What type of MRI is recommended for a shoulder injury?

MRI Type for Shoulder Injury

For acute shoulder injuries, order MRI without IV contrast, which is the appropriate imaging modality recommended by the American College of Radiology for evaluating rotator cuff tears, labral injuries, instability, and occult fractures. 1, 2

Acute Injury Setting (< 6-8 weeks)

MRI without IV contrast is preferred over MR arthrography in acute trauma because the injury itself creates a posttraumatic joint effusion or hemarthrosis that naturally distends the joint, providing excellent visualization of soft tissue structures without needing injected contrast. 1, 2

Key advantages in acute settings:

• Detects rotator cuff tears with high accuracy 1, 2
• Identifies labral and ligamentous injuries using the natural joint effusion 1
• Reveals bone marrow edema from occult fractures missed on radiographs 2, 3
• Assesses bone loss equivalent to CT 1
• Non-invasive compared to arthrography 2

Critical technical point:

Always include fat-suppressed sequences (STIR) in the protocol, as conventional T1/T2 sequences alone can miss occult fractures of the humeral tubercle indicated by bone bruising. 3

Chronic or Subacute Setting (> 6-8 weeks)

MR arthrography becomes superior to noncontrast MRI when evaluating chronic symptoms because the natural joint effusion has resolved, leaving insufficient fluid for adequate joint distention. 1, 2

When MR arthrography is indicated:

• Chronic shoulder instability without acute effusion 1, 2
• Suspected labral tears in the subacute/chronic phase (86-100% sensitivity) 2
• Equivocal partial-thickness rotator cuff tears requiring distinction from full-thickness tears 1, 2
• Patients under 35 years old with instability symptoms 1

What MR arthrography adds:

The injected dilute gadolinium solution distends the joint capsule, outlining labral structures, capsular ligaments, and the undersurface of the rotator cuff with superior detail compared to noncontrast MRI when natural effusion is absent. 1

What NOT to Order

Never order MRI shoulder with standard IV contrast (non-arthrographic gadolinium) - there is no relevant literature supporting this approach, as intravenous contrast does not provide the joint distention needed for optimal soft tissue visualization. 1, 2

Avoid MR arthrography in acute trauma - it adds unnecessary invasiveness without diagnostic benefit when natural joint effusion is already present. 1, 2

Common Pitfalls to Avoid

• Don't skip radiographs first: The American College of Radiology recommends obtaining plain radiographs (AP views in internal and external rotation plus axillary or scapula-Y view) before advancing to MRI. 2, 4
• Don't order CT for soft tissue injuries: CT is virtually useless for diagnosing rotator cuff tears, labral injuries, and muscle tears, though it remains the gold standard for characterizing complex fractures. 1
• Don't assume all shoulder pain needs arthrography: The timing of injury determines the protocol - acute trauma favors noncontrast MRI, while chronic symptoms may require arthrography. 2

Practical Algorithm

1. Obtain radiographs first (upright when possible) 2, 4
2. If radiographs negative/indeterminate with acute injury (< 6-8 weeks): Order MRI shoulder without IV contrast with fat-suppressed sequences 1, 2, 3
3. If chronic symptoms (> 6-8 weeks) with suspected labral pathology: Consider MR arthrography 1, 2
4. If patient < 35 years with instability: MR arthrography is generally recommended unless acute dislocation with effusion present 1