Knowing the difference between left and right is generally assumed throughout the brain MRI research community. However, we note widespread occurrences of left-right orientation errors in MRI open database repositories where volumes have contained systematic left-right flips between subject EPIs and anatomicals, due to having incorrect or missing file header information. Here we present a simple method in AFNI for determining the consistency of left and right within a pair of acquired volumes for a particular subject; the presence of EPI-anatomical inconsistency, for example, is a sign that dataset header information likely requires correction. The method contains both a quantitative evaluation as well as a visualizable verification. We test the functionality using publicly available datasets. Left-right flipping is not immediately obvious in most cases, so we also present visualization methods for looking at this problem (and other potential problems), using examples from both FMRI and DTI datasets.

中文翻译：

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当心（出乎意料地常见）您的 MRI 数据中的左右翻转：使用 AFNI 检查 MRI 数据集一致性的有效且稳健的方法

整个大脑 MRI 研究界通常都假设知道左右之间的差异。然而，我们注意到在 MRI 开放数据库存储库中广泛发生左右方向错误，其中卷包含主题 EPI 和解剖结构之间的系统左右翻转，因为文件头信息不正确或丢失。在这里，我们在 AFNI 中提出了一种简单的方法，用于确定特定主题的一对已获得体积内左右的一致性；例如，EPI 解剖不一致的存在表明数据集标题信息可能需要更正。该方法包含定量评估和可视化验证。我们使用公开可用的数据集测试功能。