Department of Nuclear Medicine, CHU-Nancy, Nancy, 54000, France.
Eur J Nucl Med Mol Imaging. 2014 Mar;41(3):522-8. doi: 10.1007/s00259-013-2617-2. Epub 2013 Nov 8.
Injected doses are difficult to optimize for exercise SPECT since they depend on the myocardial fraction of injected activity (MFI) that is detected by the camera. The aim of this study was to analyse the factors affecting MFI determined using a cardiac CZT camera as compared with those determined using conventional Anger cameras.
Factors affecting MFI were determined and compared in patients who had consecutive exercise SPECT acquisitions with (201)Tl (84 patients) or (99m)Tc-sestamibi (87 patients) with an Anger or a CZT camera. A predictive model was validated in a group of patients routinely referred for (201)Tl (78 patients) or (99m)Tc-sestamibi (80 patients) exercise CZT SPECT.
The predictive model involved: (1) camera type, adjusted mean MFI being ninefold higher for CZT than for Anger SPECT, (2) tracer type, adjusted mean MFI being twofold higher for (201)Tl than for (99m)Tc-sestamibi, and (3) logarithm of body weight. The CZT SPECT model led to a +1 ± 26% error in the prediction of the actual MFI from the validation group. The mean MFI values estimated for CZT SPECT were more than twofold higher in patients with a body weight of 60 kg than in patients with a body weight of 120 kg (15.9 and 6.8 ppm for (99m)Tc-sestamibi and 30.5 and 13.1ppm for (201)Tl, respectively), and for a 14-min acquisition of up to one million myocardial counts, the corresponding injected activities were only 80 and 186 MBq for (99m)Tc-sestamibi and 39 and 91 MBq for (201)Tl, respectively.
Myocardial activities acquired during exercise CZT SPECT are strongly influenced by body weight and tracer type, and are dramatically higher than those obtained using an Anger camera, allowing very low-dose protocols to be planned, especially for (99m)Tc-sestamibi and in non-obese subjects.
由于注射剂量取决于相机检测到的注射活性心肌分数（MFI），因此运动 SPECT 的注射剂量难以优化。本研究旨在分析使用心脏 CZT 相机与使用传统 Anger 相机相比，影响 MFI 的因素。
对连续进行运动 SPECT 采集的患者（201）Tl（84 例）或（99m）Tc- sestamibi（87 例），使用 Anger 或 CZT 相机进行 MFI 影响因素的确定和比较。在常规（201）Tl（78 例）或（99m）Tc-sestamibi（80 例）运动 CZT SPECT 患者中验证预测模型。
预测模型涉及：（1）相机类型，CZT 的平均 MFI 是 Anger SPECT 的九倍，（2）示踪剂类型，（201）Tl 的平均 MFI 是（99m）Tc-sestamibi 的两倍，（3）体重对数。来自验证组的实际 MFI 的 CZT SPECT 模型预测误差为+1±26%。体重为 60kg 的患者的 CZT SPECT 估计的平均 MFI 值是体重为 120kg 的患者的两倍多（（99m）Tc-sestamibi 为 15.9 和 6.8ppm，（201）Tl 为 30.5 和 13.1ppm），对于 14 分钟的采集，达到 100 万个心肌计数，相应的注射活动仅为 80 和 186MBq（99m）Tc-sestamibi 和 39 和 91MBq（201）Tl。
运动 CZT SPECT 采集的心肌活性受体重和示踪剂类型的强烈影响，明显高于使用 Anger 相机获得的活性，可计划非常低剂量方案，特别是对于（99m）Tc-sestamibi 和非肥胖患者。
