Comparison of Magnetic Properties of MRI Contrast Media Solutions at Different Magnetic Field Strengths

TLDR

The study aims to compare the relaxivity of commercially available MRI contrast media across field strengths of 0.47 T to 4.7 T in water and plasma at physiological temperature. Relaxivities were measured by NMR spectroscopy and MRI phantom experiments across 0.47 T to 4.7 T, with T1 and T2 determined by spin‑echo sequences and NMR dispersion profiles obtained in water, plasma, and whole blood. Relaxivity depends strongly on field strength and solvent, with protein binding amplifying these effects and altering T1 values at higher fields; thus, data obtained at 0.47 T are unreliable and should be replaced by measurements at 1.5 T and 3 T in plasma.

Abstract

Rationale and Objectives: To characterize and compare commercially available contrast media (CM) for magnetic resonance imaging (MRI) in terms of their relaxivity at magnetic field strengths ranging from 0.47 T to 4.7 T at physiological temperatures in water and in plasma. Relaxivities also were quantified in whole blood at1.5 T. Methods: Relaxivities of MRI-CM were determined by nuclear magnetic resonance (NMR) spectroscopy at 0.47 T and MRI phantom measurements at 1.5 T, 3 T, and 4.7 T, respectively. Both longitudinal (T1) and transverse relaxation times (T2) were measured by appropriate spin-echo sequences. Nuclear magnetic resonance dispersion (NMRD) profiles were also determined for all agents in water and in plasma. Results: Significant dependencies of relaxivities on the field strength and solvents were quantified. Protein binding leads to both increased field strength and solvent dependencies and hence to significantly altered T1 relaxivity values at higher magnetic field strengths. Conclusions: Awareness of the field strength and solvent associated with relaxivity data is crucial for the comparison and evaluation of relaxivity values. Data observed at 0.47 T can thus be misleading and should be replaced by relaxivities measured at 1.5 T and at 3 T in plasma at physiological temperature.