Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images
Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images
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优化更短的腿部可变采集时间，以实现真正的全身 PET/CT 图像
DOI：
10.1007/s13246-017-0596-5
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发表时间：
2017
影响因子：
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通讯作者：
Koizumi Mitsuru
中科院分区：
文献类型：
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作者：
Umeda Takuro;Miwa Kenta;Murata Taisuke;Miyaji Noriaki;Wagatsuma Kei;Motegi Kazuki;Terauchi Takashi;Koizumi Mitsuru
本研究旨在定性和定量评估PET图像作为不同腿部尺寸的采集时间的函数，并优化腿部的较短可变采集时间协议，以实现更好的真实全身PET/CT图像的定性和定量准确性。根据53例患者的数据定义了拟建模为体模的下肢直径。本研究分析了分别模拟人体和腿部的NEMA体模和三个塑料瓶体模（直径，5.68，8.54和10.7 cm）的PET图像。体模由两个含氟-18氟脱氧葡萄糖溶液的球体（直径，10和17 mm）组成，球体与背景比为4，背景放射性水平为2.65 kBq/mL。所有的PET数据重建的采集时间范围从10到180，和1200秒。我们直观地评价图像质量，并确定了背景的方差系数（CV），对比度和热球的定量%误差，然后确定了两个较短的变量采集协议的腿。还评价了使用所提出的方案基于患者PET图像中的最大标准化摄取值（SUVmax）确定的病变可检测性和定量准确性。较大的体模和较短的采集时间导致图像上的背景噪声增加，并降低了热球的对比度。当三腿体模的采集时间≥ 30 s，NEMA体模的采集时间≥ 120 s时，获得≥ 1.5的视觉评分。在具有高CV（扫描< 30 s）的PET图像中，腿部体模中10 mm和17 mm球体的定量%误差分别为± 15%和± 10%。在临床研究中，使用当前固定采集和两种拟议的可变采集时间方案的三个病变的平均SUVmax分别为3.1、3.1和3.2，无显著差异。每个床位置的腿部采集时间甚至为30-90 s，可实现轴向均衡、均匀的图像噪声和最小病变的最大± 15%定量准确度。使用比当前成像腿固定采集时间更短的拟议变量，总体采集时间减少了23-42%，表明这是临床环境中常规定性和定量PET/CT评估的有用且实用的方案。
The present study aimed to qualitatively and quantitatively evaluate PET images as a function of acquisition time for various leg sizes, and to optimize a shorter variable-acquisition time protocol for legs to achieve better qualitative and quantitative accuracy of true whole-body PET/CT images. The diameters of legs to be modeled as phantoms were defined based on data derived from 53 patients. This study analyzed PET images of a NEMA phantom and three plastic bottle phantoms (diameter, 5.68, 8.54 and 10.7 cm) that simulated the human body and legs, respectively. The phantoms comprised two spheres (diameters, 10 and 17 mm) containing fluorine-18 fluorodeoxyglucose solution with sphere-to-background ratios of 4 at a background radioactivity level of 2.65 kBq/mL. All PET data were reconstructed with acquisition times ranging from 10 to 180, and 1200 s. We visually evaluated image quality and determined the coefficient of variance (CV) of the background, contrast and the quantitative %error of the hot spheres, and then determined two shorter variable-acquisition protocols for legs. Lesion detectability and quantitative accuracy determined based on maximum standardized uptake values (SUVmax) in PET images of a patient using the proposed protocols were also evaluated. A larger phantom and a shorter acquisition time resulted in increased background noise on images and decreased the contrast in hot spheres. A visual score of ≥ 1.5 was obtained when the acquisition time was ≥ 30 s for three leg phantoms, and ≥ 120 s for the NEMA phantom. The quantitative %errors of the 10- and 17-mm spheres in the leg phantoms were ± 15 and ± 10%, respectively, in PET images with a high CV (scan < 30 s). The mean SUVmaxof three lesions using the current fixed-acquisition and two proposed variable-acquisition time protocols in the clinical study were 3.1, 3.1 and 3.2, respectively, which did not significantly differ. Leg acquisition time per bed position of even 30–90 s allows axial equalization, uniform image noise and a maximum ± 15% quantitative accuracy for the smallest lesion. The overall acquisition time was reduced by 23–42% using the proposed shorter variable than the current fixed-acquisition time for imaging legs, indicating that this is a useful and practical protocol for routine qualitative and quantitative PET/CT assessment in the clinical setting.