contrast enhanced breast MRI unless the benefits of having the test are considered to outweigh the risk of developing NSF. If contrast injection is needed, a reduced dose of a cyclic form of gadolinium contrast agent, pre-hydration and written informed consent from the patient should be obtained.

Patient pregnancy. There is not enough evidence to determine whether MRI is without risk during pregnancy. Whilst there are no known adverse effects, the consequences of foetal exposure to strong magnetic fields are uncertain. The intravenous contrast agent (which contains gadolinium DTPA) does cross the placenta and the long term effects on the foetus are uncertain. The hormonal effects of pregnancy may cause extensive background glandular contrast enhancement, reducing the sensitivity of breast MRI in detecting abnormalities. Breast MRI should be delayed until after delivery of the baby unless there are exceptional circumstances where the information provided by the MRI is worth the very small potential, but unproven, risk to the foetus.

Patient size. Obese patients who weigh more than the maximum weight limits for the sliding table may not fit into the magnet.

What are the adverse effects of a breast MRI?

The total incidence of adverse reactions to MRI contrast agents is approximately 2-4%.

The most common reactions are headaches, dizziness, nausea and emesis. Local injection site symptoms such as pain, warmth, or burning sensation and localised oedema may occur. Other adverse events include chest pain/tightness, fever, fatigue, arthralgias, rigors, asthenia, hot flashes, malaise, weakness, facial oedema, neck rigidity, abdominal cramps, itching, watery eyes, tingling sensation in the throat.

Moderate to major adverse reactions including airway compromise and circulatory collapse have been reported in approximately 1 in 10,000 studies.

Nephrogenic Sclerosing Fibrosis is a rare multi-systemic fibrosing disorder that principally affects the skin but may also affect other organs of patients with renal insufficiency.
See Gadolinium Contrast Medium (MRI Contrast agents) for more information.

The acoustic noise produced during MRI can be distressing for patients and can result in reversible hearing loss if the patient does not wear ear protection (disposable ear plugs or headphones are supplied to prevent this).

Are there alternative imaging tests, interventions or surgical procedures to a breast MRI?

Breast MRI is an expensive test with limited availability. It is best used for specific clinical indications in conjunction with routine breast imaging studies such as mammography and ultrasound.

It is vital that the referral contains all the relevant clinical information regarding previous history, pathology results and imaging procedures. It is vital that the patient brings all her previous breast imaging studies in to the MRI unit when she has her study performed so that the reporting radiologist can produce the most clinically relevant and accurate report possible.

MRI is very sensitive but relatively non-specific, resulting in a significant number of false positive findings. The findings on MRI may require further investigation with ultrasound and biopsy to determine their significance. Indeterminate or suspicious lesions seen on ultrasound can be biopsied using US guidance but about 20-30% of lesions may not be visible on ultrasound and will require either MRI guided biopsy or MRI guided hookwire localisation and surgical biopsy to rule out malignancy. Many of these potential abnormalities shown on MRI will be benign and the process of investigating these may cause significant patient anxiety, inconvenience and expense.

Specific clinical indications for breast MRI:

  • Screening: Certain women are at high risk for breast cancer. This includes women with a strong family1 and those who are known carriers of a mutation in the BRCA 1 and 2 genes or their first degree relatives. Referral to a high risk familial breast cancer clinic for risk assessment and development of an individualised screening protocol is recommended prior to consideration of MRI so that counselling can take place. Women with an inherited susceptibility to breast cancer have a considerably increased risk of developing breast cancer at a young age. Approximately 50% of women with a mutation in the BRCA 1 or 2 cancer susceptibility genes will have developed breast cancer by the age of 50 years. Women who have had mantle radiotherapy for Hodgkin’s disease during the period from their late teens up to age 30 subsequently have a significantly increased breast cancer risk and may benefit from having regular breast screening with MRI.
    Important advantages of using MRI in these young women are that it does not involve exposure to ionising radiation and its sensitivity is not adversely affected by the presence of dense tissue. Breast tissue in young women is more sensitive to the (cumulative) mutagenic effects of radiation. The breast is also more likely to be dense and therefore sub-optimally imaged using mammography. At present there is not enough evidence to support the use of Breast MRI as a screening modality for women with dense breasts in the absence of other high risk factors.
  • Assessing the contralateral breast in patients with a new breast malignancy: MRI can detect occult malignancy in the contralateral breast in at least 3%-5% of breast cancer patients.
  • Breast augmentation: Postoperative reconstruction and free silicone injections. The breasts can be difficult to evaluate using mammography in these cases. The integrity of silicone implants can be determined by non-contrast MRI.
  • Extent of malignant disease: MRI determines the extent of disease more accurately than standard mammography and physical examination in many patients. It remains to be conclusively shown that this alters recurrence rates relative to modern surgery, radiation, and systemic therapy.
  • Post lumpectomy with positive margins to show extent of residual disease prior to surgery.
  • Neoadjuvant chemotherapy: Breast MRI may be useful before, during, and/or after chemotherapy to evaluate treatment response and the extent of residual disease prior to surgical treatment.
  • Additional evaluation of clinical or imaging findings: Suspected recurrence of breast cancer where clinical, mammographic, and/or sonographic findings are inconclusive.
  • Metastatic cancer (axillary nodes or elsewhere) when the primary is unknown and suspected to be of breast origin. Breast MRI can often locate the primary tumour and define the disease extent to facilitate treatment planning.
  • Lesion characterisation when other imaging examinations, such as ultrasound and mammography, and physical examination are inconclusive for the presence of breast cancer, and biopsy has not been possible (e.g. possible distortion on only one mammographic view without a sonographic correlate).
  • Postoperative breast following tissue reconstruction: Evaluation of suspected cancer recurrence in patients with tissue transfer flaps (e.g. rectus abdominus, latissimus dorsi).

Cautionary note:

Inappropriate uses of breast MRI:

MRI should not supplant careful problem-solving mammographic views or ultrasound in the diagnostic setting. Because MRI will miss some cancers that mammography will detect, it should not be used as a substitute for screening mammograms. MRI should not be used in lieu of biopsy of a mammographically, clinically, and/or sonographically suspicious finding.

Breast ultrasound is the imaging modality of choice in the pregnant patient.

References and useful websites about breast MRI:

References:

  1. This statement comes from a review article by Chrisianne Kuhl, Magnetic Resonance Imaging Clinics of North America, Volume 14, Issue 3, August 2006, Page 391
*The author has no conflict of interest with this topic.

Page last modified on 26/7/2017.

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