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BACKGROUND: Diffusion-weighted imaging (DWI) has shown promise to screen for breast cancer without a contrast injection, but image distortion and low spatial resolution limit standard single-shot DWI. Multishot DWI methods address these limitations but introduce shot-to-shot phase variations requiring correction during reconstruction. PURPOSE: To investigate the performance of two multishot DWI reconstruction methods, multiplexed sensitivity encoding (MUSE) and shot locally low-rank (shot-LLR), compared to single-shot DWI in the breast. STUDY TYPE: Prospective. POPULATION: A total of 45 women who consented to have multishot DWI added to a clinically indicated breast MRI. FIELD STRENGTH/SEQUENCES: Single-shot DWI reconstructed by parallel imaging, multishot DWI with four or eight shots reconstructed by MUSE and shot-LLR, 3D T2 -weighted imaging, and contrast-enhanced MRI at 3T. ASSESSMENT: Three blinded observers scored images for 1) general image quality (perceived signal-to-noise ratio [SNR], ghosting, distortion), 2) lesion features (discernment and morphology), and 3) perceived resolution. Apparent diffusion coefficient (ADC) of the lesion was also measured and compared between methods. STATISTICAL TESTS: Image quality features and perceived resolution were assessed with a mixed-effects logistic regression. Agreement among observers was estimated with a Krippendorf's alpha using linear weighting. Lesion feature ratings were visualized using histograms, and correlation coefficients of lesion ADC between different methods were calculated. RESULTS: MUSE and shot-LLR images were rated to have significantly better perceived resolution (P < 0.001), higher SNR (P < 0.005), and a lower level of distortion (P < 0.05) with respect to single-shot DWI. Shot-LLR showed reduced ghosting artifacts with respect to both MUSE (P < 0.001) and single-shot DWI (P < 0.001). Eight-shot DWI had improved perceived SNR and perceived resolution with respect to four-shot DWI (P < 0.005). DATA CONCLUSION: Multishot DWI enables increased resolution and improved image quality with respect to single-shot DWI in the breast. Shot-LLR reconstructs multishot DWI with minimal ghosting artifacts. The improvement of multishot DWI in image quality increases with an increased number of shots. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

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OBJECTIVE: To compare positive predictive values (PPVs) of clumped vs non-clumped (homogenous and heterogeneous) internal enhancement on MRI detected linear non-mass enhancement (NME) on MRI-guided vacuum-assisted breast biopsy (MRI-VABB). METHODS: With IRB (Institutional Review Board) approval, we retrospectively reviewed 598 lesions undergoing MRI-VABB from January 2015 to April 2018 that showed linear NME. We reviewed the electronic medical records for MRI-VABB pathology, any subsequent surgery and clinical follow-up. The X2 test was performed for univariate analysis. RESULTS: There were 120/598 (20%) linear NME MRI-VABB lesions with clumped (52/120, 43%) vs non-clumped (68/120, 57%) internal enhancement, average size 1.8 cm (range 0.6-7.6 cm). On MRI-VABB, cancer was identified in 22/120 (18%) lesions, ductal carcinoma in situ (DCIS) was found in 18/22 (82%) and invasive cancer in 4 (18%). 3/31 (10%) high-risk lesions upgraded to DCIS at surgery, for a total of 25/120 (21%) malignancies. Malignancy was found in 12/52 (23%) clumped lesions and in 13/68 (19%) of non-clumped lesions that showed heterogeneous (5/13, 38%) or homogenous (8/13, 62%) internal enhancement. The PPV of linear NME with clumped internal enhancement (23.1%) was not significantly different from the PPV of non-clumped linear NME (19.1%) (p = 0.597). The PPV of linear NME lesions <1 cm (33.3%) was not significantly different from the PPV of lesions ≥1 cm (18.6%) (p = 0.157). CONCLUSIONS: Linear NME showed malignancy in 21% of our series. Linear NME with clumped or non-clumped internal enhancement patterns, regardless of lesion size, might need to undergo MRI-VABB in appropriate populations. ADVANCES IN KNOWLEDGE: Evaluation of linear NME lesions on breast MRI focuses especially on internal enhancement pattern.

