Contrast-enhanced MRI in breast cancer patients eligible for breast-conserving therapy: complementary value for subgroups of patients

The Value of Patient and Tumor Factors in Predicting Preoperative Breast MRI Outcomes

Purpose

To identify patient and tumor features that predict true-positive, false-positive, and negative breast preoperative MRI outcomes.

Materials and Methods

Using a breast MRI database from a large regional cancer center, the authors retrospectively identified all women with unilateral breast cancer who underwent preoperative MRI from January 2005 to February 2015. A total of 1396 women with complete data were included. Patient features (ie, age, breast density) and index tumor features (ie, type, grade, hormone receptor, human epidermal growth factor receptor type 2/neu, Ki-67) were extracted and compared with preoperative MRI outcomes (ie, true positive, false positive, negative) using univariate (ie, Fisher exact) and multivariate machine learning approaches (ie, least absolute shrinkage and selection operator, AutoPrognosis). Overall prediction performance was summarized using the area under the receiver operating characteristic curve (AUC), calculated using internal validation techniques (bootstrap and cross-validation) to account for model training.

Results

At the examination level, 181 additional cancers were identified among 1396 total preoperative MRI examinations (median patient age, 56 years; range, 25-94 years), resulting in a positive predictive value for biopsy of 43% (181 true-positive findings of 419 core-needle biopsies). In univariate analysis, no patient or tumor feature was associated with a true-positive outcome (P > .05), although greater mammographic density (P = .022) and younger age (< 50 years, P = .025) were associated with false-positive examinations. Machine learning approaches provided weak performance for predicting true-positive, false-positive, and negative examinations (AUC range, 0.50-0.57).

Conclusion

Commonly used patient and tumor factors driving expert opinion for the use of preoperative MRI provide limited predictive value for determining preoperative MRI outcomes in women. Supplemental material is available for this article. © RSNA, 2020See also the commentary by Grimm in this issue.

System for image-guided resection of nonpalpable breast lesions: Proof of concept

PURPOSE

In breast-conserving surgery (BCS), the cancer is sometimes incompletely excised, leading to reduced patient survival. To pursue complete excisions, radioactive seed localization (RSL) may be used to insert an iodine-125 seed into the tumor. The seed is used as a marker for the location of the tumor during surgery. RSL does not, however, show the extent of the tumor. Based on RSL, we pursue to visualize the seed location together with the extent from diagnostic images.

METHODS

A system with two gamma-camera heads and two parallel-hole collimators was recently proposed to triangulate the location of an iodine-125 seed during BCS. In the present study, this system was extended with a range camera to visualize a sphere centered on the seed in relation to the breast. This sphere contains the entire tumor and thus defines the target volume for BCS. Physical experiments with acrylic block phantoms (thickness ranging from 3.5 to 6.5 cm) were performed to assess the absolute bias and the precision with which this sphere can be visualized.

RESULTS

When a 6.5 cm thick phantom was used, along the horizontal plane, the target volume was visualized with an absolute bias and a precision of 2.1 and 0.8 mm, respectively. Along the vertical axis (i.e., z-axis), these values were 4.2 and 2.8 mm, respectively.

CONCLUSIONS

The proposed system visualizes the target volume with an absolute bias that may be acceptable for BCS.

Impact of Preoperative Breast MR Imaging and MR-guided Surgery on Diagnosis and Surgical Outcome of Women with Invasive Breast Cancer with and without DCIS Component

