title: T1 relaxivities of gadolinium-based magnetic resonance contrast agents in human whole blood at 1.5, 3, and 7 T.
abstract: OBJECTIVE
  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.
  
  
  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.
authors: 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.
authors: Yaqi
authors: Y
authors: Shen
authors: Frank L
authors: FL
authors: Goerner
authors: Christopher
authors: C
authors: Snyder
authors: John N
authors: JN
authors: Morelli
authors: Dapeng
authors: D
authors: Hao
authors: Daoyu
authors: D
authors: Hu
authors: Xiaoming
authors: X
authors: Li
authors: Val M
authors: VM
authors: Runge
mesh_terms: D001774:Blood Chemical Analysis; D003287:Contrast Media / Q000737:chemistry; D017097:Electric Impedance; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008422:Materials Testing
chemical_list: D003287:Contrast Media; D005682:Gadolinium