Why is the iodinated contrast more radiolucent on this post-injection image?
The anaesthetic arthrogram injection did not contain iodinated contrast; it was a mixture of corticosteroid and longer-acting local anaesthetic. Therefore it diluted the existing iodinated contrast making it more radiolucent.
What medications and injectates will you ask for?
Local anaesthetic for the skin i.e 1% lidocaine, iodinated contrast for confirming the needle position i.e. iohexol 300, a corticosteroid i.e. 40mg triamcinolone acetonide, and a small amount of longer acting local anaesthetic to mix with the steroid i.e. 0.5% ropivacaine.
Iodinated contrast and the anaesthetic arthrogram solution distends the joint, which outlines the irregular contour of the joint which most likely represent synovitis/ synovial hypertrophy.