Department of Diagnostic and Interventional Neuroradiology, University Hospital Hamburg-Eppendorf, Martinistr. 52, Gebauede W14, 20251, Hamburg, Germany.
Eur Radiol. 2022 Jul;32(7):4521-4526. doi: 10.1007/s00330-022-08550-8. Epub 2022 Feb 4.
Arterial spin labeling blood perfusion signal relies on the difference between a label and a control image. Background suppression pulses are commonly used to improve the contrast, yet these are based on estimates of tissue relaxation times. The aim of this study is to improve the perfusion contrast by individualizing the timing of these background suppression pulses by means of T1 mapping.
The optimized timing of the background suppression pulses is obtained by rapid T1 mapping employing the variable flip angle technique. Ten healthy volunteers were included in this study. To compare the results, visual grading and the Wilcoxon signed-rank test was used comparing three categories of image quality.
The readers confirmed that the images of the proposed method generally show a higher signal-to-background ratio and cortical structures are better visible. Noise was mostly comparable to the standard method. Relative blood flow was statistically significant higher in the modified method.
The individually optimized background suppression pulses improve the image appearance and allow for a better visualization of cortical structures. The proposed technique however prolongs scan time, which can be seen as negative result, yet needs to be further evaluated.
• Background suppression timing in ASL can vary. • Both the label and control condition can be modified for T1 mapping. • Adapting the pulse timing improves the signal-to-background ratio.
动脉自旋标记的血液灌注信号依赖于标记和对照图像之间的差异。背景抑制脉冲常用于提高对比度，但这些脉冲是基于组织弛豫时间的估计。本研究的目的是通过 T1 映射来个性化这些背景抑制脉冲的定时，以提高灌注对比度。
通过采用可变翻转角技术的快速 T1 映射获得背景抑制脉冲的最佳定时。本研究纳入了 10 名健康志愿者。为了比较结果，使用视觉分级和 Wilcoxon 符号秩检验，将图像质量分为三个类别进行比较。
读者确认，所提出的方法的图像通常显示出更高的信噪比，皮质结构更清晰可见。噪声与标准方法基本相当。改良方法的相对血流明显更高。
个性化优化的背景抑制脉冲可改善图像外观，更好地显示皮质结构。然而，所提出的技术延长了扫描时间，这可以被视为负面结果，但需要进一步评估。
ASL 中的背景抑制定时可以变化。
可以对标签和对照条件进行修改以进行 T1 映射。
调整脉冲定时可以提高信噪比。
