Milidonis Xenios, Lennen Ross J, Jansen Maurits A, Mueller Susanne, Boehm-Sturm Philipp, Holmes William M, Sena Emily S, Macleod Malcolm R, Marshall Ian
Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.
University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.
PLoS One. 2016 Sep 7;11(9):e0162545. doi: 10.1371/journal.pone.0162545. eCollection 2016.
It has recently been suggested that multicenter preclinical stroke studies should be carried out to improve translation from bench to bedside, but the accuracy of magnetic resonance imaging (MRI) scanners routinely used in experimental stroke has not yet been evaluated. We aimed to assess and compare geometric accuracy of preclinical scanners and examine the longitudinal stability of one scanner using a simple quality assurance (QA) protocol. Six 7 Tesla animal scanners across six different preclinical imaging centers throughout Europe were used to scan a small structural phantom and estimate linear scaling errors in all orthogonal directions and volumetric errors. Between-scanner imaging consisted of a standard sequence and each center's preferred sequence for the assessment of infarct size in rat models of stroke. The standard sequence was also used to evaluate the drift in accuracy of the worst performing scanner over a period of six months following basic gradient calibration. Scaling and volumetric errors using the standard sequence were less variable than corresponding errors using different stroke sequences. The errors for one scanner, estimated using the standard sequence, were very high (above 4% scaling errors for each orthogonal direction, 18.73% volumetric error). Calibration of the gradient coils in this system reduced scaling errors to within ±1.0%; these remained stable during the subsequent 6-month assessment. In conclusion, despite decades of use in experimental studies, preclinical MRI still suffers from poor and variable geometric accuracy, influenced by the use of miscalibrated systems and various types of sequences for the same purpose. For effective pooling of data in multicenter studies, centers should adopt standardized procedures for system QA and in vivo imaging.
最近有人提出，应该开展多中心临床前中风研究，以提高从实验室到临床的转化效率，但实验性中风研究中常规使用的磁共振成像（MRI）扫描仪的准确性尚未得到评估。我们旨在评估和比较临床前扫描仪的几何准确性，并使用一种简单的质量保证（QA）方案检查一台扫描仪的纵向稳定性。我们使用了欧洲六个不同临床前成像中心的六台7特斯拉动物扫描仪，对一个小型结构模型进行扫描，并估计所有正交方向上的线性缩放误差和体积误差。扫描仪之间的成像包括一个标准序列和每个中心用于评估中风大鼠模型梗死体积的首选序列。标准序列还用于评估在进行基本梯度校准后，性能最差的扫描仪在六个月时间内准确性的漂移情况。使用标准序列时的缩放误差和体积误差比使用不同中风序列时的相应误差变化更小。使用标准序列估计的一台扫描仪的误差非常高（每个正交方向的缩放误差超过4%，体积误差为18.73%）。对该系统中的梯度线圈进行校准后，缩放误差降低到了±1.0%以内；在随后的6个月评估期间，这些误差保持稳定。总之，尽管临床前MRI在实验研究中已经使用了数十年，但由于使用了校准不当的系统以及为同一目的使用了各种类型的序列，其几何准确性仍然较差且变化不定。为了在多中心研究中有效地汇总数据，各中心应该采用标准化的系统质量保证程序和体内成像程序。
