What is the recommended initial imaging modality for diagnosing rotator cuff injury and adhesive capsulitis?

Imaging for Rotator Cuff Injury and Adhesive Capsulitis

Radiography should be performed first for all patients with shoulder pain, followed by MRI without IV contrast or ultrasound as the next imaging study for suspected rotator cuff tears, while MRI without IV contrast is preferred for adhesive capsulitis. 1, 2

Initial Imaging: Radiography First

• Plain radiographs are usually appropriate as the initial imaging study for any shoulder pain etiology, including both rotator cuff injury and adhesive capsulitis 1
• A complete shoulder radiographic series should include anteroposterior views in both internal and external rotation, plus an axillary or scapular Y view, performed with the patient upright 2
• Radiographs help exclude fractures, dislocations, and can show indirect signs of rotator cuff pathology such as superior migration of the humeral head 2
• For adhesive capsulitis specifically, radiographs are primarily used to exclude other causes of shoulder pain such as arthropathy or calcific tendinitis 3

Next Imaging After Normal/Nonspecific Radiographs

For Rotator Cuff Injury

Both MRI without IV contrast and ultrasound are equally appropriate (rated 9/9) for evaluating suspected rotator cuff tears 1, 2

MRI Without IV Contrast

• MRI is generally considered the best modality for adequately assessing most soft tissue injuries, including rotator cuff pathology 1
• MRI has high sensitivity and specificity for detecting full-thickness rotator cuff tears, with sensitivities of 90-91% and specificities of 93-95% 1
• MRI has lower sensitivity compared to MR arthrography for partial-thickness tears 1
• MRI is preferred when: the patient has large body habitus, restricted range of motion due to acute pain, or when there is suspicion of other intra-articular pathologies such as labral tears 1, 2

Ultrasound

• Ultrasound has high sensitivity and specificity for full-thickness rotator cuff tears, showing performance levels similar to MRI (sensitivities 90-91%, specificities 93-95%) 1
• There is conflicting evidence on ultrasound's ability to diagnose partial-thickness rotator cuff tears 1
• Interobserver agreement for full-thickness tears can be high, but is much more variable for partial-thickness tears 1
• Ultrasound is preferred when: there is previously placed proximal humeral hardware that would create MRI susceptibility artifacts, or when MRI is contraindicated 1, 2

For Adhesive Capsulitis

MRI without IV contrast is the preferred imaging modality for confirming adhesive capsulitis 4, 5, 6, 3

Key MRI Findings

• Thickening of the coracohumeral ligament (>4 mm is abnormal; normal is approximately 2.4 mm) 6
• Thickening of the joint capsule in the rotator cuff interval (>7 mm is abnormal; normal is approximately 4.4 mm) 6
• Partial or complete obliteration of the subcoracoid fat triangle (73% partial, 26% complete in adhesive capsulitis vs. 13% partial, 1.6% complete in controls) 6
• Synovitis-like abnormality around the long biceps tendon 6
• Rotator interval fat pad obliteration has 100% specificity for adhesive capsulitis 4

MRI Technical Considerations

• Non-contrast MRI is sufficient for diagnosing all stages of adhesive capsulitis, including early stage 1 where clinical findings may be subtle 5
• Contrast-enhanced MRI may improve assessment of the rotator interval and diagnostic confidence, showing enhancement of the axillary capsule and rotator interval with high interobserver reliability (κ=0.92) 7
• However, intravenous contrast is not necessary for diagnosis 5, 3

Advanced Imaging: When to Consider MR Arthrography

• MR arthrography is NOT recommended as the initial advanced imaging study for either condition 1
• MR arthrography has shown increased sensitivity for partial-thickness articular surface rotator cuff tears compared to conventional MRI 1
• In acute trauma settings, MRI without contrast is preferred to MR arthrography because post-traumatic joint effusion provides sufficient visualization of soft tissue structures 1
• The invasive nature of MR arthrography makes it suboptimal as an initial study 1

Imaging Modalities to Avoid

• CT without contrast, CT arthrography, bone scan, and PET/CT have no role in the initial evaluation of rotator cuff injury or adhesive capsulitis 1
• CT has virtually no usefulness in diagnosing soft-tissue injuries such as rotator cuff tears 1
• Bone scintigraphy demonstrates increased activity in adhesive capsulitis but has poor resolution for pathology localization 1

Common Pitfalls to Avoid

• Do not skip initial radiographs - they are essential to exclude fractures, dislocations, and other osseous pathology 1, 2
• Do not rely solely on AP views - axillary or scapular Y views are necessary to avoid misclassifying pathology 2
• Maintain a low threshold for additional imaging if ultrasound is noncontributory, particularly for evaluating intra-articular pathology 1
• Ensure radiographs are performed upright as malalignment can be underrepresented on supine imaging 2