Purpose To (a) compare the diagnostic accuracy of breast magnetic resonance (MR) imaging with that of conventional imaging (digital mammography and breast ultrasonography) in the identification of ductal carcinoma in situ (DCIS) components of biopsy-proven invasive breast cancer before surgery and (b) investigate the surgical outcome (positive margin rates and mastectomy rates) of women with breast cancer who underwent preoperative MR imaging combined with MR-guided needle biopsy and/or MR-guided lesion localization or bracketing where appropriate. Materials and Methods The authors performed a prospective two-center study of 593 consecutive patients with biopsy-proven invasive breast cancer who underwent breast MR imaging in addition to conventional imaging. MR-guided vacuum biopsy and MR-guided lesion bracketing were performed for DCIS components visible at MR imaging alone. The accuracy of breast MR imaging was compared with that of conventional imaging, and surgical outcomes (positive margin and mastectomy rates) were investigated. Results Surgical-pathologic assessment demonstrated DCIS components in 139 of the 593 women (23.4%). The sensitivity of MR imaging for the diagnosis of DCIS components pre-operatively (84.9%; 118 of 139) was significantly higher than that of conventional imaging (36.7%; 51 of 139) (P < .0001); more than half of DCIS components (51.1%; 71 of 139) were detected only with MR imaging. The sensitivity advantage of MR imaging over conventional imaging increased with increasing relative size of DCIS components, as follows: The sensitivity of MR imaging versus conventional imaging for small, marginal DCIS components was 56.8% (21 of 37) versus 29.7% (11 of 37); the sensitivity for extensive DCIS components was 91.7% (55 of 60) versus 41.7% (25 of 60); the sensitivity for large, predominant DCIS components was 100.0% (42 of 42) versus 35.7% (15 of 42). Moreover, the sensitivity advantage of MR imaging over conventional imaging increased with increasing nuclear grade of DCIS components, as follows: The sensitivity of MR imaging versus conventional imaging for low-grade DCIS components was 74.0% (20 of 27) versus 40.7% (11 of 27); the sensitivity for intermediate-grade DCIS components was 84.1% (53 of 63) versus 34.9% (22 of 63); the sensitivity for high-grade DCIS components was 91.8% (45 of 49) versus 36.7% (18 of 49) (P < .05-.001 for all). Positive margin rates were low overall (3.7% [95% Clopper Pearson confidence interval [CI]: 2.3%, 5.6%]) and did not differ significantly between the 139 women with DCIS components (5.0% [95% CI: 2.0%, 10.1%]) compared with the 454 women without such components (3.3% [95% CI: 1.9%, 5.4%]). The same was true for mastectomy rates (10.8% [95% CI: 6.2%, 17.2%] vs 8.1% [95% CI: 5.8%, 11.1%]). Conclusion Breast MR imaging improves depiction of DCIS components of invasive breast cancers before surgery and is associated with positive margin and mastectomy rates that are low irrespective of the presence or absence of DCIS components. ^© RSNA, 2017.

Role of magnetic resonance imaging in the planning of breast cancer treatment strategies: comparison with conventional imaging techniques

OBJECTIVE

To assess the role of magnetic resonance imaging (MRI) in the planning of breast cancer treatment strategies.

MATERIALS AND METHODS

The study included 160 women diagnosed with breast cancer, who underwent breast MRI for preoperative staging. Using Pearson's correlation coefficient (r), we compared the size of the primary tumor, as determined by MRI, by conventional imaging (mammography and ultrasound), and in the pathological examination (gold standard). The identification of lesions not identified in previous examinations was also evaluated, as was its influence on treatment planning.

RESULTS

The mean age of the patients was 52.2 years (range, 30-81 years), and the most common histological type was invasive ductal carcinoma (in 60.6% of the patients). In terms of the tumor size determined, MRI correlated better with the pathological examination than did mammography (r = 0.872 vs. 0.710) or ultrasound (r = 0.836 vs. 0.704). MRI identified additional lesions in 53 patients (33.1%), including malignant lesions in 20 (12.5%), which led to change in the therapeutic planning in 23 patients (14.4%).

CONCLUSION

Breast MRI proved to be more accurate than conventional imaging in determining the dimensions of the main tumor and was able to identify lesions not identified by other methods evaluated, which altered the therapeutic planning in a significant proportion of cases.

The role of preoperative breast magnetic resonance (MR) imaging for surgical decision in patients with triple-negative breast cancer

BACKGROUND

Several reliable randomized studies do not recommend routine preoperative breast MR imaging for patients with breast cancer. However, because the principle of MR imaging is based on the dynamics of contrast enhancement, a specific biologic subgroup of tumors should sensitively respond to the imaging process.

METHODS

From 2008 to 2013, 918 eligible patients with breast cancer underwent breast surgery and were divided into two groups based on preoperative breast MR findings: patients in whom the surgical plan was changed and those in whom the surgical plan remained unchanged. We investigated the changing patterns of breast surgery based on routine mammography, ultrasound, and preoperative breast magnetic resonance (MR) findings and analyzed the association between additional suspicious lesions on breast MR imaging and clinicopathologic factors.

RESULTS

Additional suspicious breast lesions were detected on preoperative MR imaging in 104 cases (11.3%), and the surgical strategy was changed as the final decision in 97 cases (10.6%). There was no difference between oncologic results between two groups. However, the triple-negative breast cancer (TNBC) was significantly associated with changing of the surgical strategy based on breast MR findings (P = 0.048).

CONCLUSIONS

Additional preoperative breast MR imaging may be helpful in surgical decision for patients with TNBC.

