CSIRO Health and Biosecurity, Brisbane, Australia.
CSIRO Health and Biosecurity, Brisbane, Australia; Department of Molecular Imaging, Austin Health, Melbourne, Australia.
Neuroimage. 2018 Dec;183:387-393. doi: 10.1016/j.neuroimage.2018.08.044. Epub 2018 Aug 18.
The centiloid scale was recently proposed to provide a standard framework for the quantification of β-amyloid PET images, so that amyloid burden can be expressed on a standard scale. While the framework prescribes SPM8 as the standard analysis method for PET quantification, non-standard methods can be calibrated to produce centiloid values. We have previously developed a PET-only quantification: CapAIBL. In this study, we show how CapAIBL can be calibrated to the centiloid scale.
Calibration images for C-PiB, F-NAV4694, F-Florbetaben, F-Flutemetamol and F- Florbetapir were analysed using the standard method and CapAIBL. Using these images, both methods were calibrated to the centiloid scale. Centiloid values computed using CapAIBL were compared to those computed using standard method. For each tracer, a separate validation was performed using an independent dataset from the AIBL study.
Using the calibration images, there was a very strong agreement, and very little bias between the centiloid values computed using CapAIBL and those computed using the standard method with R > 0.97 across all tracers. Using images from AIBL, the agreement was also high with R > 0.96 across all tracers. In this dataset, there was a small underestimation of the centiloid values computed using CapAIBL of less than 0.8% in PiB, and a small over-estimation of 1.3% in Florbetapir, and 0.8% in Flutemetamol. There was a larger overestimation of 8% in NAV images, and 14% underestimation in Florbetaben images. However, some of these differences could be explained by the use of different scanners between the calibration scans and the ones used in AIBL.
The PET-only quantification method, CapAIBL, can produce reliable centiloid values. The bias observed in the AIBL dataset for 18F-NAV4694 and F-Florbetaben may indicate that using different scanners or reconstruction methods might require scanner-specific adjustments.
最近提出了百分位标度，为β-淀粉样蛋白 PET 图像的定量提供了一个标准框架，以便可以在标准尺度上表示淀粉样蛋白负担。虽然该框架规定了 SPM8 作为 PET 定量的标准分析方法，但也可以校准非标准方法以产生百分位值。我们之前开发了一种仅用于 PET 的定量方法：CapAIBL。在这项研究中，我们展示了如何将 CapAIBL 校准到百分位标度。
使用标准方法和 CapAIBL 分析 C-PiB、F-NAV4694、F-Florbetaben、F-Flutemetamol 和 F-Florbetapir 的校准图像。使用这些图像，两种方法都被校准到百分位标度。使用 CapAIBL 计算的百分位值与使用标准方法计算的百分位值进行比较。对于每种示踪剂，都使用 AIBL 研究中的独立数据集进行了单独验证。
使用校准图像，使用 CapAIBL 计算的百分位值与使用标准方法计算的百分位值之间存在非常强的一致性，并且几乎没有偏差，所有示踪剂的 R>0.97。使用 AIBL 的图像，所有示踪剂的一致性也很高，R>0.96。在这个数据集，CapAIBL 计算的百分位值略有低估，PIB 为小于 0.8%，Florbetapir 为 1.3%，Flutemetamol 为 0.8%。18F-NAV4694 图像的高估幅度较大，为 8%，Florbetaben 图像的低估幅度为 14%。然而，这些差异中的一些可以用校准扫描和 AIBL 中使用的扫描之间使用不同的扫描仪来解释。
仅用于 PET 的定量方法 CapAIBL 可以产生可靠的百分位值。在 AIBL 数据集观察到的 18F-NAV4694 和 F-Florbetaben 的偏差可能表明使用不同的扫描仪或重建方法可能需要针对特定扫描仪进行调整。
