MRI Anatomy of the Shoulder

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

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

4
Articular surfaces
The shoulder joint is composed of 3 bones and
five articulations. Bones Scapula Humerus Cl
avicle 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
• Between joint capsule and
• deltoid muscle
• Subcoracoid
• Between joint capsule and
• coracoid process
• Coracobrachial
• Between subscapularis and
• coracobrachialis
• Subacromial
• Between joint capsule and
• acromion
• Subscapular bursa
• Between joint capsule and
• 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

8
Ligaments

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

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Superior glenohumeral ligament
Coracohumeral ligament
Long head biceps tendon
10
SGHL Sagittal
11
SGHL Axial
12
Middle glenohumeral ligamant
13
MGHL Sagittal
14
MGHL Axial
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Inferior glenohumeral ligament
Axillary recess Subacromial-subdeltoid bursa
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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.

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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.

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.

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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. ?
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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. ?
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.
24
Buford complex
Congenital labral variant 2 Features?Anterosuper
ior 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.
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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.
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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.

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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).
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

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Axial
Supraspinatus muscle Relatively small
muscle Runs from the supraspinatous fossa of
scapula to the greater tubercle of the humerus
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
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
SITS inlcudes Subscapularis which inserts onto
the lesser tubercle of the humerus
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Axial
Pec major
Deltoid anterior
Pec minor
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

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Tip

• Coronal oblique MRI
• Supraspinatus fibres run horizontally
• Infraspinatus fibres have a slightly oblique
  orientation

36
Subscapularis
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
Deltoid as one
Coracobrachialis
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
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Teres minor(SIT)
Origin Superior part of lateral border of
scapula Insertion Inferior facet of greater
tuberosity of humerus
39
Axial
The short head of the biceps originates from the
coracoid process (2)
The long head originates from the supraglenoid
tubercle (3)
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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
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.
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Coronal Long head
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• Coronal anatomy

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Coronal
Trapezius
Posterior humeral circumflex artery and axillary
nerve
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
(Teres minor)
47
Coronal
Infraspinatus
Teres minor
Triceps
Teres major
48
Coronal
Supraspinatus
Subscapularis
Teres major
49
Sagittal Anatomy
50
Sagittal
P
A
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
Post
Co
52
Sagittal SIT
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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

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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 patients hand may help
  maintain the position

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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

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 11000 adrenaline
• Syringe connected to connecting catheter(line)

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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

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.

64
Alternative 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).

65
Other techniques

• Inject only water, no gadolinium
• 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

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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)

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).
?In that position the 3-6 o'clock region is
imaged perpendicular. ?
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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

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• 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.

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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.
• www.radiologyassistant.nl Radiology Assistant MR
  Shoulder Part I.
• http//musculoskeletal-radiology.blogspot.com/2006
  /09/glenohumoral-ligaments.html
• Jacobson et al. Aids to Successful Shoulder
  Arthrography Performed with a Fluoroscopically
  Guided Anterior Approach. Radiographics. 2003
  23373379
• Beltran et al. MR Arthrography of the Shoulder
  Variants and Pitfalls. Radiographics. 1997
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