Shoulder MR Arthrogram Explained: What the Report Means

Phrases from an arthrogram report

• “Intra-articular injection of dilute gadolinium under fluoroscopic guidance”
• “Contrast extends into the superior labrum, consistent with a SLAP tear”
• “No contrast in the subacromial-subdeltoid bursa to suggest a full-thickness tear”
• “Indirect MR arthrogram”, meaning contrast was given into a vein instead of into the joint

What it shows better than a standard MRI

• Labral tears: in a meta-analysis of 60 studies, MR arthrography found labral lesions with 88% sensitivity, compared with 76% for standard MRI.
• Partial versus full-thickness cuff tears: contrast that passes from the joint into the bursa above the cuff shows that a tear goes all the way through.
• Normal variants: a sublabral recess, which can mimic a SLAP tear, is shown more clearly than on MRI without contrast.

Safety, and why it is ordered

Arthrography is considered very safe. In a survey of experienced radiologists covering about 13,300 MR arthrograms, six reactions were reported, all minor, such as pain, fainting reactions and headaches. It is usually chosen when a labral tear or shoulder instability is suspected, or when a standard MRI left a question open.

Questions before or after the arthrogram

• What question should the arthrogram answer that my MRI did not?
• Will the injection be guided by fluoroscopy or ultrasound, and how long does it take?
• Did contrast enter the labrum or the bursa, and what does that mean for me?
• Should the team know about any allergies or earlier reactions to contrast?

Sources

1. Steinbach LS, Palmer WE, Schweitzer ME. Special focus session. MR arthrography. Radiographics. 2002;22(5):1223-1246.
2. Smith TO, Drew BT, Toms AP. A meta-analysis of the diagnostic test accuracy of MRA and MRI for the detection of glenoid labral injury. Arch Orthop Trauma Surg. 2012;132(7):905-919.
3. Smith DK, Chopp TM, Aufdemorte TB, et al. Sublabral recess of the superior glenoid labrum: study of cadavers with conventional nonenhanced MR imaging, MR arthrography, anatomic dissection, and limited histologic examination. Radiology. 1996;201(1):251-256.
4. Hugo PC 3rd, Newberg AH, Newman JS, Wetzner SM. Complications of arthrography. Semin Musculoskelet Radiol. 1998;2(4):345-348.
5. Expert Panel on Musculoskeletal Imaging; Amini B, Beckmann NM, et al. ACR Appropriateness Criteria Shoulder Pain-Traumatic. J Am Coll Radiol. 2018;15(5S):S171-S188.