McHugh Tara L, Saykin Andrew J, Wishart Heather A, Flashman Laura A, Cleavinger Howard B, Rabin Laura A, Mamourian Alexander C, Shen Li
Department of Psychiatry, Brain Imaging Laboratory, Dartmouth Medical School, Lebanon, NH, USA.
Clin Neuropsychol. 2007 Jan;21(1):130-45. doi: 10.1080/13854040601064534.
This report presents a manual segmentation protocol for the hippocampus that yields a reliable and comprehensive measure of volume, a goal that has proven difficult with prior methods. Key features of this method include alignment of the images in the long axis of the hippocampus and the use of a three-dimensional image visualization function to disambiguate anterior and posterior hippocampal boundaries. We describe procedures for hippocampal volumetry and shape analysis, provide inter- and intra-rater reliability data, and examine correlates of hippocampal volume in a sample of healthy older adults. Participants were 40 healthy older adults with no significant cognitive complaints, no evidence of mild cognitive impairment or dementia, and no other neurological or psychiatric disorder. Using a 1.5 T GE Signa scanner, three-dimensional spoiled gradient recalled acquisition in a steady state (SPGR) sequences were acquired for each participant. Images were resampled into 1 mm isotropic voxels, and realigned along the interhemispheric fissure in the axial and coronal planes, and the long axis of the hippocampus in the sagittal plane. Using the BRAINS program (Andreasen et al., 1993), the boundaries of the hippocampus were visualized in the three orthogonal views, and boundary demarcations were transferred to the coronal plane for tracing. Hippocampal volumes were calculated after adjusting for intracranial volume (ICV). Intra- and inter-rater reliabilities, measured using the intraclass correlation coefficient, exceeded .94 for both the left and right hippocampus. Total ICV-adjusted volumes were 3.48 (+/-0.43) cc for the left hippocampus and 3.68 (+/-0.42) for the right. There were no significant hippocampal volume differences between males and females (p > .05). In addition to providing a comprehensive volumetric measurement of the hippocampus, the refinements included in our tracing protocol permit analysis of changes in hippocampal shape. Shape analyses may yield novel information about structural brain changes in aging and dementia that are not reflected in volumetric measurements alone. These and other novel directions in research on hippocampal function and dysfunction will be facilitated by the use of reliable, comprehensive, and consistent segmentation and measurement methods.
本报告介绍了一种用于海马体的手动分割方案，该方案能够对体积进行可靠且全面的测量，而这一目标用先前的方法很难实现。该方法的关键特征包括将图像在海马体长轴上对齐，并使用三维图像可视化功能来明确海马体前后边界。我们描述了海马体体积测量和形状分析的程序，提供了评分者间和评分者内的可靠性数据，并在一组健康老年人样本中研究了海马体体积的相关因素。参与者为40名健康老年人，无明显认知主诉，无轻度认知障碍或痴呆证据，也无其他神经或精神疾病。使用1.5T GE Signa扫描仪，为每位参与者采集了三维稳态扰相梯度回波（SPGR）序列。图像被重采样为1mm各向同性体素，并在轴向和冠状平面上沿大脑纵裂重新对齐，在矢状平面上沿海马体长轴重新对齐。使用BRAINS程序（Andreasen等人，1993年），在三个正交视图中可视化海马体边界，并将边界划分转移到冠状平面进行追踪。在调整颅内体积（ICV）后计算海马体体积。使用组内相关系数测量的评分者内和评分者间可靠性，左右海马体均超过0.94。调整ICV后的左侧海马体总体积为3.48（±0.43）立方厘米，右侧为3.68（±0.42）立方厘米。男性和女性之间的海马体体积无显著差异（p>.05）。除了提供海马体的全面体积测量外，我们追踪方案中的改进还允许分析海马体形状的变化。形状分析可能会产生关于衰老和痴呆中脑结构变化的新信息，而这些信息仅通过体积测量无法反映。使用可靠、全面和一致的分割与测量方法将有助于海马体功能与功能障碍研究中的这些及其他新方向。
