Optimal gadolinium concentration for direct MR arthrography at high field strength up to 7 T: In vitro model

ObjectiveProspective evaluation of optimal MR arthrographic concentration of two gadolinium-based agents of different relaxivities, either in saline or iodinated carriers at 1.5, 3 and 7 T field strengths was evaluated in vitro.Materials and methodsAt 1.5, 3.0 and 7.0 T, gadobenate and gadoteridol were studied at different concentrations in both normal saline and iodinated contrast. IRT1W and multi-echo T2FSE sequences were obtained. Signal–concentration relationship of both used agents in different carriers and field strengths was plotted from their collected T1 and T2 values, as well as their derived longitudinal (r1) and transverse (r2) relaxivities.ResultsSignificant increase in T1 signal intensity (p < 0.001) of both gadobenate and gadoteridol was observed in higher fields of 3 T and 7 T, stronger for gadoteridol. Contrarily, gadoteridol showed a significantly lesser decrease (p < 0.0001) of T2 signal intensity with increasing field from 3 T to 7 T.Iodinated carriers significantly diminished T2 signal intensity (p < 0.0001) except for highest concentration (10 mmol/L) (p = 0.8899) while this was only significant (p = 0.0279) between extreme concentrations for T1 signal.ConclusionOn transitioning to high-field (3 T and 7 T) MR arthrography, keeping the least amount of iodine for intra-articular contrast delivery, and when choice is available, gadoteridol is preferable to gadobenate. However, gadobenate was still optimal at 3 T.