Breast MRIs Research Articles

Frequency and outcomes of new or suspicious MRI findings on breast MRI for patients on neoadjuvant therapy.

To assess the frequency and outcomes of indeterminate enhancing findings on breast MRI unrelated to the index primary tumor(s) in patients on neoadjuvant therapy (NAT). This retrospective review identified all diagnostic breast MRIs performed to evaluate response to NAT at our institution between 2017 and 2020. All exams with indeterminate enhancing findings (BI-RADS 3-5) unrelated to the index tumor(s) for which follow-up imaging or tissue diagnosis was recommended were included. Cases lacking a pre-treatment MRI or those with insufficient follow-up were excluded. Imaging of all post-NAT breast MRIs were re-reviewed. The electronic medical record was reviewed to evaluate patient and lesion characteristics and outcomes. Between 2017 and 2020, 614/4042 (15.2%) breast MRIs were performed to evaluate response to NAT. After exclusions, 38 of these exams (6.2%) identified 42 indeterminate enhancing findings unrelated to the index tumor for which follow-up imaging (15 exams) or tissue diagnosis (23 exams) was recommended. Fifteen of 42 (35.7%) of the findings were new compared to the pre-treatment baseline MRI, 8/42 (19.0%) increased and 19/42 (45.2%) were present on pre-treatment MRI. Most findings were contralateral to the index tumor (28, 66.7%). Findings were masses (17, 40.4%), focus (15, 35.7%), and non-mass enhancement (10, 23.8%). Of the 42 findings, 19 (45.2%) underwent percutaneous biopsy, 10 (23.8%) underwent surgical biopsy or mastectomy, and 13 (31%) were followed by imaging. Thirty-seven were benign, 4 were high-risk lesions without upgrade (atypical ductal hyperplasia, atypical lobular hyperplasia, and papillomatosis with atypical ductal hyperplasia), and one (2.4%) was malignant (invasive lobular carcinoma), which was non-mass enhancement present on the pre-treatment MRI. Indeterminate enhancing lesions unrelated to the index tumor(s) on breast MRIs performed to assess response to neoadjuvant chemotherapy are uncommon. When present, these lesions have an extremely low likelihood of malignancy, especially when new compared to the pre-treatment MRI. Because incidental indeterminate enhancing lesions on breast MRI at post-NAT follow-up are rarely malignant, radiologists should be judicious in recommending follow-up or tissue diagnosis for such lesions after NAT.

Regional lymph node changes on breast MRI in patients with early-stage breast cancer receiving neoadjuvant chemo-immunotherapy

Abstract Purpose Establishing breast MRI imaging patterns associated with neoadjuvant immunotherapy is needed to monitor response. We analyzed serial breast MRIs in patients receiving neoadjuvant chemo-immunotherapy on the I-SPY2 clinical trial. Methods Patients with stage 2–3 HER2-negative breast cancer were randomized to weekly paclitaxel (control), weekly paclitaxel and pembrolizumab, or weekly paclitaxel, pembrolizumab and intra-tumoral injection of SD-101, a TLR9 agonist. All patients received AC. Regional lymph nodes were retrospectively evaluated on breast MRI at baseline, 3, 12 and 20 weeks by a single blinded radiologist. MRIs were assessed for development of new regional lymphadenopathy, or increase in the longest diameter or cortical thickness of the largest abnormal regional lymph node. Results Between 12/2015 and 4/2021, a total of 43 patients enrolled in the control (n = 16) and paclitaxel + pembrolizumab ± SD-101 (n = 27) arms. 12 of 27 patients (44.4%) receiving chemo-immunotherapy experienced increased lymphadenopathy within the first 12 weeks compared to 1 of 16 patients (6.3%) in the control group (p = 0.014). Most patients with increased lymphadenopathy were in the SD101/pembro arm (n = 10, p = 0.002). Increased lymphadenopathy was observed despite concomitant decrease in breast tumor size at all time points. 11 of 12 patients with increased lymphadenopathy had pathologically negative nodes at surgery. There was no association between lymphadenopathy and lower residual cancer burden or immune-related toxicity. Conclusions The combination of neoadjuvant paclitaxel and pembrolizumab ± SD101 intratumoral injection was associated with early increases in regional lymphadenopathy on MRI despite decreased breast tumor size. Increased lymphadenopathy was not associated with node positive disease at surgery.

