DePuey E Gordon, Gadiraju Ramesh, Clark John, Thompson Linda, Anstett Frank, Shwartz Shuli C
Department of Radiology, Division of Nuclear Medicine, St Luke's-Roosevelt Hospital, New York, NY 10025, USA.
J Nucl Cardiol. 2008 Jul-Aug;15(4):547-63. doi: 10.1016/j.nuclcard.2008.02.035. Epub 2008 Apr 24.
Compared to filtered back projection (FBP), OSEM with resolution recovery (OSEM-RR) and wide beam reconstruction (WBR)(UltraSPECT Ltd.), which resolve resolution and suppress noise simultaneously during reconstruction, have been shown to maintain/improve myocardial perfusion SPECT quality, even with low count density half-time acquisitions. We postulated that their characteristics would be advantageous for gated SPECT, where each frame is only 1/8th the count density of the summed perfusion images.
An 9 mCi rest/32 mCi (333/1184 MBq) stress Tc(99m) sestamibi protocol was used. 15-min FBP, and additional 7-min OSEM-RR and WBR post-stress 8-frame/cardiac cycle SPECT scans were acquired with 90 degrees -angled dual-headed detectors equipped with high resolution collimators in 156 patients. In 82 patients (48F, 34M) (123-252 lbs) with perfusion defects gated image quality was graded visually: 1 (poor)-5 (excellent) Regional LV wall motion (WM) was scored: 0 (normal)-4 (dyskinesis) in a total of 50 vascular territories with defects. Using Myometrix software (GE Healthcare), post-stress EDV, ESV, and EF were calculated for each method. Additionally, for purposes of comparison, the FBP gated tomograms were processed with other commercially available packages, Emory Toolbox and Cedars QGS.
Despite half-time acquisitions, compared to FBP, image quality increased marginally with OSEM-RR (P = .09) but very significantly with WBR (P = 1.9 x 10(-21)). The WM score was greater only for WBR (P = 4.8 x 10(-8)). Although quantitative parameters correlated well with those determined by FBP (all EF r's > 0.85; all volume r's > 0.93), EFs were significantly lower (P = .0001 for OSEM-RR, 3.4 x 10(-14) for WBR), primarily due to a decrease in EDV with OSEM-RR (P = 7.3 x 10(-13)) and an increase in ESV with WBR (P = 9.2 x 10(-5)). However, inter-method differences in these parameters were of similar magnitude to differences encountered among the commercially available software methods.
Half-time OSEM-RR and particularly WBR improve gated SPECT diagnostic quality compared to full-time FBP due to increased resolution and reduced noise. However, these attributes, which affect endocardial edge detection, result in a systematic offset in EDV, ESV, and EF.
与滤波反投影（FBP）相比，具有分辨率恢复功能的有序子集期望最大化算法（OSEM-RR）和宽束重建（WBR）（UltraSPECT有限公司）在重建过程中可同时解决分辨率问题并抑制噪声，已证明即使在低计数密度半衰期采集的情况下，它们也能保持/改善心肌灌注单光子发射计算机断层扫描（SPECT）质量。我们推测它们的特性对于门控SPECT将是有利的，因为门控SPECT中每个帧的计数密度仅为总灌注图像的1/8。
采用9 mCi静息/32 mCi（333/1184 MBq）负荷锝-99m甲氧基异丁基异腈方案。使用配备高分辨率准直器的90度角双头探测器，对156例患者进行了15分钟的FBP以及负荷后7分钟的OSEM-RR和WBR的8帧/心动周期SPECT扫描。对82例（48名女性，34名男性）（体重123 - 252磅）有灌注缺损的患者，对门控图像质量进行视觉分级：1（差）-5（优）。对总共50个有缺损的血管区域的左心室壁运动（WM）进行评分：0（正常）-4（运动障碍）。使用Myometrix软件（GE医疗保健公司），计算每种方法负荷后的舒张末期容积（EDV）、收缩末期容积（ESV）和射血分数（EF）。此外，为了进行比较，用其他市售软件包Emory Toolbox和Cedars QGS对FBP门控断层图像进行处理。
尽管是半衰期采集，但与FBP相比，OSEM-RR使图像质量略有提高（P = 0.09），而WBR使图像质量显著提高（P = 1.9×10⁻²¹）。仅WBR的WM评分更高（P = 4.8×10⁻⁸）。尽管定量参数与FBP确定的参数相关性良好（所有EF的r值>0.85；所有容积的r值>0.93），但EF显著更低（OSEM-RR为P = 0.0001，WBR为3.4×10⁻¹⁴），主要是因为OSEM-RR导致EDV降低（P = 7.3×10⁻¹³），WBR导致ESV增加（P = 9.2×10⁻⁵）。然而，这些参数的方法间差异与市售软件方法之间遇到的差异幅度相似。
与全时FBP相比，半衰期的OSEM-RR尤其是WBR由于分辨率提高和噪声降低，改善了门控SPECT的诊断质量。然而，这些影响心内膜边缘检测的属性导致EDV、ESV和EF出现系统性偏移。
