Purpose: To provide a simulation framework for routine neuroimaging test data, which allows for "stress testing" of deep segmentation networks against acquisition shifts that commonly occur in clinical practice for T2 weighted (T2w) fluid attenuated inversion recovery (FLAIR) Magnetic Resonance Imaging (MRI) protocols. Approach: The approach simulates "acquisition shift derivatives" of MR images based on MR signal equations. Experiments comprise the validation of the simulated images by real MR scans and example stress tests on state-of-the-art MS lesion segmentation networks to explore a generic model function to describe the F1 score in dependence of the contrast-affecting sequence parameters echo time (TE) and inversion time (TI). Results: The differences between real and simulated images range up to 19 % in gray and white matter for extreme parameter settings. For the segmentation networks under test the F1 score dependency on TE and TI can be well described by quadratic model functions (R^2 > 0.9). The coefficients of the model functions indicate that changes of TE have more influence on the model performance than TI. Conclusions: We show that these deviations are in the range of values as may be caused by erroneous or individual differences of relaxation times as described by literature. The coefficients of the F1 model function allow for quantitative comparison of the influences of TE and TI. Limitations arise mainly from tissues with the low baseline signal (like CSF) and when the protocol contains contrast-affecting measures that cannot be modelled due to missing information in the DICOM header.

翻译：目的：提供一种常规神经影像测试数据的仿真框架，该框架允许针对临床实践中T2加权液体衰减反转恢复磁共振成像协议中常见的采集偏移，对深层分割网络进行“压力测试”。方法：该方法基于MR信号方程仿真MR图像的“采集偏移衍生图”。实验包括通过真实MR扫描对仿真图像进行验证，以及针对最先进的多发性硬化病灶分割网络进行示例压力测试，以探索描述F1分数随对比度影响序列参数回波时间和反转时间变化的通用模型函数。结果：在极端参数设置下，真实图像与仿真图像在灰质和白质中的差异高达19%。对于受测的分割网络，F1分数对TE和TI的依赖性可通过二次模型函数很好地描述（R^2 > 0.9）。模型函数的系数表明，TE变化对模型性能的影响大于TI。结论：我们表明这些偏差的范围与文献报道的由弛豫时间错误或个体差异引起的偏差范围一致。F1模型函数的系数可定量比较TE和TI的影响。局限性主要来自低基线信号的组织（如脑脊液），以及当协议包含因DICOM头文件信息缺失而无法建模的对比度影响措施时。