Shen Yaqi, Goerner Frank L, Snyder Christopher, Morelli John N, Hao Dapeng, Hu Daoyu, Li Xiaoming, Runge Val M
From the *Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China; †Department of Radiology, University of Texas Medical Branch, Galveston; ‡Department of Pediatric Radiology, Texas Children's Hospital; §Department of Radiology, Baylor College of Medicine, Houston, TX; ∥The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD; ¶Department of Radiology, The Affiliated Hospital of Medical College of Qingdao University, Qingdao, People's Republic of China; and #Institute for Diagnostic and Interventional Radiology, Clinics for Neuroradiology and Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
Invest Radiol. 2015 May;50(5):330-8. doi: 10.1097/RLI.0000000000000132.
Calculation of accurate T1 relaxivity (r1) values for gadolinium-based magnetic resonance contrast agents (GBCAs) is a complex process. As such, often referenced r1 values for the GBCAs at 1.5 T, 3 T, and 7 T are based on measurements obtained in media that are not clinically relevant, derived from only a small number of concentrations, or available for only a limited number of GBCAs. This study derives the r1 values of the 8 commercially available GBCAs in human whole blood at 1.5 T, 3 T, and 7 T.
Eight GBCAs were serially diluted in human whole blood, at 7 concentrations from 0.0625 to 4 mM. A custom-built phantom held the dilutions in air-tight cylindrical tubes maintained at 37 ± 0.5°C by a heat-circulating system. Images were acquired using inversion recovery sequences with inversion times from 30 milliseconds to 10 seconds at 1.5 T and 3 T as well as 60 milliseconds to 5 seconds at 7 T. A custom MATLAB program was used to automate signal intensity measurements from the images acquired of the phantom. SigmaPlot was used to calculate T1 relaxation times and, finally, r1.
Measured r1 values in units of s⁻¹·mM⁻¹ at 1.5 T (3 T/7 T) were 3.9 ± 0.2 (3.4 ± 0.4/2.8 ± 0.4) for Gd-DOTA, 4.6 ± 0.2 (4.5 ± 0.3/4.2 ± 0.3) for Gd-DO3A-butrol, 4.3 ± 0.4 (3.8 ± 0.2/3.1 ± 0.4) for Gd-DTPA, 6.2 ± 0.5 (5.4 ± 0.3/4.7 ± 0.1) for Gd-BOPTA, 4.5 ± 0.1 (3.9 ± 0.2/3.7 ± 0.2) for Gd-DTPA-BMA, 4.4 ± 0.2 (4.2 ± 0.2/4.3 ± 0.2) for Gd-DTPA-BMEA, 7.2 ± 0.2 (5.5 ± 0.3/4.9 ± 0.1) for Gd-EOB-DTPA, and 4.4 ± 0.6 (3.5 ± 0.6/3.4 ± 0.1) for Gd-HP-DO3A. The agents can be stratified by relaxivity, with a significant additional dependency on field strength.
This report quantifies, for the first time, T1 relaxivity for all 8 gadolinium chelates in common clinical use worldwide, at current relevant field strengths, in human whole blood at physiological temperature (37°C). The measured r1 values differ to a small degree from previously published values, where such comparisons exist, with the current r1 measurements being that most relevant to clinical practice. The macrocyclic agents, with the exception of Gd-DO3A-butrol, have slightly lower r1 values when compared with the 2 much less stable linear agents, Gd-DTPA-BMA and Gd-DTPA-BMEA. The 2 agents with hepatobiliary excretion, Gd-EOB-DTPA and Gd-BOPTA, have, at 1.5 and 3 T, substantially higher r1 values than all other agents.
计算钆基磁共振造影剂（GBCAs）准确的T1弛豫率（r1）值是一个复杂的过程。因此，常引用的1.5T、3T和7T时GBCAs的r1值是基于在与临床无关的介质中获得的测量结果，这些介质仅来自少数浓度，或者仅适用于有限数量的GBCAs。本研究得出了8种市售GBCAs在1.5T、3T和7T时人全血中的r1值。
将8种GBCAs在人全血中进行系列稀释，浓度范围为0.0625至4mM，共7个浓度。一个定制的体模将稀释液置于气密的圆柱形管中，通过热循环系统保持在37±0.5°C。使用反转恢复序列采集图像，1.5T和3T时反转时间为30毫秒至10秒，7T时为60毫秒至5秒。使用定制的MATLAB程序自动测量体模图像的信号强度。使用SigmaPlot计算T1弛豫时间，最后计算r1。
1.5T（3T/7T）时以s⁻¹·mM⁻¹为单位的测量r1值，钆喷酸葡胺（Gd-DOTA）为3.9±0.2（3.4±0.4/2.8±0.4），钆布醇（Gd-DO3A-butrol）为4.6±0.2（4.5±0.3/4.2±0.3），钆双胺（Gd-DTPA）为4.3±0.4（3.8±0.2/3.1±0.4），钆贝葡胺（Gd-BOPTA）为6.2±0.5（5.4±0.3/4.7±0.1），钆特醇（Gd-DTPA-BMA）为4.5±0.1（3.9±0.2/3.7±0.2），钆大胺（Gd-DTPA-BMEA）为4.4±0.2（4.2±0.2/4.3±0.2），钆塞酸二钠（Gd-EOB-DTPA）为7.2±0.2（5.5±0.3/4.9±0.1），钆六醇（Gd-HP-DO3A）为4.4±0.6（3.5±0.6/3.4±0.1）。这些造影剂可根据弛豫率进行分层，并且对场强有显著的额外依赖性。
本报告首次量化了全球范围内临床上常用的所有8种钆螯合物在当前相关场强下、生理温度（37°C）的人全血中的T1弛豫率。在有可比数据的情况下，测量得到的r1值与先前发表的值略有不同，当前的r1测量值与临床实践最为相关。大环类造影剂（钆布醇除外）与两种稳定性差得多的线性造影剂钆特醇和钆大胺相比，r1值略低。两种具有肝胆排泄功能的造影剂钆塞酸二钠和钆贝葡胺在1.5T和3T时的r1值明显高于所有其他造影剂。
