Department of Nuclear Medicine, University of Munich, Munich, Germany.
Mol Imaging Biol. 2010 Aug;12(4):427-34. doi: 10.1007/s11307-009-0281-5. Epub 2009 Nov 25.
The aim of this study is to evaluate a non-invasive method for measuring myocardial perfusion defect size in mice using a clinical single-photon emission computed tomography system equipped with pinhole collimators (pinhole SPECT).
Thirty days after ligation of the left anterior descending coronary artery, 13 mice (C57BL/6J) were imaged following intravenous injection of 370 MBq [99mTc]sestamibi. Eight control mice without myocardial infarction were likewise investigated. Image quality optimization had been achieved by repeated scanning of a multiple point phantom, with varying zoom factors, number of projection angles, and pinhole diameter. Volumetric sampling was used to generate polar maps, in which intensity was normalized to that of a standard septal region of interest (ROI), which was set at 100%. Receiver operating characteristic analyses were performed to define an optimal threshold as compared to histologically measured defect sizes, which were considered as gold standard.
A spatial resolution of 1.9 mm was achieved using a pinhole diameter of 0.5 mm, a zoom factor of 2, and 6 degrees projection angles. Histological results were best reproduced by a 60% threshold relative to the septal reference ROI. By applying this threshold, SPECT perfusion defect sizes revealed very high correlation to the histological results (R(2) = 0.867) with excellent intra- and interobserver reproducibility (intraclass correlation coefficients of 0.84 and 0.82).
We achieved a spatial resolution of 1.9 mm in myocardial perfusion imaging in mice using a clinical SPECT system mounted with pinhole collimators. Compared to a histological gold standard, the infarct sizes were accurately estimated, indicating that this method shows promise to monitor experimental cardiac interventions in mice.
本研究旨在评估使用配备小孔准直器的临床单光子发射计算机断层扫描系统（小孔 SPECT）测量小鼠心肌灌注缺陷大小的非侵入性方法。
在结扎左前降支 30 天后，对 13 只（C57BL/6J）小鼠静脉注射 370MBq [99mTc] sestamibi 后进行成像。同样对 8 只无心肌梗死的对照小鼠进行了研究。通过对具有不同缩放因子、投影角度和小孔直径的多点体模进行重复扫描，实现了图像质量优化。使用体积采样生成极地图，其中强度归一化为标准间隔 ROI 的强度（设为 100%）。进行了接收器操作特性分析，以定义与作为金标准的组织学测量缺陷大小相比的最佳阈值。
使用直径为 0.5mm、缩放因子为 2 和 6 度投影角度的小孔，可实现 1.9mm 的空间分辨率。相对于间隔参考 ROI 的 60%阈值，可最好地再现组织学结果。应用该阈值，SPECT 灌注缺陷大小与组织学结果高度相关（R2=0.867），并且具有出色的观察者内和观察者间可重复性（组内相关系数分别为 0.84 和 0.82）。
我们使用配备小孔准直器的临床 SPECT 系统在小鼠心肌灌注成像中实现了 1.9mm 的空间分辨率。与组织学金标准相比，梗死面积的估计非常准确，表明该方法有望监测小鼠的实验性心脏干预。