Dual-head gamma camera system for intraoperative localization of radioactive seeds

Breast-conserving surgery is a standard option for the treatment of patients with early-stage breast cancer. This form of surgery may result in incomplete excision of the tumor. Iodine-125 labeled titanium seeds are currently used in clinical practice to reduce the number of incomplete excisions. It seems likely that the number of incomplete excisions can be reduced even further if intraoperative information about the location of the radioactive seed is combined with preoperative information about the extent of the tumor. This can be combined if the location of the radioactive seed is established in a world coordinate system that can be linked to the (preoperative) image coordinate system. With this in mind, we propose a radioactive seed localization system which is composed of two static ceiling-suspended gamma camera heads and two parallel-hole collimators. Physical experiments and computer simulations which mimic realistic clinical situations were performed to estimate the localization accuracy (defined as trueness and precision) of the proposed system with respect to collimator-source distance (ranging between 50 cm and 100 cm) and imaging time (ranging between 1 s and 10 s). The goal of the study was to determine whether or not a trueness of 5 mm can be achieved if a collimator-source distance of 50 cm and imaging time of 5 s are used (these specifications were defined by a group of dedicated breast cancer surgeons). The results from the experiments indicate that the location of the radioactive seed can be established with an accuracy of 1.6 mm  ±  0.6 mm if a collimator-source distance of 50 cm and imaging time of 5 s are used (these experiments were performed with a 4.5 cm thick block phantom). Furthermore, the results from the simulations indicate that a trueness of 3.2 mm or less can be achieved if a collimator-source distance of 50 cm and imaging time of 5 s are used (this trueness was achieved for all 14 breast phantoms which were used in this study). Based on these results we conclude that the proposed system can be a valuable tool for (real-time) intraoperative breast cancer localization.

[Therapy monitoring of neoadjuvant therapy with MRI. RECIST and functional imaging]

CLINICAL/METHODICAL ISSUE

Neoadjuvant chemotherapy is increasingly being applied in patients with operable breast cancer. Thus, an early prediction of response to neoadjuvant chemotherapy is of high relevance.

STANDARD RADIOLOGICAL METHODS

The interobserver variability of clinical examination, mammography and ultrasonography in the assessment of response to neoadjuvant chemotherapy is high.

METHODICAL INNOVATIONS

Magnetic resonance imaging (MRI) allows the assessment of functional parameters in addition to changes in tumor size and morphology.

PERFORMANCE

A reliable therapy response monitoring aims at optimizing individualized patient care.

ACHIEVEMENTS

This paper summarizes current guidelines for the assessment of response to neoadjuvant chemotherapy in breast cancer according to the response evaluation criteria in solid tumors (RECIST). Furthermore, the technical principles of MRI-based therapy monitoring are described and an overview of the clinical studies that have assessed the feasibility of functional MRI in response to treatment evaluation is given.

PRACTICAL RECOMMENDATIONS

The technology of functional MRI offers promising results concerning therapy response monitoring. However, the level of evidence is not sufficiently evaluated for the technologies of functional MRI presented here.

Current clinical indications for magnetic resonance imaging of the breast

MRI is increasingly used in breast cancer patients. MRI has a high sensitivity compared to mammography and ultrasound. The specificity is moderate leading to an increased risk of false positive findings. Currently, a beneficial effect of breast MRI has been established in some patient groups and is debated in the general breast cancer population. The diagnostic ability of MRI and its role in various groups of breast cancer patients are discussed in this review.

Advanced diagnostic breast cancer imaging: variation and patterns of care in Washington state

INTRODUCTION

Because receipt of breast imaging likely occurs in nonrandom patterns, selection bias is an important issue in studies that attempt to elucidate associations between imaging and breast cancer outcomes. The purpose of this study was to analyze use of advanced diagnostic imaging in a cohort of patients with breast cancer insured by commercial, managed care, and public health plans by demographic, health insurance, and clinical variables from 2002 to 2009.

METHODS

We identified women with breast cancer diagnoses from a Surveillance Epidemiology and End Results (SEER) registry whose data could be linked to claims from participating health plans. We examined imaging that occurred between cancer diagnosis and initiation of treatment and classified patients according to receipt of (1) mammography or ultrasound only; (2) breast magnetic resonance imaging (MRI); and (3) other advanced imaging (computed tomography [CT] of the chest, abdoment, and pelvis; positron emission tomography [PET]; or PET-CT). We used logistic regression to identify factors associated with receipt of breast MRI as well as other advanced imaging.

RESULTS

Commercial health plan, younger age, and later year of diagnosis were strongly associated with receipt of breast MRI and other advanced imaging. Women with prescription drug plans and those who had less comorbidities were more likely to have received breast MRI.

CONCLUSION

Use of breast MRI and other advanced imaging is increasing among patients newly diagnosed with breast cancer; individual patient and insurance-related factors are associated with receipt of these imaging tests. Whether use of diagnostic advanced imaging affects outcomes such as re-excision, cancer recurrence, mortality rates, and costs of breast cancer treatment remains to be determined.

How to measure breast cancer tumoral size at MR imaging?

OBJECTIVE

To compare the accuracy of different MR sequences to measure tumor size.

METHODS

Eighty-six women (mean age: 53 years (30-78)) who underwent preoperative MRI for breast cancer were included. Maximal diameters of the index tumor (IT) and of the whole extent of the tumor (WET) were measured on T2-weighted (T2W) sequences, on dynamic contrast-enhanced (DCE) T1-weighted (T1W) sequences and on Maximal Intensity Projection (MIP) reconstructions. Agreements with pathological size were evaluated using concordance correlation coefficient (k).

