1. MRI Anatomy of the Shoulder

2. Functional Anatomy Glenohumeral joint is a ball and socket synovial.
Glenoid cavity inherently unstable.
Stability provided by:
Static constraints
3 glenohumeral ligaments
glenoid labrum
joint capsule
Dynamic constraints,
- rotator cuff muscles
counteract the action of the deltoid by preventing the head of the humerus from moving superiorly when the arm is raised
An imbalance between the deltoid and the rotator cuff muscle strength may result in excessive superior movement of the humeral head, causing impingement of subacromial structures.

3. The glenohumeral joint has the following supporting structures:
Superiorly
Coraco-acromial arch
Long head of the biceps tendon
Tendon of supraspinatus muscle
Anteriorly
Anterior labrum
3 Glenohumeral ligaments
SGHL, MGHL, IGHL
(anterior band)
Subscapularis tendon
Posteriorly
Posterior labrum
Posterior band of the IGHL
Infraspinatus tendon
Teres minor tendon
Lateral view
Coracoacromial arch contains: 1. Coracoacromial ligament 2. Acromion process 3. Coracoid process

4. Articular surfaces
The shoulder joint is composed of 3 bones and five articulations.
Bones:
Scapula
Humerus
Clavicle
Articulations:
Glenohumeral joint
Acromio-clavicular joint
Scapulothoracic joint
Sternoclavicular joint
Coracoclavicular joint

5. Joint capsule Attached proximally to the glenoid labrum
Attached distally to the anatomical neck of the humerus
Capsule is thickened anteriorly by glenohumeral ligaments
Herniation of synovial membrane through an anterior defect in capsule & glenohumeral ligaments forms the subscapular bursa

6. Bursae Subdeltoid Subcoracoid Coracobrachial Subacromial
Between joint capsule and
deltoid muscle
Subcoracoid
coracoid process
Coracobrachial
Between subscapularis and
coracobrachialis
Subacromial
acromion
Subscapular bursa
subscapularis tendon

7. Rotator Interval
Triangular space between the supraspinatus and subscapularis tendons
Contains long head of biceps and SGHL
Acts to prevent anterior dislocation of the shoulder
Picture: rotator cuff interval in sagittal plane, with superior capsular complex (in green), subscapularis tendon (SSC), superior glenohumeral ligament (SGHL), and long portion of biceps tendon (LPB) and passing beneath deep fibers of supraspinatus (SSP).

8. Ligaments 3 glenohumeral ligaments Coracohumeral ligament
Superior
Middle
Inferior
Coracohumeral ligament
Transverse humeral ligament
Between greater and lesser tuberosities of humerus, maintains long head of biceps in bicipital groove

9. Superior glenohumeral ligament
Coracohumeral ligament
Long head biceps tendon
A fat suppressed axial T1-weighted MR arthrogram image demonstrates the superior glenohumeral ligament (arrow), the glenoid labrum (arrowhead), the long head biceps tendon (short arrow), and the coracohumeral ligament (curved arrow
Superior glenohumeral ligament
two sites of origin
supraglenoid tubercle just anterior to long head of biceps origin on superior labrum + the base of coracoid
- inserts superior to lesser tuberosity

10. SGHL Sagittal
2 Origins: just anterior to long head of biceps AND base of coracoid
Insertion: lesser tuberosity of humeral head

11. SGHL Axial

12. Middle glenohumeral ligamant
fat suppressed oblique sagittal T1-weighted MR arthrogram image demonstrating the middle glenohumeral ligament (arrow)
Arises from the anatomic neck and inserts into the mid-anterior labrum
Middle part of the ligament is seen just posterior to subscapularis
Shows maximum variation in size and shape among all three glenohumeral ligaments

13. MGHL Sagittal Originate on the anatomic neck
Inserts in mid anterior labrum

14. MGHL Axial

15. Inferior glenohumeral ligament
A fat suppressed oblique sagittal T1-weighted MR arthrogram image, demonstrating the anterior and posterior bands of the inferior glenohumeral ligament (arrows)
Most important glenohumeral ligament, Main static stabilizer of the shoulder in the abducted or functional position
Attaches to inferior glenoid labrum
Has two band like thickenings, anterior and one posterior
Has a lax part, axillary pouch, in between
Axillary recess
Subacromial-subdeltoid bursa

16. Glenoid labrum
The glenoid labrum is a fibrocartilaginous structure that attaches to the glenoid rim and is about 4 mm wide.
increases the superior-inferior diameter of the glenoid by 75% and the anterior-posterior diameter by 50%
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.

17. Labral anatomy: Axial
The normal labrum demonstrates low signal intensity on all pulse sequences, due to the lack of mobile protons in this dense fibrocartilage.
On cross sectional imaging, the normal labrum is most commonly triangular, but can also be round, cleaved, notched, flat, or absent.

