Department of Nuclear Medicine and Comprehensive Heart Failure Center, University Hospital of Würzburg, Würzburg, Germany.
Division of Nuclear Medicine and Molecular Imaging, The Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Mol Imaging. 2022 Jul 16;2022:9810097. doi: 10.1155/2022/9810097. eCollection 2022.
Equipped with two stationary detectors, a large bore collimator for medium-sized animals has been recently introduced for dedicated preclinical single-photon emission computed tomography (SPECT) imaging. We aimed to evaluate the basic performance of the system using phantoms and healthy rabbits.
A general-purpose medium-sized animal (GP-MSA) collimator with 135 mm bore diameter and thirty-three holes of 2.5 mm diameter was installed on an ultrahigh-resolution scanner equipped with two large stationary detectors (U-SPECT5-E/CT). The sensitivity and uniformity were investigated using a point source and a cylinder phantom containing Tc-pertechnetate, respectively. Uniformity (in %) was derived using volumes of interest (VOIs) on images of the cylinder phantom and calculated as [(maximum count - minimum count)/(maximum count + minimum count) × 100], with lower values of % indicating superior performance. The spatial resolution and contrast-to-noise ratios (CNRs) were evaluated with images of a hot-rod Derenzo phantom using different activity concentrations. Feasibility of SPECT imaging was finally confirmed by rabbit imaging with the most commonly used clinical myocardial perfusion SPECT agent [Tc]Tc-sestamibi (dynamic acquisition with a scan time of 5 min).
In the performance evaluation, a sensitivity of 790 cps/MBq, a spatial resolution with the hot-rod phantom of 2.5 mm, and a uniformity of 39.2% were achieved. The CNRs of the rod size 2.5 mm were 1.37, 1.24, 1.20, and 0.85 for activity concentration of 29.2, 1.0, 0.5, and 0.1 MBq/mL, respectively. Dynamic SPECT imaging in rabbits allowed to visualize most of the thorax and to generate time-activity curves of the left myocardial wall and ventricular cavity.
Preclinical U-SPECT5-E/CT equipped with a large bore collimator demonstrated adequate sensitivity and resolution for rabbit imaging. Along with its unique features of SPECT molecular functional imaging is a superior collimator technology that is applicable to medium-sized animal models and thus may promote translational research for diagnostic purposes and development of novel therapeutics.
最近推出了一种配备两个固定探测器的大孔径准直器，用于专门的临床前单光子发射计算机断层扫描（SPECT）成像。我们旨在使用体模和健康兔来评估该系统的基本性能。
在配备两个大型固定探测器的超高分辨率扫描仪上安装了一个通用中号动物（GP-MSA）准直器，其孔径直径为 135 毫米，有 33 个 2.5 毫米直径的孔。使用点源和包含锝-pertechnetate 的圆柱体体模分别研究灵敏度和均匀性。使用圆柱体面模图像上的感兴趣区域（VOI）计算均匀性（以%表示），[(最大值计数-最小值计数)/(最大值计数+最小值计数)×100]，较低的%值表示性能更好。使用不同活度浓度的热棒 Derenzo 体模图像评估空间分辨率和对比度噪声比（CNR）。最后，使用最常用的临床心肌灌注 SPECT 试剂[Tc]Tc-sestamibi（5 分钟的动态采集）对兔进行成像，以确认 SPECT 成像的可行性。
在性能评估中，获得了 790 cps/MBq 的灵敏度、热棒体模的 2.5 毫米空间分辨率和 39.2%的均匀性。棒尺寸为 2.5 毫米的 CNR 分别为 29.2、1.0、0.5 和 0.1 MBq/mL 的活度浓度的 1.37、1.24、1.20 和 0.85。兔的动态 SPECT 成像能够可视化大部分胸部，并生成左心肌壁和心室腔的时间-活性曲线。
配备大孔径准直器的临床前 U-SPECT5-E/CT 显示出足够的灵敏度和分辨率，适用于兔成像。随着 SPECT 分子功能成像的独特特征，它是一种优越的准直器技术，适用于中型动物模型，因此可能会促进诊断目的的转化研究和新型治疗方法的开发。
