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

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。人体大脑皮层厚度的活体MRI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一个自动厚度测量方法的可靠性（精度）内和跨扫描仪平台和场强。我们还评估了不同成像采集协议（包括采集次数和成像序列）和不同数据处理或后处理（平滑厚度图）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。我们评估了全球平均皮质厚度的再现性，一个非常可靠的测量高度重复性的扫描会话，在四个测试/重新测试比较。平均而言，在相同的扫描仪平台内，全球平均皮质厚度的绝对差异小于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MP3体积的平均值来计算表面图谱每个位置处的厚度差异的组平均值（绝对值）。当比较同一扫描仪平台内的厚度测量值时，测量值变异性（定义为平均绝对厚度的差异）小于0.12 mm。尽管在比较扫描仪平台或场强之间的厚度时，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。我们还比较了用于评估厚度测量的纵向与横截面处理方法的可靠性。基于总体平均厚度测量误差，很明显，纵向处理方案可以进一步降低厚度测量的可变性。采用配对t检验，纵向方法的改善具有统计学意义。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.