Routine PET exams are increasingly performed with reduced injected activities, leading to the use of different image reconstruction parameters than the NEMA parameters, in order to prevent from any deleterious decrease in signal-to-noise ratio (SNR) and thus, in lesion detectability. This study aimed to provide a global head-to-head comparison between digital (Vereos, Philips®) and analog (Ingenuity TF, Philips®) PET cameras of the trade-off between SNR and contrast through a wide-ranging number of reconstruction iterations, and with a further reconstruction optimization based on the SNR of small lesions. Image quality parameters were compared between the two cameras on human and phantom images for a number of OSEM reconstruction iterations ranging from 1 to 10, the number of subsets being fixed at 10, and with the further identification of reconstruction parameters maximizing the SNR of spheres and adenopathies nearing 10 mm in diameter. These reconstructions were additionally obtained with and without time-of-flight (TOF) information (TOF and noTOF images, respectively) for further comparisons. On both human and phantom TOF images, the compromise between SNR and contrast was consistently more advantageous for digital than analog PET, with the difference being particularly pronounced for the lowest numbers of iterations and the smallest spheres. SNR was maximized with 1 and 2 OSEM iterations for the TOF images from digital and analog PET, respectively, whereas 4 OSEM iterations were required for the corresponding noTOF images from both cameras. On the TOF images obtained with this SNR optimization, digital PET exhibited a 37% to 44% higher SNR as compared with analog PET, depending on sphere size. These relative differences were however much lower for the noTOF images optimized for SNR (− 4 to + 18%), as well as for images reconstructed according to NEMA standards (− 4 to + 12%). SNR may be dramatically higher for digital PET than for analog PET, especially when optimized for small lesions. This superiority is mostly attributable to enhanced TOF resolution and is significantly underestimated in NEMA-based analyses.

中文翻译：

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优化人类和幻影图像的数字和模拟PET之间的头对头比较，以最大程度地提高小损伤的信噪比。

常规PET检查越来越多地以减少注射活动的方式进行，从而导致使用与NEMA参数不同的图像重建参数，以防止信噪比（SNR）以及病灶可检测性的任何有害降低。这项研究旨在通过各种重建迭代，在数字（Vereos，Philips®）和模拟（Ingenuity TF，Philips®）PET摄像机之间提供全球头对头的比较，以权衡SNR和对比度之间的关系。 ，并根据小病变的SNR进行进一步的重建优化。比较了两台相机在人像和幻像上的图像质量参数，进行了从1到10的OSEM重建迭代，子集的数量固定为10，并进一步确定了重建参数，以使球体和腺病的SNR最大化，直径接近10 mm。这些重构是在有和没有飞行时间（TOF）信息（分别为TOF和noTOF图像）的情况下获得的，以进行进一步的比较。在人像和幻像TOF图像上，SNR和对比度之间的折衷对于数字图像始终比模拟PET更为有利，并且差异在迭代次数最少和球体最小的情况下尤其明显。对于来自数字和模拟PET的TOF图像，分别使用1和2次OSEM迭代使SNR最大化，而对于这两个相机的相应noTOF图像，则需要进行4次OSEM迭代。在通过SNR优化获得的TOF图像上，数字PET与模拟PET相比，其SNR高37％至44％，具体取决于球体尺寸。但是，对于针对SNR优化的noTOF图像（− 4至+ 18％）以及根据NEMA标准重建的图像（− 4至+ 12％），这些相对差异要低得多。数字PET的SNR可能比模拟PET的SNR高得多，尤其是在针对小病变进行了优化时。这种优势主要归因于TOF分辨率的提高，并且在基于NEMA的分析中被大大低估了。特别是针对小型病变进行优化时。这种优势主要归因于TOF分辨率的提高，并且在基于NEMA的分析中被大大低估了。特别是针对小型病变进行优化时。这种优势主要归因于TOF分辨率的提高，并且在基于NEMA的分析中被大大低估了。