Jackels S C, Kroos B R, Hinson W H, Karstaedt N, Moran P R
Radiology. 1986 May;159(2):525-30. doi: 10.1148/radiology.159.2.3961187.
Paramagnetic macrocyclic chelates show promise as magnetic resonance (MR) imaging contrast agents due to stability and relaxivity comparable to those of DTPA-type chelates. For the three copper and manganese macrocyclic complexes studied in aqueous solution, T1 and T2 relaxivities ranged from 0.14 to 5.88 mM-1sec-1 at 6.25 MHz. In rats, the intravenous administration of 16 mumol/kg of Mn(cyclam) caused the liver T1 relaxation rate to double at 15 minutes after injection. T1 measurements by pulsed MR imaging and manganese analyses on excised tissue showed that both relaxation rate (1/T1) and manganese content of liver and kidney increase linearly with the dosage of Mn(cyclam). The linear relationship between 1/T1 and manganese content can be considered an "in tissue" relaxivity plot for the agent. The resulting relaxivity is 54 mM-1sec-1 in liver, compared with 3.1 mM-1sec-1 in aqueous solution. Although this work is preliminary, the implication for medical MR imaging applications is that macrocyclic contrast agents can be effective at approximately one-tenth the current typical dose used for gadolinium DTPA.
顺磁性大环螯合物由于其稳定性和弛豫性与二乙三胺五乙酸（DTPA）型螯合物相当，有望成为磁共振（MR）成像造影剂。对于在水溶液中研究的三种铜和锰大环配合物，在6.25兆赫兹时，纵向弛豫率（T1）和横向弛豫率（T2）范围为0.14至5.88毫摩尔-1秒-1。在大鼠中，静脉注射16微摩尔/千克的锰（环胺），注射后15分钟肝脏的T1弛豫率加倍。通过脉冲MR成像进行的T1测量以及对切除组织的锰分析表明，肝脏和肾脏的弛豫率（1/T1）和锰含量均随锰（环胺）剂量呈线性增加。1/T1与锰含量之间的线性关系可被视为该造影剂的“组织内”弛豫率曲线。肝脏中得到的弛豫率为54毫摩尔-1秒-1，而在水溶液中为3.1毫摩尔-1秒-1。尽管这项工作尚属初步，但对于医学MR成像应用而言，其意义在于大环造影剂的有效剂量约为目前用于钆-DTPA的典型剂量的十分之一。
