Institute of Diagnostic and Interventional Radiology, Friedrich-Schiller-University Jena, D-07740 Jena, Germany.
AJR Am J Roentgenol. 2010 Jun;194(6):1658-63. doi: 10.2214/AJR.09.3486.
Breast MRI has high sensitivity in breast cancer detection, and the BI-RADS MRI lexicon was a step toward standardized description of lesions. However, false-positive findings occur and lead to unnecessary biopsy. The purpose of this investigation was to identify criteria for false-positive findings in clinical practice.
Eligible for investigation were all breast MRI examinations from a consecutive 16-month time period that had histopathologic verification and findings classified as BI-RADS category 4-6 in the initial MRI report. Accordingly, 132 patients with 120 malignant and 31 benign lesions were enrolled. Two blinded observers categorized lesions into mass or nonmass and used BI-RADS to identify descriptor distribution differences between the benign and malignant subgroups.
The ratio of mass to nonmass lesions differed significantly (p < 0.001) between benign (1.2:1) and malignant (7:1) findings. Seventeen mass and 14 nonmass lesions were false-positive, and 105 mass and 15 nonmass lesions were true-positive. Among mass lesions, it was possible to differentiate malignant and benign lesions on the basis of margin (smooth, irregular, or spiculated) and dynamic enhancement features (p < 0.05). Among nonmass lesions, only stippled enhancement had a significant difference between the subgroups (p < 0.05). Tumor diameter had no influence on the correct diagnosis of nonmass lesions (p = 0.301). Conversely, among mass lesions, false-positive lesions were smaller than true-positive lesions (p = 0.01).
Nonmass lesions were the major cause of false-positive breast MRI findings. BI-RADS descriptors are not sufficient for differentiating benign and malignant nonmass lesions.
乳腺 MRI 在乳腺癌检测中具有很高的敏感性，BI-RADS MRI 词汇是对病变进行标准化描述的一个步骤。然而，假阳性结果会出现，并导致不必要的活检。本研究的目的是确定临床实践中假阳性结果的标准。
符合调查条件的是所有在连续 16 个月的时间内进行的乳腺 MRI 检查，这些检查均有组织病理学验证，且在初始 MRI 报告中被归类为 BI-RADS 4-6 类别。因此，共有 132 名患者（120 例恶性和 31 例良性病变）入组。两名盲法观察者将病变分为肿块或非肿块，并使用 BI-RADS 来识别良性和恶性亚组之间描述符分布的差异。
良性（1.2:1）和恶性（7:1）病变之间的肿块与非肿块病变的比例差异有统计学意义（p < 0.001）。17 个肿块和 14 个非肿块病变为假阳性，105 个肿块和 15 个非肿块病变为真阳性。在肿块病变中，基于边缘（光滑、不规则或分叶状）和动态增强特征可以区分良恶性病变（p < 0.05）。在非肿块病变中，只有点状增强在亚组之间有显著差异（p < 0.05）。肿瘤直径对非肿块病变的正确诊断没有影响（p = 0.301）。相反，在肿块病变中，假阳性病变比真阳性病变小（p = 0.01）。
非肿块病变是导致乳腺 MRI 假阳性结果的主要原因。BI-RADS 描述符不足以区分良性和恶性非肿块病变。