Abstract PO4-08-07: Background parenchymal enhancement (BPE) on breast magnetic resonance imaging as a biomarker of breast cancer risk among BRCA1/2 carriers

Abstract Introduction: BRCA1/2 carriers are recommended to undergo dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) screening of the breasts annually. Fibroglandular tissue (FGT) may enhance with MRI contrast agent termed background parenchymal enhancement (BPE). BPE is believed to be a marker of hormonally responsive breast tissue, as BPE is impacted by aromatase inhibition and by oophorectomy. BPE has been shown to be more strongly associated with breast cancer risk than breast density. We hypothesize that BPE may serve as a useful dynamic marker of breast cancer risk among BRCA1/2 mutation carriers, given their frequent MRI screening. Methods: We identified female BRCA1/2 carriers from the University of Pennsylvania Cancer Risk Evaluation Program with no personal history of breast or ovarian cancer at the time of breast MRI. Patients diagnosed within 6 months were excluded to remove prevalent cancer cases at MRI. Among 421 eligible patients, 42 were diagnosed with breast cancer. BPE was quantified from all available breast MRIs using a validated, fully automated method to segment fibroglandular tissue (FGT) and quantify BPE. For preprocessing, the N4ITK algorithm was used for bias-field artifact correction and FGT was segmented using a soft-margin support vector machine classifier using the T1-weighted nonfat-saturated breast MRI. FGT was segmented and quantified in 3D. For BPE quantification, the T1-weighted nonfat-saturated image and the derived FGT mask were registered to the pre-contrast DCE-MRI. The first post contrast DCE-MRI and FGT mask were used to compute the relative enhancement map compared to the pre-contrast image. We calculated BPE metrics in two ways. First, the median BPE enhancement was calculated as the median enhancement of all voxels within the FGT mask. Second the BPE enhancement ratio was calculated as the proportion of voxels enhancing at ≥20%. We performed Cox proportional hazards regression to estimate the hazard ratios for breast cancer per standard deviation unit increase in each BPE metric, with first MRI as the time origin and censoring upon bilateral mastectomy, ovarian cancer diagnosis, death, or loss to follow-up and adjustment for age at MRI, menopause status, volumetric breast density (VBD), body mass index (BMI), and BRCA1 vs. BRCA2 mutation. BPE, VBD, BMI, and menstrual status were included as time varying covariates, enabling inclusion of multiple BPE measurements per woman. Results: The mean age at first MRI was 39 for cases and 41 for non-cases, and the mean number of MRIs was 4. There were no significant differences in median BPE (14% vs. 14%, p=0.965) or BPE ratio (34% vs. 36%, p=0.769) between cases and non-cases. In regression analyses adjusted for age and menstrual status, median BPE was significantly associated with breast cancer risk (HR=1.12, p=0.025). The HR was similar in the fully adjusted model, though did not reach statistical significance (HR=1.11, p=0.055). Higher BPE ratio was significantly associated with increased breast cancer risk in both minimally (HR=1.21, p=0.005) and fully adjusted models (HR=1.21, p=0.012). Conclusions: Our results suggest that BPE is significantly associated with breast cancer diagnosis among BRCA1/2 carriers undergoing breast MRI screening. Both median BPE and BPE ratio metrics were associated with breast cancer risk, even after adjusting for breast density and when accounting for multiple measurements of BPE over time, suggesting that BPE may provide additional risk information for BRCA1/2 carriers. Table 1: Results of Cox proportional hazards regression with time varying covariates Citation Format: Anne Marie McCarthy, Alex Anh-Tu Nguyen, Walter Mankowski, Eric Cohen, Sarah Ehsan, Rhonda Gillette, Lauren Pantalone, Susan Weinstein, Emily Conant, Susan Domchek, Despina Kontos. Background parenchymal enhancement (BPE) on breast magnetic resonance imaging as a biomarker of breast cancer risk among BRCA1/2 carriers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-08-07.

Abstract PO1-01-09: Neoadjuvant endocrine therapy and avelumab with or without palbociclib in stage II/III endocrine receptor-positive breast cancer: the ImmunoADAPT trial

