Electrostatic interactions are important for the distribution of Gd(DTPA)(2-) in articular cartilage.
The delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) method can be used to assess the content of glycosaminoglycan in cartilage. In in vitro and model studies, the content of glycosaminoglycan is often expressed in terms of a fixed charge density (FCD). Values of the fixed charge density obtained using the dGEMRIC method differs from values obtained using other methods. The purpose of this work was to further clarify the origin of this discrepancy.



dGEMRIC experiments were performed in a μMRI setup on a custom-designed, well-defined model system capturing the relevant ionic features of cartilage. The model system allows for good control over and systematic variation of relevant parameters. The experimental data was compared with results from Monte Carlo simulations on a coarse-grained model.



Application of ideal Donnan theory on data obtained from experiments as well as simulations lead to underestimation of the fixed charge density, in agreement with previous studies.



To obtain more accurate estimates of the fixed charge density using the dGEMRIC method, interionic interactions need to be taken into account in the Donnan analysis. Furthermore, the results suggest that the combination of μMRI dGEMRIC experiments and Monte Carlo simulations are useful tools for an improved understanding of these effects. Magn Reson Med 76:500-509, 2016. © 2015 Wiley Periodicals, Inc.
Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden.
Jenny
J
Algotsson
Division of Theoretical Chemistry, Department of Chemistry, Lund University, Lund, Sweden.
Jan
J
Forsman
Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden.
Daniel
D
Topgaard
Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden.
Olle
O
Söderman
D016477:Artifacts; D002358:Cartilage, Articular / Q000737:chemistry* / Q000528:radiation effects; D004574:Electromagnetic Fields; D019786:Gadolinium DTPA / Q000737:chemistry* / Q000528:radiation effects*; D006025:Glycosaminoglycans / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D057054:Molecular Imaging / Q000295:instrumentation / Q000379:methods; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D055672:Static Electricity; D014018:Tissue Distribution / Q000528:radiation effects
D006025:Glycosaminoglycans; D019786:Gadolinium DTPA
Monte Carlo simulations; cartilage; delayed gadolinium-enhanced magnetic resonance imaging of cartilage; fixed charge density; μMRI