Department of Radiology, University of Pittsburgh, 3362 Fifth Avenue, Pittsburgh, PA 15213, USA.
Acad Radiol. 2009 Nov;16(11):1338-47. doi: 10.1016/j.acra.2009.05.005. Epub 2009 Jul 25.
Computerized determination of optimal search areas on mammograms for matching breast mass regions depicted on two ipsilateral views remains a challenge for developing multiview-based computer-aided detection (CAD) schemes. The purpose of this study was to compare three methods aimed at matching CAD-cued mass regions depicted on two views and the associated impact on CAD performance.
The three search methods used (1) an annular (fan-shaped) band, (2) a straight strip perpendicular to the estimated centerline, and (3) a mixed search area bound on the chest wall side by a straight line and an annular arc on the nipple side, respectively. An image database of 200 examinations with positive results depicting the masses on two views and 200 examinations with negative results was used for testing. Two performance assessment experiments were conducted. The first investigated the maximum matching sensitivity as a function of the search area size, and the second assessed the change in CAD performance using these three search methods.
To include all 200 paired mass regions within the search areas, maximum widths were 28 and 68 mm for the use of the straight strip and the annular band search methods, respectively. When applying a single-image-based CAD scheme to this image database, 172 masses (86% sensitivity) and 523 false-positive (FP) regions (0.33 per image) were detected and cued. Among the positive findings, 92 were cued by the CAD system on both views, and 80 were cued on only one view. In an attempt to match as many of the 172 CAD-cued masses (true-positive [TP] regions) on two views by incrementally reducing the CAD threshold inside the different search areas, the CAD scheme generated 158 TP-TP paired matches with 14 TP-FP paired matches, 142 TP-TP paired matches with 30 TP-FP paired matches, and 146 TP-TP paired matches with 26 TP-FP paired matches, using the methods involving the straight strip, the annular band, and the mixed search areas, respectively. Using the straight strip search method, the CAD also eliminated 25% of FP regions initially cued by the single-image-based CAD scheme and generated the lowest case-based FP detection rate, namely, 15% less than that generated by the annular band method.
This study showed that among these three search methods, the straight strip method required a smaller search area and achieved the highest level of CAD performance.
在双侧视图上，计算机确定匹配乳腺肿块区域的最优搜索区域仍然是开发基于多视图的计算机辅助检测（CAD）方案的挑战。本研究旨在比较三种旨在匹配双侧视图上 CAD 提示肿块区域的方法及其对 CAD 性能的影响。
使用的三种搜索方法包括（1）环形（扇形）带，（2）垂直于估计中心线的直条，（3）分别在胸壁侧用直线和乳头侧的环形弧限定的混合搜索区域。使用 200 例阳性结果显示双侧视图上的肿块和 200 例阴性结果的图像数据库进行测试。进行了两项性能评估实验。第一项研究了作为搜索区域大小函数的最大匹配灵敏度，第二项评估了使用这三种搜索方法对 CAD 性能的变化。
为了将所有 200 对肿块区域包含在搜索区域内，使用直条和环形带搜索方法的最大宽度分别为 28mm 和 68mm。当将基于单图像的 CAD 方案应用于该图像数据库时，检测到 172 个肿块（86%的灵敏度）和 523 个假阳性（FP）区域（每张图像 0.33 个）。在阳性发现中，92 个肿块在两个视图上均由 CAD 系统提示，80 个肿块仅在一个视图上提示。为了通过逐步降低不同搜索区域内的 CAD 阈值来匹配尽可能多的在双侧视图上提示的 172 个 CAD 提示肿块（真阳性[TP]区域），CAD 方案使用涉及直条、环形带和混合搜索区域的方法，分别生成 158 个 TP-TP 配对匹配，14 个 TP-FP 配对匹配，142 个 TP-TP 配对匹配，30 个 TP-FP 配对匹配，146 个 TP-TP 配对匹配，26 个 TP-FP 配对匹配。使用直条搜索方法，CAD 还消除了基于单图像的 CAD 方案最初提示的 25%的 FP 区域，并生成了最低的基于病例的 FP 检测率，即比环形带方法低 15%。
本研究表明，在这三种搜索方法中，直条方法所需的搜索区域较小，并实现了最高水平的 CAD 性能。
