This article compares the physical performance of the 4-ring digital Discovery MI (DMI) and PMT-based Discovery MI-DR (DMI-DR) PET/CT systems. Physical performance was assessed according to the NEMA NU 2-2012 standards. Performance measures included spatial resolution, image quality, scatter fraction and count rate performance, and sensitivity. Energy and timing resolutions were also measured. Published DMI and DMI-DR performance studies from other centers are reviewed and compared. 4-ring DMI spatial resolution at 1-cm radial offset in the radial, tangential and axial directions was 4.62, 4.18 and 4.57 mm, respectively, compared with the DMI-DR system values of 4.58, 4.52, and 5.31 mm. Measured sensitivity was 13.3 kcps/MBq at the center of the FOV and 13.4 kcps/MBq 10 cm off-center for the SiPM-based DMI system. DMI-DR system sensitivity was 6.3 kcps/MBq at the center of the FOV and 6.8 kcps/MBq at 10 cm off-center. DMI measured noise equivalent count rate peak was 175.6 kcps at 20.1 kBq/ml; DMI-DR was 146.7 kcps at 31.7 kBq/ml. Scatter fraction was 40.5% and 36.6%, respectively. DMI image contrast recovery (CR) values ranged from 73.2% (10 mm sphere) to 91.0% (37 mm sphere); DMI-DR, values ranged from 68.4% to 91.4%. DMI background variability (BV) was 1.8%–6.5%; DMI-DR was 2.3%–9.1%. The Q.Clear algorithm improved image quality, increasing CR and decreasing BV in both systems. The photopeak energy resolution was 9.63% and 12.19% for DMI and DMI-DR, respectively. The time-of-flight (TOF) resolution was 377.26 ps and 552.71 ps, respectively. Compared with measurements in other centers, results were similar and showed an absolute mean relative deviation of 6% for DMI and 7% for DMI-DR overall performance results. Performance measures were higher for the 4-ring DMI than the DMI-DR system. The biggest advantages of the 4-ring DMI vs DMI-DR are improved sensitivity and count rate performance. This should allow a better image signal-to-noise ratio (SNR) for the same acquisition times or, similar SNR with lower acquisition times or injected activity. In its 3-ring configuration, the DMI showed worse performance results than the PMT-based system in terms of count rate scatter fraction and image quality (for similar axial FOV).

中文翻译：

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比较不同地点的Discovery MI和Discovery MI-DR TOF PET / CT系统以及与其他商用PET / CT系统的NEMA特性。

本文比较了四环数字发现MI（DMI）和基于PMT的发现MI-DR（DMI-DR）PET / CT系统的物理性能。根据NEMA NU 2-2012标准评估了身体表现。性能指标包括空间分辨率，图像质量，散射分数和计数率性能以及灵敏度。还测量了能量和时序分辨率。审查并比较了其他中心发布的DMI和DMI-DR性能研究。径向，切线和轴向上1厘米径向偏移处的4环DMI空间分辨率分别为4.62、4.18和4.57毫米，而DMI-DR系统值分别为4.58、4.52和5.31毫米。对于基于SiPM的DMI系统，在FOV中心测得的灵敏度为13.3 kcps / MBq，在离中心10 cm处测得的灵敏度为13.4 kcps / MBq。DMI-DR系统灵敏度为6。FOV中心的速度为3 kcps / MBq，离中心10 cm的速度为6.8 kcps / MBq。DMI测得的噪声当量计数率峰值在20.1 kBq / ml时为175.6 kcps；DMI-DR为146.7 kcps，31.7 kBq / ml。散布分数分别为40.5％和36.6％。DMI图像对比度恢复（CR）值范围从73.2％（10毫米球体）到91.0％（37毫米球体）；DMI-DR，值范围从68.4％到91.4％。DMI背景差异（BV）为1.8％–6.5％；DMI-DR为2.3％–9.1％。Q.Clear算法改善了图像质量，在两个系统中均提高了CR并降低了BV。DMI和DMI-DR的光峰能量分辨率分别为9.63％和12.19％。飞行时间（TOF）分辨率分别为377.26 ps和552.71 ps。与其他中心的测量结果相比，结果相似，显示DMI的绝对平均相对偏差为6％，DMI-DR总体性能结果为7％。4环DMI的性能指标高于DMI-DR系统。4环DMI与DMI-DR相比，最大的优点是提高了灵敏度和计数率性能。对于相同的采集时间或具有较短采集时间或注入活动的相似SNR，这应该允许更好的图像信噪比（SNR）。在其3环配置中，DMI在计数率散射分数和图像质量（对于类似的轴向FOV）方面显示出比基于PMT的系统更差的性能结果。对于相同的采集时间或具有较短采集时间或注入活动的相似SNR，这应该允许更好的图像信噪比（SNR）。在其3环配置中，DMI在计数率散布率和图像质量（对于类似的轴向FOV）方面显示出比基于PMT的系统更差的性能结果。对于相同的采集时间或具有较短采集时间或注入活动的相似SNR，这应该允许更好的图像信噪比（SNR）。在其3环配置中，DMI在计数率散射分数和图像质量（对于类似的轴向FOV）方面显示出比基于PMT的系统更差的性能结果。