Abstract: Background　Ductal carcinoma in situ （DCIS） is an early lesion with tendency to develop invasive ductal carcinoma.The focus of DCIS research is to identify which type of lesions will develop into invasive cancer.If the problem is addressed，DCIS will be treated more accurately.In this study，MRI characteristics of DCIS were discussed in detail by pathological grade.Objective　To investigate MRI findings and pathology grade in DCIS.Methods　The pathological grade and MRI findings〔breast imaging reporting and data system（BI-RADS） classification，morphology and dynamic contrast-enhanced MRI of lesions，ADC value〕 of 34 cases（35 sides） of DCIS confirmed by surgery and pathology in Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine from January 2015 to January 2018 were retrospectively analyzed.Results　Pathology grade：4 cases of low grade group，and 31 cases of intermediate to high grade.BI-RADS classification：1 case of BI-RADS 3，2 cases of BI-RADS 4A，5 cases of BI-RADS 4B，12 cases of BI-RADS 4C，and 15 cases of BI-RADS 5.Morphology of lesions：6 cases of mass type，29 cases of non-mass enhancement（including 15 cases of segmental distribution，5 cases of regional enhancement，and 4 cases of line-like，and 15 cases of clustered ring and 5 cases of clumped）．Dynamic enhanced performance：10 cases of typeⅠ time-signal intensity curves（TIC），15 cases of typeⅡ and 10 cases of typeⅢ.Four 4 cases of early slow enhancement，2 cases of early moderate enhancement，29 cases of early fast enhancement.ADC value：ADC value was <1.2×10-3 mm2/s in 19 cases，and ≥1.2×10-3 mm2/s in 16 cases.The morphology and ADC value of the lesions were similar in low pathological grade group and intermediate to high pathological grade groups（P>0.05）．There were correlations between non-mass enhancement distribution，non-mass internal enhancement types，type of TIC，early enhancement rate and pathological grade （P<0.05）．Conclusion　MRI findings of DCIS are mainly observed as non-mass enhancement，among which，segmental, regional and linear enhancement, cluster small ring and cluster enhancement are common.The pathological basis is ductal invasion，and the enhancement of the surrounding matrix and ductal wall.MRI observations can reflect the pathological changes，suggest the pathologic grade，and predict whether DCIS is accompanied by infiltration and local recurrence to a certain extent，by which the biopsy and clinical treatment regimens can be modified.

Key words: Breast, Ductal carcinoma in situ, MRI, Diagnosis, Pathology

摘要： 背景　乳腺导管原位癌（DCIS）属于早期的乳腺病变，有发展为浸润性导管癌的倾向。目前DCIS研究的热点在于分辨出哪种类型的病灶将发展为浸润性癌。解决这一问题将会使DCIS得到更精确的处理。本研究就不同级别的DCIS及其MRI特征进行深入分析。目的　探讨DCIS的MRI特征及其与病理分级的关系。方法　回顾性分析上海交通大学医学院附属新华医院2015年1月—2018年1月经手术病理检查证实的34例DCIS患者（35侧）的病理分级、MRI特征〔乳腺影像报告与数据系统（BI-RADS）分类、病灶形态学和病灶动态增强表现、表观弥散系数（ADC）值〕。结果　病理分级：低级别4例，中~高级别31例。BI-RADS分类：3类1例、4A类2例、4B类5例、4C类12例、5类15例。病灶形态学：肿块型DCIS 6例，非肿块样强化DCIS 29例。非肿块样强化DCIS 29例中，节段性强化15例、区域性强化5例、线样强化4例，成簇小环形强化15例、集簇状强化5例。病灶动态增强表现：Ⅰ型时间-信号强度曲线（TIC）10例、Ⅱ型TIC 15例、Ⅲ型TIC 10例；早期缓慢强化4例，早期中度强化2例，早期快速强化29例。ADC值<1.2×10-3 mm2/s 19例，≥1.2×10-3 mm2/s 16例。低级别和中~高级别患者病灶形态学、ADC值比较，差异无统计学意义（P>0.05）；低级别和中~高级别患者非肿块样强化的分布形式、内部强化类型、TIC类型、早期强化情况比较，差异有统计学意义（P<0.05）。结论　DCIS MRI主要表现为非肿块样强化，其中又以节段性、区域性、线样强化，成簇小环形强化和集簇状强化多见，其病理基础是导管受侵，增强时导管周围基质和导管壁强化。MRI表现能反映其病理改变，并能提示病理分级，可在一定程度上预测DCIS是否伴有浸润及局部复发的可能性，以调整活检及临床治疗方案。

关键词: 乳腺, 导管原位癌, 磁共振成像, 诊断, 病理