Davison Helen, ter Voert Edwin E G W, de Galiza Barbosa Felipe, Veit-Haibach Patrick, Delso Gaspar
From the *Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, Zurich, Switzerland; †Department of Medical Physics, Royal United Hospitals Bath NHS Foundation Trust, Bath, United Kingdom; ‡Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland; and §GE Healthcare, Waukesha, WI.
Invest Radiol. 2015 Jul;50(7):423-9. doi: 10.1097/RLI.0000000000000146.
This study aimed to describe and evaluate the influence of time-of-flight (TOF) information on metal artifact reduction in positron emission tomography (PET) image quality in clinical simultaneous PET/magnetic resonance (MR) scanning.
A total of 7 patients with various malignant tumors were included and underwent a PET/MR examination after standard PET/computed tomography. Baseline TOF and non-TOF PET images were reconstructed. Next, the TOF and non-TOF PET reconstructions were repeated after the introduction of artificial signal voids in the attenuation map to simulate metal artifacts of various sizes in a range of locations. Three different sizes of signal voids were inserted in the attenuation maps for each location of interest: over the maxilla, humeral head, chest, sternum, thoracic and lumbar spine, as well as the femoral head to replicate clinically relevant metal artifacts. The reconstructed images with the artifacts were then compared with the baseline reconstructed images. The mean percentage error in a region of interest surrounding the simulated artifact was used to compare between TOF and non-TOF images. Further comparison between TOF and non-TOF images was performed using histogram analysis.
In all cases, the mean percentage error in a region of interest surrounding the simulated artifact was reduced when TOF information was included in the reconstruction. The inclusion of TOF also changes the distribution of smaller errors away from the origin of the artifact. In some anatomical regions, an increase in the number of small errors was noted with TOF, although the differences with non-TOF were minimal.
Positron emission tomographic imaging benefits from the integration of TOF information in simultaneous PET/MR. The inclusion of TOF information in simultaneous PET/MR imaging reduces errors related to metal artifacts at the site of the artifact.
本研究旨在描述和评估飞行时间（TOF）信息对临床同时进行的正电子发射断层扫描（PET）/磁共振成像（MR）扫描中PET图像质量的金属伪影减少的影响。
共纳入7例患有各种恶性肿瘤的患者，在进行标准PET/计算机断层扫描后接受PET/MR检查。重建基线TOF和非TOF PET图像。接下来，在衰减图中引入人工信号空洞以模拟一系列位置的各种大小的金属伪影后，重复进行TOF和非TOF PET重建。在每个感兴趣的位置的衰减图中插入三种不同大小的信号空洞：上颌骨、肱骨头、胸部、胸骨、胸椎和腰椎以及股骨头上方，以复制临床相关的金属伪影。然后将带有伪影的重建图像与基线重建图像进行比较。使用模拟伪影周围感兴趣区域的平均百分比误差来比较TOF和非TOF图像。使用直方图分析对TOF和非TOF图像进行进一步比较。
在所有情况下，当重建中包含TOF信息时，模拟伪影周围感兴趣区域的平均百分比误差降低。包含TOF还会使较小误差的分布远离伪影的起源。在一些解剖区域，TOF时小误差的数量有所增加，尽管与非TOF的差异很小。
正电子发射断层成像受益于在同时进行的PET/MR中整合TOF信息。在同时进行的PET/MR成像中包含TOF信息可减少与伪影部位的金属伪影相关的误差。
