Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Bldg. 62, Rm.4114, Silver Spring, MD 20993.
Acad Radiol. 2013 Nov;20(11):1364-70. doi: 10.1016/j.acra.2013.08.019.
The change in volume of lung nodules is being examined as a measure of response to treatment. The aim of this study was to determine the minimum detectable change in nodule volume with the use of computed tomography.
Four different layouts of synthetic nodules with different shapes but with the same size (5, 8, 9, or 10 mm) for each layout were placed within an anthropomorphic phantom and scanned with a 16-detector-row computed tomography scanner using multiple imaging parameters. Nodule volume estimates were determined using a previously developed matched-filter estimator. Analysis of volume change was then conducted as a detection problem. For each nodule size, the pooled distribution of volume estimates was shifted by a percentage c to simulate a changing nodule, while accounting for standard deviation. The value of c resulting in a prespecified area under the receiver operating characteristic curve (AUC) was deemed the minimum detectable change for that AUC value.
Both nodule size at baseline and choice of slice collimation protocol had an effect on the value of minimum detectable growth. For AUC = 0.95, the minimum detectable nodule growth in volume when using the thin-slice collimation protocol (16 × 0.75 mm) was 17%, 19%, and 15% for nodule sizes of 5, 8, and 9 mm, respectively.
Our results indicate that an approximate bound for detectable nodule growth in subcentimeter nodules may be relatively small, on the order of 20% or less in volume for a thin-slice CT acquisition protocol.
肺结节体积的变化正被作为评估治疗反应的一种手段进行研究。本研究的目的是确定使用计算机断层扫描（CT）检测结节体积变化的最小可检测变化量。
在人体模型内放置了 4 种不同布局的合成结节，每种布局的结节形状不同，但大小相同（5、8、9 或 10mm），并使用 16 排 CT 扫描仪和多种成像参数进行扫描。使用先前开发的匹配滤波器估计器确定结节体积估计值。然后，作为检测问题进行体积变化分析。对于每个结节大小，通过百分比 c 对结节体积的汇总分布进行偏移，以模拟变化的结节，同时考虑到标准差。导致预设接收器操作特性曲线（AUC）面积的 c 值被认为是该 AUC 值的最小可检测变化量。
基线时的结节大小和切片准直协议的选择都会影响最小可检测生长值。对于 AUC=0.95，当使用薄切片准直协议（16×0.75mm）时，5、8 和 9mm 大小的结节的最小可检测体积生长分别为 17%、19%和 15%。
我们的结果表明，在亚厘米大小的结节中，可检测到的结节生长的近似界限可能相对较小，对于薄切片 CT 采集协议，体积变化的幅度可能在 20%或以下。
