An MR arthrogram solution is a dilute solution of gadolinium that is used in MR arthrography for injection into the joint prior to imaging. The joint injection is performed under fluoroscopic guidance.
In vitro studies suggest that the ideal gadolinium medium concentration is ~2-2.5 mmol/L, however most 'off the shelf' commercial preparations have a concentration of 0.5 mol/L (or 500 mmol/L). Therefore a large volume of normal saline is required to dilute the gadolinium down about 200 times 4. A number of recipes are used but a simple approach to preparing 20 mL of solution is as follows:
- 10 mL normal saline
- 0.1 mL gadolinium
- 10 mL non-ionic iodinated contrast
The amount of contrast used will depend on the joint. Other preparations include:
- 5 mL solution made up of 0.1 mL gadolinium, 3.5 mL non-ionic iodinated contrast, and 1.5 mL 1% lidocaine for shoulder and hip joint injections
- 2.5 mL solution of 0.1 mL gadolinium and 2.5 mL non-ionic iodinated contrast for wrist, elbow and ankle injections
- adding local anaesthetic to the mixture can be done to relieve joint pain due to capsular distension, such pain may remain for 24 to 48 hours after injection, however bupivacaine is ideally avoided due to potential chondrotoxicity
Other radiologists use the same mixture but with some modification in the volume of each component.
Alternatively intra-articular location can be confirmed with iodinated contrast in a separate syringe.
Note: avoid gas bubbles as they can be confused with intra-articular loose bodies
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- 3. Kreuz PC, Steinwachs M, Angele P. Knee Surg Sports Traumatol Arthrosc. 2018 Mar;26(3):819-830. Single-dose local anesthetics exhibit a type-, dose-, and time-dependent chondrotoxic effect on chondrocytes and cartilage: a systematic review of the current literature.
- 4. Rastogi AK, Davis KW, Ross A, Rosas HG. Fundamentals of Joint Injection. (2016) AJR. American journal of roentgenology. 207 (3): 484-94. doi:10.2214/AJR.16.16243 - Pubmed