Variations in post-perfusion immersion fixation and storage alter MRI measurements of mouse brain morphometry
Variations in post-perfusion immersion fixation and storage alter MRI measurements of mouse brain morphometry
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DOI：
10.1016/j.neuroimage.2016.06.028
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发表时间：
2016-11-15
期刊：
影响因子：
5.7
通讯作者：
Nieman, Brian J.
中科院分区：
文献类型：
--
作者：
de Guzman, A. Elizabeth;Wong, Michael D.;Nieman, Brian J.
体外磁共振成像（MRI）需要化学固定来保存组织在存储或延长成像期间。虽然人们普遍认为固定可以改变组织体积和形状，但固定和储存对形态计量学分析的潜在混淆效应尚未得到很好的表征。随着越来越多地使用离体MRI进行小鼠脑表型分析和研究间比较，我们试图描述固定和/或储存时间的变化如何影响组织体积，以及这可能如何影响表型结果。根据我们的标准方案，在颅骨内灌注固定的小鼠脑样品浸入甲醛基固定液中1至5天，然后保存在盐水或水中。在整个固定和储存过程中，使用磁共振成像反复扫描样品，并分析体积膨胀或收缩。我们发现大部分大脑在固定后继续收缩，收缩的速度取决于样品被淹没的溶液。在固定和储存（PBS）期间，检测到的最大体积变化分别为每天3.5%和每月3%。最值得注意的是，变化是不均匀的，与大脑中的其他结构相比，一些结构收缩得更慢，甚至扩张得更慢。我们的研究结果强调，在解释固定和储存方案不一致的实验结果时，必须谨慎，以免将这些变化误认为是表型差异。(C) 2016年由Elsevier Inc.出版。
Ex vivo magnetic resonance imaging (MRI) requires chemical fixation to preserve tissue during storage or extended imaging sessions. Although it is commonly understood that fixation may alter tissue volume and shape, the potential confounding effects of fixation and storage on morphometric analyses have not been well characterized. With increasing use of ex vivo MRI for mouse brain phenotying and opportunities for inter-study comparisons, we sought to characterize how changes in fixation and/or storage times affected tissue volume, and how this might impact phenotyping results. Mouse brain samples that had been perfusion fixed, within the skull as per our standard protocol, were immersed in formaldehyde-based fixative for 1 to 5 days before being stored in saline or water. Throughout fixation and storage, samples were repeatedly scanned using magnetic resonance imaging, and analyzed for volume expansion or shrinkage. We found that most of the brain continued to shrink post fixation, with the rate of shrinkage dependent on the solution in which the samples were submerged. Maximum changes in volume of 3.5% per day and 3% per month were detected during fixation and storage (in PBS), respectively. Most notably, changes were non-uniform, with some structures shrinking slower, or even expanding, when compared to other structures in the brain. Our results highlight that caution is necessary when interpreting results from experiments with inconsistent fixation and storage protocols, so as not to mistake these changes for phenotypic differences. (C) 2016 Published by Elsevier Inc.