Abstract Background: Pre-clinical and clinical data suggest that CDK4/6 inhibitors can promote an immunogenic tumor microenvironment (TME) and when combined with programmed cell death ligand 1 (PD-L1) inhibitors synergistic anti-cancer effects are observed. To understand the differential effects of CDK4/6 inhibition in the context of immunotherapy we designed a study evaluating neoadjuvant endocrine therapy (ET) with a PD-L1 inhibitor (avelumab) with or without a CDK4/6 inhibitor (palbociclib, palbo) in patients (pts) with stage II/III endocrine receptor (ER)-positive breast cancer. Methods: In this randomized phase 2 pilot study, pts with stage II/III ER+, HER2-negative breast cancer were randomized 2:1 to ET (aromatase inhibitor, AI, for post-menopausal pts; tamoxifen+/-ovarian function suppression for pre-menopausal pts) with avelumab, with or without palbo (palbo vs. control arms). Avelumab was added after a 1-month lead-in of ET +/- palbo, and all drugs were continued for additional 3-month-long cycles prior to surgery. We obtained tumor tissue and breast MRIs on C1D1, C2D1, and at the end of treatment. Imaging assessment was done according to RECIST 1.1 criteria at each time point. The primary endpoint was clinical complete response (cCR) by MRI in the palbo arm (H0: cCR=10% vs. 40% at a two-sided alpha level of 0.1). Secondary endpoints included pathologic CR (pCR), overall response rates (ORR), percent sum diameter changes, and adverse effects (AE). We report descriptive statistics on patient characteristics, clinical response rates, and changes in the sum of the longest diameters of the target lesions (SLD). Translational correlatives including imaging mass cytometry, spatial transcriptomic assessments, and other pathologic biomarkers will be reported at the meeting. Results: From 2018-2023, 33 pts were enrolled, and 30 were eligible for the primary analysis, including 20 pts on the palbo arm (1 pt with bilateral breast cancer, response to each breast cancer evaluated separately) and 10 to the control arm (1 pt with missing data). Clinical and pathologic characteristics were well balanced between arms, however, there was a higher proportion of patients with node-positive disease on the palbo arm (80% vs 60%). The study did not meet its primary endpoint as only 1 pt achieved a cCR and pCR in the palbo arm (cCR/pCR rate 4.8%) vs. no pts in the control arm. ORR was numerically higher in the palbo arm, 42.9% vs. 11.1% (p=0.204). After 1-month of ET+palbo, the mean SLD decreased by 11.6% compared to 9.4% in the ET-only control group (p=0.704). After avelumab was added to both arms, the mean SLD decreased by a further 15.2% in the palbo arm in contrast to a 6.9% increase in the control arm (p=0.018). Subgroup analysis in the palbo arm did not identify clinical or pathologic variables significantly associated with responses. No new safety or toxicity signals were observed. Notably, however expected, grade 3 or higher immune-related adverse events were observed including autoimmune diabetes (n=1), hepatitis (n=1), and colitis (n=1). Conclusions: As shown in previous studies, the addition of palbo to ET did not improve responses in the neoadjuvant setting; however, increased responses to palbo+ET were seen after PD-L1 inhibition, whereas not to ET, suggesting synergy between ET/palbo and avelumab. Translational correlative analysis will aim to decipher TME changes that augment PD-L1 inhibitor responses. Future studies in high-risk pts, where the toxicity of immunotherapy is acceptable, are warranted. Citation Format: Phaedon Zavras, Ruizhe Chen, Hanfei Qi, Mary Kate Jones, Ann Folmer, Hayden Chae, Allen Khodab, Ashley Cimino-Mathews, Lisa Jacobs, Lisa Mullen, Christie Hiton, Ahmed Elkhanany, Katia Khoury, Massimo Cristofanilli, Elizabeth Jaffee, Vered Stearns, Cesar Santa-Maria. Neoadjuvant endocrine therapy and avelumab with or without palbociclib in stage II/III endocrine receptor-positive breast cancer: the ImmunoADAPT trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-01-09.

Diffusion-Weighted Imaging for Skin Pathologies of the Breast-A Feasibility Study.

Several breast pathologies can affect the skin, and clinical pathways might differ significantly depending on the underlying diagnosis. This study investigates the feasibility of using diffusion-weighted imaging (DWI) to differentiate skin pathologies in breast MRIs. This retrospective study included 88 female patients who underwent diagnostic breast MRI (1.5 or 3T), including DWI. Skin areas were manually segmented, and the apparent diffusion coefficients (ADCs) were compared between different pathologies: inflammatory breast cancer (IBC; n = 5), benign skin inflammation (BSI; n = 11), Paget's disease (PD; n = 3), and skin-involved breast cancer (SIBC; n = 11). Fifty-eight women had healthy skin (H; n = 58). The SIBC group had a significantly lower mean ADC than the BSI and IBC groups. These differences persisted for the first-order features of the ADC (mean, median, maximum, and minimum) only between the SIBC and BSI groups. The mean ADC did not differ significantly between the BSI and IBC groups. Quantitative DWI assessments demonstrated differences between various skin-affecting pathologies, but did not distinguish clearly between all of them. More extensive studies are needed to assess the utility of quantitative DWI in supplementing the diagnostic assessment of skin pathologies in breast imaging.

Abstract 776: Change in background contrast enhancement category on abbreviated breast MRI with administration of 6 months of bazedoxifene and conjugated estrogen vs wait list control

