Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom
Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom
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DOI：
10.1088/1361-6560/aa6e1b
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发表时间：
2017-07-07
影响因子：
3.5
通讯作者：
Boraxbekk, C. J.
中科院分区：
文献类型：
--
作者：
Jonasson, L. S.;Axelsson, J.;Boraxbekk, C. J.
在纵向正电子发射断层扫描（PET）中，由于现有PET相机和重建算法的有限空间分辨率引入的部分体积效应（PVE），体积随时间变化的存在可能导致对量化PET信号的真实变化的高估或低估。在这里，设计了一个3D打印的拟人大脑模型，具有三种尺寸的可连接纹状体，以实现受控的体积变化。使用一种方法来消除非放射性塑料壁，并通过添加不同数量的事件从列表模式采集操纵BP水平，我们研究了人工体积依赖性的BP由于PVE，和潜在的偏见所产生的不同的BP。比较多种重建算法，我们发现，一个高分辨率的有序子集最大化算法与空间变化的点扩散函数分辨率建模提供了最准确的数据。对于纹状体，每1%的体积变化，BP变化0.08%，但对于较小的体积，如后尾状核，BP的人为变化高达每1%的体积变化0.7%。纹状体体积的简单粗略校正是不令人满意的，因为BP上PVE的幅度根据纹状体中发生变化的位置而不同。因此，为了正确解释BP中与年龄相关的纵向变化，我们必须考虑结构内的体积变化，而不是整个体积。本3D打印技术与壁去除方法相结合，可以被实施以获得关于由不同形状的摄取区域中的PVE差异引入的可预测偏差的知识。
In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered-subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.