Image quality and detectability in Siemens Biograph PET/MRI and PET/CT systems-a phantom study
Image quality and detectability in Siemens Biograph PET/MRI and PET/CT systems-a phantom study
复制标题
DOI：
10.1186/s40658-019-0251-1
复制
发表时间：
2019-08-05
期刊：
影响因子：
4
通讯作者：
Karlberg, Anna Maria
中科院分区：
文献类型：
--
作者：
Oen, Silje Kjaernes;Aasheim, Lars Birger;Karlberg, Anna Maria
背景现代正电子发射断层扫描(PET)系统的技术不断改进，使发现更小的病变成为可能。自2010年首次推出以来，全球混合PET/磁共振成像(MRI)系统的数量不断增加。因此，就可检测性而言，评估和比较PET/MRI和成熟的PET/CT系统之间的图像质量是很重要的。为此，利用氟代脱氧葡萄糖和球本底活度比分别为8：1和4：1，模拟临床情况，制备了直径为4~20 mm热球的PET图像质量体模(ESSER)。在PET/MRI和PET/CT系统上对模型进行两种浓度的扫描，以获得一系列重建设置的对比度恢复系数(CRC)和对比度噪声比(CNR)。三名人类观察者对球体的可探测性进行了评分，包括系统和浓度以及所有重建。此外，还研究了捕获时间对信噪比和观测者可检测性的影响。结果应用点扩散函数模型的重建结果(以及PET/CT的飞行时间)总体上产生了最高的CRC和CNR，对于大多数球体大小，PET/CT显示的值略高于PET/MRI。CNR取决于重建设置，并且最大化2次迭代，像素大小小于2 mm和4 mm高斯过滤器。对97例S(正电子发射计算机断层扫描/核磁共振)和150例S(正电子发射计算机断层扫描)的采集次数得出了相似的总真实净计数。在这些采集时间内，人类观察者在8：1活动浓度下检测到的最小球体是6 mm的PET/MRI球体(CNR=5.6)和5 mm的PET/CT球体(CNR=5.5)。S的采集时间为180时，对5 mm的球体进行正电子发射计算机断层扫描(CNR=5.8)。在两个系统的4：1活度浓度中，8 mm的球体是最小的被检测球体。结论在这项实验研究中，虽然PET/MRI的采集时间增加，但PET/MRI和PET/CT的检测能力相似。
Background The technology of modern positron emission tomography (PET) systems continuously improving, and with it the possibility to detect smaller lesions. Since first introduced in 2010, the number of hybrid PET/magnetic resonance imaging (MRI) systems worldwide is constantly increasing. It is therefore important to assess and compare the image quality, in terms of detectability, between the PET/MRI and the well-established PET/computed tomography (CT) systems. For this purpose, a PET image quality phantom (Esser) with hot spheres, ranging from 4 to 20 mm in diameter, was prepared with fluorodeoxyglucose and sphere-to-background activity concentrations of 8:1 and 4:1, to mimic clinical conditions. The phantom was scanned on a PET/MRI and a PET/CT system for both concentrations to obtain contrast recovery coefficients (CRCs) and contrast-to-noise ratios (CNRs), for a range of reconstruction settings. The detectability of the spheres was scored by three human observers for both systems and concentrations and all reconstructions. Furthermore, the impact of acquisition time on CNR and observer detectability was investigated. Results Reconstructions applying point-spread-function modeling (and time-of-flight for the PET/CT) yielded the highest CRC and CNR in general, and PET/CT demonstrated slightly higher values than PET/MRI for most sphere sizes. CNR was dependent on reconstruction settings and was maximized for 2 iterations, a pixel size of less than 2 mm and a 4 mm Gaussian filter. Acquisition times of 97 s (PET/MRI) and 150 s (PET/CT) resulted in similar total net true counts. For these acquisition times, the smallest detected spheres by the human observers in the 8:1 activity concentration was the 6-mm sphere with PET/MRI (CNR = 5.6) and the 5-mm sphere with PET/CT (CNR = 5.5). With an acquisition time of 180 s, the 5-mm sphere was also detected with PET/MRI (CNR = 5.8). The 8-mm sphere was the smallest detected sphere in the 4:1 activity concentration for both systems. Conclusion In this experimental study, similar detectability was found for the PET/MRI and the PET/CT, although for an increased acquisition time for the PET/MRI.