Canadian Association of Radiologists Journal 63 (2012) 207e214www.carjonline.org

Magnetic Resonance Imaging / Formation image de r�esonance magn�etique

Preoperative Breast Magnetic Resonance Imaging: Applicationsin Clinical Practice

Supriya Kulkarni, DMRD, DNBa,*, Nitin Singh, MDb, Pavel Crystal, MDa

aDivision of Breast Imaging, Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women’s College Hospital, Princess

Margaret Hospital, Toronto, Ontario, CanadabDepartment of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Abstract

Results of large randomized trials have shown that survival rates after breast conserving surgery are equivalent to those obtained by radical

mastectomy. Breast conserving surgery with wide local excision in women with early stage breast cancer who are thought to have a singleand resectable tumour as determined by clinical examination and conventional imaging followed by postoperative irradiation is the standardof care in early breast cancer. Mapping of local disease is the key element to guide optimal surgery to obtain tumour-free margins, therebydecreasing risk of local recurrence. The usual preoperative workup of breast malignancy consists of clinical breast examination andmammography with or without ultrasound. However, mammography and ultrasound fail to accurately assess tumour extent in as many asa third of patients eligible for breast conserving therapy. It is well established that magnetic resonance imaging is far superior tomammography (with and without ultrasound) for mapping the local extent of breast cancer. Experts advocate its use despite its high costs,high number of false positive findings, and lack of evidence from randomized prospective trials and, notably, fear of ‘‘overtreatment.’’ Thisarticle discusses the current role of breast magnetic resonance imaging with its clinical advantages and applications.

R�esum�e

Les r�esultats d’essais randomis�es d’envergure ont d�emontr�e que le taux de survie �a la suite d’une chirurgie conservatrice du sein �equivaut

�a celui d�ecoulant d’une mastectomie radicale. Chez les femmes ayant recu un diagnostic de cancer du sein �a un stade pr�ecoce et chezlesquelles l’examen clinique et l’imagerie conventionnelle ont r�ev�el�e une tumeur jug�ee unique et r�es�ecable, la chirurgie conservatrice du seinavec large excision locale suivie d’une irradiation postop�eratoire repr�esentent le traitement habituel pour les cancers du sein au premier stade.La localisation de la maladie est l’�el�ement cl�e d’une chirurgie optimale qui permet d’obtenir des marges exemptes de tissu tumoral, r�eduisantainsi les risques d’une r�ecidive locale. L’�evaluation pr�eop�eratoire habituelle d’une tumeur maligne du sein consiste en un examen mammaireclinique et une mammographie avec ou sans �echographie. Toutefois, jusqu’au tiers des patientes admissibles �a une chirurgie conservatrice dusein ne peuvent subir une �evaluation exacte de l’ampleur de la tumeur au moyen de la mammographie et de l’�echographie. Il est reconnu quel’imagerie par r�esonance magn�etique est de loin sup�erieure �a la mammographie (avec ou sans �echographie) pour localiser et d�eterminerl’�etendue locale du cancer du sein. Les sp�ecialistes en pr�econisent l’utilisation malgr�e les couts �elev�es qui s’y rattachent, le grand nombre der�esultats faux-positifs ainsi que le manque d’�el�ements probants dans les essais randomis�es prospectifs et, notamment, la peur du « traitementexcessif ». Cet article traite du role actuel de l’imagerie par r�esonance magn�etique du sein, de meme que de ses avantages et applicationscliniques.� 2012 Canadian Association of Radiologists. All rights reserved.

Key Words: Preoperative; Breast; Magnetic resonance imaging

Adequate treatment of women with breast cancer relies on therapy (BCT). BCT consists of wide local excision of the

accurate depiction of the extent of the index lesion, alongwith detection of multifocal or multicentric disease. Earlybreast cancer (stage I or stage II) with an index lesion <3 cmcan be treated with either mastectomy or breast conserving

* Address for correspondence: Supriya Kulkarni, DMRD, DNB, Joint

Department of Medical Imaging, University Health Network, Mount Sinai

0846-5371/$ - see front matter � 2012 Canadian Association of Radiologists. A

doi:10.1016/j.carj.2011.02.007

tumour combined with postoperative radiotherapy. Thefactors that influence the decision of mastectomy vs BCT aretumour size, tumour location, the relation of tumour size tobreast volume, multifocality or multicentricity of the tumour,

Hospital and Women’s College Hospital, Princess Margaret Hospital 3-976,

610 University Ave, Toronto, Ontario M5G2M9, Canada.

E-mail address: supriya.kulkarni@uhn.on.ca (S. Kulkarni).

ll rights reserved.

