Optimization and performance evaluation of the microPET II scanner for in vivo small-animal imaging
Optimization and performance evaluation of the microPET II scanner for in vivo small-animal imaging
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DOI：
10.1088/0031-9155/49/12/005
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发表时间：
2004-06-21
影响因子：
3.5
通讯作者：
Cherry, SR
中科院分区：
文献类型：
--
作者：
Yang, YF;Tai, YC;Cherry, SR
MicroPET II是一种新开发的PET（正电子发射断层扫描）扫描仪，专为小动物的高分辨率成像而设计。它由17 640个LSO晶体组成，每个晶体尺寸为0.975 x 0.975 x 12.5 mm（3），排列在42个连续的环中，每个环有420个晶体。扫描仪的轴向视野（FOV）为4.9 cm，轴向FOV为8.5 cm。本研究的目的是仔细评估系统的性能，并优化体内小鼠和大鼠成像研究的设置。发现体积图像分辨率强烈依赖于所采用的重建算法，并且当使用具有精确系统建模的统计重建算法时，跨轴向FOV的中心3 cm的平均值为1.1 mm（1.4穆尔）。在不同的能量和时间窗下，测量了小鼠和大鼠大小的幻影的灵敏度、散射分数和噪声等效计数（NEC）率。使用宽开放能量窗口（150-750 keV）和10 ns定时窗口优化小鼠成像，导致FOV中心处的灵敏度为3.3%，并且对于体模中80 MBq（2.2 mCi）的总活性，峰值NEC速率为235 000 cps。大鼠成像，由于更高的散射分数，和活动的视野之外，实现了最大NEC率为24600 cps的总活动80 MBq（2.2 mCi）的体模，能量窗口为250-750 keV和6 Ins的定时窗口。对于这些设置，FOV中心的灵敏度为2.1%。这项工作表明，不同的扫描仪设置是必要的，以优化NEC计数率为不同大小的动物和不同的注射剂量。最后，幻影和在体内动物研究，以证明microPET II的小动物成像研究的能力。
MicroPET II is a newly developed PET (positron emission tomography) scanner designed for high-resolution imaging of small animals. It consists of 17 640 LSO crystals each measuring 0.975 x 0.975 x 12.5 mm(3), which are arranged in 42 contiguous rings, with 420 crystals per ring. The scanner has an axial field of view (FOV) of 4.9 cm and a transaxial FOV of 8.5 cm. The purpose of this study was to carefully evaluate the performance of the system and to optimize settings for in vivo mouse and rat imaging studies. The volumetric image resolution was found to depend strongly on the reconstruction algorithm employed and averaged 1.1 mm (1.4 mul) across the central 3 cm of the transaxial FOV when using a statistical reconstruction algorithm with accurate system modelling. The sensitivity, scatter fraction and noise-equivalent count (NEC) rate for mouse- and rat-sized phantoms were measured for different energy and timing windows. Mouse imaging was optimized with a wide open energy window (150-750 keV) and a 10 ns timing window, leading to a sensitivity of 3.3% at the centre of the FOV and a peak NEC rate of 235 000 cps for a total activity of 80 MBq (2.2 mCi) in the phantom. Rat imaging, due to the higher scatter fraction, and the activity that lies outside of the field of view, achieved a maximum NEC rate of 24600 cps for a total activity of 80 MBq (2.2 mCi) in the phantom, with an energy window of 250-750 keV and a 6 Ins timing window. The sensitivity at the centre of the FOV for these settings is 2.1%. This work demonstrates that different scanner settings are necessary to optimize the NEC count rate for different-sized animals and different injected doses. Finally, phantom and in vivo animal studies are presented to demonstrate the capabilities of microPET II for small-animal imaging studies.