本研究旨在描述新的病变，即乳腺癌患者经新辅助化疗（NAC）后乳腺磁共振成像（MRI）非肿瘤性乳腺组织中所称的环状强化病变，并研究影响其发生的因素。我们回顾性地研究了2020年1月至2021年12月间接受NAC治疗的811名连续乳腺癌患者（平均年龄为50.0岁，范围为24-81岁），识别具有新环状强化病变的病例。我们分析了MRI检查结果，并通过卡方检验、单因素和多因素 Logistic 回归分析确定潜在相关环状强化病变因素。其中，47（5.8%）名患者在接受NAC治疗后出现了新的环状强化病变。与环状强化病变相关的变量包括绝经前状态（p = 0.0007）、年龄较小（p = 0.0011）、较高的乳腺 X 线密度（p = 0.0076）以及基线MRI中较高的背景实质增强（BPE）（p = 0.0001）。其中，高 BPE 与环状强化病变的发生有独立关联（p = 0.0294，OR = 2.08；CI：1.08-4.03）。在高 BPE 患者的子集中，观察到 HER2阳性癌与环状强化病变之间的关联（比值比 = 5.51 vs. 2.54）。新病变的发展与任何特定的NAC药物无关（每种药物的p值为0.1676-0.7583）。环状强化病变经常出现在NAC后的MRI上，并且大多数在随后的MRI扫描中消失。MRI中的高 BPE 与此发现有关，HER2阳性癌增强了其发生。了解此发现可避免不必要的活检。Copyright © 2023 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

This study aimed to describe new lesions called ring enhancement in non-neoplastic breast tissue on breast magnetic resonance imaging (MRI) after neoadjuvant chemotherapy (NAC) in breast cancer patients, and to investigate the factors influencing their occurrence.We retrospectively reviewed 811 consecutive patients (mean age; 50.0 [range, 24-81] years) with breast cancer who had undergone NAC between January 2020 and December 2021, identifying cases with new ring enhancement on post-NAC MRI. We analyzed the MRI findings and identified factors that were potentially associated with ring enhancement through statistical analyses using the chi-square test, univariate and multivariate logistic regression analysis.Forty-seven (5.8%) patients developed new ring enhancement on post-NAC MRI. The variables associated with ring enhancement were premenopausal status (p = 0.0007), younger age (p = 0.0011), high mammographic density (p = 0.0076), and high background parenchymal enhancement (BPE) on baseline MRI (p = 0.0001). Among these, high BPE was independently associated with the occurrence of ring enhancement (p = 0.0294, OR = 2.08; CI: 1.08-4.03). In a subset of high BPE patients, an association between HER2-positive cancers and ring enhancement was observed (odds ratio = 5.51 vs. 2.54). New lesion development exhibited no association with any specific NAC drug (p = 0.1676-0.7583 per drug).Ring enhancement often occurs on post-NAC MRI and mostly disappears on subsequent MRI scans. High BPE on MRI was associated with this finding and HER2-positive cancers potentiated it. Knowledge of this finding can prevent unnecessary biopsies.Copyright © 2023 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.