Diffusion weighted MRI (DWI) holds potential to improve the detection and biological characterization of breast cancer. DWI is increasingly being incorporated into breast MRI protocols to address some of the shortcomings of routine clinical breast MRI. Potential benefits include improved differentiation of benign and malignant breast lesions, assessment and prediction of therapeutic efficacy, and non-contrast detection of breast cancer. The breast presents a unique imaging environment with significant physiologic and inter-subject variations, as well as specific challenges to achieving reliable high quality diffusion weighted MR images. Technical innovations are helping to overcome many of the image quality issues that have limited widespread use of DWI for breast imaging. Advanced modeling approaches to further characterize tissue perfusion, complexity, and glandular organization may expand knowledge and yield improved diagnostic tools.

Purpose:To investigate whether qualitative magnetic resonance (MR) imaging assessments of background parenchymal enhancement (BPE), amount of fibroglandular tissue (FGT), and mammographic density are associated with risk of developing breast cancer in women who are at high risk. Materials and Methods:In this institutional review board-approved HIPAA-compliant retrospective study, all screening breast MR images obtained from January 2006 to December 2011 in women aged 18 years or older and at high risk for but without a history of breast cancer were identified. Women in whom breast cancer was diagnosed after index MR imaging comprised the cancer cohort, and one-to-one matching (age and BRCA status) of each woman with breast cancer to a control subject was performed by using MR images obtained in women who did not develop breast cancer with follow-up time maximized. Amount of BPE, BPE pattern (peripheral vs central), amount of FGT at MR imaging, and mammographic density were assessed on index images. Imaging features were compared between cancer and control cohorts by using conditional logistic regression. Results:Twenty-three women at high risk (mean age, 47 years 6 10 [standard deviation]; six women had BRCA mutations) with no history of breast cancer underwent screening breast MR imaging; in these women, a diagnosis of breast cancer (invasive, n = 12; in situ, n = 11) was made during the follow-up interval. Women with mild, moderate, or marked BPE were nine times more likely to receive a diagnosis of breast cancer during the follow-up interval than were those with minimal BPE (P = .007; odds ratio = 9.0; 95% confidence interval: 1.1, 71.0). BPE pattern, MR imaging amount of FGT, and mammographic density were not significantly different between the cohorts (P = .5, P = .5, and P = .4, respectively). Conclusion:Greater BPE was associated with a higher probability of developing breast cancer in women at high risk for cancer and warrants further study.q RSNA, 2015

Importance: Improved screening methods for women with dense breasts are needed because of their increased risk of breast cancer and of failed early diagnosis by screening mammography. Objective: To compare the screening performance of abbreviated breast MRI (AB-MR), and digital breast tomosynthesis (DBT) in women with dense breasts. Design, Setting, and Participants: Cross-sectional study with longitudinal follow-up at 48 academic, community hospital, and private practice sites in the US and Germany, conducted between December 2016 and November 2017, that included average-risk women aged 40-75 years with heterogeneously dense or extremely dense breasts undergoing routine screening. Follow up ascertainment of cancer diagnoses was complete through September 12 th , 2019. Exposure: All women underwent screening by both DBT and AB-MR, performed in randomized order and read independently to avoid interpretation bias. Main outcome measures: The primary endpoint was the invasive cancer detection rate. Secondary outcomes included sensitivity, specificity, the additional-imaging-recommendation-rate, and positive predictive value (PPV) of biopsy, using invasive cancer and DCIS to define a positive reference standard. All outcomes are reported at the participant level. Pathology of core or surgical biopsy was the reference standard for cancer detection rate and PPV; interval cancers reported until the next annual screen were included in the reference standard for sensitivity and specificity. Results: Among 1516 enrolled women, 1444 (median age 54, range 40-75) completed both examinations and were included in the analysis. The reference standard was positive for invasive cancer with or without DCIS in 17 women, and for DCIS alone in another 6. No interval cancers were observed during follow-up. AB-MR detected all 17 women with invasive cancer, and 5/6 women with DCIS. DBT detected 7/17 women with invasive cancer, and 2/6 women with DCIS. The invasive-cancer-detection-rate was 11.8 per 1000 women [95% CI 7.4-18.8] for AB-MR versus 4.8 per 1000 women [95% CI 2.4-10.0] for DBT, a difference of 7 per 1000 women [95% CI for the difference 2.2-11.6] (exact McNemar p=0.002). For detection of invasive cancer and Comstock et al.

