Sousa João M, Appel Lieuwe, Engström Mathias, Papadimitriou Stergios, Nyholm Dag, Ahlström Håkan, Lubberink Mark
Radiology & Molecular Imaging, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
Radiology & Molecular Imaging, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; Medical Imaging Centre, Uppsala University Hospital, Uppsala, Sweden.
Phys Med. 2022 May;97:36-43. doi: 10.1016/j.ejmp.2022.03.012. Epub 2022 Mar 24.
In positron emission tomography (PET), Ge-transmission scanning is considered the gold standard in attenuation correction (AC) though not available in current dual imaging systems. In this experimental study we evaluated a novel AC method for PET/magnetic resonance (MR) imaging which is essentially based on a composite database of multiple Ge-transmission maps and T1-weighted (T1w) MR image-pairs (composite transmission, CTR-AC). This proof-of-concept study used retrospectively a database with 125 pairs of co-registered Ge-AC maps and T1w MR images from anatomical normal subjects and a validation dataset comprising dynamic [C]PE2I PET data from nine patients with Parkinsonism. CTR-AC maps were generated by non-rigid image registration of all database T1w MRI to each subject's T1w, applying the same transformation to every Ge-AC map, and averaging the resulting Ge-AC maps. [C]PE2I PET images were reconstructed using CTR-AC and a patient-specific Ge-AC map as the reference standard. Standardized uptake values (SUV) and quantitative parameters of kinetic analysis were compared, i.e., relative delivery (R) and non-displaceable binding potential (BP). CTR-AC showed high accuracy for whole-brain SUV (mean %bias ± SD: 0.5 ± 3.5%), whole-brain R (-0.1 ± 3.2%), and putamen BP (3.7 ± 8.1%). SUV and R precision (SD of %bias) were modest and lowest in the anterior cortex, with an R %bias of -1.1 ± 6.4%). The prototype CTR-AC is capable of providing accurate MRAC-maps with continuous linear attenuation coefficients though still experimental. The method's accuracy is comparable to the best MRAC methods published so far, both in SUV and as found for ZTE-AC in quantitative parameters of kinetic modelling.
在正电子发射断层扫描（PET）中，锗传输扫描虽在当前双成像系统中不可用，但被视为衰减校正（AC）的金标准。在本实验研究中，我们评估了一种用于PET/磁共振（MR）成像的新型AC方法，该方法主要基于多个锗传输图和T1加权（T1w）MR图像对的复合数据库（复合传输，CTR-AC）。这项概念验证研究回顾性地使用了一个数据库，该数据库包含125对来自解剖学正常受试者的配准锗AC图和T1w MR图像，以及一个验证数据集，该数据集包含来自9名帕金森病患者的动态[C]PE2I PET数据。通过将所有数据库T1w MRI非刚性图像配准到每个受试者的T1w，对每个锗AC图应用相同的变换，并对所得的锗AC图进行平均，生成CTR-AC图。使用CTR-AC和患者特异性锗AC图作为参考标准重建[C]PE2I PET图像。比较了标准化摄取值（SUV）和动力学分析的定量参数，即相对递送（R）和不可置换结合潜力（BP）。CTR-AC在全脑SUV（平均%偏差±标准差：0.5±3.5%）、全脑R（-0.1±3.2%）和壳核BP（3.7±8.1%）方面显示出高精度。SUV和R精度（%偏差的标准差）适中，在前额叶皮质中最低，R%偏差为-1.1±6.4%）。原型CTR-AC能够提供具有连续线性衰减系数的准确MRAC图，尽管仍处于实验阶段。该方法的准确性在SUV方面以及在动力学建模的定量参数中与迄今为止发表的最佳MRAC方法相当，如在ZTE-AC中所发现的那样。
