Carlson Mackenzie L, Smith Viktorija, Johns Emily, Young Christina B, Vossler Hillary, Ward Tyler, Harrison Theresa M, Tosun Duygu, Hohman Timothy, Landau Susan M, Mormino Elizabeth C
Departments of Neurology and Neurological Sciences, Stanford University, Stanford, CA, United States.
Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA, United States.
Imaging Neurosci (Camb). 2024 Nov 13;2. doi: 10.1162/imag_a_00369. eCollection 2024.
Tau positron emission tomography (PET) imaging in Alzheimer's Disease (AD) is becoming increasingly common to assesstau burden. MR images are often acquired to assist with processing of PET data, including for region-of-interest definitions in native space and for normalization to template space. However, in the real-world setting, corresponding MRIs may not be available and PET processing may require MRI-free pipelines. This is particularly important and challenging as the field moves towards early detection among clinically unimpaired (CU) individuals where changes in tau PET signal are expected to be subtle. We used two independent [F]Flortaucipir tau PET datasets to evaluate whether MRI-free PET processing can detect subtle tau PET uptake differences in Amyloid+ (A+) CU individuals (preclinical AD) versus A-. Standardized Uptake Value Ratios (SUVRs) from MRI-free compared to MRI-based methods were evaluated using linear regression and linear mixed-effects regression models. Effect size differences between A+/- CU groups in MRI-free processed cross-sectional and longitudinal tau PET SUVRs were compared to differences quantified through MRI-based processing. Regional MRI-free SUVRs were highly correlated with MRI-based SUVRs within CU individuals (average ICC = 0.90 for ADNI CU and 0.81 for A4 CU). MRI-free and MRI-based pipelines resulted in similar estimates of cross-sectional and longitudinal differences between A- and A+ CU, even in early focal regions within the medial temporal lobe.
在阿尔茨海默病（AD）中，使用tau正电子发射断层扫描（PET）成像来评估tau蛋白负担变得越来越普遍。通常会采集磁共振成像（MRI）图像以辅助PET数据处理，包括用于在原始空间中定义感兴趣区域以及用于归一化到模板空间。然而，在实际临床环境中，可能无法获得相应的MRI图像，PET处理可能需要无MRI的流程。随着该领域朝着在临床未受损（CU）个体中进行早期检测发展，这一点尤为重要且具有挑战性，因为预计tau PET信号变化在这些个体中会很细微。我们使用了两个独立的[F]氟替卡匹尔tau PET数据集，以评估无MRI的PET处理能否检测出淀粉样蛋白阳性（A +）CU个体（临床前期AD）与A -个体之间细微的tau PET摄取差异。使用线性回归和线性混合效应回归模型评估了无MRI方法与基于MRI方法的标准化摄取值比率（SUVR）。将无MRI处理的横断面和纵向tau PET SUVR中A + / - CU组之间的效应大小差异与通过基于MRI的处理量化的差异进行比较。在CU个体中，区域无MRI的SUVR与基于MRI的SUVR高度相关（ADNI CU个体的平均组内相关系数[ICC] = 0.90，A4 CU个体的平均ICC = 0.81）。即使在内侧颞叶的早期局灶区域，无MRI和基于MRI的流程对A -和A + CU之间横断面和纵向差异的估计结果也相似。
