Chen Kevin T, Salcedo Stephanie, Gong Kuang, Chonde Daniel B, Izquierdo-Garcia David, Drzezga Alexander E, Rosen Bruce, Qi Jinyi, Dickerson Bradford C, Catana Ciprian
Massachusetts General Hospital, United States.
UC Davis, United States.
J Nucl Med. 2018 Jun 22;60(2):272-8. doi: 10.2967/jnumed.117.207142.
A main advantage of PET is that it provides quantitative measures of the radiotracer concentration, but its accuracy is confounded by several factors, including attenuation, subject motion, and limited spatial resolution. Using the information from one simultaneously acquired morphological MR sequence with embedded navigators, we propose an efficient method called MR-assisted PET data optimization (MaPET) to perform attenuation correction (AC), motion correction, and anatomy-aided reconstruction. For attenuation correction, voxel-wise linear attenuation coefficient maps were generated using an SPM8-based approach method on the MR volume. The embedded navigators were used to derive head motion estimates for event-based PET motion correction. The anatomy provided by the MR volume was incorporated into the PET image reconstruction using a kernel-based method. Region-based analyses were carried out to assess the quality of images generated through various stages of PET data optimization. The optimized PET images reconstructed with MaPET was superior in image quality compared to images reconstructed using only attenuation correction, with high SNR and low coefficient of variation (5.08 and 0.229 in a composite cortical region compared to 3.12 and 0.570). The optimized images were also shown using the Cohen's d metric to achieve a greater effect size in distinguishing cortical regions with hypometabolism from regions of preserved metabolism in each individual for different diagnosis groups. We have shown the spatiotemporally correlated data acquired using a single MR sequence can be used for PET attenuation, motion and partial volume effects corrections and the MaPET method may enable more accurate assessment of pathological changes in dementia and other brain disorders.
正电子发射断层扫描（PET）的一个主要优点是它能提供放射性示踪剂浓度的定量测量，但它的准确性会受到几个因素的影响，包括衰减、受试者运动和有限的空间分辨率。利用同时采集的带有嵌入式导航器的形态学磁共振（MR）序列信息，我们提出了一种名为MR辅助PET数据优化（MaPET）的有效方法，用于进行衰减校正（AC）、运动校正和解剖学辅助重建。对于衰减校正，使用基于SPM8的方法在MR体积上生成体素级线性衰减系数图。嵌入式导航器用于推导基于事件的PET运动校正的头部运动估计值。利用基于核的方法将MR体积提供的解剖结构纳入PET图像重建。进行基于区域的分析以评估通过PET数据优化的各个阶段生成的图像质量。与仅使用衰减校正重建的图像相比，用MaPET重建的优化PET图像在图像质量上更优，具有高信噪比和低变异系数（在复合皮质区域中分别为5.08和0.229，而仅使用衰减校正时为3.12和0.570）。对于不同诊断组的每个个体，优化后的图像还使用科恩d指标显示在区分代谢减低的皮质区域和代谢保留区域方面具有更大的效应量。我们已经表明，使用单个MR序列采集的时空相关数据可用于PET衰减、运动和部分容积效应校正，并且MaPET方法可能能够更准确地评估痴呆和其他脑部疾病的病理变化。
