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Published on: April 28, 2015
Relaxivity of liposomal paramagnetic MRI contrast agents
G J Strijkers1, W J M Mulder, R B van Heeswijk
1Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands. g.j.strijkers@tue. nl
Magma (New York, N.Y.)
|September 13, 2005
Summary
Paramagnetic liposomes enhance magnetic resonance imaging contrast. Optimized lipid composition and cholesterol improve their effectiveness as potent MRI contrast agents for various applications.
Area of Science:
- Biomedical Engineering
- Materials Science
- Radiology
Background:
- Paramagnetic liposomes are lipid bilayer spheres designed as potent MRI contrast agents.
- They can carry high payloads of Gadolinium (Gd)-containing lipids.
- Pegylated liposomes (~100 nm) exhibit favorable in vivo pharmacokinetic properties.
Purpose of the Study:
- To investigate the relaxation properties of paramagnetic liposomes.
- To understand how composition, temperature, and magnetic field strength affect relaxivity.
- To assess their potential as effective MRI contrast agents.
Main Methods:
- Synthesis of pegylated paramagnetic liposomes with varying lipid compositions (DOPC vs. DSPC) and cholesterol content.
- Measurement of proton relaxivity (T1 relaxation rate per mmol Gd(III)).
- Nuclear magnetic relaxation dispersion (NMRD) studies to probe water exchange dynamics.
Main Results:
- Liposomes with unsaturated (DOPC) phospholipids showed higher proton relaxivity than those with saturated (DSPC) lipids.
- Cholesterol addition was crucial for liposome monodispersity and slightly increased relaxivity.
- NMRD measurements indicated that water exchange across the liposome membrane limits relaxivity.
Conclusions:
- Paramagnetic liposomes demonstrate high effectiveness as MRI contrast agents.
- Lipid composition and cholesterol content significantly influence their relaxivity.
- These findings support their candidacy for diverse magnetic resonance imaging applications.
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