Figure 1. (A) A 39-year-old lactating woman with a right palpable finding; dense mammogram with an ill-defined mass. (B) Ultrasound, showing an irregular,

suspicious mass. (C) Multifocal multicentric cancer (pathology: invasive ductal carcinoma with an extensive intraductal component).

Figure 2. Involvement of pectoralis muscle with pleural deposits (locally

advanced breast cancer).

208 S. Kulkarni et al. / Canadian Association of Radiologists Journal 63 (2012) 207e214

and patient preference [1]. The identification of multifocal ormulticentric foci of disease results in higher local recurrencerates and is a contraindication for BCT and hence preoper-ative identification is important for appropriate treatment[2,3]. The 5-year local-recurrence rate after BCT is about5%, and it doubles if tumour is incompletely excised.Complete gross excision of the tumour maximizes localcontrol, which, in turn, results in better survival [4,5].

Comparative studies of breast magnetic resonanceimaging (MRI) and conventional imaging with clinicalassessment show consistently that MRI has higher accuracyfor determining the extent of disease [6,7]. With remarkableimprovement in technique, preoperative MRI is nowdetecting foci of disease otherwise occult to conventionalimaging with a high sensitivity of 94%-100% [8,9]. Docu-mentation of higher tumour load often leads to an alterationof management (wider excisions and more mastectomies),thereby negating the results of several long-standingrandomized control trials, which have shown that outcomeswith BCT with breast irradiation are similar to those withradical disfiguring surgery [10,11]. At the same time, thevery high negative predictive value of breast MRI helps topredict the absence of breast cancer in the same or thecontralateral breast with a very high confidence (99.6%) andcan be used to justify a more focused therapeutic approach(eg, partial breast irradiation) or avoid prophylactic contra-lateral mastectomy [12]. It also can help convert a possibleipsilateral mastectomy into a lumpectomy in women withvery dense breasts on mammography.

In this article, we will review the utilisation of preoper-ative breast MRI and its impact on management in:

� Ipsilateral tumour mapping,� Assessment of the contralateral breast,� Patients undergoing neoadjuvant therapy, and� Preoperative assessment of residual tumour.

We will also briefly highlight the shortcomings of MRI inpreoperative imaging.

Ipsilateral Tumour Mapping

The term preoperative staging is a misleading term,because this ‘‘stage’’ is different from the stage as specifiedby the American Joint Committee on Cancer. Hence,preoperative mapping is a better term [13]. The InternationalConsensus Consortium II [14] recommends by using anoverall size of the lesion (which includes both the in situ andthe invasive components of the tumour) and a prognostic sizeof the tumour, which indicates the invasive component. Theoverall size is mapping because it pertains to local recurrencerates, and the prognostic size relates to stage and systemicrecurrence rates.

Results of studies reveal that MRI is the best method fordepicting overall size and multifocal and multicentric ipsi-lateral disease [15]. Multifocality is defined as satellite lesionslocated within the same quadrant as the index lesion, whereasmulticentric disease is defined as a separate focus of cancer

Figure 3. (A) Left breast mass; heterogeous dense breast tissue with interstitial oedema. (B) Ultrasound, showing irregular suspicious mass. (C) Magnetic

resonance image, showing a large tumour mass, with multifocal and multicentric disease. (D) Multicentric disease (pathology: invasive ductal carcinoma with

high-grade ductal carcinoma in situ).

Figure 4. (A) Palpable left inferior quadrant mass; history of radiation for gastric lymphoma that involved the left lower chest wall; dense breast tissue; no

definite abnormality. (B) Ultrasound, showing a mass with malignant morphology. (C) Magnetic resonance imaging, showing multifocal and multicentric

tumour nodules. (D) Pathology: invasive ductal carcinoma with extensive intraductal component.

