Radiotracer Dose Reduction in Integrated PET/MR: Implications from National Electrical Manufacturers Association Phantom Studies
Radiotracer Dose Reduction in Integrated PET/MR: Implications from National Electrical Manufacturers Association Phantom Studies
复制标题
DOI：
10.2967/jnumed.114.139147
复制
发表时间：
2014-08-01
影响因子：
9.3
通讯作者：
Quick, Harald H.
中科院分区：
文献类型：
--
作者：
Oehmigen, Mark;Ziegler, Susanne;Quick, Harald H.
随着电离CT被MR成像所取代，与PET/CT相比，在特定的临床应用中，PET/MR集成可能会降低患者的总体辐射剂量。进一步降低放射性示踪剂剂量的潜力，同时保持PET/MR集成中的PET图像质量（IQ），可以通过增加PET采集持续时间来匹配MR数据采集所需的较长时间来实现。为了在受控条件下系统地验证这一假设，根据美国国家电气制造商协会（NEMA）的IQ协议，使用标准化模型进行了剂量减少研究。方法：所有测量均在PET/MR整体混合系统上进行。NEMA IQ模体充满水，F-18-FDG的总活性为50.35 MBq。球体与背景活动比为8:1。以列表模式格式获取20分钟采集时间的多个PET数据块，并以F-18-FDG半衰期的倍数定期启动。重建不同时间（2、4、8、16 min）的波形图。利用基于ct的衰减图模板对填充的NEMA模体进行衰减校正。衰减校正后的PET图像随后按照NEMA IQ方案进行定量评估，研究对比度恢复、背景变异性和信噪比。对具有一半活动和两倍获取时间的图像组进行评估。为了更好的统计，实验重复了3次。结果：对比恢复、背景变异性和信噪比在3个半衰期内几乎保持不变，当降低的放射性示踪剂活性（100%、50%、25%和12.5%）被增加的采集时间（2、4、8和16分钟）所补偿。对比恢复在3个半衰期的变化很小（-6%至+7%），与参考设置（100%，2分钟）相比，平均变化为2%。热球的信噪比在3个半衰期（5%）内变化不大。图像阅读器不能区分不同PET采集设置的主观智商。结论：提出了一种降低PET/MR综合成像中注射放射性示踪剂活性，同时保持PET 10的方法，并在理想的实验条件下进行了验证。与传统的PET/CT研究相比，该实验可作为进一步临床PET/MR研究的基础，使用减少的放射性示踪剂剂量。
With the replacement of ionizing CT by MR imaging, integrated PET/MR in selected clinical applications may reduce the overall patient radiation dose when compared with PET/CT. Further potential for radiotracer dose reduction, while maintaining PET image quality (IQ) in integrated PET/MR, may be achieved by increasing the PET acquisition duration to match the longer time needed for MR data acquisition. To systematically verify this hypothesis under controlled conditions, this dose-reduction study was performed using a standardized phantom following the National Electrical Manufacturers Association (NEMA) IQ protocol. Methods: All measurements were performed on an integrated PET/MR whole-body hybrid system. The NEMA IQ phantom was filled with water and a total activity of 50.35 MBq of F-18-FDG. The sphere-to-background activity ratio was 8:1. Multiple PET data blocks of 20-min acquisition time were acquired in list-mode format and were started periodically at multiples of the F-18-FDG half-lives. Different sinograms (2, 4, 8, and 16 min in duration) were reconstructed. Attenuation correction of the filled NEMA phantom was performed using a CT-based attenuation map template. The attenuation-corrected PET images were then quantitatively evaluated following the NEMA IQ protocol, investigating contrast recovery, background variability, and signal-to-noise ratio. Image groups with half the activity and twice the acquisition time were evaluated. For better statistics, the experiment was repeated 3 times. Results: Contrast recovery, background variability, and signal-to-noise ratio remained almost constant over 3 half-life periods when the decreasing radiotracer activity (100%, 50%, 25%, and 12.5%) was compensated by increasing acquisition time (2, 4, 8, and 16 min). The variation of contrast recovery over 3 half-life periods was small (-6% to +7%), with a mean variation of 2%, compared with the reference setting (100%, 2 min). The signal-to-noise ratio of the hot spheres showed only minor variations over 3 half-life periods (5%). Image readers could not distinguish subjective IQ between the different PET acquisition setups. Conclusion: An approach to reduce the injected radiotracer activity in integrated PET/MR imaging, while maintaining PET 10, was presented and verified under idealized experimental conditions. This experiment may serve as a basis for further clinical PET/MR studies using reduced radiotracer dose as compared with conventional PET/CT studies.