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Contrast‐agent phase effects: An experimental system for analysis of susceptibility, concentration, and bolus input function kinetics
Author(s) -
Akbudak Erbil,
Norberg Richard E.,
Conturo Thomas E.
Publication year - 1997
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910380619
Subject(s) - kinetics , contrast (vision) , phase contrast microscopy , bolus (digestion) , chemistry , phase (matter) , nuclear magnetic resonance , medicine , computer science , physics , optics , artificial intelligence , organic chemistry , quantum mechanics
Abstract A system is presented for experimental arterial input function (AIF) simulation and for accurate measurement of the concentration, susceptibility effects, and magnetic moment of paramagnetic MR contrast agents. Signal effects of contrast agents are evaluated with a stable, well‐characterized, and precise experimental setup. A cylindrical phantom and a closed‐loop circulating flow system were designed for AIF simulation, assessment of the physical determinants of contrast‐agent phase effects, and measurement of contrast agent properties under controlled conditions. A mathematical model of the AIF dynamics is proposed. From the experimental phase shift (Δϕ), either the concentration or molar susceptibility, x M , is determined. The linear dependence of Δϕ on concentration and echo time ( TE ), the orientation dependence, and the lack of dependence on T 1 , T 2 , and diffusion time are proven precisely for water solutions under a wide variety of conditions. The measured effective magnetic moment of Gd +3 , μ eff , was 7.924 ± 0.015 Bohr magnetons in agreement with the theoretical value of 7.937.