Breast MRI for Evaluation of Response to Neoadjuvant Therapy.

Neoadjuvant therapy is increasingly being used to treat early-stage triple-negative and human epidermal growth factor 2-overexpressing breast cancers, as well as locally advanced and inflammatory breast cancers. The rationales for neoadjuvant therapy are to shrink tumor size and potentially decrease the extent of surgery, to serve as an in vivo test of response to therapy, and to reveal prognostic information for the patient. MRI is the most accurate modality to demonstrate response to therapy and to help ensure accurate presurgical planning. Changes in lesion diameter, volume, and enhancement are used to predict complete response, partial response, or nonresponse to therapy. However, residual disease may be overestimated or underestimated at MRI. Fibrosis, necrotic tumors, and residual benign masses may be causes of overestimation of residual disease. Nonmass lesions, invasive lobular carcinoma, hormone receptor-positive tumors, nonconcentric shrinkage patterns, the use of antiangiogenic therapy, and late-enhancing foci may be causes of underestimation of residual disease. In patients with known axillary lymph node metastasis, neoadjuvant therapy may be followed by targeted axillary dissection to avoid the potential morbidity associated with an axillary lymph node dissection. Diffusion-weighted imaging, radiomics, machine learning, and deep learning methods are under investigation to improve MRI accuracy in predicting treatment response.©RSNA, 2021.

Abbreviated MR Imaging for Breast Cancer.

Breast MR imaging is the most sensitive imaging method for the detection of breast cancer and detects more aggressive malignancies than mammography and ultrasound examination. Despite these advantages, breast MR imaging has low use rates for breast cancer screening. Abbreviated breast MR imaging, in which a limited number of breast imaging sequences are obtained, has been proposed as a way to solve cost and patient tolerance issues while preserving the high cancer detection rate of breast MR imaging. This review discusses abbreviated breast MR imaging, including protocols, multicenter clinical trial results, clinical workflow implementation challenges, and future directions.

Abbreviated Breast MRI: Road to Clinical Implementation.

Breast MRI offers high sensitivity for breast cancer detection, with preferential detection of high-grade invasive cancers when compared to mammography and ultrasound. Despite the clear benefits of breast MRI in cancer screening, its cost, patient tolerance, and low utilization remain key issues. Abbreviated breast MRI, in which only a select number of sequences and postcontrast imaging are acquired, exploits the high sensitivity of breast MRI while reducing table time and reading time to maximize availability, patient tolerance, and accessibility. Worldwide studies of varying patient populations have demonstrated that the comparable diagnostic accuracy of abbreviated breast MRI is comparable to a full diagnostic protocol, highlighting the emerging role of abbreviated MRI screening in patients with an intermediate and high lifetime risk of breast cancer. The purpose of this review is to summarize the background and current literature relating to abbreviated MRI, highlight various protocols utilized in current multicenter clinical trials, describe workflow and clinical implementation issues, and discuss the future of abbreviated protocols, including advanced MRI techniques.

Overstated Harms of Breast Cancer Screening? A Large Outcomes Analysis of Complications Associated With 9-Gauge Stereotactic Vacuum-Assisted Breast Biopsy.