Abstract Background MRI background contrast enhancement (BPE) has found to be a marker of breast cancer risk providing information beyond that provided by assessment of breast density. BPE is qualitatively classified into categories that correspond to BPE estimates as minimal, <25% BPE; mild, 25-50% BPE; moderate, 50-75% BPE; and marked, >75% BPE. We divided minimal into minimal and almost none (≤5%). We conducted a feasibility study of change in BPE after 6 months of the selective estrogen receptor modulator bazedoxifene (BZA) 20 mg + conjugated estrogen (CE) 0.45 mg marketed commercially as Duavee™ for relief of hot flashes and prevention of osteoporosis in postmenopausal women. Methods STUDY00145121 started 5-27-2020 with randomization to 6 months of Duavee™ vs waitlist control but was stopped after 11 entrants because participants were unable to receive follow-up breast MRIs due to COVID and Duavee™ became unavailable. STUDY0014761 was opened in early 2022 when a source of BZA was found. Doses of BZA and CE were the same as Duavee™ but given as two pills instead of one. 16 women have been randomized to 6 months of BZA/CE vs a wait list control between 2-14-2022 and 9-19-2023. Inclusion criteria are postmenopausal women ages 45-65 at increased risk for breast cancer, BMI < 36 kg/m2 and having current vasomotor symptoms. Participants had a blood draw, 3D mammogram, and abbreviated breast MRI at baseline and the studies were repeated at 6 months. Volumetric density was assessed by Volpara™ fully automated software. Research evaluation of abbreviated MRI background parenchymal contrast enhancement (BPE) was assessed by 5 categories as almost none, minimal, mild, moderate, and marked. BPE was evaluated by a single radiologist blinded to treatment assignment and compared to the 4-category clinical assessment. Results A total of 27 women have been entered in these studies. Six were not evaluable from STUDY00145121 because of the inability to perform 6-month MRI. Two women on STUDY0014761 are not endpoint evaluable due to early drop out and 3 have not yet completed study. A total of 16 women have completed the 6-month portion of the study and abbreviated MRI, with median age 55 (range 47-62) and median BMI 26 kg/m2 (20-33 kg/m2). At baseline, BPE were 3 almost none, 4 minimal, 8 mild, 1 moderate, and 0 marked. There was little correlation between absolute baseline mammographic fibroglandular volume and baseline BPE. A shift in BPE category using the 5-category assessment was noted in 6/11 women (all but one decreased) randomized to BZA +CE and 2/5 women (both decreased) on waitlist. The one increase and four categorical decreases would not have been detected without expansion of BPE to a 5-category system. Conclusion Using the 5-category classification, abbreviated MRI BPE may have promise as a response biomarker in prevention trials for postmenopausal high-risk women. Citation Format: Carol J. Fabian, Onilisa Winblad, Amy Kreutzjans, Krystal Pittman, Christy Altman, Kandy R. Powers, Mary McCarthy, Lauren Nye, Bruce F. Kimler. Change in background contrast enhancement category on abbreviated breast MRI with administration of 6 months of bazedoxifene and conjugated estrogen vs wait list control [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 776.

Multiparametric MR-based radiomics fusion combined with quantitative stratified ADC-defined tumor habitats for differentiating TNBC versus non-TNBC

Objective. To investigate the incremental value of quantitative stratified apparent diffusion coefficient (ADC) defined tumor habitats for differentiating triple negative breast cancer (TNBC) from non-TNBC on multiparametric MRI (mpMRI) based feature-fusion radiomics (RFF) model. Approach. 466 breast cancer patients (54 TNBC, 412 non-TNBC) who underwent routine breast MRIs in our hospital were retrospectively analyzed. Radiomics features were extracted from whole tumor on T2WI, diffusion-weighted imaging, ADC maps and the 2nd phase of dynamic contrast-enhanced MRI. Four models including the RFF model (fused features from all MRI sequences), RADC model (ADC radiomics feature), StratifiedADC model (tumor habitas defined on stratified ADC parameters) and combinational RFF-StratifiedADC model were constructed to distinguish TNBC versus non-TNBC. All cases were randomly divided into a training (n = 337) and test set (n = 129). The four competing models were validated using the area under the curve (AUC), sensitivity, specificity and accuracy. Main results. Both the RFF and StratifiedADC models demonstrated good performance in distinguishing TNBC from non-TNBC, with best AUCs of 0.818 and 0.773 in the training and test sets. StratifiedADC model revealed significant different tumor habitats (necrosis/cysts habitat, chaotic habitat or proliferative tumor core) between TNBC and non-TNBC with its top three discriminative parameters (p < 0.05). The integrated RFF-StratifiedADC model demonstrated superior accuracy over the other three models, with higher AUCs of 0.832 and 0.784 in the training and test set, respectively (p < 0.05). Significance. The RFF-StratifiedADC model through integrating various tumor habitats’ information from whole-tumor ADC maps-based StratifiedADC model and radiomics information from mpMRI-based RFF model, exhibits tremendous promise for identifying TNBC.

Quantifying changes in shoulder orientation between the prone and supine positions from magnetic resonance imaging

BackgroundPredicting breast tissue motion using biomechanical models can provide navigational guidance during breast cancer treatment procedures. These models typically do not account for changes in posture between procedures. Difference in shoulder position can alter the shape of the pectoral muscles and breast. A greater understanding of the differences in the shoulder orientation between prone and supine could improve the accuracy of breast biomechanical models. Methods19 landmarks were placed on the sternum, clavicle, scapula, and humerus of the shoulder girdle in prone and supine breast MRIs (N = 10). These landmarks were used in an optimization framework to fit subject-specific skeletal models and compare joint angles of the shoulder girdle between these positions. FindingsThe mean Euclidean distance between joint locations from the fitted skeletal model and the manually identified joint locations was 15.7 mm ± 2.7 mm. Significant differences were observed between prone and supine. Compared to supine position, the shoulder girdle in the prone position had the lateral end of the clavicle in more anterior translation (i.e., scapula more protracted) (P < 0.05), the scapula in more protraction (P < 0.01), the scapula in more upward rotation (associated with humerus elevation) (P < 0.05); and the humerus more elevated (P < 0.05) for both the left and right sides. InterpretationShoulder girdle orientation was found to be different between prone and supine. These differences would affect the shape of multiple pectoral muscles, which would affect breast shape and the accuracy of biomechanical models.

