This article presents system performance studies for the Discovery MI PET/CT system, a new time-of-flight system based on silicon photomultipliers. System performance and clinical imaging were compared between this next-generation system and other commercially available PET/CT and PET/MR systems, as well as between different reconstruction algorithms. Methods: Spatial resolution, sensitivity, noise-equivalent counting rate, scatter fraction, counting rate accuracy, and image quality were characterized with the National Electrical Manufacturers Association NU-2 2012 standards. Energy resolution and coincidence time resolution were measured. Tests were conducted independently on two Discovery MI scanners installed at Stanford University and Uppsala University, and the results were averaged. Back-to-back patient scans were also performed between the Discovery MI, Discovery 690 PET/CT, and SIGNA PET/MR systems. Clinical images were reconstructed using both ordered-subset expectation maximization and Q.Clear (block-sequential regularized expectation maximization with point-spread function modeling) and were examined qualitatively. Results: The averaged full widths at half maximum (FWHMs) of the radial/tangential/axial spatial resolution reconstructed with filtered backprojection at 1, 10, and 20 cm from the system center were, respectively, 4.10/4.19/4.48 mm, 5.47/4.49/6.01 mm, and 7.53/4.90/6.10 mm. The averaged sensitivity was 13.7 cps/kBq at the center of the field of view. The averaged peak noise-equivalent counting rate was 193.4 kcps at 21.9 kBq/mL, with a scatter fraction of 40.6%. The averaged contrast recovery coefficients for the image-quality phantom were 53.7, 64.0, 73.1, 82.7, 86.8, and 90.7 for the 10-, 13-, 17-, 22-, 28-, and 37-mm-diameter spheres, respectively. The average photopeak energy resolution was 9.40% FWHM, and the average coincidence time resolution was 375.4 ps FWHM. Clinical image comparisons between the PET/CT systems demonstrated the high quality of the Discovery MI. Comparisons between the Discovery MI and SIGNA showed a similar spatial resolution and overall imaging performance. Lastly, the results indicated significantly enhanced image quality and contrast-to-noise performance for Q.Clear, compared with ordered-subset expectation maximization. Conclusion: Excellent performance was achieved with the Discovery MI, including 375 ps FWHM coincidence time resolution and sensitivity of 14 cps/kBq. Comparisons between reconstruction algorithms and other multimodal silicon photomultiplier and non–silicon photomultiplier PET detector system designs indicated that performance can be substantially enhanced with this next-generation system.

本文介绍了Discovery MI PET / CT系统的系统性能研究，Discovery MI PET / CT系统是一种基于硅光电倍增管的新型飞行时间系统。在此下一代系统与其他商用PET / CT和PET / MR系统之间以及不同的重建算法之间，比较了系统性能和临床影像。方法：使用国家电气制造商协会NU-2 2012标准对空间分辨率，灵敏度，等效噪声计数率，散射分数，计数率准确性和图像质量进行了表征。测量能量分辨率和同时时间分辨率。测试是分别在斯坦福大学和乌普萨拉大学安装的两台Discovery MI扫描仪上进行的，并对结果取平均值。还在Discovery MI，Discovery 690 PET / CT和SIGNA PET / MR系统之间进行了背对背的患者扫描。使用有序子集期望最大化和Q.Clear（具有点扩散函数模型的块序列正则化期望最大化）重构临床图像，并进行定性检查。结果：在距系统中心1、10和20 cm处通过滤波后的反投影重建的径向/切向/轴向空间分辨率的半峰平均全宽（FWHM）分别为4.10 / 4.19 / 4.48 mm，5.47 / 4.49 / 6.01毫米和7.53 / 4.90 / 6.10毫米。视场中央的平均灵敏度为13.7 cps / kBq。在21.9 kBq / mL处，平均等效噪声峰值计数率为193.4 kcps，散射分数为40.6％。直径为10毫米，13毫米，17毫米，22毫米，28毫米和37毫米的球体的图像质量体模的平均对比度恢复系数分别为53.7、64.0、73.1、82.7、86.8和90.7 。平均光峰能量分辨率为9.40％FWHM，平均重合时间分辨率为375.4 ps FWHM。PET / CT系统之间的临床图像比较证明了Discovery MI的高质量。Discovery MI和SIGNA之间的比较显示出相似的空间分辨率和整体成像性能。最后，结果表明与有序子集期望最大化相比，Q.Clear的图像质量和对比度噪声性能得到了显着提高。结论： Discovery MI获得了出色的性能，包括375 ps FWHM重合时间分辨率和14 cps / kBq的灵敏度。重建算法与其他多峰硅光电倍增管和非硅光电倍增管PET检测器系统设计之间的比较表明，这种下一代系统可以显着提高性能。