Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
J Nucl Cardiol. 2011 Oct;18(5):840-6. doi: 10.1007/s12350-011-9423-7. Epub 2011 Jul 12.
A novel ultra-fast solid-state cardiac camera (Discovery NM 530c, General Electric) allows much shorter acquisition times compared to standard dual-detector SPECT cameras. This design enables investigation of the potential for early myocardial perfusion imaging (MPI) following a rest injection of technetium-99m (Tc-99m) rather than the conventional 45-60 minute delay in image acquisition.
A total of 30 patients underwent MPI at rest using Tc-99m sestamibi (n = 9) or tetrofosmin (n = 21). A 12 minute image acquisition in list mode was performed immediately following isotope injection. Patients also underwent a conventional delayed image acquisition 60 minutes following the rest isotope injection (image acquisition over 4 minutes). The immediate 12 minute acquisition was divided into three 4-minute intervals for image reconstruction (0-4, 4-8, and 8-12 minutes). The perfusion images were interpreted by two experienced physicians who evaluated each study for overall image quality (good, acceptable, or unacceptable) and graded each image using the summed rest score (SRS) and the standard 17-segment, 5-point scale model.
The images acquired in the 0-8 minute time interval were predominantly uninterpretable due to excessive blood pool uptake. The images acquired in the 8-12 minute time interval were interpretable and compared to the conventional images obtained at 60 minutes. Overall image quality was better on the 60 minute image (17 good, 13 acceptable) compared with 8-12 minute image (3 good, 25 acceptable, 2 unacceptable). Sixteen of the 30 patients had an improvement in overall image quality by at least one category using the 60 minute delayed image. Nine of the 30 patients (2 Tc-99m sestamibi; 7 Tc-99m tetrofosmin) had at least one uninterpretable myocardial segment due to liver and/or bowel overlapping the myocardium on the 8-12 minute images vs 1 patient (1 myocardial segment) with this problem on the 60 minute delayed images (P = .005). Uninterpretable segments (total of 16) on the 8-12 minute images were confined to the apex and inferior wall. The mean SRS of the interpretable 8-12 minute images (n = 21) was 3.2 (95% confidence intervals; 1.0, 5.4) compared to 1.6 (95% confidence intervals; 0, 3.3) on the 60 minute delayed images in those patients (P = .005).
Overall image quality was better with fewer uninterpretable studies and a lower SRS on the rest images obtained at 60 minutes compared to early image acquisition (8-12 minutes following isotope injection). These findings do not support the routine use of early image acquisition with this new solid-state ultra-fast camera system.
一种新型的超快速固态心脏相机（通用电气公司的 Discovery NM 530c）与标准的双探测器 SPECT 相机相比，可以缩短采集时间。这种设计使得研究在静息状态下注射锝-99m（Tc-99m）后进行早期心肌灌注成像（MPI）成为可能，而不是常规的 45-60 分钟延迟采集图像。
共有 30 名患者使用 Tc-99m sestamibi（n=9）或 tetrofosmin（n=21）进行 MPI 静息。注射示踪剂后立即以列表模式进行 12 分钟的图像采集。患者还进行了常规延迟图像采集，即在静息同位素注射后 60 分钟（4 分钟采集图像）。立即进行的 12 分钟采集分为三个 4 分钟间隔进行图像重建（0-4、4-8 和 8-12 分钟）。由两位有经验的医生对灌注图像进行解读，他们评估了每个研究的整体图像质量（好、可接受或不可接受），并使用总和静息评分（SRS）和标准的 17 节段、5 分制模型对每个图像进行评分。
0-8 分钟时间间隔采集的图像由于血池摄取过多，主要无法解读。8-12 分钟时间间隔采集的图像可解读，并与 60 分钟时获得的常规图像进行比较。60 分钟图像的整体图像质量更好（17 个好，13 个可接受），而 8-12 分钟图像的整体图像质量较差（3 个好，25 个可接受，2 个不可接受）。使用 60 分钟延迟图像，30 名患者中有 16 名的整体图像质量至少提高了一个等级。与 60 分钟延迟图像相比，30 名患者中有 9 名（2 名 Tc-99m sestamibi；7 名 Tc-99m tetrofosmin）有至少一个心肌节段因肝脏和/或肠重叠在心肌上而无法解读（95%置信区间；1.0，5.4），而该问题在 1 名患者（1 个心肌节段）的 60 分钟延迟图像上出现（P=0.005）。在 8-12 分钟图像上无法解读的节段（共 16 个）仅限于心尖和下壁。可解读的 8-12 分钟图像的平均 SRS（n=21）为 3.2（95%置信区间；1.0，5.4），而在接受同位素注射后 60 分钟延迟图像上的 SRS 为 1.6（95%置信区间；0，3.3）（P=0.005）。
与早期图像采集（注射同位素后 8-12 分钟）相比，在 60 分钟时获得的静息图像的整体图像质量更好，不可解读的研究更少，SRS 更低。这些发现不支持常规使用这种新型固态超快速相机系统进行早期图像采集。