How Does Diagnostic Accuracy Evolve with Increased Breast MRI Experience?

Introduction: Our institution is part of a provincial program providing annual breast MRI screenings to high-risk women. We assessed how MRI experience, background parenchymal enhancement (BPE), and the amount of fibroglandular tissue (FGT) affect the biopsy-proven predictive value (PPV3) and accuracy for detecting suspicious MRI findings. Methods: From all high-risk screening breast MRIs conducted between 1 July 2011 and 30 June 2020, we reviewed all BI-RADS 4/5 observations with pathological tissue diagnoses. Overall and annual PPV3s were computed. Radiologists with fewer than ten observations were excluded from performance analyses. PPV3s were computed for each radiologist. We assessed how MRI experience, BPE, and FGT impacted diagnostic accuracy using logistic regression analyses, defining positive cases as malignancies alone (definition A) or malignant or high-risk lesions (definition B). Findings: There were 536 BI-RADS 4/5 observations with tissue diagnoses, including 77 malignant and 51 high-risk lesions. A total of 516 observations were included in the radiologist performance analyses. The average radiologist's PPV3 was 16 ± 6% (definition A) and 25 ± 8% (definition B). MRI experience in years correlated significantly with positive cases (definition B, OR = 1.05, p = 0.03), independent of BPE or FGT. Diagnostic accuracy improved exponentially with increased MRI experience (definition B, OR of 1.27 and 1.61 for 5 and 10 years, respectively, p = 0.03 for both). Lower levels of BPE significantly correlated with increased odds of findings being malignant, independent of FGT and MRI experience. Summary: More extensive MRI reading experience improves radiologists' diagnostic accuracy for high-risk or malignant lesions, even in MRI studies with increased BPE.

Clinical and Imaging Features of MRI Screen-Detected Breast Cancer

BackgroundSupplemental screening with breast MRI is recommended annually for patients who have greater than 20% lifetime risk for breast cancer. While there is robust data regarding features of mammographic screen-detected breast cancers, there is limited data regarding MRI-screen-detected cancers. Patients and MethodsScreening breast MRIs performed between August 1, 2016 and July 30, 2022 identified 50 screen-detected breast cancers in 47 patients. Clinical and imaging features of all eligible cancers were recorded. ResultsDuring the study period, 50 MRI-screen detected cancers were identified in 47 patients. The majority of MRI-screen detected cancers (32/50, 64%) were invasive. Pathology revealed ductal carcinoma in situ (DCIS) in 36% (18/50), invasive ductal carcinoma (IDC) in 52% (26/50), invasive lobular carcinoma in 10% (5/50), and angiosarcoma in 2% (1/50). The majority of patients (43/47, 91%) were stage 0 or 1 at diagnosis and there were no breast cancer-related deaths during the follow-up periods. Cancers presented as masses in 50% (25/50), nonmass enhancement in 48% (25/50), and a focus in 2% (1/50). DCIS was more likely to present as nonmass enhancement (94.4%, 17/18), whereas invasive cancers were more likely to present as masses (75%, 24/32) (P < .001). All cancers that were stage 2 at diagnosis were detected either on a baseline exam or more than 4 years since the prior MRI exam. ConclusionMRI screen-detected breast cancers were most often invasive cancers. Cancers detected by MRI screening had an excellent prognosis in our study population. Invasive cancers most commonly presented as a mass.

Breast MRI in patients with implantable loop recorder: initial experience.

To investigate the feasibility of breast MRI exams and guided biopsies in patients with an implantable loop recorder (ILR) as well as the impact ILRs may have on image interpretation. This retrospective study examined breast MRIs of patients with ILR, from April 2008 to September 2022. Radiological reports and electronic medical records were reviewed for demographic characteristics, safety concerns, and imaging findings. MR images were analyzed and compared statistically for artifact quantification on the various pulse sequences. Overall, 40/82,778 (0.049%) MRIs during the study period included ILR. All MRIs were completed without early termination. No patient-related or device-related adverse events occurred. ILRs were most commonly located in the left lower-inner quadrant (64.6%). The main artifact was a signal intensity (SI) void in a dipole formation in the ILR bed with or without areas of peripheral high SI. Artifacts appeared greatest in the cranio-caudal axis (p < 0.001), followed by the anterior-posterior axis (p < 0.001), and then the right-left axis. High peripheral rim-like SI artifacts appeared on the post-contrast and subtracted T1-weighted images, mimicking suspicious enhancement. Artifacts were most prominent on diffusion-weighted (p < 0.001), followed by T2-weighted and T1-weighted images. In eight patients, suspicious findings were found on MRI, resulting in four additional malignant lesions. Of six patients with left breast cancer, the tumor was completely visible in five cases and partially obscured in one. Breast MRI is feasible and safe among patients with ILR and may provide a significant diagnostic value, albeit with localized, characteristic artifacts. Indicated breast MRI exams and guided biopsies can be safely performed in patients with implantable loop recorder. Nevertheless, radiologists should be aware of associated limitations including limited assessment of the inner left breast and pseudo-enhancement artifacts. • Breast MRI in patients with an implantable loop recorder is an infrequent, feasible, and safe procedure. • Despite limited breast visualization of the implantable loop recorder bed and characteristic artifacts, MRI depicted additional lesions in 8/40 (20%) of cases, half of which were malignant. • Breast MRI in patients with an implantable loop recorder should be performed when indicated, taking into consideration typical associated artifacts.