18. Labral Anatomy: Coronal
A fat suppressed oblique coronal T2-weighted MR image demonstrates homogeneously low signal intensity in the normal superior labrum.

19. Labral variants
These normal variants are all located in the 11-3 o'clock position.
There are many labral variants

20. It is important to recognise these variants, because they can mimick a SLAP tear.
These normal variants will usually not mimick a Bankart-lesion, since these are located at the 3-6 o'clock position, where these normal variants do not occur.
Labral tears can occur at 3-6 o’clock

21. Sublabral recess
Synovial recess between the superior labrum and the glenoid rim created by the attachment of the biceps tendon on the supraglenoid tubercle. Because of this recess, the labrum does not attach to the glenoid rim at the 12 o'clock position.
There are 3 types of attachments of the superior labrum:
Type I No recess between glenoid cartilage and labrum
Type II Small recess.
Type III Large sublabral recess. 

This sublabral recess can be difficult to distinguish from a SLAP-tear or a sublabral foramen.

22. Sublabral Foramen
An unattached anterosuperior labrum at the 1-3 o'clock position.
Anterior to biceps tendon

It is seen in 11% of individuals.

Not to be confused with a sublabral recess or SLAP-tear, which are also located in this region. 

Sublabral recess located at 12 o’clock where biceos tendon inserts, does not extend to the 1-3 o’clock position
SLAP tears can extend to the 1-3 o’clock poisition but the attachment of the biceps tendon to the superior labrum should be involved

23. Differences between an sublabral recess and a SLAP-tear:

A recess more than 3-5 mm is always abnormal and should be regarded as a SLAP-tear.
Shows how difficult it can be to tell the difference

24. Buford complex Congenital labral variant
2 Features:
Anterosuperior labrum is absent in the 1-3 o'clock position
Middle glenohumeral ligament is usually thickened.

It is present in approximately 1.5% of individuals.
Images show the absent anterosuperior labrum and thickened middle ghl

25. Os Acromiale
On MR an os acromiale is best seen on superior axial images.
Results from failure of one of the acromial ossification centers to fuse.

5% of the population.

Usually an incidental finding, regarded as a normal variant.

May cause impingement because if it is unstable, it may be pulled inferiorly during abduction by the deltoid, which attaches here.

26. Acromion: 3 types
Type 1 is a flat undersurface with a high angle of inclination.
Type 2 is a curved arc and decreased angle of inclination.
Type 3 is hooked anteriorly with a decreased angle of inclination.

27. Axial Anatomy

28. The axillary artery begins at the lateral border of the first rib as a continuation of the subclavian artery. It changes its name to brachial artery at lower inferior border of the teres major muscle (8).
MRI of the shoulder. Axial T1-weighted view. Image 1 1, Axillary vein and artery. 2, Clavicle. 3, Acromioclavicular joint. 4, Acromion. 5, Supraspinatus muscle

29. Axial
Deltoid
Anterior clavicular fibres – arise from superior anterior aspect of lateral clavicle
Lateral acromial fibres – arise from superior aspect of acromion process
Posterior fibres – arise from posterior border of spine of scapula
1, Axillary vein and artery. 2, Deltoid muscle. 3, Coracoid process. 4, Supraspinatus muscle. 5, Acromion

30. Axial Supraspinatus muscle Relatively small muscle
Runs from the supraspinatous fossa of scapula to the greater tubercle of the humerus
1, Pectoralis major muscle. 2, Axillary vein and artery. 3, Coracoid process. 4, Deltoid muscle. 5, Supraspinatus muscle. 6, Acromion. 7, Scapula. 8, Subscapularis muscle

31. Axis of supraspinatous tendon
The supraspinatus tendon is the most important structure of the rotator cuff and subject to tendinopathy and tears.

Tears of the supraspinatus tendon are best seen on coronal oblique and ABER-series.

In many cases the axis of the supraspinatus tendon (arrowheads) is rotated more anteriorly compared to the axis of the muscle (yellow arrow).

When you plan the coronal oblique series, it is best to focus on the axis of the supraspinatus tendon.

