Sohlberg Antti, Watabe Hiroshi, Iida Hidehiro
National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan.
Ann Nucl Med. 2008 Aug;22(7):549-56. doi: 10.1007/s12149-008-0170-z. Epub 2008 Aug 29.
The quality of single-photon emission computed tomography (SPECT) imaging is hampered by attenuation, collimator blurring, and scatter. Correction for all of these three factors is required for accurate reconstruction, but unfortunately, reconstruction-based compensation often leads to clinically unacceptable long reconstruction times. Especially, efficient scatter correction has proved to be difficult to achieve. The objective of this article was to extend the well-known transmission-dependent convolution subtraction (TDCS) scatter-correction approach into a rapid reconstruction-based scatter-compensation method and to include it into a fast 3D reconstruction algorithm with attenuation and collimator-blurring corrections.
Ordered subsets expectation maximization algorithm with attenuation, collimator blurring, and accelerated transmission-dependent scatter compensation were implemented. The new reconstruction method was compared with TDCS-based scatter correction and with one other transmission-dependent scatter-correction method using Monte Carlo simulated projection data of (99m)Tc-ECD and (123)I-FP-CIT brain studies.
The new reconstruction-based scatter compensation outperformed the other two scatter-correction methods in terms of quantitative accuracy and contrast measured with normalized mean-squared error, gray-to-white matter and striatum-to-background ratios, and also in visual quality. Highest accuracy was achieved when all the corrections (i.e., attenuation, collimator blurring, and scatter) were applied.
The developed 3D reconstruction algorithm with transmission-dependent scatter compensation is a promising alternative to accurate and efficient SPECT reconstruction.
单光子发射计算机断层扫描（SPECT）成像的质量受到衰减、准直器模糊和散射的影响。准确重建需要对这三个因素进行校正，但不幸的是，基于重建的补偿往往会导致临床上难以接受的长时间重建。特别是，有效的散射校正已被证明难以实现。本文的目的是将著名的基于传输的卷积减法（TDCS）散射校正方法扩展为一种基于快速重建的散射补偿方法，并将其纳入一种具有衰减和准直器模糊校正的快速三维重建算法中。
实施了带有衰减、准直器模糊和加速的基于传输的散射补偿的有序子集期望最大化算法。使用（99m）Tc-ECD和（123）I-FP-CIT脑研究的蒙特卡罗模拟投影数据，将新的重建方法与基于TDCS的散射校正以及另一种基于传输的散射校正方法进行比较。
在以归一化均方误差、灰质与白质以及纹状体与背景比值衡量的定量准确性和对比度方面，以及在视觉质量方面，新的基于重建的散射补偿均优于其他两种散射校正方法。当应用所有校正（即衰减、准直器模糊和散射）时，可实现最高的准确性。
所开发的具有基于传输的散射补偿的三维重建算法是准确高效的SPECT重建的一种有前途的替代方法。
