Position PaperMagnetic resonance imaging of the breast: Recommendations from the EUSOMA working group
Introduction
The use of magnetic resonance imaging (MRI) of the breast is rapidly increasing1 as this technique becomes more widely available and despite the lack of clear evidence of its effectiveness in many clinical settings. It has been firmly established that breast MRI should be carried out routinely with gadolinium-based contrast agent injection except for evaluating breast implant integrity (when unenhanced MRI has been shown to be effective2).
The lack of clear evidence is illustrated by the small number of available meta-analyses on breast MRI (Table 1): only 11 from 1995 to June 2009 (0.8 per year over more than 14 years).3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
The European Society of Breast Cancer Specialists (EUSOMA) organised a workshop in Milan on 20–21st October 2008 to evaluate the evidence currently available on the clinical value and indications for breast MRI. Twenty-three experts from the disciplines involved in breast disease management – including epidemiologists, geneticists, oncologists, radiologists, radiation oncologists, and surgeons – discussed the evidence for the use of this technology in plenary and focused sessions. Prior to the meeting, the group performed a literature review on predefined topics; defined questions to be answered at the meeting were identified. This paper presents the consensus reached by this working group on the recommendations for the use of MRI for each indication including, where applicable, a measure of the level of evidence (LoE) from 1a (highest) to 5 (lowest) and degree of recommendation (DoR) from A to D, respectively, using the methodology defined by the Centre for Evidence-Based Medicine, Oxford, United Kingdom,14 when applicable. Clinical recommendations not based on scientific evidence were explicitly labelled as experts panel opinions (EPO). Following the meeting, the literature review has been updated to June 2009. The working group intends to further update these recommendations as and when new relevant evidence becomes available.
Section snippets
General recommendations
We recommend that breast MRI is performed in specialist breast units or in departments of radiology with experience in conventional breast imaging – X-ray mammography (XRM) and breast ultrasound (US) – and in needle-biopsy procedures (under stereotactic or sonographic guidance), as well as in second-look targeted US for findings detected at MRI and not revealed by conventional imaging prior to MRI. A direct link to all other diagnostic procedures, including pathology, should be available. A
Technical requirements, methodology, and interpretation
We recommend the use of MR units with magnets with intensity field ⩾1.0 T and gradients ⩾20 mT/m, equipped with bilateral dedicated coils, preferably multichannel. Regular checks using standardized quality control of MR units are recommended, including magnetic field homogeneity, breast coil performance, etc., according to national regulations.
In order to reduce the risk of false positives, we recommend that premenopausal women undergo the examination ideally on day 6–13 of the menstrual cycle,
Background
The basic background to be taken into account is that breast conserving treatment (BCT), including local excision or quadrantectomy plus radiation therapy, is generally accepted as the preferable alternative to mastectomy for tumours up to 3 cm in size. This preference is based on the results of a number of randomised controlled trials (RCTs) with long-term follow-up without significant difference between mastectomy and BCT in terms of mortality rate, confirmed by a recent meta-analysis22
Background
Several genes with high penetrance mutations predispose women to an increased risk of developing breast cancer. Approximately 3% of all breast cancers occur in women with BRCA1 and BRCA2 deleterious mutations. A further small percentage occurs in women with TP53 mutations (Li-Fraumeni syndrome) or rare moderate-penetrance alleles such as CHEK2, ATM and BRIP1, or low penetrance more common alleles.82BRCA mutation carriers and their untested first-degree relatives should be considered at high
Background
In large breast tumours, neoadjuvant chemotherapy (NAC) is administered prior to surgical treatment with the aim of reducing the tumour to a size that allows for optimal local surgery, preferably BCT. The selection of patients eligible for NAC has become part of patient management by a multidisciplinary team. NAC is usually indicated in two clinical situations:
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inoperable breast tumours at initial presentation;
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large operable breast tumours (stage IIa, IIb, IIIa) not amenable to primary BCT.
In
Background
Breast augmentation is increasingly performed for either cosmetic only purposes or to assist cosmesis in the surgical treatment of breast cancer. The number of women with breast implants in the United States was estimated to be between one and two million in 1995.166 According to the American Society of Plastic Surgeons, 237,000 breast augmentations procedures were performed in that country in 2002 and 347,000 in 2007.167 In Europe, the overall number of women with implants is unknown.168
The
Background
Occult primary breast cancer has been classically defined as a condition characterised by a histopathologically confirmed cancer of breast type first presenting as a metastatic disease (mainly as axillary lymphoadenopathy) with negative CBE. It represents a type of ‘carcinoma of unknown primary’ syndrome and accounts for up to 1% of breast cancers.190, 191 To detect the breast origin in these patients has relevant treatment and prognostic implications.192, 193 However, in these patients, XRM
Background and evidence overview
The incidence of relapse following BCT is relatively low. Long-term data62 show an 8.8% cumulative rate of ipsilateral recurrence 20 years after BCT. However, a recent retrospective study202 on 476 primary invasive cancers with a median follow-up of 5.4 years, reported only 1.7% for ipsilateral recurrence (n = 8; mean diameter 1.6 cm) and 2.3% for contralateral cancer (n = 11; mean diameter 1.5 cm), 4% overall; of 19 women with ipsilateral or contralateral relapse, 18 were alive and free of metastases.
Background and evidence overview
Nipple discharge is a common symptom. If multiduct or bilateral, breast imaging is not required. However, single duct nipple discharge, is considered an indication for further investigation including XRM and/or US. If the discharge is blood containing, fluid cytology is performed. In the case of single duct nipple discharge, incidence of malignant or high-risk pathology is reported as high as 15%, that of malignancy in case of negative CBE and conventional imaging as high as 10%.74 Conventional
Characterisation of equivocal findings at conventional imaging
There is no evidence in favour of breast MRI as a diagnostic tool to characterise equivocal findings at conventional imaging when needle-biopsy procedures can be performed.12, 15, 209 This has been also confirmed by a systematic review from the Blue Cross and Blue Shield Association Technology Evaluation Center210: the sensitivity of MRI ranged from 91% to 99%. Also considering the 90% sensitivity reported in the meta-analysis by Peters et al.,13 the use of MRI as an alternative to needle
Inflammatory breast cancer
Inflammatory breast cancer accounts for 1–4% of all breast malignancies.212 The diagnostic challenge is the differentiation from acute mastitis. Excluding papers on the MRI evaluation of the response of inflammatory breast cancers to chemotherapy, from 1994 to 2008, seven papers were published on the use of MRI in this setting, for a total of 139 patients (range 5–48).212, 213, 214, 215, 216, 217, 218, 219 Most authors report a large overlapping of MRI morphologic and kinetic features of the
Male breast
Male breast cancers account for approximately 1% of all breast cancers. The American Cancer Society estimates that about 2000 new cases of invasive breast cancer are diagnosed in men each year and approximately 450 men die from breast cancer annually in the United States.220 Only one paper is available on the use of contrast-enhanced MRI for studying breasts in males,221 demonstrating that benign and malignant breast diseases have the same imaging features in men and women. No evidence exists
Conclusions
Breast MRI is an imaging technique that is increasingly being used in clinical practice. However, it should not be used when it is not indicated. This document highlights the indications for which evidence can be found in the literature or a consensus opinion has been reached. However, there remain many research issues deserving of high quality primary studies and secondary studies (systematic reviews, meta-analyses, and decision-making analyses) in order to clearly define clinical
Conflict of interest statement
None declared.
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