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Invest Radiol. 2015 May;50（5）:330-8. doi: 10.1097/RLI.0000000000000132. T1 relaxivities of gadolinium-based magnetic resonance contrast agents in human whole blood at 1.5, 3, and 7 T. Shen Y1, Goerner FL, Snyder C, Morelli JN, Hao D, Hu D, Li X, Runge VM. Author information Abstract OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. PMID: 25658049 DOI: 10.1097/RLI.0000000000000132 [PubMed - indexed for MEDLINE]
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