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

点击翻译按钮获取中文摘要

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.