SLAP lesion: what is it...really?

[Magnetic resonance imaging of the shoulder: impingement and instability related abnormalities--update 2013]

Magnetic resonance imaging (MRI) plays an important role in the diagnosis and differentiation of numerous shoulder abnormalities and chronic shoulder pain. Important indications for MRI are assessment of the rotator cuff and the labrocapsular complex. The assessment of the rotator cuff muscles is crucial. The value of MR arthrography is discussed. The potential benefit of MR arthrography is the accurate evaluation of subtle rotator cuff abnormalities, shoulder instability-related lesions and the assessment of pathological conditions of the long biceps tendon. The following article describes the most common pathological findings of the shoulder joint and gives a description of the relevant findings for the orthopedic shoulder surgeon. The current article represents an update of an article previously published in 2006 with the same title (Zanetti and Saupe, Radiologe 46:79-89, 2006).

Gradient-recalled echo sequences in direct shoulder MR arthrography for evaluating the labrum

OBJECTIVE

The purpose of this study was to determine the utility of fat-suppressed gradient-recalled echo (GRE) compared with conventional spin echo T1-weighted (T1W) sequences in direct shoulder MR arthrography for evaluating labral tears.

MATERIALS AND METHODS

Three musculoskeletal radiologists retrospectively reviewed MR arthrograms performed over a 12-month period for which surgical correlation was available. Of 180 serial arthrograms, 31 patients had surgery with a mean of 48 days following imaging. Paired coronal oblique and axial T1W or GRE sequences were analyzed by consensus for labral tear (coronal oblique two-dimensional multi-echo data image combination, 2D MEDIC; and axial three-dimensional double-echo steady-state, 3D DESS; Siemens MAGNETOM Sonata 1.5-T MR system). Interpretations were correlated with operative reports.

RESULTS

Of 31 shoulders, 25 had labral tears at surgery. The GRE sequences depicted labral tears in 22, while T1W images depicted tears in 16 (sensitivity 88% versus 64%; p<0.05). Subdividing the labrum, GRE was significantly more sensitive for the posterior labrum (75% versus 25%; p<0.05) with a trend toward greater sensitivity at the anterior labrum (78% versus 56%; p=0.157) but not significantly different for the superior labrum (50% versus 57%; p>0.7). Specificities were somewhat lower for GRE.

CONCLUSION

Thin section GRE sequences are more sensitive than T1W for the detection of anterior and posterior labral tears. As the specificity of GRE was lower, it should be considered as an adjunctive imaging sequence that may improve depiction of labral tears, particularly smaller tears, in routine MR arthrography protocols.

Imaging in shoulder disorders

Clinical assessment of the patient with shoulder symptoms can usually localize the cause to one of a few syndromes, each associated with specific imaging questions. MRI is used as the primary form of investigation for recurrent dislocation, SLAP lesions and PSI, as well as articular cartilage, synovial disease, tumours and infection. Ultrasound plays the leading role in impingement, acromioclavicular disease, dynamic assessment and guided therapy. Both techniques are reported to play a role in adhesive capsulitis. In our hospital, approximately four times as many shoulder ultrasound examinations as shoulder MRI are carried out, but elsewhere these proportions will vary according to the prevalence of clinical syndromes in the population being treated.