EXTEND SCOPE & LEVEL OF DETAIL OF ANATOMICAL MODELS FROM IN VIVO DATA

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。体内mri衍生的人类大脑皮层厚度测量为正常和异常神经解剖学提供了新的见解，但对其可靠性知之甚少。这项工作的目的是评估自动化厚度测量方法的可靠性（精度），包括扫描平台内部和跨平台和场强。我们还评估了不同的成像采集方案（包括采集数量和成像序列）和不同的数据处理或后处理（厚度图平滑）方案对厚度测量可靠性的影响。最后，我们研究了扫描仪升级对厚度测量再现性的影响。在四次测试/重复测试比较中，我们评估了整体平均皮质厚度的可重复性，这是一个非常可靠的测量，在扫描过程中具有高度可重复性。平均而言，在相同的扫描平台内，整体平均皮质厚度的绝对差小于0.03 mm。为了评估皮质厚度测量的局部变异性，我们使用两个MPRAGE体积的平均值来计算表面图谱每个位置的厚度差异的组平均（绝对值）。测量变异性，定义为平均绝对厚度的差异，当比较相同扫描仪平台内的厚度测量值时，大部分皮质的测量值小于0.12 mm。虽然当比较不同扫描平台的厚度或场强时，平均绝对差异略有增加，但当平台单独不同时，大多数皮质的变异性仍然小于0.15 mm，当场强不同时，变异性小于0.2 mm。我们还比较了评估厚度测量的纵向和截面加工方法的可靠性。基于整体平均厚度测量误差，纵向加工方案可以进一步减小厚度测量的可变性。使用配对t检验，发现纵向方法的改进具有统计学显著性。最近发表的这项研究的结果可以帮助设计和评估需要在多个扫描仪平台或主要扫描仪升级中积累数据的多站点或纵向研究。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In vivo MRI-derived measurements of human cerebral cortex thickness are providing novel insights into normal and abnormal neuroanatomy, but little is known about their reliability. The purpose of this work was to evaluate the reliability (precision) of an automated thickness measurement method both within and across scanner platforms and field strengths. We also evaluated the effects of different imaging acquisition protocols (including number of acquisitions and imaging sequences) and different data processing or post processing (smoothing of thickness map) schemes on thickness measurement reliability. Finally, we investigated the impact of scanner upgrade on thickness measurement reproducibility. We assessed the reproducibility of global mean cortical thickness, an exceedingly reliable measure highly reproducible across scan sessions, in four test/retest comparisons. On average, the absolute difference in global mean cortical thickness was less than 0.03 mm within the same scanner platform. To assess the local variability of cortical thickness measurements, we used the average of two MPRAGE volumes to compute the group-wise mean (in absolute value) of thickness differences at every location of the surface atlas. Measurement variability, defined as the difference in average absolute thickness, was less than 0.12 mm for the bulk of the cortex when comparing thickness measurements within the same scanner platform. Although the average absolute difference increased slightly when comparing thickness across scanner platforms or field strengths, variability was still less than 0.15 mm for most of the cortex when platform alone differed, and less than 0.2 mm when field strength differed. We also compared the reliability of longitudinal versus cross-sectional processing methods for evaluating thickness measurements. Based on overall mean thickness measurement error, it is clear that the longitudinal processing scheme can further reduce the variability of thickness measurements. Using a paired t-test, improvements attributable to the longitudinal method were found to be statistically significant. The results of this study, recently published, can aid in the design and assessment of multi-site or longitudinal studies that require accumulating data across multiple scanner platforms or across major scanner upgrades.