A Diagnostic Dilemma: New Enhancing Suspicious Findings on Breast MRI Following Neoadjuvant Chemotherapy.

Evaluate the incidence and outcome of new enhancing findings on breast MRI after neoadjuvant chemotherapy (NAC). This IRB-approved retrospective review included women with breast cancer undergoing MRI to evaluate NAC response at our institution from January 1, 1998 to March 3, 2021. Post-NAC MRIs given BI-RADS 4 or 5 with new enhancing findings were identified. Patients were excluded if they lacked pretreatment MRI or insufficient follow-up, or if the finding was a satellite of the primary tumor. Medical records and imaging studies were reviewed to identify patients and to find characteristics and outcomes. Over the study period, 2880 post-NAC breast MRIs were performed. Of 128 post-NAC MRIs given BI-RADS 4 or 5 (4.4%), 35 new suspicious findings were found on 32 MRIs, incidence rate 1.1% (32/2880). Most were characterized as nonmass enhancement (17/35, 49%), followed by mass (11/35, 31%), and then focus (7/35, 20%), with an average maximum dimension of 1.3 cm (range 0.3-7.1 cm). New findings were ipsilateral to the index cancer in 20/35 (57%) of cases. Of the 35 suspicious findings, 22 underwent image-guided biopsy (62%), 1 was surgically excised (3%), 7 underwent mastectomy (20%), 5 were stable or resolved on follow-up (8%), and none were malignant. Thirty-three were benign (94%), and two were benign high-risk lesions (atypical ductal hyperplasia, radial scar) (6%). New suspicious breast MRI findings after NAC are uncommon with a low likelihood of malignancy. Further study is warranted using multi-institutional data for this low incidence finding.

Circumscribed Masses on Breast MRI: Can MRI Features Guide Management?

Management of circumscribed breast masses seen on MRI is largely extrapolated from mammography and US data with limited MRI-specific data available. This study aimed to assess clinical and MRI imaging features of malignant circumscribed breast masses. In this IRB-approved retrospective study, breast MRIs performed between April 1, 2008, and August 30, 2020, containing circumscribed masses, excluding multiple bilateral circumscribed masses, were reviewed. Clinical and imaging features of all eligible masses were recorded, and associations with malignant outcomes were assessed using Fisher's exact test and Wilcoxon rank sum test, with P < 0.05 considered significant. For the 165 masses that met study criteria in 158 women, the mean age was 48 years (SD 12.0 years). Nine of 165 masses were malignant (5.5%). Round masses were significantly more likely to be malignant (7/37, 18.9%) compared to oval masses (2/128, 1.7%) (P < 0.001). Among masses with available dynamic contrast kinetics data, the malignancy rate was 0/84 (0%) for persistent kinetics, 2/23 (8.7%) for plateau kinetics, and 4/24 (16.7%) for washout kinetics (P = 0.002). The malignancy rate for oval masses without washout kinetics was 0% (0/92). T2 hyperintense masses had a malignancy rate of 7/104 (6.7%), and homogeneously enhancing masses had a malignancy rate of 5/91 (5.5%). These data support the use of mass shape and dynamic contrast enhancement kinetics to guide management of circumscribed breast masses seen by MRI, with oval masses without washout kinetics and any circumscribed mass with persistent kinetics showing no malignancies in this study.

Abstract 3029: Barriers to optimal breast cancer screening modalities for high-risk patients in the primary care setting

Abstract Background: Annual screening breast MRIs are endorsed by current breast cancer screening guidelines as an adjunctive screening modality for high-risk patients (defined by more than 20% lifetime risk) in addition to a screening mammogram. Recent studies showed screening breast MRI remained underutilized despite the current recommendations. On the other hand, validated breast cancer risk models for identifying high-risk patients also remained under-recognized among primary care providers. This study aims to identify the potential barriers for primary care providers (PCPs) to using breast cancer risk models and referring high-risk patients to breast MRI for screening. Methods: An anonymous survey was distributed via email to the PCPs and OB/GYN providers in the network of Mount Auburn Hospital, a community teaching hospital affiliated with Harvard Medical School in Cambridge, Massachusetts. The survey included questions regarding breast cancer screening in average-risk and high-risk patients, providers’ understanding of breast cancer risk models, and current referral status of breast MRIs and high-risk/genetic clinics. Results: The survey was sent to 104 providers, and 43 responses were received. When asked about performing breast cancer risk assessments, 58% reported “Always (91-100%)” and 33% said “Often (71-90%)”. For factors to consider when performing risk assessments, most of the providers considered personal medical history (98%), family history (100%), genetic syndrome history (86%), and previous breast biopsy results (90%). When asked about breast cancer risk models, 58% of the providers had not heard of or used one. 33% of the providers have used the Gail model, and 26% have used the Tyrer-Cuzick model. 51% of the providers correctly identified high-risk as lifetime risk &amp;gt;20%. 56% correctly answered annual mammograms with MRI for breast cancer screening for high-risk patients. The majority of the providers (84%) would prefer to refer patients to the high-risk clinic for risk assessment and screening management. For barriers to referring to MRI, the insurance approval process (49%) was reported to be the largest barrier. 72% of the providers prefer not ordering it and defer to the high-risk/genetic clinic for ordering the test. Conclusions: Our survey has shown different barriers to breast cancer screening in high-risk patients in the primary care setting, including knowledge and logistic barriers. Further education for PCPs is needed for correctly identifying high-risk patients, utilizing risk models, and referring high-risk patients for breast MRI screening. Citation Format: Yu Jen Jan, Prudence B. Lam. Barriers to optimal breast cancer screening modalities for high-risk patients in the primary care setting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3029.

