Martin C C, Williams R F, Gao J H, Nickerson L D, Xiong J, Fox P T
Research Imaging Center, University of Texas Health Science Center, San Antonio 78284, USA.
J Magn Reson Imaging. 1997 Sep-Oct;7(5):848-54. doi: 10.1002/jmri.1880070512.
In this work, a compartmental model to predict the concentration of hyperpolarized xenon (Xe) in the brain is developed based on the well established kinetics of Xe and estimated T1 values for the compartments. For the gaseous compartments, T1 was set to 12 seconds. For the tissue compartments, T1 was set to 6 seconds. Three gas delivery techniques were modeled: hyperventilation followed by breath-hold, continual breathing, and hyperventilation followed by continual breathing. Based on Xe CT, it is estimated that the maximum concentration of Xe that could be breathed is 80%. Based on this value and the estimated maximum polarization of 50%, the peak gray matter concentration of hyperpolarized Xe is calculated to be .036 mM. This leads to an estimated signal-to-noise ratio (SNR), at 2 T, for hyperpolarized Xe that is a factor of 50 lower than the SNR for proton MRI. The peak concentration of hyperpolarized Xe was also calculated over a wide range of gas and tissue T1 values. This model also predicts that the arterial blood will have a concentration of hyperpolarized Xe that is 10 times greater than the concentration in gray matter. An interactive version of the model can be found on the World Wide Web at http:(/)/ric.uthscsa.edu/staff /charlesmartinphd.html.
在这项工作中，基于已确立的氙（Xe）动力学和各腔室的估计T1值，开发了一个用于预测大脑中超极化氙（Xe）浓度的房室模型。对于气态腔室，T1设定为12秒。对于组织腔室，T1设定为6秒。对三种气体输送技术进行了建模：过度换气后屏气、持续呼吸以及过度换气后持续呼吸。基于Xe CT估计，可吸入的Xe的最大浓度为80%。基于该值和估计的50%的最大极化率，计算出超极化Xe在灰质中的峰值浓度为0.036 mM。这导致在2 T时，超极化Xe的估计信噪比（SNR）比质子MRI的SNR低50倍。还在广泛的气体和组织T1值范围内计算了超极化Xe的峰值浓度。该模型还预测动脉血中超极化Xe的浓度将比灰质中的浓度大10倍。该模型的交互式版本可在万维网http://ric.uthscsa.edu/staff /charlesmartinphd.html上找到。