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BACKGROUND: To evaluate imaging characteristics, outcome of surgical excision or imaging follow-up on high-risk lesions diagnosed at MRI-guided vacuum-assisted breast biopsy (MRI-VABB). METHODS: We retrospectively reviewed 598 lesions undergoing 9-gauge MRI-VABB from January 2015 to April 2018 to identify high risk breast lesions. We collected patient demographics, breast MRI BI-RADS descriptors, histopathological diagnosis at MRI-VABB and surgical excision, frequency of upgrade to malignancy and imaging follow-up of high-risk lesions. The x2 test and Fisher exact tests were performed for univariate analysis. RESULTS: 114 patients with 124/598 findings (20.7%) had high-risk lesions at MRI-VABB, including atypical ductal hyperplasia (ADH) (21/124, 16.9%), lobular neoplasia (40/124, 32.3%), radial scar/complex sclerosing lesion (RS/CSL) (13/124, 10.5%), papillary lesions (49/124, 39.5%), and flat epithelial atypia (FEA) (1/124, 0.8%). 84/124 (67.7%) high-risk lesions were excised. 19/84 (22.6%) were upgraded to malignancy (7 invasive cancer, 12 DCIS). The upgrade rate for ADH and lobular neoplasia was 7/18 (38.9%) and 9/31 (29.0%), respectively. The upgrade rate for RS/CSL was 1/10 (10%). Of the 25 papillary lesions excised, 2 (8%) demonstrated pathologic atypia and were upgraded to DCIS. The other 23 papillary lesions had no upgrade or atypia. Excised high-risk lesions showing upgrade varied from 0.4 to 6 cm in length (mean 1.6 cm). There was a non-significant trend (p = 0.054) between larger lesion and upgrade to malignancy; however, there were no other specific imaging features to predict malignancy upgrade. CONCLUSIONS: There were no specific MRI imaging characteristics of high-risk lesions to predict malignancy upgrade. Therefore, surgical excision is recommended for high-risk lesions, especially ADH or lobular neoplasia.

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OBJECTIVE: Fibrocystic change (FCC) is considered one of the most common benign findings in the breast and may be commonly seen on breast MRI. We performed this study to identify MRI characteristics of pure FCC on MRI-guided vacuum-assisted breast biopsy (VABB) without other associated pathologies and describe the findings on MRI follow-up and outcomes. METHODS: A retrospective review was performed for 598 lesions undergoing 9-gauge MRI-guided VABB at our institution from January 2015 to April 2018, identifying 49 pure FCC lesions in 43 patients. The associations between variables and lesion changes on follow-up MRI were analyzed using exact Mann-Whitney tests and Fisher's exact tests. RESULTS: MRI features of pure FCC are predominantly clumped nonmass enhancement (19/49, 39%) or irregular masses with initial fast/late washout kinetics (9/49, 18%). There was no upgrade to high-risk or cancerous lesions among the 11 patients (25.6%) who underwent surgery. There were 22 pure FCC lesions in 19 (44.2%) patients who had follow-up MRI (mean 18.0 months, range 11-41 months) showing regression (13, 59%), stability (8, 36%), or progression (1, 5%) of the lesion size, and no cancers were found on follow-up at the site of the MRI biopsy for fibrocystic changes. No patient demographics or lesion features were associated with lesion regression or stability (P > 0.05). CONCLUSION: Our study shows that MRI features of VABB-proven FCC lesions may mimic malignancy. After VABB of pure FCC, given that adequate sampling has been performed, a 12-month follow-up MRI may be reasonable.

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PURPOSE: To compare the detectability of unenhanced abbreviated magnetic resonance imaging (MRI) based on diffusion-weighted imaging (DWI) and abbreviated postcontrast MRI for breast cancer. METHODS: The study population consisted of 87 patients undergoing breast MRI between December 2016 and March 2017 in a clinical setting. All breast MRIs were performed using a 1.5-T MRI scanner with a 16-channel breast radiofrequency coil. The abbreviated protocols based on DWI (AP1) and postcontrast MRI (AP2) were assessed independently by two radiologists. Sensitivity and specificity were calculated. Receiver operating characteristic analysis was performed and the areas under the curves (AUCs) were compared between AP1 and AP2. RESULTS: The study included 87 patients with 89 breast cancer lesions ≤ 2 cm in diameter. The sensitivity/specificity for AP1 and AP2 for reader 1 was 89.9/97.6% and 95.5/90.6%, respectively, and those for reader 2 was 95.5/94.1% and 98.9/94.1%, respectively. The AUCs for AP1 and AP2 for reader 1 were 0.9629 and 0.9640 (p = 0.95), respectively, and those for reader 2 were 0.9755 and 0.9843 (p = 0.46), respectively. CONCLUSIONS: The detectability of the unenhanced abbreviated protocol based on DWI would be comparable to that of abbreviated postcontrast MRI for breast cancer.

