Borges-Neto Salvador, Pagnanelli Robert A, Shaw Linda K, Honeycutt Emily, Shwartz Shuli C, Adams George L, Coleman Ralph Edward
Department of Radiology, Division of Nuclear Medicine, Duke University Medical Center, Durham, NC 27710, USA.
J Nucl Cardiol. 2007 Jul;14(4):555-65. doi: 10.1016/j.nuclcard.2007.04.022.
Newly developed reconstruction algorithms enable the acquisition of images at half of the scan time while maintaining image quality. The purpose of this investigation was to evaluate a novel wide beam reconstruction (WBR) method developed by UltraSPECT for decreasing scan times and to compare it with filtered backprojection (FBP), which is the technique routinely used.
Phantom and clinical studies were performed. Hot and cold sphere and cardiac phantom acquisitions were reconstructed via WBR, FBP, and ordered-subsets expectation maximization. Fifty patients were prospectively studied by use of both a standard and a short protocol. The short protocol was performed first on 29 of 50 patients via 8-frame gated technetium 99m stress single photon emission computed tomography and low-energy high-resolution collimators. Stress Tc-99m studies (30-45 mCi) were scanned for 20 seconds per frame. For the short protocol, all parameters remained constant except for the time per frame, which was reduced by 50% on Tc-99m studies. All resting Tc-99m scans (36/50 patients) were processed with FBP for the standard full-scan time studies and with WBR for the short scan studies. The images were interpreted by use of a 17-segment model and 5-degree severity score, and the perfusion and functional variables were determined. Distributions including mean, median, and interquartile ranges were examined for all variables. The differences (FBP - WBR) were computed for all variables and were examined by use of nonparametric signed rank tests to determine whether the median difference was 0. The absolute value of the difference was also examined. Spearman rank-order correlation, a nonparametric measure of association, was used for the 2 methods to determine significant correlations between variables. The hot and cold sphere phantom studies demonstrated that WBR had improved contrast recovery and slightly better background uniformity than did the ordered-subsets expectation maximization. The cardiac phantom studies performed with attenuating medium and background activity showed that the half-scan time images processed with WBR had better contrast recovery and background uniformity than did the full-scan time FBP reconstruction. In the clinical studies, highly significant correlations were observed between WBR and FBP for functional as well as perfusion variables (P < .0001). The summed stress score, summed rest scores, and summed difference score were not statistically different for FBP and WBR (P > .05). Left ventricular volumes had a high correlation coefficient but were significantly larger with FBP than with WBR.
Our study results suggest that cardiac single photon emission computed tomography perfusion studies may be performed with the WBR algorithm using half of the scan time without compromising qualitative or quantitative imaging results.
新开发的重建算法能够在保持图像质量的同时，将扫描时间缩短一半。本研究的目的是评估由UltraSPECT开发的一种新型宽束重建（WBR）方法以缩短扫描时间，并将其与常规使用的滤波反投影（FBP）技术进行比较。
进行了体模和临床研究。通过WBR、FBP和有序子集期望最大化算法对热球和冷球以及心脏体模采集进行重建。对50例患者进行前瞻性研究，采用标准方案和短方案。短方案首先在50例患者中的29例中通过8帧门控锝99m负荷单光子发射计算机断层扫描和低能高分辨率准直器进行。负荷Tc-99m研究（30 - 45 mCi）每帧扫描20秒。对于短方案，除每帧时间外，所有参数保持不变，在Tc-99m研究中每帧时间减少50%。所有静息Tc-99m扫描（36/50例患者）在标准全扫描时间研究中采用FBP处理，在短扫描研究中采用WBR处理。图像采用17节段模型和5度严重程度评分进行解读，并确定灌注和功能变量。检查所有变量的分布，包括均值、中位数和四分位数间距。计算所有变量的差异（FBP - WBR），并通过非参数符号秩检验进行检查，以确定中位数差异是否为0。还检查了差异的绝对值。Spearman等级相关（一种非参数关联度量）用于两种方法，以确定变量之间的显著相关性。热球和冷球体模研究表明，WBR的对比恢复优于有序子集期望最大化算法，背景均匀性略好。在有衰减介质和背景活性的情况下进行的心脏体模研究表明，与全扫描时间的FBP重建相比，用WBR处理的半扫描时间图像具有更好的对比恢复和背景均匀性。在临床研究中，观察到WBR和FBP在功能以及灌注变量方面具有高度显著的相关性（P <.0001）。FBP和WBR的总负荷评分、总静息评分和总分差评分无统计学差异（P >.05）。左心室容积的相关系数较高，但FBP测得的值显著大于WBR测得的值。
我们的研究结果表明，使用WBR算法进行心脏单光子发射计算机断层扫描灌注研究时，扫描时间可缩短一半，而不会影响定性或定量成像结果。
