Vemuri Prashanthi, Senjem Matthew L, Gunter Jeffrey L, Lundt Emily S, Tosakulwong Nirubol, Weigand Stephen D, Borowski Bret J, Bernstein Matt A, Zuk Samantha M, Lowe Val J, Knopman David S, Petersen Ronald C, Fox Nick C, Thompson Paul M, Weiner Michael W, Jack Clifford R
Departments of Radiology, MN, USA.
Departments of Radiology, MN, USA; Information Technology, MN, USA.
Neuroimage. 2015 Jun;113:61-9. doi: 10.1016/j.neuroimage.2015.03.026. Epub 2015 Mar 20.
Our primary objective was to compare the performance of unaccelerated vs. accelerated structural MRI for measuring disease progression using serial scans in Alzheimer's disease (AD).
We identified cognitively normal (CN), early mild cognitive impairment (EMCI), late mild cognitive impairment (LMCI) and AD subjects from all available Alzheimer's Disease Neuroimaging Initiative (ADNI) subjects with usable pairs of accelerated and unaccelerated scans. There were a total of 696 subjects with baseline and 3 month scans, 628 subjects with baseline and 6 month scans and 464 subjects with baseline and 12 month scans available. We employed the Symmetric Diffeomorphic Image Normalization method (SyN) for normalization of the serial scans to obtain tensor based morphometry (TBM) maps which indicate the structural changes between pairs of scans. We computed a TBM-SyN summary score of annualized structural changes over 31 regions of interest (ROIs) that are characteristically affected in AD. TBM-SyN scores were computed using accelerated and unaccelerated scan pairs and compared in terms of agreement, group-wise discrimination, and sample size estimates for a hypothetical therapeutic trial.
We observed a number of systematic differences between TBM-SyN scores computed from accelerated and unaccelerated pairs of scans. TBM-SyN scores computed from accelerated scans tended to have overall higher estimated values than those from unaccelerated scans. However, the performance of accelerated scans was comparable to unaccelerated scans in terms of discrimination between clinical groups and sample sizes required in each clinical group for a therapeutic trial. We also found that the quality of both accelerated vs. unaccelerated scans were similar.
Accelerated scanning protocols reduce scan time considerably. Their group-wise discrimination and sample size estimates were comparable to those obtained with unaccelerated scans. The two protocols did not produce interchangeable TBM-SyN estimates, so it is arguably important to use either accelerated pairs of scans or unaccelerated pairs of scans throughout the study duration.
我们的主要目标是比较在阿尔茨海默病（AD）中使用连续扫描测量疾病进展时，非加速与加速结构磁共振成像（MRI）的性能。
我们从所有可用的阿尔茨海默病神经影像倡议（ADNI）受试者中识别出认知正常（CN）、早期轻度认知障碍（EMCI）、晚期轻度认知障碍（LMCI）和AD受试者，这些受试者拥有可用的加速和非加速扫描配对。共有696名受试者有基线和3个月扫描数据，628名受试者有基线和6个月扫描数据，464名受试者有基线和12个月扫描数据。我们采用对称微分同胚图像归一化方法（SyN）对连续扫描进行归一化，以获得基于张量的形态计量学（TBM）图，该图指示扫描对之间的结构变化。我们计算了31个在AD中典型受影响的感兴趣区域（ROI）上的年化结构变化的TBM-SyN总分。使用加速和非加速扫描对计算TBM-SyN分数，并在一致性、组间区分以及假设治疗试验的样本量估计方面进行比较。
我们观察到从加速和非加速扫描对计算出的TBM-SyN分数存在一些系统性差异。从加速扫描计算出的TBM-SyN分数总体估计值往往高于非加速扫描。然而，在临床组之间的区分以及治疗试验中每个临床组所需的样本量方面，加速扫描的性能与非加速扫描相当。我们还发现加速与非加速扫描质量相似。
加速扫描方案可显著减少扫描时间。它们在组间区分和样本量估计方面与非加速扫描相当。这两种方案不会产生可互换的TBM-SyN估计值，因此在整个研究期间使用加速扫描对或非加速扫描对可能很重要。
