MR arthrography of the shoulder: Techniques and role in diagnosis of rotator cuff and labral pathology Werner Harmse July 2011

MR shoulder arthrogram Technique whereby injection of contrast media into the joint allows for evaluation of capsule and internal joint structures. Originally performed using plain radiography. Now injection of gadolinium allows MR arthrography. CT arthrograms can also be performed.

Technique Fluoroscopically guided anterior approach is most widely performed. Perform routine preparation Correct patient Correct side No iodine allergies Explain procedure to patient. ? Informed consent Confirm indication

Indications Assessment of integrity of rotator cuff Evaluation of shoulder instability Diagnosis of labral pathology Diagnosis of adhesive capsulitis

Technique Sterile procedure Fluoroscopically guided Obtain control images of shoulder Patient supine, AP view Arm in external and internal rotation Angle tube to view acromion in profile – clear visualisation of sub-acromial space Evaluate for calcium deposition in tendons

Positioning Supine position creates oblique orientation of glenoid surface. Posterior glenoid overlaps humeral head Anterior glenoid is however medial of humeral head. Thus needle directed AP at humeral head will not injure anterior labrum External rotation exposes a larger articular surface anteriorly Placing a sandbag in the patient’s hand may help maintain the position

Technique Determine skin entry site Just lateral to the medial cortex of the humeral head (never medial) At junction of middle and lower third Ideally central in fluoroscopic image Locally anaethetise skin and sub-cutaneous tissue

Technique Prepare contrast whilst allowing local anaestethic to take effect (can also be done before procedure starts) Our protocol: 20 ml syringe 10 ml sterile water 5 ml iodine based non-ionic LOCM (eg.Ultravist) 5 ml lignocaine 0.1 ml gadolinium Other: Test injection with 1-2 ml of lignocaine Contrast: 10 ml saline, 10 ml Iodine LOCM, 0.1 ml gadolinium, 0.3 ml 1:1000 adrenaline Syringe connected to connecting catheter(line)

Technique Advance needle (usually 20G spinal needle with stylet) in direct AP direction posteriorly. Continue until contact with humeral head. Consider test injection with lignocaine. Should only meet low resistance when in joint space If high resistance – possibly in hyaline cartilige – carefully manipulate needle by rotation and minimal retraction (few mm) Loss of resistance indicates intra-articular or bursal location

Technique Inject iodinated contrast to distinguish between intra-articular and bursal location Intra-articular contrast will collect in gleno-humeral joint space If intra-articular position is confirmed – continue with proper contrast injection Usually inject between 14 – 16 ml of contrast, depending on patient and pathology.

Advantages Joint distension, outlining intra-articular structures Improved detection of tears, including articular surface partial tears Demonstration of communication between joint and extra-articular abnormalities eg. Paralabral cysts and bursae.

Disadvantages and pitfalls Risks assoc with needle placement into joint: infection, haemorrhage, synovial reaction. Avoid oblique position – glenoid in profile – aiming for joint space places the labrum at risk Correct needle positioning is essential Extra articular contrast can complicate findings on MR and simulate tears

Posterior approach When suspecting anterior pathology. Avoids the interpretative difficulties that may be associated with anterior extracapsular contrast extravasation Aim for the inferomedial quadrant of humeral head within boundary of anatomic neck (interrupted line).

Other techniques Advance needle with stylet removed and lignocaine placed in needle hub – drop in fluid level indicates intra-articular position Internal rotation when needle against humeral head – facilitates intra-articular placement Ultrasound guided approach

MR technique Three plane T1 with fat sat T2 with fat sat axial and coronal oblique (Consider Ax GRE to evaluate for calcification) Sagittal oblique T1/PD without fat suppression Some protocols suggest pre contrast T2 sequences. Detection of intra-substance and bursal surface tears. Pre-existing fluid collections and cysts Coronal oblique parallel to supraspinatus tendon (not muscle) Sagittal oblique perpendicular to glenoid surface (ABER – Abduction and External rotation sometimes used for evaluation of anterior and inferior GHLs)

Other techniques Inject only water, no gadolinium Indirect arthrogram Achieves effect of distension Need to use T2 sequences Difficult to distinguish between small full thickness and partial tears Indirect arthrogram 1 mmol/kg Gd IV Exercise joint for 5 to 5 minutes Gd passes into joint space Can perform T1 images Joint however not distended Beware – extra-articular structures will also enhance

Rotator cuff tears Arthrography improves detection of tears as the joint is being distended and contrast forced into small defects. T1 (quicker) sequences with improved SNR can be used Diagnoses full thickness tears and articular surface partial thickness tear Not of value in intra-substance or bursal surface partial thickness tears

Full-thickness tear will demonstrate the gadolinium contrast solution extending first through a defect in the cuff and then into the subacromial-subdeltoid bursa. Articular-surface partial-thickness tears show a focal extension of the contrast solution into the substance of the tendon. Fat suppression is necessary as peribursal fat may mimic contrast.

