EM reconstruction of dual isotope PET using staggered injections and prompt gamma positron emitters.
EM reconstruction of dual isotope PET using staggered injections and prompt gamma positron emitters.
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DOI：
10.1118/1.4861714
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发表时间：
2014-02
期刊：
影响因子：
3.8
通讯作者：
A. Andreyev;Arkadiusz Sitek;Anna Ceeller
中科院分区：
文献类型：
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作者：
A. Andreyev;Arkadiusz Sitek;Anna Ceeller
目的双同位素正电子发射断层扫描（DIPET）的目的是建立两种共注入的PET示踪剂的两个独立图像。与两种放射性示踪剂独立成像（顺序PET研究）相比，DIPET缩短了研究的持续时间，减少了患者的不适，并产生了完美的共配图像。同时获得两种PET放射性示踪剂的数据重建是困难的，因为任何同位素的正电子衰变只产生511个keV光子；因此，不能根据检测到的能量来区分同位素。最近，作者提出了一种DIPET技术，该技术使用放射性示踪剂a（纯正电子发射器，如（18）F或（11）C）和放射性示踪剂B的组合，其中正电子衰变伴随着高能（HE）提示γ（如（38）K或（60）Cu）的发射。作为HE伽玛与对应的两个511 keV光子的三重巧合而检测到的事件允许作者识别同位素b的响应线（LORs）。这些LORs用于使用专用图像重建算法分离两个纠缠在一起的分布。在这项工作中，作者提出了一个新版本的基于DIPET em的重建算法，该算法允许作者包括一个额外的、独立的放射性示踪剂a分布估计，如果使用交错注射方法给药，可能会获得放射性同位素。在这项工作中，该方法在静态PET采集的简单模拟上进行了测试。使用蒙特卡罗模拟和静态采集进行的实验表明，与正电子- γ DIPET方法或单独交错注入相比，组合方法提供了更好的结果（串扰误差减少高达50%）。作者证明，作者的新EM算法结合了三重重合与提示伽马和交错注射的信息，提高了静态采集的DIPET重建的准确性，因此它们几乎达到了完美分离示踪剂计算的基准水平。
PURPOSE The aim of dual isotope positron emission tomography (DIPET) is to create two separate images of two coinjected PET radiotracers. DIPET shortens the duration of the study, reduces patient discomfort, and produces perfectly coregistered images compared to the case when two radiotracers would be imaged independently (sequential PET studies). Reconstruction of data from such simultaneous acquisition of two PET radiotracers is difficult because positron decay of any isotope creates only 511 keV photons; therefore, the isotopes cannot be differentiated based on the detected energy. METHODS Recently, the authors have proposed a DIPET technique that uses a combination of radiotracer A which is a pure positron emitter (such as(18)F or (11)C) and radiotracer B in which positron decay is accompanied by the emission of a high-energy (HE) prompt gamma (such as (38)K or (60)Cu). Events that are detected as triple coincidences of HE gammas with the corresponding two 511 keV photons allow the authors to identify the lines-of-response (LORs) of isotope B. These LORs are used to separate the two intertwined distributions, using a dedicated image reconstruction algorithm. In this work the authors propose a new version of the DIPET EM-based reconstruction algorithm that allows the authors to include an additional, independent estimate of radiotracer A distribution which may be obtained if radioisotopes are administered using a staggered injections method. In this work the method is tested on simple simulations of static PET acquisitions. RESULTS The authors' experiments performed using Monte-Carlo simulations with static acquisitions demonstrate that the combined method provides better results (crosstalk errors decrease by up to 50%) than the positron-gamma DIPET method or staggered injections alone. CONCLUSIONS The authors demonstrate that the authors' new EM algorithm which combines information from triple coincidences with prompt gammas and staggered injections improves the accuracy of DIPET reconstructions for static acquisitions so they reach almost the benchmark level calculated for perfectly separated tracers.