On the use of R1 and R2* for measurement of contrast agent concentration in isolated perfused rat liver
On the use of R1 and R2* for measurement of contrast agent concentration in isolated perfused rat liver
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DOI：
10.1002/nbm.846
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发表时间：
2003-08-01
影响因子：
2.9
通讯作者：
Volk, A
中科院分区：
文献类型：
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作者：
Dimicoli, JL;Patry, J;Volk, A
我们提出了在4.7 T下定量测定多它灵（R）在离体灌注大鼠肝脏中分布体积的实验MRI方案。该程序涉及恒定的造影剂（CA）浓度或团注给药条件。R-1和R-2* 的CA在肝脏和灌注液中的影响，通过改变激励角度或回波时间，使用梯度回波快速成像（GEFI）实验测量。在MRI后，还通过电感耦合等离子体原子发射光谱法测量了肝脏和灌注液中的CA浓度，以确定灌注液中的原位弛豫率（r（1）=4.2+/-0.1 s（-1）mm（-1），r（2）*=17+/-2 s（-1）mm（-1））和肝脏中的原位弛豫率（r（1）=7.2+/-0.2 s（-1）mm（-1），r（2）* =99+/-5 s（-1）mm（-1））。当根据R、测量值和r（1）估计CA浓度时，推注（0.31+/-0.01）和静止（0.32+/-0.05）实验得出的肝脏中CA分布体积估计值无显著差异。相反，推注后，来自R-2* 和r（2）* 的CA浓度在肝脏中被高估，在灌注液中甚至更高。然而，在CA推注给药之前测量R-1和R-2*，在多次推注期间根据多次TE测量计算的零回波时间信号强度产生了对R的良好估计，从而校正了肝脏和灌注液中的CA浓度。在这些条件下，单次多回波GEFI采集应足以确定浓度-时间曲线。因此，当必须避免多次推注时，该方案应适于快速估计体内分布体积。版权所有（C）2003约翰威利父子有限公司。
We present experimental MRI protocols at 4.7 T for quantitative determination of the Dotarem(R) distribution volume in isolated perfused rat liver. The procedures involved either constant contrast agent (CA) concentration or bolus administration conditions. R-1 and R-2* effects of the CA in liver and perfusate were measured using gradient echo fast imaging (GEFI) experiments by varying either the excitation angle or the echo time. CA concentrations in liver and perfusate were also measured after MRI by inductively coupled plasma atomic emission spectroscopy, in order to determine in situ relaxivities in the perfusate (r(1)=4.2+/-0.1 s(-1)mm(-1), r(2)*=17+/-2 s(-1)mm(-1)) and in the liver (r(1)=7.2+/-0.2 s(-1)mm(-1), r(2)* =99+/-5 s(-1) mm(-1)). When CA concentrations were estimated from R, measurements and r(1), the CA distribution volume estimations in liver resulting from bolus (0.31+/-0.01) and stationary (0.32+/-0.05) experiments were not significantly different. In contrast, after a bolus, CA concentrations derived from R-2* and r(2)* were overestimated in liver and even more in perfusate. However, with R-1 and R-2* being measured before CA bolus administration, zero echo time signal intensities computed from multiple TE measurements during multiple boli yielded good estimations of R, and thus correct CA concentrations in liver and in perfusate. Under these conditions, a single multi-echo GEFI acquisition should be sufficient to determine the concentration-time curves. Consequently, this protocol should be appropriate to rapidly estimate the distribution volume in vivo when multiple boli have to be avoided. Copyright (C) 2003 John Wiley Sons, Ltd.