MRI of Shoulder Flashcards
rotator cuff is composed of the tendons of four muscles that converge on the greater and lesser tuberosities of the humerus, namely:
supraspinatus, infraspinatus, subscapularis, teres minor
of the rotator cuff muscles, this most commonly causes clinically significant problems and is the one that is most commonly surgically treated
supraspinatus
lies just superior to the scapula and inferior to the AC joint and acromion. it inserts into the greater tuberosity of the humerus
supraspinatus
2 to 3 centimeters proximal to the insertion of supraspinatus is a section of the tendon called the
“critical zone”
critical zone is reported to have ____ and is therfore less likely to heal following trauma
decreased vascularity
critical zone of the supraspinatus tendon is a common location for
rotator cuff tears
a fibricartilaginous ring that surounds the periphery of the bony glenoid of the scapula
glenoid labrum
serves as an attachment site for the capsule and broadens the base of the glenohumeral joint to allow increased stability
glenoid labrum
tears and detachment of the glenoid labrum most commonly occur from and result in
dislocations or instability of the humerus
one of the most common procedurs for shoulder pain whereby the coracoacromial ligament was cut, the anterolateral portion of the acromion was removed, and AC joint osteophytes were resected
Coracoacromial arch decompression
most likely source of most rotator cuff problems
intrinsic degeneration
treating intrinsic degeneration requires
debriding the abnormal tissue and repairing the cuff
rotator cuff is best seen on what view
oblique coronal images that are aligned parallel to the supraspinatus muscle and on oblique sagittal images
primary sequence for imaging the rotator cuff
FSE T2W oblique coronal sequence with slice thickness no greater than 5mm and 3 mm
MR arthrogram is typically performed by injecting how many cc of saline or gadolinium
10 to 15 cc
useful landmark for noting the anterior portion of supraspinatus tendon is the ____, with the anterior most fibers of the supraspinatus found immediately posterolateral to the groove
biccipital groove
normal supraspinatus tendon is said to be of what signal
uniformly low in signal on all pulse sequences
if the signal in the tendon gets brighter on the T2W, it is abnormal and represents
tendinosis or tendinopathy or a partial thickness tear
vast majority of partial tears occur on what side
articular side
partial tear that occurs at the insetion of the fibers of the cuff onto the greater tuberosity
rim-rent-tear
bone impaction on the posterosuperior aspect of the humeral head and can be seen in patients with anterior instability of the glenohumeral joint. this is called
Hill-Sachs lesion
A Hill-Sachs lesion almost always indicated that the anteroinferior labrum will be torn or detached, which is called
Bankart lesion
normal labrum appears as
triangular shaped low signal structure on axial image
what is larger, anterior or posterior labrum
anterior
superior labrum is evaluated in what view
oblique coronal views
if joint fluid extends between the bony glenoid and the base of the labrum, a _____ is present
detached labrum
often seen in throwing athletes secondary to the pull of long head of biceps that insert on the superior labrum
superior labral tears, called superior labrum anterior to posterior lesions (SLAP)
normal variant: an opening beneath the anterosuperior labrum and the bony glenoid that mimics a detachment
sublabral foramen
normal variant: consists of an absent anterosuperior labrum in association with a thickened “cord-like” middle glenohumeral ligament
Buford complex
seen only on the anterior part of the superior labrum and should be thin and smooth and extends medially
sublabral recess
SLAP tear in comparison to sublabral reces
more irregular and extends superiorly and laterally
runs in the bicipital groove between the greater and lesser tuberosities and insters onto the superior labrum
long head of biceps tendon
suprascapular nerve is made up of branches from the
C4, C5 and C6 roots of the brachial plexus
nerve that runs superior to the scapula, from anterior to posterior, just medial to the coracoid process
suprascapular nerve
suprascapular nerve innervates the
supraspinatus and infraspinatus
this syndrome is most commonly seen in males who are athletic, particularly weight lifters and in this population is almost always associated with a tear of the superior and/or posterior labrum and the subsequent formation of a paralabral ganglion in the spinoglenoid notch
suprascpular nerve entrapment
if infraspinatus is smaller than the other muscles and/or has fatty infiltration, _________ is the likely diagnosis
suprascapular nerve entrapment secondary to a ganglion in the spinoglenoid notch
if teres minor has fatty atrophy, what is the diagnosis
quadrilateral space syndrome
most commonly occurs from fibrous bands or scar tissue in the quadrilateral space impinging on the axillary nerve
quadrilateral space syndrome
space that lies between the teres minor superiorly, teres major inferiorly, long head of triceps medially and diaphysis of the humerus laterally
quadrilateral space
what nerve traverses the quadrilateral space and innervates the teres minor and deltoid muscles
axillary nerve
what muscle is never involved in quadrilateral space syndrome
deltoid muscle
image sequence that are useful for identifying muscle edema
oblique sagittal fat-supressed T2 weighted images
in about 1% of cases, neurogenic edema is found in muscle groups that correspond to a particular nerve distribution. this is characteristic for
Parsonage-turner syndrome
Parsonage-turner syndrome may be associated with
prior vaccinations, viral illness or general anesthesia
Parsonage-turner syndrome can affect what nerves
axillary or suprascapular nerve or both
