When is MRI (Magnetic Resonance Imaging) recommended for patients with shoulder pain?

MRI Imaging for Shoulder Pain

MRI shoulder without IV contrast is the gold standard imaging modality for evaluating soft tissue injuries including rotator cuff tears, labral pathology, and ligamentous injuries after initial radiographs, and should be ordered based on specific clinical scenarios outlined below. 1

Initial Imaging Algorithm

Always start with plain radiographs regardless of the suspected pathology—this is non-negotiable for any acute shoulder pain presentation. 1

When to Order MRI: Clinical Scenarios

Suspected Occult Fracture (Normal/Nonspecific X-rays)

• Order MRI shoulder without IV contrast when radiographs are normal but you suspect an occult fracture based on mechanism of injury or focal bone tenderness. 1
• MRI demonstrates bone marrow edema patterns that reveal occult fractures missed on plain films. 1
• Alternative: CT without contrast is equally appropriate if you need detailed osseous anatomy for surgical planning. 1

Suspected Rotator Cuff Tear

• Order MRI shoulder without IV contrast when physical examination suggests rotator cuff pathology (weakness with resisted external rotation, positive drop arm test, supraspinatus tenderness). 1
• MRI has 90-91% sensitivity and 93-95% specificity for full-thickness tears. 1
• Important caveat: MRI has lower sensitivity for partial-thickness tears compared to MR arthrography, but in acute trauma settings, the post-traumatic joint effusion acts as natural contrast, making standard MRI sufficient. 1
• Ultrasound is an equivalent alternative with similar diagnostic accuracy for full-thickness tears (90-91% sensitivity), but choose MRI over ultrasound when: 1
  • Large body habitus limits ultrasound visualization
  • Restricted range of motion from acute pain prevents adequate positioning
  • You suspect additional intra-articular pathology (labral tears, cartilage injury)

Suspected Dislocation/Instability

• Order MRI shoulder without IV contrast when history and examination suggest glenohumeral instability (positive apprehension test, history of dislocation with spontaneous reduction, anterior shoulder pain with abduction/external rotation). 1
• In acute dislocation, the post-traumatic hemarthrosis provides sufficient joint distention—do not order MR arthrography acutely. 1
• MR arthrography is reserved for subacute/chronic settings when joint effusion has resolved and you need detailed labral assessment. 1, 2
• CT without contrast may be appropriate if you specifically need to assess bone loss (Hill-Sachs lesion, glenoid deficiency) for surgical planning. 1

Suspected Labral Tear

• Order MRI shoulder without IV contrast in acute trauma when post-traumatic effusion is present (within 7-10 days of injury). 1, 2
• Order MR arthrography in subacute/chronic presentations (>2 weeks from injury) when joint effusion is too small to adequately distend the joint—this is the reference standard for labral pathology. 1, 2
• MR arthrography has superior sensitivity for detecting partial-thickness articular surface tears compared to conventional MRI. 1
• CT arthrography is the fallback if MRI is contraindicated (pacemaker, severe claustrophobia, metallic foreign body). 1, 2

Known Fracture Requiring Soft Tissue Assessment

• Order MRI shoulder without IV contrast when radiographs show proximal humerus, scapular, or clavicle fracture AND you suspect concomitant rotator cuff injury in patients NOT planned for surgical fracture fixation. 1
• Do not order MRI for fracture characterization—CT without contrast is superior for evaluating fracture planes and surgical planning. 1

MRI Protocol Specifications

• Standard protocol: MRI shoulder without IV contrast 1
• Do not order: MRI with IV contrast alone or MRI without and with IV contrast—there is no evidence supporting these protocols for shoulder pain evaluation. 1
• MR arthrography indications: Subacute/chronic labral tears, partial-thickness rotator cuff tears in non-acute settings. 1, 2

Common Pitfalls to Avoid

• Do not skip radiographs: Even with obvious soft tissue injury on examination, radiographs may reveal unsuspected fractures, calcific tendinitis, or degenerative changes that alter management. 1, 2
• Do not order MR arthrography acutely: In acute trauma (<2 weeks), natural joint effusion/hemarthrosis provides adequate contrast—MR arthrography adds unnecessary invasiveness and cost. 1
• Recognize ultrasound limitations: While ultrasound matches MRI for full-thickness rotator cuff tears, it has poor interobserver reliability for partial-thickness tears and completely misses labral pathology, bone contusions, and instability. 1, 3
• Consider hardware artifacts: If proximal humeral hardware is present, ultrasound may be preferable to MRI due to susceptibility artifacts degrading MRI image quality. 1

Special Populations

Large Body Habitus

• Choose MRI over ultrasound—adipose tissue limits ultrasound penetration and visualization of deeper shoulder structures. 1

Restricted Range of Motion

• Choose MRI over ultrasound—dynamic ultrasound examination requires patient cooperation and shoulder movement, which may be impossible in acute pain. 1

MRI Contraindications

• Order ultrasound for rotator cuff evaluation (full-thickness tears only). 1
• Order CT arthrography for labral pathology assessment. 1, 2