Is a mixture of gadolinium and iodinated contract material safe during MR arthrography?

OBJECTIVE. This study was designed to determine whether a mixture of iodina ted contrast material and gadopentetate dimeglumine used during MR arthrogr aphy yields free gadolinium ion, a systemically toxic metal. MATERIALS AND METHODS, Mixtures of commercially available nonionic and ioni c iodinated contrast agent, gadopentetate dimeglumine, lidocaine, and epine phrine were analyzed using a spectrophotometric titration with a gadolinium ion titrant and methyl thymol blue indicator. RESULTS. We found no significant dissociation of gadolinium ion when gadope ntetate dimeglumine was mixed with iodinated contrast agents, lidocaine, or epinephrine in any of the dilutions tested. CONCLUSION. Gadopentetate dimeglumine and iodinated contrast material can b e mixed before MR imaging without any release of free gadolinium and are th erefore safe for confirming the intraarticular placement of contrast materi al before MR arthrography.