OBJECTIVE: The purpose of this study was to assess the rate, type, and severity of complications related to 9-gauge stereotactic vacuum-assisted breast biopsy (SVAB) and to delineate associated factors that may contribute to a higher rate of complications. MATERIALS AND METHODS: This retrospective study included 4776 patients who underwent SVAB between 2003 and 2016. A total of 319 patients with documented postbiopsy complications were identified. Complications were subcategorized as bleeding, pain, lightheadedness, bruising, and other complications, and their severity was classified as minor, moderate, or severe. Hematoma volumes were correlated with biopsy location and complication severity. A group of control subjects who underwent SVAB but had no complications was compared with the group of study patients with regard to age, biopsy location, lesion type, and pathologic findings. Postbiopsy screening adherence was assessed. Statistical analyses were performed using the Fisher exact, Mann-Whitney, Kruskal-Wallis, and Spearman rank correlation tests. RESULTS: Of the 319 patients with complications who were identified (representing 6.7% of the 4776 patients who underwent SVAB), 307 (96.2%) had mild complications, 12 (3.8%) had moderate complications, and no patients had severe complications. The most common complication was bleeding or hematoma (89.3% of patients [285/319]), followed by pain (6.9% [22/319]), lightheadedness (0.9% [3/319]), bruising (0.9% [3/319]), and other complications (1.9% [6/319]). No significant differences were noted between the study group and the control group in terms of age (p = 0.474), biopsy location (p = 0.065), histologic findings (p = 0.056), or lesion type (p = 0.568). Hematoma volume (median, 7.5 cm3) did not correspond to the severity of complications. Larger hematoma volumes were associated with a posterior biopsy location (p = 0.008). The rate of return to annual screening after biopsy was not adversely affected by the presence of biopsy complications. CONCLUSION: Clinically significant complications associated with SVAB were exceedingly rare (0.3%) in this large study spanning 13 years.

Canceled MRI-guided Breast Biopsies Due to Nonvisualization: Follow-up and Outcomes.

RATIONALE AND OBJECTIVE: The objective of this study was to evaluate breast lesion outcomes in patients after canceled MRI-guided breast biopsy due to lesion nonvisualization. MATERIALS AND METHODS: Electronic medical records (January 2007-December 2014) were searched for patients with canceled magnetic resonance imaging (MRI)-guided breast biopsies due to lesion nonvisualization. A total of 1403 MRI-detected lesions were scheduled for MRI-guided biopsy and 89 were canceled because of nonvisualization. Imaging studies and medical records were reviewed for patient demographics, lesion characteristics, and subsequent malignancy. Patients without adequate MRI follow-up imaging were excluded. Statistical analysis was employed to determine if patient demographics or lesion characteristics were predictive of lesion resolution or lesion biopsy after subsequent follow-up. RESULTS: Eighty-nine (6.3% [89/1403]; 95% confidence interval, 5.2%-7.7%) biopsies in 89 women were canceled because of nonvisualization. Follow-up MRIs greater than 5.5 months were available for 60.7% (54/89) of women. In 74.1% (40/54) of these patients, the lesions completely resolved on follow-up. In 25.9% (14/54) of the patients, the lesion persisted on follow-up; 42.9% (6/14) of these patients underwent biopsy. One case (1.9% [1/54]) yielded ductal carcinoma in situ with microinvasion at the 6-month follow-up. No patient demographics or lesion features were associated with lesion resolution or lesion biopsy. CONCLUSIONS: The majority of canceled MRI-guided biopsy lesions resolved on later follow-up; however, because of the small possibility of a missed malignancy, follow-up MRI imaging at 6 months is recommended.

Stereotactic Breast Biopsy With Benign Results Does Not Negatively Affect Future Screening Adherence.

PURPOSE: To evaluate whether false-positive stereotactic vacuum-assisted breast biopsy (SVAB) affects subsequent mammographic screening adherence. MATERIALS AND METHODS: This Institutional Review Board-approved, HIPAA-compliant retrospective review of women with SVAB was performed between 2012 and 2014. Patient age, clinical history, biopsy pathology, and first postbiopsy screening mammogram were reviewed. Statistical analyses were performed using Fisher's exact, Mann-Whitney, and χ2 tests. RESULTS: There were 913 SVABs performed in 2012 to 2014 for imaging detected lesions; of these, malignant or high-risk lesions or biopsies resulting in a recommendation of surgical excision were excluded, leaving 395 SVABs yielding benign pathology in 395 women. Findings were matched with a control population consisting of 45,126 women who had a BI-RADS 1 or 2 screening mammogram and did not undergo breast biopsy. In all, 191 of 395 (48.4%) women with a biopsy with benign results and 22,668 of 45,126 (50.2%) women without biopsy returned for annual follow-up >9 months and ≤18 months after the index examination (P = .479). In addition, 57 of 395 (14.4%) women with a biopsy with benign results and 3,336 of 45,126 (7.4%) women without biopsy returned for annual follow-up >18 months after the index examination (P < .001). Older women, women with personal history of breast cancer, and women with postbiopsy complication after benign SVAB were more likely to return for screening (P = .026, P = .028, and P = .026, respectively). CONCLUSION: The findings in our study suggest that SVABs with benign results do not negatively impact screening mammography adherence. The previously described "harms" of false-positive mammography and biopsy may be exaggerated.

