Miwa Kenta, Umeda Takuro, Murata Taisuke, Wagatsuma Kei, Miyaji Noriaki, Terauchi Takashi, Koizumi Mitsuru, Sasaki Masayuki
aDepartment of Health Sciences, Division of Medical Quantum Science, Faculty of Medical Sciences, Kyushu University, Fukuoka bDepartment of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research cResearch Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo dDepartment of Radiology, Chiba University Hospital, Chiba Prefecture, Japan.
Nucl Med Commun. 2016 Feb;37(2):147-54. doi: 10.1097/MNM.0000000000000403.
Overcorrection of scatter caused by patient motion during whole-body PET/computed tomography (CT) imaging can induce the appearance of photopenic artifacts in the PET images. The present study aimed to quantify the accuracy of scatter limitation correction (SLC) for eliminating photopenic artifacts.
This study analyzed photopenic artifacts in (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT images acquired from 12 patients and from a National Electrical Manufacturers Association phantom with two peripheral plastic bottles that simulated the human body and arms, respectively. The phantom comprised a sphere (diameter, 10 or 37 mm) containing fluorine-18 solutions with target-to-background ratios of 2, 4, and 8. The plastic bottles were moved 10 cm posteriorly between CT and PET acquisitions. All PET data were reconstructed using model-based scatter correction (SC), no scatter correction (NSC), and SLC, and the presence or absence of artifacts on the PET images was visually evaluated. The SC and SLC images were also semiquantitatively evaluated using standardized uptake values (SUVs).
Photopenic artifacts were not recognizable in any NSC and SLC image from all 12 patients in the clinical study. The SUVmax of mismatched SLC PET/CT images were almost equal to those of matched SC and SLC PET/CT images. Applying NSC and SLC substantially eliminated the photopenic artifacts on SC PET images in the phantom study. SLC improved the activity concentration of the sphere for all target-to-background ratios. The highest %errors of the 10 and 37-mm spheres were 93.3 and 58.3%, respectively, for mismatched SC, and 73.2 and 22.0%, respectively, for mismatched SLC.
Photopenic artifacts caused by SC error induced by CT and PET image misalignment were corrected using SLC, indicating that this method is useful and practical for clinical qualitative and quantitative PET/CT assessment.
在全身正电子发射断层扫描/计算机断层扫描（PET/CT）成像过程中，患者运动引起的散射过度校正可导致PET图像中出现放射性缺损伪影。本研究旨在量化散射限制校正（SLC）消除放射性缺损伪影的准确性。
本研究分析了12例患者以及一个美国国家电气制造商协会体模的（18）F-氟脱氧葡萄糖（（18）F-FDG）PET/CT图像中的放射性缺损伪影，该体模带有两个分别模拟人体和手臂的外周塑料瓶。体模包含一个直径为10或37mm的球体，其中含有氟-18溶液，靶本底比分别为2、4和8。在CT和PET采集之间，将塑料瓶向后移动10cm。所有PET数据均使用基于模型的散射校正（SC）、无散射校正（NSC）和SLC进行重建，并通过视觉评估PET图像上是否存在伪影。还使用标准化摄取值（SUV）对SC和SLC图像进行半定量评估。
在临床研究中，所有12例患者的任何NSC和SLC图像中均未发现放射性缺损伪影。不匹配的SLC PET/CT图像的SUVmax几乎与匹配的SC和SLC PET/CT图像的SUVmax相等。在体模研究中，应用NSC和SLC基本消除了SC PET图像上的放射性缺损伪影。对于所有靶本底比，SLC均提高了球体的活度浓度。对于不匹配的SC，10mm和37mm球体的最高%误差分别为93.3%和58.3%，对于不匹配的SLC，分别为73.2%和22.0%。
使用SLC校正了由CT和PET图像未对准引起的SC误差导致的放射性缺损伪影，表明该方法对于临床PET/CT定性和定量评估是有用且实用的。