32. Sagittal Supraspinatus Infraspinatus Teres minor
The attachments of the 3 rotator cuff muscles that insert onto the greater tubercle of the humerus can be abbreviated SIT when viewed from superior to inferior:
Supraspinatus
Infraspinatus
Teres minor
Sagittal
post
post
2, Subscapularis tendon. 3, Biceps tendon (long head). 4, Supraspinatus muscle. 5, Acromion. 6, Infraspinatus muscle. 7, Deltoid muscle. 8, Teres minor muscle.
Greater tubercle - anterolateral
SITS inlcudes Subscapularis which inserts onto the lesser tubercle of the humerus

33. Axial Pec major Deltoid anterior Pec minor
Now going to look at infraspinatus and subscapularis1, Pectoralis major muscle. 2, Deltoid muscle (anterior). 3, Coracoid process. 4, Humeral head. 5, Glenoid. 6, Supraspinatus muscle. 7, Scapula. 8, Deltoid muscle. 9, Infraspinatus muscle. 10, Subscapularis muscle. 11, Axillary vein and artery. 12, Pectoralis minor muscle.
Supraspinatus inserts most superiorly to greater tuberosity humeral head
Subscapularis
Infraspinatus
Deltoid posterior

34. Infraspinatus (SIT)
Thick triangular muscle which occupies most of the infraspinatous fossa
Attaches medially to the infraspinatus fossa and laterally to the middle facet of the greater tubercle of the humerus
Trapezoidal insertion of infraspinatus onto humerus is much larger than the insertion of the supraspinatus
Coronal views of the 3 facets of the greater tubercle of the humerus

35. *Tip* Coronal oblique MRI Supraspinatus – fibres run horizontally
Infraspinatus – fibres have a slightly oblique orientation
7 – supraspinatus
2 - infraspinatus

36. Subscapularis Subscapular fossa = anterior
Large triangular muscle which fills the subscapular fossa
Inserts onto the lesser tubercle of the humerus
Subscapular fossa = anterior
Infraspinatous fossa = posterior
ant
post

37. Axial Coracobrachialis Deltoid as one
Coracobrachialis is the smallest of the three muscles that attach to the coracoid process. The other 2 muscles are pectoralis minor and biceps brachii. Distal insertion upper medial aspect of arm
Teres minor
1, Pectoralis major muscle. 2, Biceps tendon (long head). 3, Deltoid muscle (anterior). 4, Humeral head. 5, Glenoid. 6, Teres minor muscle. 7, Deltoid muscle. 8, Infraspinatus muscle. 9, Subscapularis muscle. 10, Coracobrachialis muscle. 11, Pectoralis minor muscle.
Teres minor most inferior of the SIT muscles

38. Teres minor (SIT) Origin: Superior part of lateral border of scapula
Insertion:
Inferior facet of greater tuberosity of humerus
Coronal view: 2 – infraspinatus, 4 – teres minor

39. Axial
The short head of the biceps originates from the coracoid process (2)
1, Pectoralis major muscle. 2, Biceps tendon (short head). 3, Biceps tendon (long head). 4, Deltoid muscle (anterior). 5, Humeral head. 6, Glenoid. 7, Teres minor muscle. 8, Deltoid muscle. 9, Infraspinatus muscle. 10, Subscapularis muscle. 11, Coracobrachialis muscle. 12, Pectoralis minor muscle.
The long head originates from the supraglenoid tubercle (3)

40. Tendon of long head passes down along the intertubercular/bicipital groove of the humerus into the joint capsule
Both heads arise on the scapula and join to form a single muscle belly which is attached to the upper forearm.
Long head forms biceps-labral complex with superior glenohumeral ligament
Biceps labral complex: 1. long head biceps 2. superior labrum 3. SGHL
When the humerus is in motion, the tendon of the long head is held firmly in place in the bicipital groove by the greater and lesser tubercles and the overlying transverse humeral ligament.

41. Coronal
Long head

44. Coronal anatomy

45. Coronal
Trapezius
Posterior humeral circumflex artery and axillary nerve
1, Trapezius muscle. 2, Acromion. 3, Deltoid muscle. 4, Humeral head. 5, Infraspinatus muscle. 6, Teres minor muscle. 7, Teres major muscle. 8, Tricipital muscle. Arrow, Posterior humeral circumflex artery and axillary nerve.
Going to look at teres major
extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to spine of the scapula
Teres major
Triceps

46. Teres major
It arises from the dorsal surface of the inferior angle of the scapula
Inserts onto intertubercular sulcus of humerus
1, Trapezius muscle. 2, Acromioclavicular joint. 3, Acromion. 4, Deltoid muscle. 5, Humeral head. 6, Supraspinatus muscle. 7, Spine of the scapula. 8, Infraspinatus muscle. 9, Scapula. 10, Subscapularis muscle. 11, Teres major muscle.
(Teres minor)

47. Coronal Infraspinatus Teres minor Triceps Teres major
Nice picture of the insertions of infraspinatus (3) and teres minor (7) onto the greater tubercle of the humerus
Teres major

48. Coronal Supraspinatus Subscapularis Teres major
Been over these muscles
1, Trapezius muscle. 2, Clavicle. 3, Acromioclavicular joint. 4, Acromion. 5, Deltoid muscle. 6, Greater tuberosity. 7, Humeral head. 8, Supraspinatus muscle. 9, Glenoid. 10, Subscapularis muscle. 11, Teres major muscle.
Subscapularis
Teres major

49. Sagittal Anatomy

50. Sagittal P A 2 patterns on sagittal: SIT (posterior tendon insertions)
CCA (bonesof AC joint from ant to post)
1, Coracobrachialis. 2, Subscapularis tendon. 3, Humeral head. 4, Coracoid process. 5, Deltoid muscle. 6, Biceps tendon (long head). 7, Clavicle. 8, Acromioclavicular joint. 9, Supraspinatus muscle. 10, Acromion. 11, Infraspinatus muscle. 12, Deltoid muscle. 13, Teres minor muscle.