Digital Breast Tomosynthesis Practice Patterns Following 2011 FDA Approval: A Survey of Breast Imaging Radiologists.

RATIONALE AND OBJECTIVES: To evaluate uptake, patterns of use, and perception of digital breast tomosynthesis (DBT) among practicing breast radiologists. MATERIALS AND METHODS: Institutional Review Board exemption was obtained for this Health Insurance Portability and Accountability Act-compliant electronic survey, sent to 7023 breast radiologists identified via the Radiological Society of North America database. Respondents were asked of their geographic location and practice type. DBT users reported length of use, selection criteria, interpretive sequences, recall rate, and reading time. Radiologist satisfaction with DBT as a diagnostic tool was assessed (1-5 scale). RESULTS: There were 1156 (16.5%) responders, 65.8% from the United States and 34.2% from abroad. Of these, 749 (68.6%) use DBT; 22.6% in academia, 56.5% private, and 21% other. Participants are equally likely to report use of DBT if they worked in academics versus in private practice (78.2% [169 of 216] vs 71% [423 of 596]) (odds ratio, 1.10; 95% confidence interval: 0.87-1.40; P = 1.000). Of nonusers, 43% (147 of 343) plan to adopt DBT. No US regional differences in uptake were observed (P = 1.000). Although 59.3% (416 of 702) of DBT users include synthetic 2D (s2D) for interpretation, only 24.2% (170 of 702) use s2D alone. Majority (66%; 441 of 672) do not perform DBT-guided procedures. Radiologist (76.6%) (544 of 710) satisfaction with DBT as a diagnostic tool is high (score ≥ 4/5). CONCLUSIONS: DBT is being adopted worldwide across all practice types, yet variations in examination indication, patient selection, utilization of s2D images, and access to DBT-guided procedures persist, highlighting the need for consensus and standardization.

Magnetic Resonance Imaging-Directed Ultrasound Imaging of Non-Mass Enhancement in the Breast: Outcomes and Frequency of Malignancy.

OBJECTIVES: This study was performed to determine the frequency, predictors, and outcomes of ultrasound (US) correlates for non-mass enhancement. METHODS: From January 2005 to December 2011, a retrospective review of 5837 consecutive breast magnetic resonance imaging examinations at our institution identified 918 non-mass enhancing lesions for which follow-up or biopsy was recommended. Retrospective review of the images identified 879 of 918 lesions (96%) meeting criteria for non-mass enhancement. Patient demographics, pathologic results, and the presence of an adjacent landmark were recorded. Targeted US examinations were recommended for 331 of 879 cases (38%), and 284 of 331 women (86%) underwent US evaluations. RESULTS: The US correlate rate for non-mass enhancement was 23% (64 of 284). An adjacent landmark was significantly associated with a US correlate (P < .001). Biopsy was recommended for 43 of 64 correlates (67%). Ultrasound-guided biopsy was performed on 39 of 43 (91%); 7 of 39 (18%) were malignant. No correlate was seen for 220 of 284 lesions (77%). At magnetic resonance imaging-guided biopsy, 14 of 117 (12%) were malignancies. For all biopsied non-mass enhancements, the malignancy rate was 18% (55 of 308) and was significantly more prevalent in the setting of a known index cancer (P < .001), older age (P < .001), the presence of a landmark (P = .002), and larger lesion size (P = .019). CONCLUSIONS: Non-mass enhancement with an adjacent landmark is more likely to have a US correlate compared to non-mass enhancement without an adjacent landmark. Non-mass enhancement in the setting of a known index cancer, older age, a landmark, and larger lesion size is more likely to be malignant. However, no statistical difference was detected in the rate of malignancy between non-mass enhancement with (18%) or without (12%) a correlate. Absence of a correlate does not obviate the need to biopsy suspicious non-mass enhancement.