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OBJECTIVE: The purpose of this study is to analyze the association between the probability of malignancy and breast mass descriptors in the BI-RADS 5th edition and to devise criteria for grading mass lesions, including subcategorization of category 4 lesions with or without apparent diffusion coefficient (ADC) values. MATERIALS AND METHODS: A total of 519 breast masses in 499 patients were selected. Breast MRI was performed with a 1.5-T MRI scanner using a 16-channel dedicated breast radiofrequency coil. Two radiologists determined the morphologic and kinetic features of the breast masses. Mean ADC values were measured on ADC maps by placing round ROIs that encircled the largest possible solid mass portions. An optimal ADC threshold was chosen to maximize the Youden index. Corresponding pathologic diagnoses were obtained by either biopsy or surgery. RESULTS: A total of 472 masses were malignant. Multivariate model analysis showed that shape (irregular, p < 0.001), margin type (not circumscribed, p < 0.001), internal enhancement (rim enhancement and heterogeneous enhancement, p = 0.0001), and delayed phase (washout, p = 0.0003) were the significant explanatory variables. The 3-point scoring system for findings suspicious for malignancy and the proposed classification system for breast mass descriptors (with points for category designation ranging from 0 to > 4) were significant with respect to malignancy (p < 0.01). The inclusion of ADC values improved the positive predictive values for categories 3, 4A, and 4B. CONCLUSION: The 3-point scoring system for findings suspicious for malignancy and the proposed classification system for breast mass descriptors would be valid as a categorization system. ADC values may be used to downgrade benign lesions in categories 3, 4A, and 4B.

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PURPOSE: To analyze the association of breast non-mass enhancement descriptors in the BI-RADS 5th edition with malignancy, and to establish a grading system and categorization of descriptors. MATERIALS AND METHODS: This study was approved by our institutional review board. A total of 213 patients were enrolled. Breast MRI was performed with a 1.5-T MRI scanner using a 16-channel breast radiofrequency coil. Two radiologists determined internal enhancement and distribution of non-mass enhancement by consensus. Corresponding pathologic diagnoses were obtained by either biopsy or surgery. The probability of malignancy by descriptor was analyzed using Fisher's exact test and multivariate logistic regression analysis. The probability of malignancy by category was analyzed using Fisher's exact and multi-group comparison tests. RESULTS: One hundred seventy-eight lesions were malignant. Multivariate model analysis showed that internal enhancement (homogeneous vs others, p < 0.001, heterogeneous and clumped vs clustered ring, p = 0.003) and distribution (focal and linear vs segmental, p < 0.001) were the significant explanatory variables. The descriptors were classified into three grades of suspicion, and the categorization (3, 4A, 4B, 4C, and 5) by sum-up grades showed an incremental increase in the probability of malignancy (p < 0.0001). CONCLUSION: The three-grade criteria and categorization by sum-up grades of descriptors appear valid for non-mass enhancement.

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Except for squamous cell carcinoma and adenocarcinoma, lesions that protrude into the esophagus are rare, and include benign and malignant tumors. The imaging findings of these lesions on esophagography, computed tomography (CT), and magnetic resonance imaging (MRI) are often non-specific. However, some of them reveal characteristic imaging findings. In addition, esophagography, CT, and MRI are useful to evaluate location, extent, invasion, vascularity, lymphadenopathy, and metastasis. Knowledge of the imaging features of protruding esophageal lesions helps to narrow the differential diagnosis. We describe the main features of esophageal protruding lesions.

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BACKGROUND: To clarify appropriate timing for magnetic resonance examination to predict pathological complete response to neoadjuvant chemotherapy for patients with human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancers in terms of tumor volume change. METHODS: Between September 2009 and December 2014, 113 women with HER2-positive (n = 51) and triple-negative (n = 62) invasive breast cancers undergoing neoadjuvant chemotherapy were enrolled. Patients with HER2-positive tumors underwent neoadjuvant chemotherapy with an anthracycline-based regimen followed by docetaxel with trastuzumab. Patients with triple-negative tumors underwent neoadjuvant chemotherapy with anthracycline-based (first in most cases) and taxane-based regimens. Magnetic resonance imaging was performed before neoadjuvant chemotherapy, between the regimens (midpoint examination), and after neoadjuvant chemotherapy (final examination). Response ratio of tumor volume was calculated and receiver-operating characteristic analyses for them for both subtypes were performed at the midpoint and final examinations. RESULTS: Twenty-eight women with HER2-positive tumors (54.9 %) and 29 women with triple-negative tumors (46.8 %) had pathological complete response. The response ratios were better in cases with pathological complete response than in those without (p = 0.0341, p < 0.0001). The area under the curve at the final examination was higher than that at the midpoint examination for HER2-positive tumors (p = 0.039); whereas for the triple-negative tumors, no significant difference between the two examinations was shown (p = 0.5218). CONCLUSIONS: Magnetic resonance examination to predict pathological complete response would be feasible after completion of a regimen including trastuzumab for HER2-positive tumors and at the midpoint of neoadjuvant chemotherapy for triple-negative tumors.

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