RESULTS

Median pathological size of IT was 20mm (13-25 mm, interquartile range). Median pathological size of the WET was 29 mm (16-50mm, interquartile range). Measurement of IT showed a good concordance with pathological size, with best results using T2W (k = 0.690) compared to MIP (k = 0.667), early-subtracted DCE frame (k = 0.630) and early-native DCE frame (k = 0.588). IT was visible on T2W in 83.7% and accurately measured within 5mm in 69.9%. Measurement of WET was superior using early-subtracted DCE frame (k = 0.642) compared to late-native frame (k = 0.635), early-native frame (k = 0.631), late-subtracted frame (k = 0.620) and MIP (k = 0.565). However, even using early-subtracted frame, WET was accurately measured within 5mm only 39.3%.

CONCLUSION

If visible, IT size is best measured on T2W with a good accuracy (69%) whereas WET is best estimated on early-subtracted DCE frame. However, when adjacent additional sites exist around IT, suspected surrounding disease components need to be proved by pathological analysis.

Preoperative breast MRI can reduce the rate of tumor-positive resection margins and reoperations in patients undergoing breast-conserving surgery

OBJECTIVE

In breast cancer patients eligible for breast-conserving surgery, we evaluated whether the information provided by preoperative MRI of the breast would result in fewer tumor-positive resection margins and fewer reoperations.

SUBJECTS AND METHODS

The study group consisted of 123 consecutive patients diagnosed with either breast cancer or ductal carcinoma in situ eligible for breast-conserving surgery between April 2007 and July 2010. For these patients, a first plan for breast-conserving surgery was made on the basis of clinical examination and conventional imaging. The final surgical plan was made with knowledge of the preoperative breast MRI. The rates of tumor-positive resection margins and reoperations were compared with those of a historical control group consisting of 119 patients who underwent 123 breast-conserving procedures between January 2005 and December 2006. The percentage of change in the surgical plan was recorded.

RESULTS

Preoperative breast MRI changed the surgical plan to more extensive surgery in 42 patients (34.1%), mainly to mastectomy (29 patients, 23.6%). Ninety-four patients underwent 95 breast-conserving procedures. Significantly fewer patients had tumor-positive resection margins than in the control group (15.8%, 15/95 versus 29.3%, 36/123; p < 0.01). Patients in the study group underwent significantly fewer reoperations compared with the historical control group (18.9%, 18/95 vs 37.4%, 46/123; p < 0.01).

CONCLUSION

Preoperative breast MRI can substantially decrease the rate of tumor-positive resection margins and reoperations in breast cancer patients eligible for breast-conserving surgery.

MR-guided high-intensity focused ultrasound ablation of breast cancer with a dedicated breast platform

Optimizing the treatment of breast cancer remains a major topic of interest. In current clinical practice, breast-conserving therapy is the standard of care for patients with localized breast cancer. Technological developments have fueled interest in less invasive breast cancer treatment. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a completely noninvasive ablation technique. Focused beams of ultrasound are used for ablation of the target lesion without disrupting the skin and subcutaneous tissues in the beam path. MRI is an excellent imaging method for tumor targeting, treatment monitoring, and evaluation of treatment results. The combination of HIFU and MR imaging offers an opportunity for image-guided ablation of breast cancer. Previous studies of MR-HIFU in breast cancer patients reported a limited efficacy, which hampered the clinical translation of this technique. These prior studies were performed without an MR-HIFU system specifically developed for breast cancer treatment. In this article, a novel and dedicated MR-HIFU breast platform is presented. This system has been designed for safe and effective MR-HIFU ablation of breast cancer. Furthermore, both clinical and technical challenges are discussed, which have to be solved before MR-HIFU ablation of breast cancer can be implemented in routine clinical practice.

Has partial breast irradiation by IORT or brachytherapy been prematurely introduced into the clinic?

In contrast to most new oncology treatments, wide clinical introduction of partial breast irradiation (PBI) is not based on level A trial evidence. Despite promising phase I/II data, new reports based upon large cohorts of patients mention more recurrences and/or complications from PBI compared with whole breast irradiation (WBI), necessitating more careful selection of patients for PBI while awaiting long term results of major clinical trials. In an attempt to improve this we give preoperative PBI within a prospective trial.

[Using magnetic resonance imaging for staging can change the therapeutic management in patients with breast cancer]

OBJECTIVE

To compare two series of patients with breast cancer, one staged using preoperative MRI and the other staged using conventional techniques, analyzing the changes to treatment, the number of mastectomies, and the number of reinterventions due to involvement of the margins.

