Department of Clinical Radiology, University Hospital Muenster, Muenster, Germany.
Magn Reson Med. 2012 Dec;68(6):1924-31. doi: 10.1002/mrm.24180. Epub 2012 Feb 24.
At high magnetic fields diagnostic proton MRI of the lung is problematic, because of fast T2* relaxation. The application of superparamagnetic contrast agents and the exploitation of the corresponding T2* effect is inefficient with conventional MRI methods, which limits the early detection of lung diseases. However, a simple theoretical treatment shows that in the lung, by the use of ultra-short echo time sequences, T2* effects can be neglected while T(1) shortening effects can be used for signal detection. In our study, we have applied a theoretically and experimentally optimized 3D ultra-short echo time sequence to lung phantoms and to a mouse model of lung inflammation, which was induced by systemic bacterial infection. Following the systemic application of very small superparamagnetic iron oxide nanoparticles, a significant signal increase in the lung of infected animals was detected already at 24 h postinfection, compared to control mice (17%, P < 0.001). Iron accumulation in the lung parenchyma as consequence of the host immune response was histologically confirmed. By conventional T2*- and T(2)-weighted imaging, neither structural changes nor formation of substantial edema were observed.
在高磁场下，由于快速 T2弛豫，肺部的诊断质子 MRI 存在问题。传统 MRI 方法应用超顺磁对比剂和利用相应的 T2效应效率低下，这限制了肺部疾病的早期检测。然而，简单的理论处理表明，在肺部，可以通过使用超短回波时间序列，忽略 T2效应，而利用 T1 缩短效应进行信号检测。在我们的研究中，我们应用了经过理论和实验优化的 3D 超短回波时间序列来进行肺部体模和肺部炎症的小鼠模型的研究，肺部炎症是通过全身细菌感染诱导的。在全身应用非常小的超顺磁氧化铁纳米颗粒后，与对照组小鼠相比，感染动物的肺部信号在感染后 24 小时就明显增加（17%，P<0.001）。宿主免疫反应导致的铁在肺实质中的积累在组织学上得到了证实。通过传统的 T2-和 T2-加权成像，既没有观察到结构变化，也没有形成大量的水肿。
