Maddage Rajika, Marques José P, Gruetter Rolf
Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Magn Reson Med. 2014 Nov;72(5):1246-56. doi: 10.1002/mrm.25037. Epub 2013 Nov 20.
As the magnetic susceptibility induced frequency shift increases linearly with magnetic field strength, the present work evaluates manganese as a phase imaging contrast agent and investigates the dose dependence of brain enhancement in comparison to T(1) -weighted imaging after intravenous administration of MnCl(2).
Experiments were carried out on 12 Sprague-Dawley rats. MnCl(2) was infused intravenously with the following doses: 25, 75, 125 mg/kg (n=4). Phase, T(1) -weighted images and T(1) maps were acquired before and 24 h post MnCl(2) administration at 14.1 Tesla.
Manganese enhancement was manifested in phase imaging by an increase in frequency shift differences between regions rich in calcium gated channels and other tissues, together with local increase in signal to noise ratio (from the T(1) reduction). Such contrast improvement allowed a better visualization of brain cytoarchitecture. The measured T(1) decrease observed across different manganese doses and in different brain regions were consistent with the increase in the contrast to noise ratio (CNR) measured by both T(1) -weighted and phase imaging, with the strongest variations being observed in the dentate gyrus and olfactory bulb.
Overall from its high sensitivity to manganese combined with excellent CNR, phase imaging is a promising alternative imaging protocol to assess manganese enhanced MRI at ultra high field.
由于磁化率诱导的频率偏移随磁场强度呈线性增加，本研究评估锰作为一种相位成像造影剂，并在静脉注射氯化锰后，与T(1)加权成像相比，研究脑强化的剂量依赖性。
对12只Sprague-Dawley大鼠进行实验。静脉注射以下剂量的氯化锰：25、75、125mg/kg（n = 4）。在14.1特斯拉下，于注射氯化锰前及注射后24小时采集相位、T(1)加权图像和T(1)图谱。
锰增强在相位成像中表现为富含钙门控通道的区域与其他组织之间的频移差异增加，同时局部信噪比增加（由于T(1)降低）。这种对比度的改善使得脑细结构的可视化更好。在不同锰剂量和不同脑区观察到的T(1)降低与通过T(1)加权成像和相位成像测量的对比度噪声比（CNR）增加一致，在齿状回和嗅球中观察到的变化最为明显。
总体而言，由于其对锰的高敏感性以及出色的CNR，相位成像在超高场评估锰增强MRI方面是一种有前景的替代成像方案。