Delineating Extramammary Findings at Breast MR Imaging.

Breast magnetic resonance (MR) imaging is the only breast imaging modality that consistently encompasses extramammary structures in the thorax and upper abdomen. Incidental extramammary findings on breast MR images of patients with a history of breast cancer or other malignancies are significantly more likely to be malignant and may affect staging and treatment. An understanding of the frequency, distribution, and context of extramammary findings on breast MR images and a familiarity with common and uncommon sites of breast cancer metastasis inform the differential diagnosis and prompt the appropriate diagnostic next step, to differentiate benign from malignant findings. High-yield organ systems on breast MR images, as reflected by a high positive predictive value for malignancy, are correlated with known distant sites of breast cancer metastasis in the bone, lung, liver, and lymph nodes. Staging is considered when disease involves the skin and chest wall. Unusual sites of breast cancer metastasis from invasive lobular carcinoma are discussed, including the gastrointestinal tract, peritoneum, and adrenal glands. Nonmalignant clinically important findings involving the cardiovascular and gastrointestinal systems are reviewed, and potential pitfalls in diagnosis and interpretation are highlighted. A consistently systematic diagnostic approach is emphasized for identifying extramammary abnormalities on breast MR images. All things considered, the radiologist should be able to improve diagnostic sensitivity and specificity while interpreting extramammary findings on breast MR images. ©RSNA, 2017.

The role of dynamic contrast-enhanced screening breast MRI in populations at increased risk for breast cancer.

Breast MRI is more sensitive than mammography in detecting breast cancer. However, MRI as a screening tool is limited to high-risk patients due to cost, low specificity and insufficient evidence for its use in intermediate-risk populations. Nonetheless, in the past decade, there has been a dramatic increase in the use of breast-screening MRI in the community setting. In this review, we set to describe the current literature on the use of screening MRI in high- and intermediate-risk populations. We will also describe novel applications of breast MRI including abbreviated breast MRI protocols, background parenchymal enhancement and diffusion-weighted imaging.

Microinvasive ductal carcinoma in situ: clinical presentation, imaging features, pathologic findings, and outcome.

OBJECTIVE: The purpose of our study was to describe the clinical features, imaging characteristics, pathologic findings and outcome of microinvasive ductal carcinoma in situ (DCISM). MATERIALS AND METHODS: The records of 21 women diagnosed with microinvasive ductal carcinoma in situ (DCISM) from November 1993 to September 2006 were retrospectively reviewed. The clinical presentation, imaging and histopathologic features, and clinical follow-up were reviewed. RESULTS: The 21 lesions all occurred in women with a mean age of 56 years (range, 27-79 years). Clinical findings were present in ten (48%): 10 with palpable masses, four with associated nipple discharge. Mean lesion size was 21mm (range, 9-65mm). The lesion size in 62% was 15mm or smaller. Mammographic findings were calcifications only in nine (43%) and an associated or other finding in nine (43%) [mass (n=7), asymmetry (n=1), architectural distortion (n=1)]. Three lesions were mammographically occult. Sonographic findings available in 11 lesions showed a solid hypoechoic mass in 10 cases (eight irregular in shape, one round, one oval). One lesion was not seen on sonography. On histopathologic examination, all lesions were diagnosed as DCISM, with a focus of invasive carcinoma less than or equal to 1mm in diameter within an area of DCIS. Sixteen (76%) lesions were high nuclear grade, four (19%) were intermediate and one was low grade (5%). Sixteen (76%) had the presence of necrosis. Positivity for ER and PR was noted in 75% and 38%. Nodal metastasis was present in one case with axillary lymph node dissection. Mean follow-up time for 16 women was 36 months without evidence of local or systemic recurrence. One patient developed a second primary in the contralateral breast 3 years later. CONCLUSION: The clinical presentation and radiologic appearance of a mass are commonly encountered in DCISM lesions (48% and 57%, respectively), irrespective of lesion size, mimicking findings seen in invasive carcinoma. Despite its potential for nodal metastasis (5% in our series), mean follow-up at 36 months was good with no evidence of local or systemic recurrence at follow-up. Knowledge of these clinical and imaging findings in DCISM lesions may alert the clinician to the possibility of microinvasion and guide appropriate management.

