在体模研究中利用计算机断层扫描对非实性肺结节体积进行定量评估。
Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study.
作者信息
Gavrielides Marios A, Berman Benjamin P, Supanich Mark, Schultz Kurt, Li Qin, Petrick Nicholas, Zeng Rongping, Siegelman Jenifer
机构信息
Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, , Office of In Vitro Diagnostics and Radiological Health, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA.
Division of Radiological Health, Office of In Vitro Diagnostics and Radiological Health, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA.
出版信息
Quant Imaging Med Surg. 2017 Dec;7(6):623-635. doi: 10.21037/qims.2017.12.07.
BACKGROUND
To assess the volumetric measurement of small (≤1 cm) nonsolid nodules with computed tomography (CT), focusing on the interaction of state of the art iterative reconstruction (IR) methods and dose with nodule densities, sizes, and shapes.
METHODS
Twelve synthetic nodules [5 and 10 mm in diameter, densities of -800, -630 and -10 Hounsfield units (HU), spherical and spiculated shapes] were scanned within an anthropomorphic phantom. Dose [computed tomography scan dose index (CTDI)] ranged from standard (4.1 mGy) to below screening levels (0.3 mGy). Data was reconstructed using filtered back-projection and two state-of-the-art IR methods (adaptive and model-based). Measurements were extracted with a previously validated matched filter-based estimator. Analysis of accuracy and precision was based on evaluation of percent bias (PB) and the repeatability coefficient (RC) respectively.
RESULTS
Density had the most important effect on measurement error followed by the interaction of density with nodule size. The nonsolid -630 HU nodules had high accuracy and precision at levels comparable to solid (-10 HU) nonsolid, regardless of reconstruction method and with CTDI as low as 0.6 mGy. PB was <5% and <11% for the 10- and 5-mm in nominal diameter -630 HU nodules respectively, and RC was <5% and <12% for the same nodules. For nonsolid -800 HU nodules, PB increased to <11% and <30% for the 10- and 5-mm nodules respectively, whereas RC increased slightly overall but varied widely across dose and reconstruction algorithms for the 5-mm nodules. Model-based IR improved measurement accuracy for the 5-mm, low-density (-800, -630 HU) nodules. For other nodules the effect of reconstruction method was small. Dose did not affect volumetric accuracy and only affected slightly the precision of 5-mm nonsolid nodules.
CONCLUSIONS
Reasonable values of both accuracy and precision were achieved for volumetric measurements of all 10-mm nonsolid nodules, and for the 5-mm nodules with -630 HU or higher density, when derived from scans acquired with below screening dose levels as low as 0.6 mGy and regardless of reconstruction algorithm.
背景
旨在评估采用计算机断层扫描（CT）对小（≤1 cm）非实性结节进行体积测量，重点关注当前迭代重建（IR）方法与剂量同结节密度、大小及形状之间的相互作用。
方法
在一个仿真人体模型内扫描12个合成结节[直径5和10 mm，密度为-800、-630和-10亨氏单位（HU），球形及毛刺状]。剂量[计算机断层扫描剂量指数（CTDI）]范围从标准剂量（4.1 mGy）至低于筛查水平（0.3 mGy）。数据采用滤波反投影法及两种当前的IR方法（自适应法和基于模型法）进行重建。使用先前验证过的基于匹配滤波器的估计器提取测量值。分别基于百分比偏差（PB）和重复性系数（RC）评估准确性和精密度。
结果
密度对测量误差影响最大，其次是密度与结节大小的相互作用。无论采用何种重建方法，当CTDI低至0.6 mGy时，非实性-630 HU结节在与实性（-10 HU）非实性结节相当的水平上具有较高的准确性和精密度。标称直径10 mm和5 mm的-630 HU结节的PB分别<5%和<11%，相同结节的RC分别<5%和<12%。对于非实性-800 HU结节，10 mm和5 mm结节的PB分别增至<11%和<30%，而5 mm结节的RC总体略有增加，但因剂量和重建算法不同而差异很大。基于模型的IR提高了5 mm低密度（-800、-630 HU）结节的测量准确性。对于其他结节，重建方法的影响较小。剂量不影响体积测量的准确性，仅轻微影响5 mm非实性结节的精密度。
结论
当扫描剂量低至0.6 mGy且低于筛查剂量水平时，无论采用何种重建算法，对于所有10 mm非实性结节以及密度为-630 HU或更高的5 mm结节，体积测量均可获得合理的准确性和精密度值。
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