MATERIAL AND METHODS

We reviewed 600 patients divided into 300 patients with preoperative MRI (series 1) and 300 without preoperative MRI (series 2). We recorded the following variables: age, menopausal status, tumor size on pathological examination, multiplicity and bilaterality, surgical treatment and type of treatment, the administration of neoadjuvant chemotherapy, and reintervention for involved margins. We used Student's t-test and the chi-square test to compare the variables between the two series.

RESULTS

The mean age of patients in the two series was similar (51.5 and 51.8 years, P=0.71). The mean size of the tumor was smaller in series 1 (16.9 mm vs 22.3 mm) (P<.001). More multiple tumors were detected in series 1 (28.7 vs 15.7%) (P<.001). The rate of mastectomies was lower in series 1 (25 vs 48%) (P<.001). Oncoplastic and bilateral surgeries were performed only in series 1. Neoadjuvant chemotherapy was administered more often in series 1 (30.7 vs 9.3%) (P<.001). The difference in the number of reinterventions for involved margins did not reach significance (7.2% in series 1 vs 3.2% in series 2) (P=.095).

CONCLUSION

When MRI was used for staging, neoadjuvant chemotherapy and oncoplastic surgery were used more often and the mastectomy rate decreased. Despite the increase in conservative surgery in patients staged with MRI, the number of reinterventions for involved margins did not increase, although there was a trend towards significance.

Yield of Selective Magnetic Resonance Imaging in Preoperative Workup of Newly Diagnosed Breast Cancer Patients Planned for Breast Conserving Surgery

The role of routine preoperative magnetic resonance imaging (MRI) in newly diagnosed breast cancer patients planned for breast conserving surgery is presently being debated. In our medical center we practice selective use of preoperative MRI; we sought to examine the yield of MRI in this highly selected group of patients. A retrospective study of all newly diagnosed breast cancer patients presenting between January 2007 and July 2010 to the Tel Aviv Sourasky Medical Center (Tel Aviv, Israel) was completed. Patients planned for breast conserving surgery who underwent preoperative MRI were included in this study. Patients and tumor characteristics, indication for MRI, findings on MRI, consequent workup, and impact on surgical treatment were recorded. Association between preoperative characteristics and yield of MRI was examined. During the study period, 105 patients that were candidates for breast conserving surgery underwent pre-operative evaluation with MRI. Use of breast MRI increased over time. Rates of mastectomy were stable throughout the study years. Dense mammogram was the most frequent (51, 68%) indication for MRI. Additional suspicious findings were found in 41 (39%) patients, prompting further workup including 36 biopsies in 25 patients, of which 22 (61%) were with cancer. These additional findings prompted a change in the surgical plan in a third of the patients. In most patients (92; 88%) clear margins were achieved. Limiting the use of MRI in the preoperative workup of breast cancer patients to a selected group of patients can increase the yield of MRI.

Preoperative breast magnetic resonance imaging: applications in clinical practice

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 single and resectable tumour as determined by clinical examination and conventional imaging followed by postoperative irradiation is the standard of care in early breast cancer. Mapping of local disease is the key element to guide optimal surgery to obtain tumour-free margins, thereby decreasing risk of local recurrence. The usual preoperative workup of breast malignancy consists of clinical breast examination and mammography with or without ultrasound. However, mammography and ultrasound fail to accurately assess tumour extent in as many as a third of patients eligible for breast conserving therapy. It is well established that magnetic resonance imaging is far superior to mammography (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." This article discusses the current role of breast magnetic resonance imaging with its clinical advantages and applications.

Disease Extent ≥4 cm Is a Prognostic Marker of Local Recurrence in T1-2 Breast Cancer

Despite improvements of the therapy for breast cancer, a proportion of the patients still get local recurrence. The status of the surgical margins is the most often used parameter for decision regarding additional treatment. However, a negative margin is not a guarantee that there is not residual cancer left in the breast; additional parameters are needed to better predict the risk of local recurrence. The disease extent was evaluated in the surgical specimen from 313 women after breast-conserving therapy using large-section histology and was correlated to the incidence of local recurrence. A disease extent ≥4 cm was shown to be an independent marker for local recurrence; the cumulative 10-year local relapse rate for the group with a disease extent ≥4 cm was 20.5%, and for the rest 6.7%. We conclude that disease extent ≥4 cm seems to be an important factor when evaluating the risk for local recurrence.

Precise correlation between MRI and histopathology - exploring treatment margins for MRI-guided localized breast cancer therapy

BACKGROUND

Magnetic resonance imaging (MRI) is more often considered to guide, evaluate or select patients for partial breast irradiation (PBI) or minimally invasive therapy. Safe treatment margins around the MRI-visible lesion (MRI-GTV) are needed to account for surrounding subclinical occult disease.

PURPOSE

To precisely compare MRI findings with histopathology, and to obtain detailed knowledge about type, rate, quantity and distance of occult disease around the MRI-GTV.

METHODS AND MATERIALS

Patients undergoing MRI and breast-conserving therapy were prospectively included. The wide local excision specimens were subjected to detailed microscopic examination. The size of the invasive (index) tumor was compared with the MRI-GTV. The gross tumor volume (GTV) was defined as the pre-treatment visible lesion. Subclinical tumor foci were reconstructed at various distances to the MRI-GTV.

RESULTS

Sixty-two patients (64 breasts) were included. The mean size difference between MRI-GTV and the index tumor was 1.3mm. Subclinical disease occurred in 52% and 25% of the specimens at distances ≥10mm and ≥20mm, respectively, from the MRI-GTV.

CONCLUSIONS

For MRI-guided minimally invasive therapy, typical treatment margins of 10mm around the MRI-GTV may include occult disease in 52% of patients. When surgery achieves a 10mm tumor-free margin around the MRI-GTV, radiotherapy to the tumor bed may require clinical target volume margins >10mm in up to one-fourth of the patients.

Magnetic resonance imaging of the breast: recommendations from the EUSOMA working group

The use of breast magnetic resonance imaging (MRI) is rapidly increasing. EUSOMA organised a workshop in Milan on 20-21st October 2008 to evaluate the evidence currently available on 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. This paper presents the consensus reached by this working group. General recommendations, technical requirements, methodology, and interpretation were firstly considered. For the following ten indications, an overview of the evidence, a list of recommendations, and a number of research issues were defined: staging before treatment planning; screening of high-risk women; evaluation of response to neoadjuvant chemotherapy; patients with breast augmentation or reconstruction; occult primary breast cancer; breast cancer recurrence; nipple discharge; characterisation of equivocal findings at conventional imaging; inflammatory breast cancer; and male breast. The working group strongly suggests that all breast cancer specialists cooperate for an optimal clinical use of this emerging technology and for future research, focusing on patient outcome as primary end-point.

Diagnostic breast MR imaging: current status and future directions

Breast MRI has become an integral component in breast imaging. Indications have become clearer and better defined. Guidelines and recommendations are evolving and many are recognized and published. Future applications are exciting and may possibly improve our ability to diagnose breast cancer, improving the patient's treatment options and ultimately patient outcome.

Role of magnetic resonance imaging in managing selected women with newly diagnosed breast cancer

The purpose of this study is evaluation of therapeutic impact of magnetic resonance imaging (MRI) in breast cancer patients that cannot be imaged adequately with traditional radiology: dense breasts, microcalcifications suspicious for carcinoma in situ or discordance between mammography and ultrasound. A review was performed of 493 patients' records: determination of breast MRI effect on clinical management was made for the selected 70 cases by analysing pre-MRI and post-MRI therapeutic plans. Analysis of final pathology was useful to determine if the change in surgical plan prompted by MRI was appropriate. Breast MRI added clinical information in 52.9% of patients that resulted in 44.3% of management changes that were judged as appropriate in 83.9% of cases. Breast MRI provides additional useful information, but causes more extensive surgery (40%) with no proven prognostic benefit. MRI should be considered optional in the clinical staging of breast cancer and performed in selected cases.

The impact of breast MRI on surgical decision-making: are patients at risk for mastectomy?

BACKGROUND AND OBJECTIVES

The goal of the current study was to determine whether MRI impacts multidisciplinary treatment planning and if it leads to increased mastectomy rates.

METHODS

A retrospective review was conducted of 441 patients treated for breast cancer between January 2005 and May 2008 who underwent breast MRI. Data included number of additional findings and their imaging and pathologic work-up. This was analyzed to determine impact of MRI on treatment planning.

RESULTS

Of 441 patients, 45% had > or =1 additional finding on MRI. Of 410 patients with complete records, 29% had changes in the treatment plan, including 36 patients who were initially considered for breast conservation but proceeded directly to mastectomy based on MRI findings of suspected multicentricity. Twenty-three of those patients did not have a biopsy of the MRI lesion, with 87% having unicentric disease on final pathology. Overall, the mastectomy rate was 44%, which was significantly increased compared to patients not undergoing MRI (32%, P < 0.05).

CONCLUSIONS

Breast MRI alters the treatment planning for many patients with newly diagnosed breast cancer. Mastectomy rates are increased when MRI results alone direct surgical planning. Biopsy of MRI-identified lesions should be performed to avoid over-treatment.

Obtaining adequate surgical margins in breast-conserving therapy for patients with early-stage breast cancer: current modalities and future directions

Inadequate surgical margins represent a high risk for adverse clinical outcome in breast-conserving therapy (BCT) for early-stage breast cancer. The majority of studies report positive resection margins in 20% to 40% of the patients who underwent BCT. This may result in an increased local recurrence (LR) rate or additional surgery and, consequently, adverse affects on cosmesis, psychological distress, and health costs. In the literature, various risk factors are reported to be associated with positive margin status after lumpectomy, which may allow the surgeon to distinguish those patients with a higher a priori risk for re-excision. However, most risk factors are related to tumor biology and patient characteristics, which cannot be modified as such. Therefore, efforts to reduce the number of positive margins should focus on optimizing the surgical procedure itself, because the surgeon lacks real-time intraoperative information on the presence of positive resection margins during breast-conserving surgery. This review presents the status of pre- and intraoperative modalities currently used in BCT. Furthermore, innovative intraoperative approaches, such as positron emission tomography, radioguided occult lesion localization, and near-infrared fluorescence optical imaging, are addressed, which have to prove their potential value in improving surgical outcome and reducing the need for re-excision in BCT.

The importance of preoperative breast MRI for patients newly diagnosed with breast cancer

The use of preoperative breast magnetic resonance imaging (bMRI) for patients newly diagnosed with breast cancer has been criticized for increasing the number of therapeutic mastectomies performed, as well as increasing the cost of treatment. The purpose of this report is to examine one surgeon's practice and to describe the MRI findings for patients with breast cancer to determine if those findings changed the therapeutic options for those patients in. Data were collected prospectively between August 2003 and January 2006 for patients newly diagnosed with breast cancer. Diagnoses were made by core biopsy or fine-needle aspiration; all lesions were intact at the time of MRI. Twenty-five percent of patients were found to have previously occult, but suspicious lesions on MRI that required additional diagnostic evaluation, including ultrasound, core biopsy, excisional biopsy, or any combination; for approximately half of these patients a separate cancer was confirmed. For most of these patients, the new lesion was ipsilateral and multicentric, and most required mastectomy. For the remaining 75% of patients, MRI confirmed the index lesion was the only area of concern, and appropriate surgical treatment was completed. Preoperative bMRI for patients newly diagnosed with breast cancer identified previously occult and separate tumors in 13% of patients, resulting in surgical treatment change for many.

The effect of margins on the clinical management of ductal carcinoma in situ of the breast

Complete excision is key to successful breast-conserving treatment for patients diagnosed with ductal carcinoma in situ (DCIS). Patients with extensive DCIS should be considered the choice of mastectomy (followed by reconstruction), while for smaller DCIS breast-conserving treatment should be performed by complete excision. This review reports on the effect of margins on the clinical management of patients with a diagnosis of DCIS. The role of preoperative imaging including MRI, surgical procedures, and pathology are described.

Dynamic contrast-enhanced MRI for prediction of breast cancer response to neoadjuvant chemotherapy: initial results

OBJECTIVE

The aim of this study was to establish changes in contrast-enhanced MRI of breast cancer during neoadjuvant chemotherapy that are indicative of pathology outcome.

MATERIALS AND METHODS

In 54 patients with breast cancer, dynamic contrast-enhanced MRI was performed before chemotherapy and after two chemotherapy cycles. Imaging was correlated with final histopathology. Multivariate analysis with cross-validation was performed on MRI features describing kinetics and morphology of contrast uptake in the early and late phases of enhancement. Receiver operating characteristic (ROC) analysis was used to develop a guideline that switches patients at high risk for incomplete remission to a different chemotherapy regimen while maintaining first-line therapy in 95% of patients who are not at risk (i.e., high specificity).

RESULTS

Change in largest diameter of late enhancement during chemotherapy was the single most predictive MRI characteristic for tumor response in multivariate analysis (A(z) [area under the ROC curve] = 0.73, p < 0.00001). Insufficient (< 25%) decrease in largest diameter of late enhancement during chemotherapy was most indicative of residual tumor at final pathology. Using this criterion, the fraction of unfavorable responders indicated by MRI was 41% (22/54). Approximately half (44%, 14/32) of the patients who showed favorable response at MRI achieved complete remission at pathology. Conversely, 95% (21/22) of patients who showed unfavorable response at MRI had residual tumor at pathology.

CONCLUSION

Reduction of less than 25% in largest diameter of late enhancement during neoadjuvant chemotherapy shows the potential to predict residual tumor after therapy with high specificity.

[Role of MRI in the presurgical work-up of breast cancer: appropriate utilization of MRI as a complement to mammography and ultrasound]

The role of MRI for presurgical local staging of breast cancers amenable to conservative treatment has been the subject of multiple publications and tends to become a "validated" indication in routine practice. The purpose of the paper is to review the advantages and limitations of this imaging modality that is part of a comprehensive management that must be validated by clinical data especially with regards to local recurrence and survival. Knowledge of these elements combined with more precise indications should result in improved patient management while avoiding overtreatment or unnecessary anxiety-producing examinations.

New potential and applications of contrast-enhanced ultrasound of the breast: Own investigations and review of the literature

Imaging of angiogenesis is a challenge for modern imaging. Velocimetry in malignant breast lesions and density of malignant vessels are very low. In breast imaging, first results of contrast-enhanced ultrasound (CEUS) were disappointing. Microbubbles are fragile when examined with high frequency US, commonly used in breast imaging. Second-generation contrast agents increase intensively the signal level of breast lesions and new sequences like CPS (Coherence Pulse Sequencing) might be accurate to detect malignant vessels in breast lesions for characterization, to assess the extent of infiltrative breast carcinoma or to evaluate the tumor response after chemotherapy. Another interesting clinical application is the differentiation between post-operative changes and recurrences. In this review, we detail the main results obtained with contrast ultrasonography in a characterization study. In malignant lesions, enhancement was fast, starting with less than 20s. Compared to MR, enhancement appeared faster. Malignant vessels were predominant in the external ring of the nodule, conversely vessels were seen in the center of the lesion in benign nodules. Malignant vessels were also seen outside the lesion. This knowledge could lead the surgeon to perform a larger lumpectomy in these cases, to obtain sane margins and to reduce recurrences.

Gadobenate dimeglumine as a contrast agent for dynamic breast magnetic resonance imaging: effect of higher initial enhancement thresholds on diagnostic performance

RATIONALE AND OBJECTIVE

Gadobenate dimeglumine (Gd-BOPTA), a high-relaxivity contrast agent, has been recently proposed for dynamic MR imaging of the breast. The objective of this study was to optimize the diagnostic performance of Gd-BOPTA-enhanced dynamic breast MR imaging by using adjusted initial enhancement thresholds.

METHODS

Thirty-four patients with 36 breast lesions (malignant/benign = 28/8) underwent dynamic breast MRI with 0.1 mmol/kg Gd-BOPTA and 120-second time resolution. A score system based on shape (round/oval/lobular = 0; linear/dendritic/stellate = 1), margins (defined = 0; undefined = 1), pattern (homogeneous = 0; inhomogeneous = 1; rim = 2), kinetics (continuous = 0; plateau = 1; washout = 2), and initial enhancement was used. Initial enhancement was determined with standard (<50% = 0; 50%-100% = 1; >100% = 2) and adjusted (<100% = 0; 100%-240% = 1; >240% = 2) thresholds. Scores of 0 to 3 indicated benign lesions and scores of 4 to 8 malignant lesions. Diagnostic performance was assessed in terms of sensitivity, specificity, positive and negative predictive values, and overall accuracy.

RESULTS

The initial enhancement was >100% for 26 malignant and 7 benign lesions and >240% for 16 and 1 lesions, respectively. The overall score was 5.89 +/- 1.34 with standard thresholds and 5.50 +/- 1.53 with adjusted thresholds (P = 0.003) for cancers, 4.00 +/- 1.93 and 3.25 +/- 1.75 (P = 0.028) for benign lesions, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy was 96%, 13%, 79%, 50%, and 78%, respectively, with standard thresholds and 96%, 75%, 93%, 86%, and 92%, respectively, with adjusted thresholds. A ductal carcinoma in situ was false negative whereas a fat necrosis and a papilloma were false positive with both thresholds. Three fibroadenomas, 1 adenosis, and 1 fibrosis were false positive with standard thresholds but true negatives with adjusted thresholds.

CONCLUSIONS

Lesion characterization with Gd-BOPTA requires higher thresholds for initial enhancement than those used with conventional Gd-chelates, leading to improved specificity, predictive values, and accuracy.

Diagnostic Breast MR Imaging: Current Status and Future Directions

Breast MRI has become an integral component in breast imaging. Indications have become clearer and better defined. Guidelines and recommendations are evolving and many are recognized and published. Future applications are exciting and may possibly improve our ability to diagnose breast cancer, improving the patient's treatment options and ultimately patient outcome.

[Indications of MRI in the initial local staging of early-stage breast cancer]

MR Imaging is the most sensitive technique for detecting breast cancer. In patients with breast cancer, the additional value of MRI is validated in patients candidates for a breast-conserving surgery and when: cancer is occult, size evaluation is difficult at standard imaging, parietal involvement is suspected, and before neoadjuvant chemotherapy. In fatty breasts, MRI is not routinely recommended, because of same performances as in standard imaging. In dense breasts, MRI becomes significantly more sensitive than mammography for detecting multifocality and multicentricity with a positive predictive value of 60% for detected additional foci. Thus, a decision of mastectomy should not be made solely on the basis of MRI and may require additional tissue sampling of areas of concern identified by breast MRI. The additional value of breast MRI is particularly useful in patients with dense breasts and high risk factors for local recurrence: young age (< 40 years), familial high risk, or because of a high-grade invasive cancer greater than 2 cm in size. Performing breast MRI in such patients underlies requirements: an expert breast imaging team, optimal MRI protocols, and radiologists working in concert with the multidisciplinary treatment team.