Is breast MRI helpful in the evaluation of inconclusive mammographic findings?

OBJECTIVE: The purpose of this study was to evaluate the usefulness of MRI of the breast in cases in which mammographic or sonographic findings are inconclusive. MATERIALS AND METHODS: We retrospectively reviewed images from 115 MRI examinations of the breast performed from 1999 to 2005 for the indication of problem-solving for inconclusive findings on a mammogram. Forty-eight of the 115 women (41.8%) were at high risk. We discerned whether sonography or MRI was used as an adjunctive tool and correlated the findings with those in the pathology database. RESULTS: The equivocal findings most frequently leading to MRI were asymmetry and architectural distortion. No suspicious MRI correlate was found in 100 of 115 cases (87%). These cases were found stable at follow-up mammography or MRI after a mean of 34 months. Fifteen enhancing masses (13%) that corresponded to the mammographic abnormality were seen on MR images. All masses identified at MRI were accurately localized for biopsy, and six malignant lesions were identified. Four of six malignant tumors were seen in one mammographic view only; two were seen on second-look ultrasound images. MRI had a sensitivity of 100% and compared with mammography had significantly higher specificity (91.7% vs 80.7%, p = 0.029), positive predictive value (40% vs 8.7%, p = 0.032), and overall accuracy (92.2% vs 78.3%, p = 0.0052). Eighteen incidental lesions (15.7%) were detected at MRI, and all were subsequently found benign. CONCLUSION: We found breast MRI to be a useful adjunctive tool when findings at conventional imaging were equivocal. Strict patient selection criteria should be used because of the high frequency of incidental lesions seen on MR images.

Sonographically guided marker placement for confirmation of removal of mammographically occult lesions after localization.

OBJECTIVE: We evaluated the benefit of placing a marker under sonographic guidance at the time of localization to aid in identifying mammographically occult lesions within the specimen at the time of surgical excision and to evaluate margin status. MATERIALS AND METHODS: We reviewed 135 sonographically guided needle localizations performed on mammographically occult lesions. Imaging during the localization procedure, marker placement, and specimen radiographs were reviewed, and the findings were correlated with the histopathologic findings. RESULTS: Of the 135 mammographically occult lesions, 77 were localized without marker placement and 58 with marker placement. The 58 localizations with marker placement were for masses with a mean lesion size of 9 mm. Specimen radiography of these lesions showed a marker within the specimen in 56 cases (97%) and visualization of the lesion in only seven cases (12%). Specimen radiography of localizations without marker placement showed visualization of the lesion in 18 cases (23%). Of the 11 malignant lesions (19%) localized with marker placement, none had a positive inked margin, but five (46%) had close margins necessitating reexcision. Of the 26 malignant lesions (34%) localized without marker placement, two (8%) had a positive inked margin, and eight (31%) had close margins necessitating reexcision. CONCLUSION: At needle localization of breast lesions, marker placement under sonographic guidance is beneficial because it enables immediate confirmation of accurate surgical removal of the localized lesion at surgical excision. Use of marker placement, however, does not reduce the percentage of cases with close margins necessitating reexcision.

Fine-needle aspiration biopsy of benign adenomyoepithelioma of the breast: radiologic and pathologic correlation in four cases.

Benign adenomyoepithelioma of the breast is a rare tumor in which the cytologic findings have been described in only a few cases. While benign, the imaging and pathologic features may be mistaken for malignancy. We report the aspiration biopsy findings in four cases of adenomyoepithelioma with radiologic and histologic correlation. Cytopathologists should familiarize themselves with this entity to avoid a misdiagnosis of carcinoma.