209Preoperative breast MRI / Canadian Association of Radiologists Journal 63 (2012) 207e214

Figure 5. (A) Postmantle radiation, with a palpable mass seen on mammography. (B, C) Ducts distended with soft-tissue mass confirmed on biopsy to be

intermediate-grade ductal carcinoma in situ. (D) Magnetic resonance imaging, showing very minimal to no enhancement in inferior quadrant.

Figure 6. A 55-year-old womanwhowas a BRCA2mutation carrier with prior

left lumpectomy. Preoperative magnetic resonance imaging (MRI) before

prophylactic bilateral mastectomy revealed enhancing lesion in right breast

otherwise occult. MRI biopsy showed high-grade ductal carcinoma in situ.

210 S. Kulkarni et al. / Canadian Association of Radiologists Journal 63 (2012) 207e214

more than 5.0 cm away from the index lesion or tumours thatextended to another quadrant through a discontinuous growthpattern (Figure 1) [13] . Meta-analysis of 19 observationalstudies that consists of 2610 women showed additional foci ofdisease in 16%, of which 66% were malignant on histology.Incremental MRI-only detection varies between approxi-mately 1% and 28% formultifocal cancer and between 2% and15% for multicentric cancer [16], which parallels what isknown from landmark histologic studies.

The additional foci diagnosed by breast MRI have the samesize and the same histology as the cancers detected byconventional imaging. They, however, do exhibit a highernuclear grading [15] and are associated with a higher biologicaggressiveness [12]. The MRI findings of additional foci ofcancer coupled with the findings at the index lesion haveimpacted surgical therapy in women with breast cancer. Apooled study of 12 studies with more than 1908 womenshowed that MRI impacted planning in 15%-27% as improvedselection of BCT, decreased surgical procedures with tumour-free margins, and detection of contralateral cancer; 11.3% hadmore extensive surgery than initially planned; 8.1% BCTeligible converted to mastectomy for MRI only lesions; and5.5% had more extensive surgery due to false-positive find-ings on MRI [13,16]. High sensitivity of MRI also results insignificant false-positive findings, which may necessitatefurther imaging, needle biopsy, or surgical biopsy [17].

The contraindications to BCT are nipple involvement,chest-wall invasion (Figure 2), inadequate lesion to breastsize ratio, and larger than clinically evident size of mass andextensive intraductal component (EIC) of ductal carcinomain situ (DCIS) surrounding the invasive component Thesecontraindications are best assessed with MRI than otherconventional imaging techniques.

Preoperative breast MRI has been particularly useful inthe following subgroup of women:

� Women with heterogeneously dense breast tissue(Figure 3).

� Women with EIC of DCIS surrounding the invasivecomponent, seen in 30%-40% of all invasive breastcarcinomas. EIC occult to conventional imaging isa frequently encountered problem is women with invasiveductal carcinoma and DCIS, and is the most importanttreatment-related risk factor for recurrent disease. Thesepatients will need a second surgical procedure; a consid-erable number of these patients end up requiringmastectomies [18]. High-resolution, high-contrast breastMRI accurately depicts DCIS and better demonstrates theextent of disease than mammography (Figure 4). Thereported sensitivity of MRI for DCIS has ranged from77%-96% [19]. False underestimation may occur in

Figure 7. A 46-year-old woman, left biopsy-proven multifocal invasive ductal

carcinoma (IDC). Magnetic resonance imaging (MRI), showing enhancing

lesion in the right breast, which was localized under MRI guidance;

pathology: 0.6-cm IDC surrounded by 2.5-cm DCIS.

211Preoperative breast MRI / Canadian Association of Radiologists Journal 63 (2012) 207e214

a non-high-grade noncomedo type of DCIS, and over-estimation may occur due to benign proliferativepathology (Figure 5) [20].

� Women with the notoriously difficult to image invasivelobular carcinoma (ILC). Studies show that additionalipsilateral lesions were noted in 32% of cases only withMRI and an additional 7% showed contralateral lesions.Surgical management changed in 28%, of which 88%were found necessary based on pathology. Preoperativebreast MRI in women with ILC would reduce BCTfailure and re-excisions [21].

� High-risk women with breast cancer are likely to benefitfrom staging MRI because the rate of multifocal andmulticentric disease is as high as 45%-50% [22].

Figure 8. (A) A 51-year-old woman with right biopsy-proven invasive ductal carc

IDC.

