**2.3 Supraspinatus tendon**

*Tendons*

steps [2]:

tendon.

including the insertion of the pectoralis muscle. The coronal oblique images are obtained with planes made parallel to the supraspinatus tendon or in a plane perpendicular to the articular surface of the glenoid, ranging from the coracoid process to the infraspinatus muscle. Finally, the sagittal oblique images are acquired with planes parallel to the articular surface of the glenoid, from the scapular neck through the lateral aspect of the humerus [1]. A standard shoulder MRI usually includes sagittal oblique T1-weighted image (T1WI), fast spin echo (FSE) T2-weighted image (T2WI) with fat suppression, coronal oblique FSE T2WI with fat suppression, and

Sonographic evaluation of the shoulder can be performed with the following

1.Long head of biceps brachii tendon: The patient places the hand on his or her lap, as this position rotates the bicipital groove anteriorly. The transducer is placed in the axial plane over the anterior aspect of the shoulder to identify the bicipital groove, where the long head of the biceps brachii tendon is found. The long head of the biceps brachii tendon is followed proximally to where the bicipital groove becomes shallow and then distal to the level of the pectoralis major tendon. The transducer is then turned 90° to visualize the tendon in long axis from the humeral head to the pectoralis

2.Subscapularis tendon: The transducer is placed in the axial plane, as in the previous step, to first visualize the bicipital groove and then centered over the lesser tuberosity at the medial aspect of the bicipital groove. Then the patient rotates the shoulder externally to pull the subscapularis tendon laterally, which will orient the tendon fibers perpendicular to the transducer sound beam and eliminate anisotropy. Then it may be moved laterally over the bicipital groove to ensure that the long head of the biceps brachii tendon is within the bicipital groove, and rule out subluxation or dislocation, which may be present only in external rotation [3]. The subscapularis tendon can also be evaluated in short

3.Supraspinatus and infraspinatus tendon: One way to evaluate the supraspinatus tendon is to ask the patient to place the dorsum of his or her ipsilateral hand behind the back, called the Crass position [4]. This position pulls the tendon out from under the acromion. The Crass position is very helpful in localizing the greater tuberosity but its limitations include poor visualization of the rotator interval and patient discomfort [3]. Because of these disadvantages the modified Crass position is more commonly used, by asking the patient to place his or her ipsilateral hand on the hip or buttock region. This position places the greater tuberosity more lateral than with the Crass position, and also allows easy visualization of the rotator interval with little patient discomfort [5]. Either in the Crass or modified Crass position, supraspinatus evaluation should begin by observing the tendon in long axis as this allows visualization of the three surfaces (articular, bursal, greater tuberosity) [6]. Scanning should be continued anteriorly along the greater tuberosity until the intraarticular portion of the biceps tendon is identified. The infraspinatus tendon is evaluated by moving the transducer posteriorly over the middle facet of the

axial FSE T2WI and FSE proton density (PD) with fat suppression.

**2.2 Ultrasound examination technique**

axis by turning the transducer 90°.

**16**

greater tuberosity.

The supraspinatus tendon arises from the supraspinous fossa, runs between the undersurface of the acromion and the top of the humeral head, and inserts into the most superior facet of the greater tuberosity of the humerus. On MRI, the entire length of the supraspinatus tendon can be seen well in the coronal oblique plain, running at an angle of approximately 45° [7]. The musculotendinous junction of the tendon normally is located just lateral to the acromioclavicular joint. On sagittal oblique images, the supraspinatus tendon is imaged in cross section, which is valuable to confirm the status of the tendon when abnormalities are seen in the plane of imaging, where the tendon is viewed longitudinally.

The normal sonographic appearance of the supraspinatus tendon is hyperechoic and fibrillar with a convex superior margin at the level of the superior facet of the greater tuberosity of the humerus [8]. It parallels the curved contour of the humeral head, flattening out as it inserts into the greater tuberosity. The subacromial-subdeltoid bursa should be seen as a single thin hyperechoic line paralleling the tendon superiorly.

