Mevel Katell, Desgranges Béatrice, Baron Jean-Claude, Landeau Brigitte, De la Sayette Vincent, Viader Fausto, Eustache Francis, Chételat Gaël
Inserm E0218-EPHE-Université de Caen Basse-Normandie, Laboratoire de Neuropsychologie, GIP Cyceron, CHU Côte de Nacre, Bd H Becquerel, 14074 Caen cedex, Caen, France.
Neuroimage. 2007 Aug 1;37(1):18-25. doi: 10.1016/j.neuroimage.2007.04.048. Epub 2007 May 8.
While the hippocampus is constantly reported as the site of earliest and highest structural alteration in Alzheimer's disease (AD), findings regarding the metabolic status of this region are rather heterogeneous. It has been proposed that only a time-consuming individual region-of-interest (ROI) approach would allow the detection of hypometabolism in this complex and small area. Our main goal with this study is to assess whether more automatic and clinically useful methods would be sensitive enough when considering other methodological confounds. From a single PET data set collected in 28 patients with amnestic Mild Cognitive Impairment (aMCI) and 19 controls, we assessed the effects of partial volume effect (PVE) correction, scaling (using vermis or global means), and analysis method (individual ROI versus more automatic template-based ROI or voxel-based approaches) on hippocampal hypometabolism detection in aMCI. PVE correction and scaling both showed a significant effect on group comparison, while the analysis method (individual versus template-based ROI) surprisingly did not. Hippocampal metabolic decrease was significant in all vermis-scaled conditions, and more so after PVE correction. Our findings highlight the crucial relevance of using reference-region-based (instead of global) scaling, and the higher sensitivity of PVE-corrected PET measures, to detect hippocampal hypometabolism in aMCI. They also show that hippocampal metabolic decline can be detected using template-based ROI as well as voxel-based methods. These findings have clinical relevance since they support the validity of more automatic and time-saving approaches to assess hippocampal metabolism changes in aMCI and early AD.
虽然海马体一直被认为是阿尔茨海默病（AD）中最早出现且结构改变最显著的部位，但有关该区域代谢状态的研究结果却相当不一致。有人提出，只有采用耗时的个体感兴趣区（ROI）方法才能检测出这个复杂小区域的代谢减低。本研究的主要目的是评估在考虑其他方法学混杂因素时，更自动化且临床实用的方法是否足够敏感。我们从28例遗忘型轻度认知障碍（aMCI）患者和19名对照者收集的单一PET数据集中，评估了部分容积效应（PVE）校正、标化（使用蚓部或全脑均值）以及分析方法（个体ROI与更自动化的基于模板的ROI或基于体素的方法）对aMCI中海马体代谢减低检测的影响。PVE校正和标化在组间比较中均显示出显著效应，而分析方法（个体ROI与基于模板的ROI）出人意料地未显示出显著效应。在所有基于蚓部标化的情况下，海马体代谢减低均显著，PVE校正后更为显著。我们的研究结果强调了使用基于参考区域（而非全脑）标化的关键相关性，以及PVE校正后的PET测量对检测aMCI中海马体代谢减低具有更高的敏感性。它们还表明，使用基于模板的ROI以及基于体素的方法均可检测出海马体代谢下降。这些研究结果具有临床相关性，因为它们支持了采用更自动化且省时的方法来评估aMCI和早期AD中海马体代谢变化的有效性。