Full thickness rotator cuff tear with contrast extending through the supraspinatus tendon into the sub-acromial sub-deltoid bursa.

Full thickness tear (A) T1-weighted image with fat saturation and (B) T2-weighted image with fat saturation depict contrast within the joint (yellow arrows). Note the presence of contrast within the subacromial-subdeltoid bursa (red arrows) due to the full-thickness tear within the distal supraspinatus tendon (green arrow)

Partial thickness tear articular surface A) T1-weighted image with fat saturation and (B) T2-weighted image with fat saturation depict a partial-thickness articular surface tear (red arrows) of the supraspinatus tendon. Contrast enters the tear, and the tear is seen as a hyperintense area on both pulse sequences. Although there is a small amount of hyperintense fluid in the subacromial-subdeltoid bursa on the T2-weighted image, no contrast enters the bursa.

Intra substance tear (A) T1-weighted image with fat saturation and (B) T2-weighted image with fat saturation depict contrast within the joint (yellow arrows). Note the intrasubstance tear (red arrow) of the distal supraspinatus tendon, seen as a hyperintense zone on the T2-weighted image. Note that contrast does not enter this area since the tear does not communicate with the articular surface of the tendon. There is hyperintense fluid in the subacromial-subdeltoid bursa on the T2-weighted image, but this area is hypointense on the T1-weighted image. This fluid should not be confused with contrast in the bursa.

Subscapularis tendon Subscapularis tendon tears are common. They can result from acute trauma on an adducted arm in hyperextension or in external rotation. They can result from an anterior shoulder dislocation, they can be associated with massive tears of the rotator cuff and with biceps tendon dislocations, or they can result from subcoracoid impingement. Tears of the subscapularis tendon are best evaluated on axial MRIs, where the entire length of the tendon is evident or on sagittal images. The tears are seen best on T2W images or on T1W images after intra-articular gadolinium injection. Tears may be seen as tendon discontinuity, contrast media entering into the tendon substance, intrasubstance abnormal tendon signal, abnormal caliber of the tendon, and abnormal position of the tendon. Other helpful accessory signs are the leakage of intra-articular contrast material under the insertion of the subscapularis tendon onto the lesser tuberosity and fatty atrophy of the subscapularis muscle, usually localized at the cranial aspect of the muscle and seen as high signal intensity streaks on T1W images. Abnormalities in the course of the long head of the biceps tendon (subluxation or dislocation) usually are associated with subscapularis tendon tears. They often extend into the subscapularis muscle.

A, T1 fat-suppressed axial shoulder MR arthrogram A, T1 fat-suppressed axial shoulder MR arthrogram. The bicipital groove is empty. The biceps tendon (arrowhead) is located over the anterior glenohumeral joint and posterior to the subscapularis tendon (arrow), which has been avulsed from its attachment to the lesser tuberosity of the humerus. B, T1 fat-suppressed coronal oblique shoulder MR arthrogram. The biceps tendon (arrowheads) is dislocated medially overlying the shoulder joint.

Labral anatomy and pathology The glenoid labrum is a fibrocartilaginous structure that attaches to the glenoid rim and is about 4 mm wide. Anteriorly, the glenoid labrum blends with the anterior band of the inferior glenohumeral ligament. Superiorly, it blends with the biceps tendon and the superior glenohumeral ligament. It is usually rounded or triangular on cross-sectional images.

Variants Sublabral recess 12’o clock

Sub-labral foramen 2’o clock position. Anterior to biceps tendon

Buford complex Cord-like thickening of middle glenohumeral ligament with absence of anterior superior labrum.

Anterior labrum

Bankart lesion The Bankart lesion is the most common injury following anterior dislocation of the glenohumeral joint. It is a detachment of the anteroinferior labrum (with or without labral tears) from the glenoid with a tear of the anterior scapular periosteum The Bankart lesion may or may not be associated with a fracture of the anteroinferior glenoid.

Bankart lesions A, T1 fat-suppressed axial shoulder MR arthrogram. The anteroinferior labrum is detached from the glenoid (arrowhead) and is irregular in shape and high signal from tears. There is no linear periosteum seen attached to the labrum because it has been torn. The flat posterolateral humerus in the lower portion of the joint is normal and not from a Hill-Sachs impaction fracture. B, T1 fat-suppressed axial shoulder MR arthrogram (different patient than in A). The anteroinferior labrum is absent from its normal position adjacent to the glenoid; it has been completely detached and torn free of the scapular periosteum, coming to rest in the medial aspect of the joint (open arrow).

