Reconstruction of multiple-pinhole micro-SPECT data using origin ensembles.
Reconstruction of multiple-pinhole micro-SPECT data using origin ensembles.
复制标题
使用原始集合重建多针孔显微 SPECT 数据。
DOI：
10.1118/1.4962480
复制
发表时间：
2016
期刊：
影响因子：
3.8
通讯作者：
Moore,StephenC
中科院分区：
文献类型：
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作者：
Lyon,MorganC;Sitek,Arkadiusz;Metzler,ScottD;Moore,StephenC
作者目前正在开发一种基于三台大型NaI（Tl）γ相机的双分辨率多针孔microSPECT成像系统。将依次使用两个多针孔钨准直管对小鼠进行全身“定位”成像，然后对感兴趣器官（如心脏或大脑）进行高分辨率（hi-res）成像。理想情况下，全身图像将在真实的时间内重建，因此只需要采集数据，直到感兴趣区域可以足够好地可视化，以确定高分辨率扫描的定位。作者研究了起源集成（OE）算法的在线和离线重建的侦察数据的效用。该算法直接在图像空间中操作，并且可以沿着重构图像提供图像不确定性的估计。加速OE重建的技术也进行了介绍和evaluated.MethodsSystem矩阵计算我们的39针定位准直器设计。使用MOBY数字小鼠体模模拟一系列计数水平的SPECT投影。模拟数据用于比较OE和最大似然期望最大化（MLEM）重建。通过计算总图像熵和测量包含心脏的感兴趣体积（VOI）中的计数来评价OE算法的收敛性。总图像熵也计算模拟MOBY数据重建使用OE与各种水平的parallelization. ResultsVOI测量心脏，肝脏，膀胱和软组织，MLEM和OE重建图像同意在6%以内。图像熵在OE的2000次迭代后收敛，而心脏中的计数在OE的2000次迭代时更早地收敛。OE的加速版本对于6.8M计数数据集在<9分钟内完成1000次迭代，图像熵性能有所损失，而相同的数据集需要1079分钟才能完成1000次传统OE迭代。与传统OE相比，两种方法的组合显示出减少的重建时间和没有性能损失。结论OE重建图像被发现在定量和定性上与MLEM相似，但OE也提供了图像不确定性的估计。通过使用并行计算可以获得重建的一些加速。OE算法对于重建多针孔SPECT数据非常有用，并且可以很容易地修改以进行真实的实时重建。
PurposeThe authors are currently developing a dual‐resolution multiple‐pinhole microSPECT imaging system based on three large NaI(Tl) gamma cameras. Two multiple‐pinhole tungsten collimator tubes will be used sequentially for whole‐body “scout” imaging of a mouse, followed by high‐resolution (hi‐res) imaging of an organ of interest, such as the heart or brain. Ideally, the whole‐body image will be reconstructed in real time such that data need only be acquired until the area of interest can be visualized well‐enough to determine positioning for the hi‐res scan. The authors investigated the utility of the origin ensemble (OE) algorithm for online and offline reconstructions of the scout data. This algorithm operates directly in image space, and can provide estimates of image uncertainty, along with reconstructed images. Techniques for accelerating the OE reconstruction were also introduced and evaluated.MethodsSystem matrices were calculated for our 39‐pinhole scout collimator design. SPECT projections were simulated for a range of count levels using the MOBY digital mouse phantom. Simulated data were used for a comparison of OE and maximum‐likelihood expectation maximization (MLEM) reconstructions. The OE algorithm convergence was evaluated by calculating the total‐image entropy and by measuring the counts in a volume‐of‐interest (VOI) containing the heart. Total‐image entropy was also calculated for simulated MOBY data reconstructed using OE with various levels of parallelization.ResultsFor VOI measurements in the heart, liver, bladder, and soft‐tissue, MLEM and OE reconstructed images agreed within 6%. Image entropy converged after ∼2000 iterations of OE, while the counts in the heart converged earlier at ∼200 iterations of OE. An accelerated version of OE completed 1000 iterations in <9 min for a 6.8M count data set, with some loss of image entropy performance, whereas the same dataset required ∼79 min to complete 1000 iterations of conventional OE. A combination of the two methods showed decreased reconstruction time and no loss of performance when compared to conventional OE alone.ConclusionsOE‐reconstructed images were found to be quantitatively and qualitatively similar to MLEM, yet OE also provided estimates of image uncertainty. Some acceleration of the reconstruction can be gained through the use of parallel computing. The OE algorithm is useful for reconstructing multiple‐pinhole SPECT data and can be easily modified for real‐time reconstruction.