� Younger women with lesion with irregular margins onmammography and a size discrepancy of 10 mm betweenmammography and ultrasonography have added utility ofpreoperative MRI [23].

� Women selected for accelerated partial-breast irradiation(APBI) and intraoperative radiation therapy (IORT).Traditionally, when a separate cancer, occult to conven-tional imaging, is present in the same breast (multicentricfocus), BCT would involve excision of the index lesion,with clear margins that leave behind the undetectedmulticentric focus, which would be taken care of by thewhole breast irradiation (WBI). Over the past severalyears, there has been growing interest in the use of APBIand IORT as an alternative to WBI. APBI and IORT offerdecreased overall treatment time and may allowa decrease in the radiation dose delivered to uninvolvedportions of the breast and adjacent organs [24]. Detectionof additional foci of disease is of critical importance inpatients selected for APBI and IORT because thesemulticentric foci do not get irradiated.

Contralateral Breast Cancer

Women with diagnosed unilateral breast cancer havea 5 times higher risk of developing contralateral synchronousor metachronous breast cancer than the general population[25]. Numerous risk factors have been implicated fordevelopment of bilateral breast cancer: nulliparity; youngerage at first breast carcinoma; lobular histology; and multi-centricity of first carcinoma and family history, that is,women with a first-degree relative with early age onset breastcarcinoma and BRCA mutations (40 times more risk at10 years) (Figure 6) [26] have a higher risk of developingbilateral breast cancer. In addition, young women treatedwith irradiation for postpartum mastitis, Hodgkin disease,and tuberculosis also are at an increased risk.

The prevalence of synchronous cancer is 1%-3% and thatof metachronous cancer is 5%-7%. MRI detects synchronous,contralateral breast cancer that is not detected clinically or

inoma (IDC). (B) Left enhancing lesion; magnetic resonance imaging biopsy,

Figure 10. Excision for invasive ductal carcinoma referred for magnetic

resonance imaging after pathology reports of positive surgical margins;

residual tumour was seen around surgical cavity, with extension into the

nipple.

Figure 9. (A) Biopsy-proven invasive ductal carcinoma: Preneoadjuvant therapy. (B) After neoadjuvant therapy, showing shrinkage of mass with residual

tumour tissue (partial response).

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with mammography in 1%-18% of newly affected women(Figure 7). The ACRIN (American College of RadiologyImaging Network) trial 6667 found that MRI detected mam-mographically and clinically occult cancers in the contralat-eral breast with a sensitivity of 91% and a specificity of 88%.The negative predictive value of MRI was 99% [27]. Thehistology for the contralateral malignancies is DCIS inapproximately 35% and invasive cancer in 65% [28]. Earlydetection of in situ or node-negative invasive disease in thecontralateral breast can lead to simultaneous treatment ofsynchronous cancers rather than multiple treatments onseparate occasions (Figure 8).

Monitoring Preoperative Neoadjuvant Treatment

Systemic chemotherapy is known to improve survivalfor patients with invasive breast cancer and is consideredthe standard of care for patients who are node positive withlarge primary tumours and for many patients with high-risk,node-negative disease. A number of trials have comparedpreoperative chemotherapy with postoperative chemotherapy.Although, there was no difference in disease-free survival andoverall survival, more women who received preoperativechemotherapy were able to undergo breast conservation.These findings have led to the increased use of preoperative orneoadjuvant chemotherapy. The National Surgical AdjuvantBreast and Bowel Project B-18 and other studies havedemonstrated that response of the primary tumour to treat-ment, as measured clinically or by histopathology, is associ-ated with both disease-free and overall survival. Thus,preoperative chemotherapy allows the opportunity to monitorthe primary tumour response.

MRI in women on neoadjuvant treatment is used for theinitial determination of extent of disease for proper staging,early identification of poor responders, and identificationof the presence, and accurately demonstrates the extent ofresidual disease before definitive surgery. MRI is more reli-able than the conventional methods in the assessment oftumour size and vascularity changes during and afterchemotherapy. The addition of advanced imaging techniques,

such as magnetic resonance spectroscopy, to further charac-terize tumour cellularity, and metabolic features appearspromising (Figure 9) [29].

