Performance Measurements of the Siemens mMR Integrated Whole-Body PET/MR Scanner
Performance Measurements of the Siemens mMR Integrated Whole-Body PET/MR Scanner
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DOI：
10.2967/jnumed.111.092726
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发表时间：
2011-12-01
影响因子：
9.3
通讯作者：
Ziegler, Sibylle I.
中科院分区：
文献类型：
--
作者：
Delso, Gaspar;Fuerst, Sebastian;Ziegler, Sibylle I.
最近发布的Bioggraph MMR是第一款商业化的一体化全身PET/MR扫描仪。在单个扫描仪中集成这两种模式有相当大的优势，可以实现真正的同时采集。然而，也有人担心在一个集成的系统中PET和MR的性能可能会下降。本文评估了Bioggraph MMR在独立和同时采集PET和形态MR数据时的性能。方法：按照NEMA NU 2-2007标准对PET性能进行研究。进行了以下测量：空间分辨率；散射分数、计数丢失和随机数；灵敏度；计数丢失和随机数校正的准确性；以及图像质量。按照美国放射学会的质量控制手册研究MR表现。进行以下测量：几何精度、空间分辨率、低对比度可探测性、信噪比、静电场(B-0)均匀度、射频场(B-1)均匀度和射频噪声。结果：在距视野中心1 cm处测得半高全宽平均空间分辨率为4.3 mm。系统沿扫描仪中心的灵敏度为15.0kCPS/MBq。当浓度为23.1kBq/mL时，散射分数为37.9%，峰值噪声当量计数率为184kCPS。死区损失和随机因素造成的相对计数率误差的最大绝对值为5.5%。散射和衰减校正的平均残差为12.1%。所有MR参数均在美国放射学会定义的公差范围内。测量半径120 mm范围内小于1ppm的B0不均一性。B1的均匀性和信噪比与标准MR扫描仪相当。未检测到射频干扰。结论：这些结果与其他最先进的PET/CT和PET/MR扫描仪相比是有利的，表明PET探测器在MR扫描仪中的集成及其在磁场中的操作不会对总体性能产生明显的影响。MR子系统的运行基本上类似于独立系统。然而，需要进一步的工作来评估更先进的磁共振应用，如功能成像和光谱学。
The recently released Biograph mMR is the first commercially available integrated whole-body PET/MR scanner. There are considerable advantages to integrating both modalities in a single scanner that enables truly simultaneous acquisition. However, there are also concerns about the possible degradation of both PET and MR performance in an integrated system. This paper evaluates the performance of the Biograph mMR during independent and simultaneous acquisition of PET and morphologic MR data. Methods: The NEMA NU 2-2007 protocol was followed for studying the PET performance. The following measurements were performed: spatial resolution; scatter fraction, count losses, and randoms; sensitivity; accuracy of the correction for count losses and randoms; and image quality. The quality control manual of the American College of Radiology was followed for studying the MR performance. The following measurements were performed: geometric accuracy, spatial resolution, low-contrast detectability, signal-to-noise ratio, static field (B-0) homogeneity, radiofrequency field (B-1) homogeneity, and radiofrequency noise. Results: An average spatial resolution of 4.3 mm in full width at half maximum was measured at 1 cm offset from the center of the field of view. The system sensitivity was 15.0 kcps/MBq along the center of the scanner. The scatter fraction was 37.9%, and the peak noise-equivalent count rate was 184 kcps at 23.1 kBq/mL. The maximum absolute value of the relative count rate error due to dead-time losses and randoms was 5.5%. The average residual error in scatter and attenuation correction was 12.1%. All MR parameters were within the tolerances defined by the American College of Radiology. B0 inhomogeneities below 1 ppm were measured in a 120-mm radius. B1 homogeneity and signal-to-noise ratio were equivalent to those of a standard MR scanner. No radiofrequency interference was detected. Conclusion: These results compare favorably with other state-of-the-art PET/CT and PET/MR scanners, indicating that the integration of the PET detectors in the MR scanner and their operation within the magnetic field do not have a perceptible impact on the overall performance. The MR subsystem performs essentially like a standalone system. However, further work is necessary to evaluate the more advanced MR applications, such as functional imaging and spectroscopy.