The Wales Research and Diagnostic Positron Emission Tomography Imaging Centre, Cardiff University, School of Medicine, Cardiff, CF14 4XN, Wales, United Kingdom.
Radiology, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, CF14 4XW, Wales, United Kingdom.
Biomed Phys Eng Express. 2024 Feb 20;10(2). doi: 10.1088/2057-1976/ad286c.
A performance evaluation was conducted on the new General Electric (GE) digital Omni Legend PET-CT system with 32 cm extended field of view. The first commercially available clinical digital bismuth germanate system. The system does not use time of flight (ToF). Testing was performed in accordance with the NEMA NU2-2018 standard. A comparison was made between two other commercial GE scanners with extended fields of view; the Discovery MI - 6 ring (ToF enabled) and the Discovery IQ (non-ToF). A genetic evolutionary algorithm was developed to optimize image reconstruction parameters from image quality assessments. The Omni demonstrated average spatial resolutions at 1 cm radial offset as 3.9 mm FWHM. The total system sensitivity at the center was 44.36 cps/kBq. The peak NECR was measured as 501 kcps at 17.8 kBq mlwith a 35.48% scatter fraction. The maximum count-rate error below NECR peak was 5.5%. Using standard iterative reconstructions, sphere contrast recovery coefficients were from 52.7 ± 3.2% (10 mm) to 92.5 ± 2.4% (37 mm). The PET-CT co-registration accuracy was 2.4 mm. In place of ToF, the Omni employs software corrections through a pre-trained neural network (PDL) (trained on non-ToF to ToF) that takes Bayesian penalized likelihood reconstruction (Q.Clear) images as input. The optimum parameters for image reconstruction, determined using the genetic algorithm were a Q.Clear parameter,, of 350 and a 'medium' PDL setting. Using standard iterative reconstructions, the Omni initially showed increased background variability compared to the Discovery MI. With optimized PDL reconstruction parameters selected using the genetic algorithm the performance of the Omni surpassed that of the Discovery MI on all NEMA tests. The genetic algorithm's demonstrated ability to enhance image quality in PET-CT imaging underscores the importance of algorithm driven optimization and underscores the requirement to validate its use in the clinical setting.
对具有 32cm 扩展视野的新型通用电气（GE）数字 Omni Legend PET-CT 系统进行了性能评估。这是第一个商用临床数字铋锗酸盐系统。该系统不使用飞行时间（ToF）。测试是根据 NEMA NU2-2018 标准进行的。对另外两个具有扩展视野的商业 GE 扫描仪进行了比较；Discovery MI-6 环（启用 ToF）和 Discovery IQ（非 ToF）。开发了一种遗传进化算法，从图像质量评估中优化图像重建参数。Omni 在 1cm 径向偏移处的平均空间分辨率为 3.9mm FWHM。中心的总系统灵敏度为 44.36cps/kBq。在 17.8kBq/ml 和 35.48%散射分数下，测量到的峰值 NECR 为 501kcps。在 NECR 峰值以下，最大计数率误差为 5.5%。使用标准迭代重建，球状体对比恢复系数为 52.7±3.2%（10mm）至 92.5±2.4%（37mm）。PET-CT 配准精度为 2.4mm。代替 ToF，Omni 通过预训练的神经网络（PDL）（在非 ToF 到 ToF 上进行训练）进行软件校正，该网络将贝叶斯惩罚似然重建（Q.Clear）图像作为输入。使用遗传算法确定的图像重建最佳参数是 Q.Clear 参数为 350 和“中等”PDL 设置。使用标准迭代重建，Omni 最初与 Discovery MI 相比显示出背景变化增加。使用遗传算法选择优化的 PDL 重建参数后，Omni 在所有 NEMA 测试中的性能均超过了 Discovery MI。遗传算法在 PET-CT 成像中提高图像质量的能力突显了算法驱动优化的重要性，并强调了在临床环境中验证其使用的必要性。