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Purpose: Conventional breast MRI is highly sensitive for cancer detection but prompts some false-positives. We performed a prospective, multicenter study to determine whether apparent diffusion coefficients (ADCs) from diffusion weighted imaging (DWI) can decrease MRI false-positives. Experimental Design: 107 women with MRI-detected BI-RADS 3, 4, or 5 lesions were enrolled from March 2014 to April 2015. ADCs were measured both centrally and at participating sites. Receiver operating characteristic (ROC) analysis was employed to assess diagnostic performance of centrally-measured ADCs and identify optimal ADC thresholds to reduce unnecessary biopsies. Lesion reference standard was based on either definitive biopsy result or at least 337 days of follow-up after the initial MRI procedure. Results: Of 107 women enrolled, 67 patients (median age 49, range 24–75 years) with 81 lesions with confirmed reference standard (28 malignant, 53 benign) and evaluable DWI were analyzed. 67/81 lesions were BI-RADS 4 (n=63) or 5 (n=4) and recommended for biopsy. Malignancies exhibited lower mean centrally-measured ADCs (mm2/s) than benign lesions (1.21×10−3 vs.1.47×10−3, p<0.0001, area under ROC curve=0.75, 95% confidence interval [CI] 0.65–0.84). In centralized analysis, application of an ADC threshold (1.53×10−3 mm2/s) lowered the biopsy rate by 20.9% (14/67; 95% CI 11.2–31.2%) without affecting sensitivity. Application of a more conservative threshold (1.68×10−3mm2/s) to site-derived ADCs reduced the biopsy rate by 26.2%(16/61) but missed three cancers. Conclusion: DWI can re-classify a substantial fraction of suspicious breast MRI findings as benign and thereby decrease unnecessary biopsies. ADC thresholds identified in this trial should be validated in future Phase III studies.

Synopsis Breast MRI has increased in popularity over the past two decades due to evidence for its high sensitivity for cancer detection. Current clinical MRI approaches rely on the use of a dynamic contrast enhanced (DCE-MRI) acquisition that facilitates morphologic and semi-quantitative kinetic assessments of breast lesions. The use of more functional and quantitative parameters, such as pharmacokinetic features from high temporal resolution DCE-MRI, apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) on diffusion weighted MRI, and choline concentrations on MR spectroscopy, hold promise to broaden the utility of MRI and improve its specificity. However, due to wide variations in approach among centers for measuring these parameters and the considerable technical challenges, robust multicenter data supporting their routine use is not yet available, limiting current applications of many of these tools to research purposes.

This study investigated the relationship between apparent diffusion coefficient (ADC) measures and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) kinetics in breast lesions, and evaluated the relative diagnostic value of each quantitative parameter. Seventy-seven women with 100 breast lesions (27 malignant and 73 benign) underwent both DCE-MRI and diffusion weighted MRI (DWI). DCE-MRI kinetic parameters included peak initial enhancement, predominant delayed kinetic curve type (persistent, plateau or washout), and worst delayed kinetic curve type (washout>plateau>persistent). Associations between ADC and DCE-MRI kinetic parameters and predictions of malignancy were evaluated. Results showed that ADC was significantly associated with predominant curve type (ADC was higher for lesions exhibiting predominantly persistent enhancement compared to those exhibiting predominantly washout or plateau, p=0.006), but was not significantly associated with peak initial enhancement or worst curve type (p>0.05). Univariate analysis showed significant differences between benign and malignant lesions in both ADC (p<0.001) and worst curve (p =0.003). In multivariate analysis, worst curve type and ADC were significant independent predictors of benign versus malignant outcome and in combination produced the highest area under the ROC curve (AUC = 0.85, AUC=0.78 with 5-fold cross-validation).

The approach to breast masses in children differs from that in adults in many ways, including the differential diagnostic considerations, imaging algorithm and appropriateness of biopsy as a means of further characterization. Most pediatric breast masses are benign, either related to breast development or benign neoplastic processes. Biopsy is rarely needed and can damage the developing breast; thus radiologists must be familiar with the imaging appearance of common entities so that biopsies are judiciously recommended. The purpose of this article is to describe the imaging appearances of the normally developing pediatric breast as well as illustrate the imaging findings of a spectrum of diseases, including those that are benign (fibroadenoma, juvenile papillomatosis, pseudoangiomatous stromal hyperplasia, gynecomastia, abscess and fat necrosis), malignant (breast carcinoma and metastases), and have variable malignant potential (phyllodes tumor).