Case James A, Hsu Bai Ling, Bateman Timothy M, Cullom S James
Cardiovascular Imaging Technologies, LLC, Kansas City, MO 64111, USA.
J Nucl Cardiol. 2007 May-Jun;14(3):324-33. doi: 10.1016/j.nuclcard.2007.02.004. Epub 2007 Apr 27.
High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data.
The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients (mean SD, 0.005 cm(-1) vs 0.011 cm(-1); P < .0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall variability (4.8% to 4.1%, P = .02) for all BMI groups with the new method compared with FBP.
This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum of patient BMI values and significantly improves attenuation-corrected perfusion images.
高质量的衰减图对于心肌灌注单光子发射计算机断层扫描研究的衰减校正至关重要。滤波反投影（FBP）方法可能会引入误差，尤其是在低计数传输数据的情况下。我们提出了一种新的衰减图重建方法，并在体模和患者数据中检验其性能。
贝叶斯迭代传输梯度算法结合了空间变化的伽马先验函数，该函数优先将估计的衰减系数加权至软组织值，同时允许对肺和骨区域采用数据驱动的解决方案。在体模研究和按体重指数（BMI）分组的50例低可能性患者中，评估了经衰减校正的锝99m甲氧基异丁基异腈临床图像的性能。在体模研究中，该算法在15次迭代中收敛。对于临床研究，软组织估计的纵隔系数均匀性显著更高（平均标准差，0.005 cm⁻¹ 对0.011 cm⁻¹；P <.0001）。贝叶斯迭代传输梯度算法的准确性和均匀性与BMI无关，而在较高BMI值时，FBP的准确性和均匀性均下降。与FBP相比，新方法使所有BMI组的衰减校正灌注图像的心肌壁变异性得到改善（从4.8%降至4.1%，P =.02）。
这种新的衰减图重建方法在广泛的患者BMI值范围内提供了快速收敛且准确的衰减图，并显著改善了衰减校正的灌注图像。