Patterns of Screening Mammography and Breast MRI During the COVID-19 Pandemic: A Retrospective, Chart-Review Study.

This study examined patterns of breast cancer screening during the COVID-19 pandemic. This retrospective study was approved by the Georgetown University IRB. Review of electronic medical records identified screening mammograms and breast MRIs between March 13, 2018 and December 31, 2020, for female patients aged 18 to 85 years. Descriptive statistics characterized patterns of breast cancer screening before and during the COVID-19 pandemic. Logistic regression analyses examined whether receipt of breast MRI differed over time and demographic and clinical factors associated with receipt of breast MRI in 2020. Data included 47 956 mammography visits in 32 778 patients and 407 screening breast MRI visits in 340 patients. After an initial decrease following the declaration of the COVID-19 pandemic, both screening mammograms and screening breast MRI demonstrated early recovery. Although the mammography receipt remained sustained, the receipt of screening breast MRI decreased in late 2020. Odds of having a breast MRI did not differ between 2018 and 2019 (OR = 1.07; 95% CI = 0.92%-1.25%; P = 0.384) but were significantly lower in 2020 versus 2019 (OR = 0.76; 95% CI = 0.61%-0.94%; P = 0.011). No demographic or clinical factors were associated with receipt of breast MRI during the COVID-19 pandemic (all P-values ≥0.225). Breast cancer screening decreased following the declaration of the COVID-19 pandemic. Although both procedures demonstrated early recovery, the rebound in screening breast MRI was not sustained. Interventions promoting return to screening breast MRI may be needed for high-risk women.

MRI-Guided Breast Intervention: Biopsy and Needle Localization

In Korea, the number of institutions providing breast MRI, as well as the number of breast MRIs, has recently increased. However, MRI-guided procedures, including biopsy and needle localization, are rarely performed compared to ultrasound-guided or stereotactic biopsy. As breast MRI has high sensitivity but limited specificity, lesions detected only on MRI require pathologic confirmation through MRI-guided biopsy or surgical excision with MRI-guided needle localization. Thus, we aimed to review MRI-guided procedures, including their indications, techniques, procedural considerations, and limitations.

Evaluation of treatment responses among subgroups of breast cancer patients receiving neoadjuvant chemotherapy.

Breast MRIs are helpful for determining treatment plans, responses, and prospective survival analyses. In this retrospective cross-sectional study, we compared the preoperative MRI treatment response to neoadjuvant chemotherapy (NAC) administration with the postoperative pathological response in breast cancer patients. We analyzed data from 108 hospitalized patients receiving NAC between 2020 and 2022. We used MRI to evaluate the treatment response to NAC in patients with locally advanced breast cancers who had not received any prior treatment. We recorded the longest diameter of the primary tumor and the numbers of secondary tumors and axillary lymph nodes. In addition, we examined the correlation between the MRI response rate and pathological specimen results. In our subgroup analyses, we found the best pathological response in patients with luminal B (Ki-67 index >14%) breast cancer and positivity for both hormone receptor and HER-2 markers. After comparing the pathological and radiological treatment responses in tumors and lymph nodes, the sensitivities were 90.3% for the pathological assessment and 42.8% for the radiological assessment, while the accuracies were 84.2% for the pathological assessment and 61.1% for the radiological assessment. Using MRI techniques and sequence intervals and examining the histopathological characteristics of tumors may help increase the accuracy of the pathological complete response.

A Retrospective Analysis of Sternal Lesions Detected on Breast MRI in Patients Without History of Cancer.

To determine the imaging characteristics and stability over time of sternal lesions identified on breast MRI in patients without history of cancer. An IRB-approved retrospective analysis of all breast MRIs performed at our institution from September 1, 2017 to December 1, 2021 that included one of several key words related to the sternum. Studies with history of non-dermatologic malignancy including breast cancer, absence of a true sternal lesion, or presence of symptoms during the examination were excluded. Imaging was reviewed for size, distribution, signal characteristics, and presence of contrast enhancement, perilesional edema, periosteal edema, or intralesional fat. Available comparison imaging, clinical history, and follow-up recommendations were reviewed. Descriptive statistics were used to summarize lesion data. Of 60 lesions included from 60 patients, 40 lesions with more than two years of comparison imaging were either stable or decreased in size and none demonstrated change in signal characteristics. The majority of these presumed benign lesions demonstrated hypointense signal on T1-weighted sequences (21/40, 52.5%), hyperintense signal on fluid-sensitive sequences (33/40, 82.5%), contrast enhancement (32/40, 80.0%), and absence of clear intralesional fat (29/40, 72.5%). One patient who did not have comparison imaging was diagnosed with malignancy (multiple myeloma) eight months following their MRI. This lesion demonstrated uniquely diffuse and heterogeneous enhancement but did not undergo biopsy. Sternal lesions in women without history of non-dermatologic malignancy have a very low likelihood of malignancy. Common imaging characteristics of the presumed benign lesions can inform imaging recommendations when incidental sternal lesions are discovered.

Does Double Reading of Screening Breast MRI Scans Impact Recall Rates and Cancer Detection?

Objective: To investigate the effect of double reads by a second radiologist on cancer detection rate (CDR), positive predictive value of recommendation for tissue diagnosis (PPV2), and the positive predictive value of biopsy performed (PPV3) for biopsy recommendations in high-risk screening breast MRIs. Methods: The policy of second reads on biopsies recommended for MRIs was prospectively implemented in October 2019. This IRB approved retrospective analysis compared consecutive high-risk screening breast MRI scans performed in a single academic institution between 06/01/2018 to 06/01/2019 (pre-intervention) with screening breast MRI scans performed between 10/31/2019 to 10/31/2020 (post-intervention). Pathology results after biopsy were recorded. Testing of association was performed using the Chi-square test. Results/Discussion: A total of 1124 screening breast MRIs in the pre-intervention and 1672 screening breast MRIs were performed in the post-intervention periods. Biopsies were recommended in 8.6% (97/1124) of pre-intervention and 5.5% (92/1672) of post-intervention MRIs (P = .0012). There was a non-significant increase in PPV2 from pre-intervention 10.3% (10/97) to post-intervention 18.4% (17/92) (P = .109) and in PPV3 from 14% (10/71) to 22.9% (17/74), respectively (P = .17). Similar cancer detection rates, 8.9/1000 (10/1124) and 10.2/1000 (17/1672) (P = .736) were diagnosed in pre-intervention and post-intervention periods, respectively. Conclusion: Double reading of screening breast MRI scans significantly reduced the number of unnecessary biopsies without significant impact in the PPVs or cancer detection rate.

Improving the breast MRI process: A longitudinal QI project at the Houston VA.

371 Background: The number of female veterans is increasing by more than 18,000 per year, and 700 veterans enrolled in VA healthcare are diagnosed with breast cancer each year. The American Cancer Society recommends screening MRI in women with 20-25% or greater lifetime risk of breast cancer, and primary care physicians and oncologists order breast MRIs regularly. The Michael E. DeBakey Veteran’s Affairs Medical Center (MEDVAMC) performs mammograms and ultrasounds on site, but breast MRI is not currently available. Care in the Community arranges for veterans to obtain these studies at outside facilities. This is a complex process, requiring coordination among multiple departments at the MEDVAMC, outside MRI facilities, and patients. Methods: We created a comprehensive process map for the current breast MRI ordering process to determine areas for improvement. We reviewed all breast MRI orders from 1/2019 to 5/2021 at the MEDVAMC and determined the cancellation rate and the rate of benign (BIRADS 1-2) vs non benign (BIRADS 0, 3-5) screening outcomes. We created a Pareto analysis of cancellation reasons. Our process measures were percentage of placed breast MRI orders that were cancelled and delay from MRI order to MRI performed. Our outcome measures were percentage of order cancellations due to incorrect or incomplete orders and delay from MRI order placement to results uploaded. Results: Of the 434 orders that were placed for breast MRIs, 64% were cancelled. Only 117 of the 167 patients that had MRIs ordered ultimately received one. Of the 104 patients without known malignancy who competed an MRI, 45% had non-benign findings requiring follow-up. Our pareto analysis showed that the top cancellation reason was incorrect orders, usually contrast or side verbiage. In June 2021, the CITC order set for MRI was changed from a free text box to discrete, clickable options for side and contrast. In December 2021, we held educational interventions on how to avoid delay or cancellation. Our p-chart of percentage of cancellations due to incorrect ordering shows an extremely promising decrease, with the last seven consecutive subgroups of 15 patients below the mean. The order cancellation percentage is also decreasing. The average delay pre-intervention from MRI order placement to results uploaded was 67 days. In January 2022, we implemented a breast MRI nurse navigator to help acquire results and expedite scheduling. Post-intervention, the average delay has decreased to 38.5 days. Using XmR and S charts, we have also shown an increase in precision. Conclusions: Providing discrete, clickable options within the MRI order set reduced the number of cancellations due to incorrect verbiage. Early data suggests that the educational intervention improved the cancellation rate. Instituting a nurse navigator decreased both the delay and variability for the time from order placement to results received, which will reduce the delay to follow-up of non-benign findings.