51. Acromioclavicular joint
Axial: Clavicle medial
Acromion lateral
Sagittal: Acromion posterior
Coracoid anterior
The undersurface of the acromion should align with the undersurface of the clavicle Cl Ac
Ant Co
Post

52. Sagittal: SIT
SIT 4, 6 8
2, Subscapularis tendon. 3, Biceps tendon (long head). 4, Supraspinatus muscle. 5, Acromion. 6, Infraspinatus muscle. 7, Deltoid muscle. 8, Teres minor muscle.

53. 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.

54. 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.

55. 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

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

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

58. 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

59. Patient Positioning
Supine position creates oblique orientation of glenoid surface.
Posterior glenoid overlaps humeral head on AP
Anterior glenoid lies medial to 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
Arthrogram – axial MRI. contrast material distending the glenohumeral joint and long head of the biceps brachii tendon sheath (arrowhead). Note the oblique orientation of the glenoid articular surface (curved arrow) and medial location of the anterior labrum (straight arrow) relative to the humerus.

60. Technique Determine skin entry site using fluoroscopy
Just lateral to the medial cortex of the humeral head (never medial)
At junction of middle and lower third of humeral head
Ideally central in fluoroscopic image
Locally anaesthetise skin and subcutaneous tissue
AP fluoroscopic image demonstrates a spinal needle (arrow) centered over the needle hub, just lateral to the medial cortex of the humeral head. Note the sclerotic line, which approximates the lateral border of the glenohumeral joint (arrowheads) – anatomic neck.

61. Technique
Prepare contrast whilst allowing local anaesthetic to take effect (can also be done before procedure starts)
Bloem protocol:
20 ml syringe
10 ml sterile water
5 ml iodine based non-ionic LOCM (eg.Ultravist, Omnipaque)
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)

62. 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 either intra-articular or bursal location
Don’t use gadolimium for test injection to avoid inadvertant injection of Gad outside the joint leading to misinterpretation as rotator cuff/capsular injury

63. Technique
Inject iodinated contrast to distinguish between intra-articular and bursal location
Intra-articular contrast will collect in glenohumeral joint space
If intra-articular position is confirmed, continue with proper contrast injection
Usually inject 14 – 16 ml of contrast, depending on patient and pathology.
A patient with chronic shoulder subluxation may require more volume, whereas a patient with adhesive capsulitis requires less.
has been shown that exercise after shoulder arthrography has no beneficial or detrimental effect on MR image quality or on the depiction of rotator cuff or labral tears

64. Alternative: Posterior approach
Can also do ultrasound guided appraoch
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).

65. Other techniques Inject only water, no gadolinium Indirect arthrogram
Achieves effect of distension
Need to use T2 sequences
Disadvantage:
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
Disadvantages:
Joint not distended
Extra-articular structures will also enhance

66. 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 GHL’s)

67. ABER view
Labral tears
The abduction external rotation (ABER) view is excellent for assessing the anteroinferior labrum at the 3-6 o'clock position, where most labral tears are located.

Inferior glenohumeral ligament stretched resulting in tension on the anteroinferior labrum, allowing intra-articular contrast to get between the labral tear and the glenoid.
Rotator cuff tears
Very useful for both partial- and full-thickness tears of the rotator cuff. 
Releases tension on the cuff relative to the normal coronal view obtained with the arm in adduction. 

Images in the ABER position are obtained in an axial way 45º off the coronal plane (figure).
Notice red arrow indicating a small Perthes-lesion, which was not seen on the standard axial views.

68. 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

69. 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.

70. References
Ryan S, McNicholas M, Eustace S. Anatomy for diagnostic imaging.
CT and MR Arthrography of the Normal and Pathologic Anterosuperior Labrum and Labral-Bicipital Complex. October 2000 RadioGraphics, 20, S67-S81.
Radiology Assistant: MR Shoulder Part I.
Jacobson et al. Aids to Successful Shoulder Arthrography Performed with a Fluoroscopically Guided Anterior Approach. Radiographics. 2003; 23:373–379
Beltran et al. MR Arthrography of the Shoulder: Variants and Pitfalls. Radiographics. 1997; 17: