A Clinical Oncologic Perspective on Breast Magnetic Resonance Imaging

Relationship between preoperative breast MRI and surgical treatment of non-metastatic breast cancer

BACKGROUND AND OBJECTIVES

More extensive surgical treatments for early stage breast cancer are increasing. The patterns of preoperative MRI overall and by stage for this trend has not been well established.

METHODS

Using Breast Cancer Surveillance Consortium registry data from 2010 through 2014, we identified women with an incident non-metastatic breast cancer and determined use of preoperative MRI and initial surgical treatment (mastectomy, with or without contralateral prophylactic mastectomy (CPM), reconstruction, and breast conserving surgery ± radiation). Clinical and sociodemographic covariates were included in multivariable logistic regression models to estimate adjusted odds ratios and 95% confidence intervals.

RESULTS

Of the 13 097 women, 2217 (16.9%) had a preoperative MRI. Among the women with MRI, results indicated 32% higher odds of unilateral mastectomy compared to breast conserving surgery and of mastectomy with CPM compared to unilateral mastectomy. Women with preoperative MRI also had 56% higher odds of reconstruction.

CONCLUSION

Preoperative MRI in women with DCIS and early stage invasive breast cancer is associated with more frequent mastectomy, CPM, and reconstruction surgical treatment. Use of more extensive surgical treatment and reconstruction among women with DCIS and early stage invasive cancer whom undergo MRI warrants further investigation.

Accuracy of diffusion kurtosis imaging in characterization of breast lesions

OBJECTIVE

The aim of this study was to evaluate the accuracy of diffusion kurtosis in the characterization and differentiation of breast lesions.

METHODS

49 females with 53 breast lesions underwent breast MRI. The MRI magnetic field is 1.5 T, and the protocol is standard MRI sequences, dynamic sequences pre- and post-contrast agent administration and diffusion images. Diffusion kurtosis imaging (DKI) was applied as part of our standard breast MRΙ protocol. Two experienced radiologists on breast MRI, blinded to the final diagnosis, reviewed the parametric maps and placed a volume of interest on all slices including each lesion. Kurtosis [K apparent (K_app)] and corrected apparent diffusion coefficient [D apparent (D_app)] median values were then calculated from the whole-lesion histogram analysis. Receiver-operating characteristic analysis was used to determine the most effective cut-off values for the differentiation between benign and malignant pathologies. Histological analysis of the breast lesions was performed, and further comparative analysis of the results was performed to investigate the accuracy of the method.

RESULTS

Benign (n = 19) and malignant lesions (n = 34) had mean diameters of 20.8 mm (10.1-31.5 mm) and 26.4 mm (10.5-42.3 mm), respectively. The lowest and the highest kurtosis values (K_app) of malignant lesions were significantly higher than those of benign lesions. A cut-off of 0.71 provided specificity of 93.7% and sensitivity 97.1%, and the area under the curve (AUC) was 0.976 (p < 0.0001). The lowest and the highest D_app values of malignant lesions were lower than those of benign lesions. A cut-off value of 1.57 × 10^-3 mm² s^-1 provided specificity of 93.7% and sensitivity of 91.2% with AUC of 0.949 (p < 0.0001).

CONCLUSION

DKI is an accurate additional tool for the characterization and differentiation of breast lesions with high K_app and D_app sensitivity and specificity rates. Advances in knowledge: DKI is able to distinguish benign from malignant breast pathologies. DKI increases the specificity of breast MRI.

Incremental Cancer Detection of Locoregional Restaging with Diagnostic Mammography Combined with Whole-Breast and Regional Nodal Ultrasound in Women with Newly Diagnosed Breast Cancer

RATIONALE AND OBJECTIVES

This study aims to determine if locoregional restaging with diagnostic mammography and ultrasound (US) of the whole breast and regional nodes performed for quality assurance in women with newly diagnosed breast cancer who were referred to a tertiary care center yields incremental cancer detection.

MATERIALS AND METHODS

An institutional review board-approved retrospective, single-institution database review was performed on the first 1000 women referred to our center in 2010 with a provisional breast cancer diagnosis. Locoregional restaging consisted of diagnostic full-field digital mammography combined with US of the whole breast and regional nodal basins. Bilateral whole-breast US was performed in women with contralateral mammographic abnormality or had heterogeneously or extremely dense parenchyma. Demographic, clinical, and pathologic factors were analyzed.

RESULTS

Final analyses included 401 women. Of the 401 women, 138 (34%) did not have their outside images available for review upon referral. The median age was 54 years (range 21-92); the median tumor size was 2.9 cm (range 0.6-18.0) for women whose disease was upstaged and 2.2 cm (range 0.4-15.0) for women whose disease was not upstaged. Incremental cancer detection rates were 15.5% (62 of 401) in the ipsilateral breast and 3.9% (6 of 154) in the contralateral breast (P < 0.0001). The total upstage rate was 25% (100 of 401). Surgical management changed from segmentectomy to mastectomy in 12% (50 of 401). The re-excision rate after segmentectomy was 19% (35 of 189).

CONCLUSIONS

Locoregional restaging with diagnostic mammography combined with whole-breast and regional nodal US that is performed for standardization of the imaging workup for newly diagnosed breast cancer patients can reduce underestimation of disease burden and impact therapeutic planning.

Whole-lesion apparent diffusion coefficient (ADC) metrics as a marker of breast tumour characterization-comparison between ADC value and ADC entropy

OBJECTIVE

To prospectively assess the role of whole-lesion apparent diffusion coefficient (ADC) metrics in the characterization of breast tumours by comparing ADC value with ADC entropy.

METHODS

49 patients with 53 breast lesions underwent phased-array breast coil 1.5-T MRI. Two radiologists experienced in breast MRI, blinded to the final diagnosis, reviewed the ADC maps and placed a volume of interest on all slices including each lesion on the ADC map to obtain whole-lesion mean ADC value and ADC entropy. The mean ADC value and ADC entropy in benign and malignant lesions were compared by the Mann-Whitney U-test. Receiver-operating characteristic analysis was performed to assess the sensitivity and specificity of the two variables in the characterization of the breast lesions.

RESULTS

The benign (n = 19) and malignant lesions (n = 34) had mean diameters of 20.8 mm (10.1-31.5 mm) and 26.4 mm (10.5-42.3 mm), respectively. The mean ADC value of the malignant lesions was significantly lower than that of the benign ones (0.87 × 10^-3 vs 1.49 × 10^-3 mm² s^-1; p < 0.0001). Malignant ADC entropy was higher than benign entropy, without reaching levels of statistical significance (5.4 vs 5.0; p = 0.064). At a mean ADC cut-off value of 1.16 × 10^-3 mm² s^-1, the sensitivity and specificity for diagnosing malignancy became optimal (97.1% and 93.7, respectively) with an area under the curve (AUC) of 0.975. With regard to ADC entropy, the sensitivity and specificity at a cut-off of 5.18 were 67.6 and 68.7%, respectively, with an AUC of 0.664.

CONCLUSION

Whole-lesion mean ADC could be a helpful index in the characterization of suspicious breast lesions, with higher sensitivity and specificity than ADC entropy. Advances in knowledge: Two separate parameters of the whole-lesion histogram were compared for their diagnostic accuracy in characterizing breast lesions. Mean ADC was found to be able to characterize breast lesions, whereas entropy proved to be unable to differentiate benign from malignant breast lesions. It is, however, likely that entropy may distinguish these two groups if a larger cohort were used, or the fact that this may be influenced by the molecular subtypes of breast cancers included.

Real-time intraoperative detection of breast cancer using near-infrared fluorescence imaging and Methylene Blue

BACKGROUND

Despite recent developments in preoperative breast cancer imaging, intraoperative localization of tumor tissue can be challenging, resulting in tumor-positive resection margins during breast conserving surgery. Based on certain physicochemical similarities between Technetium((99m)Tc)-sestamibi (MIBI), an SPECT radiodiagnostic with a sensitivity of 83-90% to detect breast cancer preoperatively, and the near-infrared (NIR) fluorophore Methylene Blue (MB), we hypothesized that MB might detect breast cancer intraoperatively using NIR fluorescence imaging.

METHODS

Twenty-four patients with breast cancer, planned for surgical resection, were included. Patients were divided in 2 administration groups, which differed with respect to the timing of MB administration. N = 12 patients per group were administered 1.0 mg/kg MB intravenously either immediately or 3 h before surgery. The mini-FLARE imaging system was used to identify the NIR fluorescent signal during surgery and on post-resected specimens transferred to the pathology department. Results were confirmed by NIR fluorescence microscopy.

RESULTS

20/24 (83%) of breast tumors (carcinoma in N = 21 and ductal carcinoma in situ in N = 3) were identified in the resected specimen using NIR fluorescence imaging. Patients with non-detectable tumors were significantly older. No significant relation to receptor status or tumor grade was seen. Overall tumor-to-background ratio (TBR) was 2.4 ± 0.8. There was no significant difference between TBR and background signal between administration groups. In 2/4 patients with positive resection margins, breast cancer tissue identified in the wound bed during surgery would have changed surgical management. Histology confirmed the concordance of fluorescence signal and tumor tissue.

CONCLUSIONS

This feasibility study demonstrated an overall breast cancer identification rate using MB of 83%, with real-time intraoperative guidance having the potential to alter patient management.

Geographic and temporal trends in the management of occult primary breast cancer: a systematic review and meta-analysis

BACKGROUND

Management of occult primary breast cancer (OPBC), including the role of magnetic resonance imaging (MRI), is controversial. We conducted a pooled analysis of OPBC patients and a meta-analysis of MRI accuracy in OPBC in order to elucidate current practices.

METHODS

A literature search yielded 201 studies. Patient-level data for clinically/mammographically OPBC from studies published after 1993 and from our institution were pooled; logistic regression examined associations between patient/study data and outcomes, including treatments and recurrence. We report adjusted odds ratios (OR) and 95 % confidence intervals (95 % CI) significant at 2-tailed p < 0.05. Meta-analysis included data for patients who received MRIs for workup of clinically/mammographically OPBC. We report pooled sensitivity and specificity with 95 % CIs.

RESULTS

The pooled analysis included 92 patients (15 studies [n = 85] plus our institution [n = 7]). Patients from Asia were more likely to receive breast surgery (OR = 5.98, 95 % CI = 2.02-17.65) but not chemotherapy (OR = 0.32, 95 % CI = 0.13-0.82); patients from the United States were more likely to receive chemotherapy (OR = 13.08, 95 % CI = 2.64-64.78). Patients from studies published after 2003 were more likely to receive radiotherapy (OR = 3.86, 95 % CI = 1.41-10.55). Chemotherapy recipients were more likely to have distant recurrence (OR = 9.77, 95 % CI = 1.10-87.21). More patients with positive MRIs received chemotherapy than patients with negative MRIs (10 of 12 [83.3 %] vs 5 of 13 [38.5 %]; p = 0.0414). In the MRI-accuracy meta-analysis (10 studies, n = 262), pooled sensitivity and specificity were 96 % (95 % CI = 91-98 %) and 63 % (95 % CI = 42-81 %), respectively.

CONCLUSIONS

OPBC management varied geographically and over time. We recommend establishing an international OPBC patient registry to facilitate longitudinal study and develop global treatment standards.

Occult primary breast cancer at a comprehensive cancer center

BACKGROUND

Management of occult primary breast cancer (OPBC), that is, breast cancer that first presents through regional nodal or distant disease without clinical or mammographic evidence of disease in the breast, has been controversial and inconsistent. Here, we review OPBC patients treated at our institution.

METHODS

We conducted a retrospective review of women diagnosed with a first primary breast cancer between March 1999 and September 2010 to identify patients who presented with isolated axillary lymphadenopathy proven to be histologically consistent with primary breast malignancy but had no evidence of a breast mass on physical examination, mammography, or ultrasound. Descriptions of treatments received, recurrence, morbidity, and mortality as of October 2012 are reported.

RESULTS

Of 5533 patients reviewed, seven (0.1%) patients were identified. The median age was 65 y old (range, 40-72), and the median length of follow-up was 86 mo (range, 42-124). Four patients underwent modified radical mastectomy, one patient had a lumpectomy and axillary lymph node dissection, and two patients had axillary lymph node dissection without breast surgery. Four patients received adjuvant radiation therapy. All seven patients received chemotherapy. Three patients received endocrine therapy, and two patients received anti-HER2 therapy. At the last follow-up, all seven patients were alive with no evidence of disease.

CONCLUSIONS

Although there was some variation in the management of OPBC at our institution, our patients had excellent outcomes after multimodal treatment. Our results support a curative intent approach to the treatment of OPBC and illustrate the need for individualized treatment algorithms based on tumor biology and extent of the disease at diagnosis.

Breast Cancer Tumor Size Assessment with Mammography, Ultrasonography, and Magnetic Resonance Imaging at a Community Based Multidisciplinary Breast Center

Paramount to staging and patient management is accurately measuring the size of invasive breast cancers. We assessed the accuracy of mammography (MG), ultrasonography (US), and magnetic resonance imaging (MRI) at our community-based hospital in which multiple radiologists and imaging machines are used in the care of our patients. We performed a retrospective analysis of a prospectively maintained database of 277 patients seen at our breast center from 2009 to 2010. We tabulated MG, US, and MRI-reported tumor sizes in 161 women with pathology-proven invasive breast cancer and compared the preoperative size measurements with final pathologic tumor size. In the 161 patients, 169 lesions were identified. Imaging using all three modalities was available in 47 patients. When compared with final pathology, MRI had a correlation of r = 0.75 to mean tumor size as compared with US (r = 0.67) and MG (r = 0.76). Mean tumor size was 1.90 cm by MG, 1.87 cm by US, 2.40 cm by MRI, and 2.19 cm by pathology. We were able to achieve an excellent correlation of pathologic tumor size to preoperative imaging. The absolute differences in size between the modalities were small. MRI, in select patients, added to the assessment of tumor size based on US and MG.

MRI for breast cancer screening, diagnosis, and treatment

MRI is used widely both for screening women who are at increased risk of breast cancer and for treatment selection. Prospective studies confirm that MRI screening of women with known or suspected genetic mutation results in a higher sensitivity for cancer detection than does mammography. However, survival data are not available. In women with breast cancer, MRI detects cancer not identified with other types of screening. In two randomised trials, this increased sensitivity did not translate into improved selection of surgical treatment or a reduction in the number of operations. Data for longer-term outcomes such as ipsilateral breast tumour recurrence rates and contralateral breast cancer incidence are scarce, but to date do not show clear benefit for MRI. MRI is better than other methods of assessing the response to neoadjuvant chemotherapy, and is helpful in identifying the primary tumour in patients who present with axillary adenopathy.

Image-guided tumor resection using real-time near-infrared fluorescence in a syngeneic rat model of primary breast cancer

Tumor involvement of resection margins is found in a large proportion of patients who undergo breast-conserving surgery. Near-infrared (NIR) fluorescence imaging is an experimental technique to visualize cancer cells during surgery. To determine the accuracy of real-time NIR fluorescence imaging in obtaining tumor-free resection margins, a protease-activatable NIR fluorescence probe and an intraoperative camera system were used in the EMR86 orthotopic syngeneic breast cancer rat model. Influence of concentration, timing and number of tumor cells were tested in the MCR86 rat breast cancer cell line. These variables were significantly associated with NIR fluorescence probe activation. Dosing and tumor size were also significantly associated with fluorescence intensity in the EMR86 rat model, whereas time of imaging was not. Real-time NIR fluorescence guidance of tumor resection resulted in a complete resection of 17 out of 17 tumors with minimal excision of normal healthy tissue (mean minimum and a mean maximum tumor-free margin of 0.2 ± 0.2 mm and 1.3 ± 0.6 mm, respectively). Moreover, the technique enabled identification of remnant tumor tissue in the surgical cavity. Histological analysis revealed that the NIR fluorescence signal was highest at the invasive tumor border and in the stromal compartment of the tumor. In conclusion, NIR fluorescence detection of breast tumor margins was successful in a rat model. This study suggests that clinical introduction of intraoperative NIR fluorescence imaging has the potential to increase the number of complete tumor resections in breast cancer patients undergoing breast-conserving surgery.