PURPOSE: To evaluate the variability and repeatability of repeated magnetic resonance imaging (MRI) measurements in normal breast tissues between and within subjects. METHODS: Eighteen normal premenopausal subjects underwent two contrast-enhanced MRI scans within 72 hours or during the same menstrual phase in two consecutive months. A subset of nine women also completed diffusion-weighted imaging (DWI). Fibroglandular tissue (FGT) density and FGT enhancement were measured on the contrast-enhanced MRI. Apparent diffusion coefficient (ADC) values were computed from DWI. Between- and within-subject coefficients of variation (bCV and wCV, respectively) were assessed. Repeatability of all measurements was assessed by the coefficient of repeatability (CR) and Bland-Altman plots. RESULTS: The bCV of FGT density and FGT enhancement at visit 1 and visit 2 ranged from 47% to 63%. The wCV was 13% for FGT density, 22% for FGT enhancement, and 11% for ADC. The CRs of FGT density and FGT enhancement were 0.15 and 0.19, respectively, and for ADC, it was 6.1 x 10^-4 mm²/s. CONCLUSIONS: We present an estimate of the variability and repeatability of MR measurements in normal breasts. These estimates provide the basis for understanding the normal variation of healthy breast tissue in MRI and establishing thresholds for agreement between measurements.

目的：评估受试者之间和受试者内部正常乳腺组织中重复磁共振成像 (MRI) 测量的可变性和可重复性。方法： 18 名正常绝经前受试者在 72 小时内或在连续两个月的同一月经期接受了两次对比增强 MRI 扫描。九名女性的子集​​也完成了弥散加权成像 (DWI)。在对比增强 MRI 上测量纤维腺体组织 (FGT) 密度和 FGT 增强。从 DWI 计算表观扩散系数 (ADC) 值。受试者间和受试者内变异系数（bCV和wCV，分别）进行了评估。所有测量的重复性通过重复性系数 (CR) 和 Bland-Altman 图进行评估。结果：访问 1 和访问 2 时 FGT 密度和 FGT 增强的bCV范围为 47% 至 63%。FGT 密度的wCV为 13%，FGT 增强为 22%，ADC 为 11%。FGT密度和FGT增强的CR分别为0.15和0.19，ADC为6.1 x 10 ^-4 mm ² /s。结论：我们对正常乳房中 MR 测量的可变性和可重复性进行了估计。这些估计为了解 MRI 中健康乳房组织的正常变化和建立测量之间的一致性阈值提供了基础。