ALPSA [anterior labroligamentous periosteal sleeve avulsion] Variant of Bankart. Periosteum stripped from scapula, not torn. Potential of healing if reduced

GLAD (Gleno-labral articular disruption) lesion GLAD refers to a nondisplaced anteroinferior labral tear with an associated chondral injury This lesion results more from an impaction type of injury, rather than a shearing injury, as occurs with Bankart lesions. The labrum remains attached to the anterior scapular periosteum, distinguishing this from a Bankart lesion, which has a torn periosteum. On MR arthrography, contrast material extends into the cartilaginous defect. These patients complain of pain rather than instability.

Anterior labral lesions

SLAP (Superior Labrum Anterior to Posterior) lesions

SLAP

SLAP

The inferior glenohumeral ligament is the ligament most frequently affected with instability. It may be affected at its labral or its humeral attachment. Avulsion of the inferior glenohumeral ligament from the humerus, called a HAGL lesion (humeral avulsion of the glenohumeral ligament), may result from shoulder dislocation. It often is associated with a tear of the subscapularis tendon. HAGL lesions can be identified on axial, coronal, or sagittal MRIs The inferior glenohumeral ligament may show high signal intensity on T2 images, and may show morphologic disruption at its insertion on the anatomic neck of the humerus and wavy contours of the residual ligament, and the ligament may be displaced inferiorly. The diagnosis also can be inferred on MR arthrography when extravasation of contrast material from the joint occurs in the region of the ligament insertion on the humerus.

HAGL A, T1 fat-suppressed coronal oblique shoulder MR arthrogram. The anterior limb of the inferior glenohumeral ligament (arrowhead) is detached from the humerus (arrow) in this patient with a previous anterior dislocation. There also is a bucket-handle superior labral anterior and posterior (SLAP) tear of the superior labrum. B, T1 fat-suppressed sagittal oblique shoulder MR arthrogram (different patient than in A). The anterior limb of the inferior glenohumeral ligament (open arrow) is avulsed from its humeral attachment, is thickened, and is drooping inferiorly (compare with normal posteroinferior glenohumeral ligament [arrowhead]). The patient had several prior dislocations.

Indirect MR arhtrogram Anterior glenoid labrum tear Complete tear of supraspinatus

Acronyms and Eponyms Related to the Shoulder ALPSA: Anterior labroligamentous periosteal sleeve avulsion. A variation of the Bankart lesion with injury to the anteroinferior labrum, but the anterior scapular periosteum is intact. Bankart lesion: Tear of the anteroinferior glenoid labrum with torn anterior scapular periosteum. May have an associated fracture of the anteroinferior glenoid rim. Bennett lesion: Mineralization of the posterior band of the inferior glenohumeral ligament and posterior capsule from chronic traction forces. HAGL lesion: Humeral avulsion of the glenohumeral ligament occurs from shoulder dislocation with avulsion of the inferior glenohumeral ligament from the anatomic neck of the humerus. BHAGL lesion: Bony HAGL lesion. Buford complex: Congenital absence of the anterosuperior glenoid labrum associated with a thickened middle glenohumeral ligament. GLAD lesion: Glenolabral articular disruption is a tear of the anteroinferior labrum with a glenoid chondral defect. Hill-Sachs lesion: Impaction fracture of the posterolateral aspect of the humeral head from anterior shoulder dislocation. SLAP lesion: Superior labrum tear propagating anterior and posterior to the biceps anchor. DYN: Drives you nuts.

References Jacobson et al. Aids to Successful Shoulder Arthrography Performed with a Fluoroscopically Guided Anterior Approach. Radiographics. 2003; 23:373–379 Angelica et al. Arthrography of the shoulder: A modified ultrasound guided technique of joint injection at the rotator interval European Journal of Radiology. 2009 January. Beltran et al. MR Arthrography of the Shoulder: Variants and Pitfalls. Radiographics. 1997; 17:1403-14 12 De Maeseneer et al. CT and MR Arthrography of the Normal and Pathologic Anterosuperior Labrum and Labral-Bicipital Complex. Radiographics. 2000; 20:S67–S81 Helms, Major, Anderson. Muskuloskletal MRI. 2nd ed. Chapter 10 Stoller D. MRI in orthopaedics and sports medicine. Volume II. Chapter 8. Tuite et al. Rotator cuff injury MRI. Medscape Reference URL: http://emedicine.medscape.com/article/401714-overview Thank you