Volumetric breast density evaluation from ultrasound tomography images
Volumetric breast density evaluation from ultrasound tomography images
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DOI：
10.1118/1.2964092
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发表时间：
2008-09-01
期刊：
影响因子：
3.8
通讯作者：
Littrup, Peter
中科院分区：
文献类型：
--
作者：
Glide-Hurst, Carri K.;Duric, Neb;Littrup, Peter
我们小组以前进行的超声断层扫描工作显示，在体外测量的声速和物理密度之间存在直接关联，并且在体内的声速随着乳房X光摄影密度的增加而增加，这是乳腺癌的已知危险因素。在这些经验结果的基础上，这项工作的目的是探索一种度量标准，使用我们的超声波断层扫描声速图像来量化乳房密度，其方式类似于用于乳房密度分析的计算机辅助乳房X光照片分割。因此，体积超声百分比密度(USPD)是通过使用k-均值聚类例程从每个断层图像中分割高声速区域，在整个乳房体积上整合这些结果，并除以整个乳房体积来确定的。首先，使用我们的超声断层扫描临床样机(空间分辨率为4 mm)和CT扫描了四次由嵌入纤维腺组织中的脂肪包裹体组成的乳房体模。使用半自动分割程序对冠状断层图像和CT图像进行分析，并比较4次重复扫描中体模的脂肪包裹体的积分面积。包裹体分割的平均变异性分别类似于7%和2%，并且在两种模式之间的综合区域中观察到了密切的相关性。接下来，对93名患者进行成像，得出乳房的体积覆盖率(每个患者45-75个声速断层图)。USPD与乳房X线片百分比密度(MPD)的相关性通过两种方法进行评估：(1)定性，由放射科医生使用BI-RADS标准的视觉评估确定；(2)定量，通过数字化和半自动分割头尾部和内侧斜面乳房X线片。BI-RADS分类与USPD之间有很强的正相关性[Spearman Rho=0.69(p<；0.001)]，单因素方差分析和Scheffe后验分析显示，所有BI-RADS分类之间存在显著差异。此外，将USPD与计算的乳房X光摄影密度进行比较，发现CC和MLO视图之间存在中到强的正相关(r(2)分别为0.75和0.59)。这些结果支持这样一种假设，即利用USPD作为乳房X光照相的类似物是可行的，提供了一种非电离的、全乳房分析。(C)2008年美国医学物理学家协会。
Previous ultrasound tomography work conducted by our group showed a direct correlation between measured sound speed and physical density in vitro, and increased in vivo sound speed with increasing mammographic density, a known risk factor for breast cancer. Building on these empirical results, the purpose of this work was to explore a metric to quantify breast density using our ultrasound tomography sound speed images in a manner analogous to computer-assisted mammogram segmentation for breast density analysis. Therefore, volumetric ultrasound percent density (USPD) is determined by segmenting high sound speed areas from each tomogram using a k-means clustering routine, integrating these results over the entire volume of the breast, and dividing by whole-breast volume. First, a breast phantom comprised of fat inclusions embedded in fibroglandular tissue was scanned four times with both our ultrasound tomography clinical prototype (with 4 mm spatial resolution) and CT. The coronal transmission tomograms and CT images were analyzed using semiautomatic segmentation routines, and the integrated areas of the phantom's fat inclusions were compared between the four repeated scans. The average variability for inclusion segmentation was similar to 7% and similar to 2%, respectively, and a close correlation was observed in the integrated areas between the two modalities. Next, a cohort of 93 patients was imaged, yielding volumetric coverage of the breast (45-75 sound speed tomograms/patient). The association of USPD with mammographic percent density (MPD) was evaluated using two measures: (1) qualitative, as determined by a radiologist's visual assessment using BI-RADS Criteria and (2) quantitative, via digitization and semiautomatic segmentation of craniocaudal and mediolateral oblique mammograms. A strong positive association between BI-RADS category and USPD was demonstrated [Spearman rho=0.69 (p < 0.001)], with significant differences between all BI-RADS categories as assessed by one-way ANOVA and Scheffe posthoc analysis. Furthermore, comparing USPD to calculated mammographic density yielded moderate to strong positive associations for CC and MLO views (r(2)=0.75 and 0.59, respectively). These results support the hypothesis that utilizing USPD as an analogue to mammographic breast density is feasible, providing a nonionizing, whole-breast analysis. (C) 2008 American Association of Physicists in Medicine.