What concentration of gadolinium-based contrast material is used when performing MR arthrography? What are the components of the MR arthrogram injectate?
For MR arthrography, the injectate is diluted to a concentration of 1 to 2.5 mM. The final gadolinium dilution ratio should be 1 : 100 to 1 : 250 to achieve maximal signal intensity on T1-weighted MR images. Although the final injectate solution slightly varies from institution to institution, a suggested injectate solution may consist of 10 ml of saline, 10 ml of iodinated contrast material, 0.2 ml of gadolinium-based contrast material, and 0.1 ml of epinephrine (although not used for hip injections).
What will occur if the concentration of gadolinium in the injectate is too high?
If the intraarticular concentration of gadolinium in the injectate for MR arthrography is too high, for example with a gadolinium dilution ratio of 1 : 5, this will result in a “black arthrogram” seen on MRI, where the injectate appears low in signal intensity. If this occurs, one option is to perform MRI after a waiting period of several hours.