Interpolated CT for attenuation correction on respiratory gating cardiac SPECT/CT - A simulation study.
Interpolated CT for attenuation correction on respiratory gating cardiac SPECT/CT - A simulation study.
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DOI：
10.1002/mp.13513
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发表时间：
2019-06
期刊：
影响因子：
3.8
通讯作者：
Duo Zhang;Michael Ghaly;G. Mok
中科院分区：
文献类型：
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作者：
Duo Zhang;Michael Ghaly;G. Mok
目的：呼吸门控四维（4D）单光子发射计算机断层扫描（SPECT）与相位匹配CT减少呼吸模糊和衰减校正（AC）伪影。本研究的目的是开发和研究插值CT （ICT）方法的有效性，通过模拟改进心脏SPECT AC。方法：我们使用4D XCAT模型模拟了10例不同性别、解剖结构、99m Tc-sestamibi分布、呼吸模式和疾病状态的患者。模拟的120个SPECT投影数据被重组为6个等计数门。每个门的活动和衰减图作为门控SPECT和CT （GCT）平均。在吸气末（HCT-IN）、呼气末（HCT-EX）和呼吸中期（HCT-MID）模拟三个螺旋ct。利用仿射配准和b样条配准在HCT-EX和HCT-IN之间产生的运动向量场，获得了它们之间的ict。通过OS-EM方法，利用GCT、ICT和3个hct对AC进行投影重建。每个门的重建图像被注册到末端到期并平均以生成极坐标图。以GCT AC图像为参考，计算各节段的相对差值和相对缺陷尺寸。结果噪声HCT-IN、HCT-MID、HCT-EX和ICT - AC数据的最大相对差平均值分别为7.93±4.71%、2.50±0.98%、3.58±0.74%和2.14±0.56%。ICT显示出与GCT最接近的缺陷大小，而与hct的差异可超过40%。结论ICT的性能与GCT相似。与传统的HCT相比，它提高了呼吸门控心脏SPECT的图像质量和定量准确性，同时可以进一步降低GCT的辐射剂量。
PURPOSE Respiratory gated four-dimensional (4D) single photon emission computed tomography (SPECT) with phase-matched CT reduces respiratory blurring and attenuation correction (AC) artifacts in cardiac SPECT. This study aims to develop and investigate the effectiveness of an interpolated CT (ICT) method for improved cardiac SPECT AC using simulations. METHODS We used the 4D XCAT phantom to simulate a population of ten patients varied in gender, anatomy, 99m Tc-sestamibi distribution, respiratory patterns, and disease states. Simulated 120 SPECT projection data were rebinned into six equal count gates. Activity and attenuation maps in each gate were averaged as gated SPECT and CT (GCT). Three helical CTs were simulated at end-inspiration (HCT-IN), end-expiration (HCT-EX), and mid-respiration (HCT-MID). The ICTs were obtained from HCT-EX and HCT-IN using the motion vector field generated between them from affine plus b-spline registration. Projections were reconstructed by OS-EM method, using GCT, ICT, and three HCTs for AC. Reconstructed images of each gate were registered to end-expiration and averaged to generate the polar plots. Relative difference for each segment and relative defect size were computed using images of GCT AC as reference. RESULTS The average of maximum relative difference through ten phantoms was 7.93 ± 4.71%, 2.50 ± 0.98%, 3.58 ± 0.74%, and 2.14 ± 0.56% for noisy HCT-IN, HCT-MID, HCT-EX, and ICT AC data, respectively. The ICT showed closest defect size to GCT while the differences from HCTs can be over 40%. CONCLUSION We conclude that the performance of ICT is similar to GCT. It improves the image quality and quantitative accuracy for respiratory-gated cardiac SPECT as compared to conventional HCT, while it can potentially further reduce the radiation dose of GCT.