Jafari Tadi Mojtaba, Teuho Jarmo, Lehtonen Eero, Saraste Antti, Pänkäälä Mikko, Koivisto Tero, Teräs Mika
Turku PET Center, University of Turku, Finland. Department of Future Technologies, University of Turku, Finland.
Phys Med Biol. 2017 Oct 4;62(20):8080-8101. doi: 10.1088/1361-6560/aa8b09.
Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i.e. tri-axial accelerometer and gyroscope. This approach can be used for optimized selection of quiescent phases of cardiac and respiratory cycles. Cardiomechanical activity according to echocardiography observations was investigated to confirm whether this dual sensor solution can provide accurate trigger timings for cardiac gating. Additionally, longitudinal chest motions originating from breathing were measured by accelerometric- and gyroscopic-derived respiratory (ADR and GDR) tracking. The ADR and GDR signals were evaluated against Varian real-time position management (RPM) signals in terms of amplitude and phase. Accordingly, high linear correlation and agreement were achieved between the reference electrocardiography, RPM, and measured MEMS signals. We also performed a Ge-68 phantom study to evaluate possible metal artifacts caused by the integrated read-out electronics including mechanical sensors and semiconductors. The reconstructed phantom images did not reveal any image artifacts. Thus, it was concluded that MEMS-driven dual gating can be used in PET studies without an effect on the quantitative or visual accuracy of the PET images. Finally, the applicability of MEMS dual gating for cardiac PET imaging was investigated with two atherosclerosis patients. Dual gated PET images were successfully reconstructed using only MEMS signals and both qualitative and quantitative assessments revealed encouraging results that warrant further investigation of this method.
正电子发射断层扫描（PET）是一种非侵入性成像技术，可被视为用于检查动脉粥样硬化所致心脏炎症的先进技术。PET的一个基本局限性在于心脏和呼吸运动会降低所获图像的质量。当前的运动补偿方法包括根据心脏和呼吸周期静止期的时间对PET数据进行门控。在本研究中，我们提出了一种名为微机电（MEMS）双门控的新型门控方法，该方法依赖于联合非电传感器，即三轴加速度计和陀螺仪。这种方法可用于优化选择心脏和呼吸周期的静止期。根据超声心动图观察研究心脏机械活动，以确认这种双传感器解决方案是否能为心脏门控提供准确的触发时机。此外，通过基于加速度计和陀螺仪的呼吸（ADR和GDR）跟踪测量源于呼吸的纵向胸部运动。将ADR和GDR信号在幅度和相位方面与Varian实时位置管理（RPM）信号进行比较。因此，在参考心电图、RPM和测量的MEMS信号之间实现了高度的线性相关性和一致性。我们还进行了一项锗 - 68体模研究，以评估由包括机械传感器和半导体在内的集成读出电子设备可能引起的金属伪影。重建的体模图像未显示任何图像伪影。因此，得出结论，MEMS驱动的双门控可用于PET研究，而不会对PET图像的定量或视觉准确性产生影响。最后，用两名动脉粥样硬化患者研究了MEMS双门控在心脏PET成像中的适用性。仅使用MEMS信号成功重建了双门控PET图像，定性和定量评估均显示出令人鼓舞的结果，值得对该方法进行进一步研究。