Preoperative MRI Before Re-excision

Residual tumour after excisional biopsy has been reportedin 32%-63% of cases of breast cancer. The sensitivity,specificity, and accuracy of MRI in showing the presence andextent of residual disease is 61.2%, 69.7%, and 64.6%,respectively [30]. MRI before re-excision can detect addi-tional foci of multifocal or multicentric and contralateraltumour occult to conventional imaging, which, if detected,could change surgical management provided histologiccorelation can be established (Figure 10).

Figure 11. (A) A 45-year-old woman with an axillary mass, which was biopsied and revealed invasive ductal carcinoma (IDC). (B) Magnetic resonance

imaging (MRI), showing a second lesion, which underwent MRI wire localization. Pathology, 0.8-cm IDC surrounded by 4.5-cm ductal carcinoma in situ (not

seen on MRI); the patient had completion mastectomy.

213Preoperative breast MRI / Canadian Association of Radiologists Journal 63 (2012) 207e214

Because MRI usually is performed weeks after the initialexcisional biopsy, differentiating contrast enhancement dueto residual cancer from postsurgical inflammatory change isdifficult. Benign postoperative enhancement usually is thinand rim-like around the seroma cavity. Any enhancementthat appears nodular or irregular would need additionalworkup. The time interval between lumpectomy and MRIinfluences the specificity of MRI, with the greatest specificityof 75% being achieved when MRI is performed between28 and 35 postoperative days [31].

Conclusion

In summarizing the available data, in comparison withconventional imaging, breast MRI increases the detection oftumour foci in addition to the known index lesion within theipsilateral breast and synchronous tumour in the contralateralbreast, which has significant impact on surgical planning,particularly in the specific subgroups of women previouslydescribed. With such a high-detection rate comes thecontroversy of the high number of false positives, which maylead to overtreatment. Results of studies show that additionof MRI to preoperative workup causes more-extensivesurgery, additional utilisation of resources, and delay insurgery, with no impact in overall survival benefit (Figure 11)[32]. The recently published COMICE (Comparative Effec-tiveness of MRI in Breast Cancer) trial negates the impact ofMRI on the re-excision rates in women with preoperativeMRI compared with those with no preoperative MRI [33].However, this study commenced during the time when therewas an absence of accurate MRI-guided interventions. Theircases had extremely wide surgical margins, and the impact ofMRI in such cases may not be significant. However, ininstitutes where surgical techniques aim at removal ofsmaller resection volumes, the impact of MRI can besignificant in reducing re-operation rates [34].

Despite the lack of randomized trials to show survivalbenefit or improved surgical outcome (re-excision andrecurrence rates) and the additional workup of false posi-tives, MRI is a modality of significant clinical impact, which

leads us to the exciting era of APBR and IORT. MRI hasbeen shown to reduce the positive margin rate in women withILCs without increasing mastectomy rates [34]. The highstaging accuracy of breast MRI makes it an attractive methodfor assessing tumour distribution and for measuring responseto preoperative chemotherapy. In centres with expertise inMRI interpretation and intervention, it can be a phenomenaladjunctive tool for patient care. The high negative predictivevalue of MRI might reduce the number of unnecessarymastectomies and allay patient anxiety. Preoperative MRIshould be interpreted by taking into account clinical breastexamination, mammography, and sonography, and does notreplace a good traditional workup of lesions. All findings thatwould impact surgical planning should be worked up andverified with image-guided biopsy, and this would potentiallyreduce the chances of overtreatment due to MRI-only find-ings [35]. Centres that run a breast MRI program shouldensure proper equipment and imaging technique, and providetraining necessary to achieve high-quality breast MRI, andshould have the ability to perform MRI-guided biopsy orneedle localization for MRI only detected lesions. Allworkups should be completed within a time frame ofa maximum 1 month to avoid surgical delay.

As radiologists, our job is to give maximum informationwith appropriate workup. Women newly diagnosed withbreast cancer should always be informed of the potential risksand benefits of preoperative MRI. The MRI-only lesionscannot be ignored. Evolving understanding of these subclin-ical MRI-only lesions and improvement of MRI interventionwill pave the way for MRI-guided lumpectomies, whichallows breast conservation. A multidisciplinary approachshould be instituted to address any changes in managementthat result from preoperative MRI, thus providing appropriatecare and allaying women’s and their physicians’ anxietiesregarding overtreatment of women with breast cancer.

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