Tuesday, December 18, 2018

How To Read A Shoulder MRI

Shoulder MRI is a common musculoskeletal imaging exam. The exam is typically ordered for shoulder pain with suspicion of underlying rotator cuff pathology. Contrast is not needed. If there is a concern for labral pathology, an MRI arthrogram may be ordered. The arthrogram requires gadolinium-based contrast to be injected intra-articularly under fluoroscopic guidance prior to the MRI. The steps below are for a routine, non-contrast MRI.

The MRI shoulder is usually acquired in 3 planes (axial, sagittal, and coronal) obliqued to the plane of the scapula. Usually each plane is acquired as PD and T2, with one of the planes being done as a T1 instead of PD.

Prior to looking at the MRI, it is helpful to compare with any prior shoulder x-rays available.

On the MRI, the assessment should include:
  • Long heads of the biceps tendon: Start on the axial sequences and follow it along its course in the bicipital group to its origin at the biceps labral anchor
  • Supraspinatus (SS)
  • Infraspinatus (IS)
  • Teres Minor
  • Subscapularis (SSc)
  • Rotator Interval [2]
  • Labrum: best seen on the axial and coronal sequences; should appear hypointense and symmetric. Better assessed on MR arthrogram. 
  • Coracohumeral ligament (CHL): best seen on the coronals as a hypointense structure arising from the lateral coracoid, with its medial band inserting on the lesser tuberosity, and lateral band, greater tuberosity
  • Inferior glenohumeral ligament (IGHL): also assessed on the coronal
  • Acromioclavicular joint
  • Humerus and other bony structures
  • Spinoglenoid notch
  • Suprascapular notch
  • Quadrilateral space

Shoulder MRI Pearls:
  • Fluid in the subcoracoid bursa is suggestive of a tear [1]
  • Articular side anterosuperior rotator cuff tears (ie SSc and SS tears) can dissect into the CHL
  • IGHL is greater than 4 mm in capsulitis, but this should be a clinical diagnosis ultimately

This post is derived from notes I took during training. Any images are copyright their respective owners.

Revised: 2019-01-25



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