Contrast enhanced cartilage imaging: Comparison of ionic and non-ionic contrast agents

Abstract 

Our objective was to compare relaxation effects, dynamics and spatial distributions of ionic and non-ionic contrast agents in articular cartilage at concentrations typically used for direct MR arthrography at 1.5T.

Dynamic MR-studies over 11h were performed in 15 bovine patella specimens. For each of the contrast agents gadopentetate dimeglumine, gadobenate dimeglumine, gadoteridol and mangafodipir trinatrium three patellae were placed in 2.5mmol/L contrast solution. Simultaneous measurements of T₁ and T₂ were performed every 30min using a high-spatial-resolution “MIX”-sequence. T₁, T₂ and ΔR₁, ΔR₂ profile plots across cartilage thickness were calculated to demonstrate the spatial and temporal distributions. The charge is one of the main factors which controls the amount of the contrast media diffusing into intact cartilage, but independent of the charge, the spatial distribution across cartilage thickness remains highly inhomogeneous even after 11h of diffusion. The absolute ΔR₂-effect in cartilage is at least as large as the ΔR₁-effect for all contrast agents. Maximum changes were 5–12s⁻¹ for ΔR₁ and 8–15s⁻¹ for ΔR₂. This study indicates that for morphologically intact cartilage only the amount of contrast agents within cartilage is determined by the charge but not the spatial distribution across cartilage thickness. In addition, ΔR₂ can be considered for quantification of contrast agent concentrations, since it is of the same magnitude and less time consuming to measure than ΔR₁.

Keywords: MRI, Arthrography, Contrast agent, Cartilage, Relaxation rates