The supraspinatus tendon is the most commonly affected when compared to the other tendons of the shoulder [8]. There are multiple pathologies that may limit the space within the coracoacromial arch, producing impingement of this tendon. Abnormalities from impingement range from tendon degeneration to partial-thickness or full-thickness tears. Most partial-thickness tears occur in the articular aspect of the tendon, rather than on the bursal surface. Tears are usually located distally, either near its attachment to the greater tuberosity or in the critical zone located approximately 1 cm proximal to its insertion, and start in the anterior portion as rim rent tears and spread posteriorly [7]. Rim rent tears refer to disruption of the insertional fibers on the greater tuberosity. Complete disruption of the fibers with communication between the joint and the overlying bursa indicates a full-thickness tear (**Figure 1**).

Tendon degeneration usually demonstrates increased signal intensity on T1WI and T2WI, although not as high signal as fluid. However, a partial thickness tear demonstrates increased signal intensity on T2WI similar to fluid. Indications of a full thickness tear include: tendon discontinuity, fluid signal in tendon gap, and retraction of musculotendinous junction [7].

Tears in ultrasound are demonstrated as anechoic or hypoechoic defects, although acute tears will more likely appear anechoic like fluid [8]. As a supraspinatus tendon tear enlarges, tendon retraction and volume loss occur, with loss of the normal superior convex shape. The length or degree of retraction of a full thickness tear can be measured on longitudinal views oriented parallel to the long axis of the cuff and the width can be measured on transverse views oriented perpendicular to the long axis of the cuff [2]. On the other hand, tendinosis is usually less defined, and may be associated with increased tendon thickness, and not usually associated with adjacent cortical irregularity of the greater tuberosity.

### **2.4 Long head of biceps brachii tendon**

The long head of biceps brachii tendon originates from the supraglenoid tubercle of the scapula, courses intra-articularly to the entrance of the bicipital groove and continues caudally, inserting along the radial tuberosity of the proximal radius. On MRI, portions of this tendon can be evaluated on coronal oblique images, from its origin at the superior labrum and inferiorly in the bicipital groove. The portion that is located within the bicipital groove is seen on axial images as a round or oval structure, and sometimes it may blend with the low signal intensity cortex of the humerus, making it difficult to identify. It is normal to find a small amount of fluid

### **Figure 1.**

*Magnetic resonance arthrogram T1 fat saturated coronal oblique image shows a full thickness tear of the supraspinatus tendon with contrast leaking from the joint capsule into the subdeltoid space.*

in the dependent side of the long head of the biceps tendon sheath, as the tendon sheath normally communicates with the glenohumeral joint. High signal round structures found lateral to the tendon within the bicipital groove represent the anterior circumflex humeral artery/vein and should not be confused with tenosynovitis [7].

The long head of biceps brachii tendon should be found within the intertubercular groove upon sonographic evaluation of the shoulder. The tendon fibers should be seen without tears, heterogeneity or thickening. The normal tendon will appear hyperechoic; however, because the tendon courses deep, it may appear artifactually hypoechoic due to anisotropy [8]. Adjusting the transducer to aim the sound beam perpendicular to the tendon fibers can eliminate this artifact.

The proximal aspect of the tendon may be affected by impingement in the same ways as the supraspinatus tendon because of its similar location and course beneath the supraspinatus tendon. Tears associated with impingement usually occur proximal to the bicipital groove and are usually seen in the older population. Acute tears unrelated to impingement are commonly secondary to a traumatic injury in young individuals, and usually occur distally in the tendon, near the musculotendinous junction [7]. When a full-thickness tear occurs, axial MRI images of the shoulder may show an empty bicipital groove, without evidence of the oval, low signal long head of the biceps tendon. An empty bicipital groove may also indicate tendon dislocation, which is also associated with disruption of the transverse humeral ligament that holds the biceps tendon in place. In this case, the low signal round tendon is seen medial to the bicipital groove, either deep or superficial to the subscapularis tendon, which usually also tears as well.

**19**

*Imaging of Tendons*

*DOI: http://dx.doi.org/10.5772/intechopen.84521*

superficial to the lesser tuberosity.

**3.2 Ultrasound examination technique**

with the arm internally rotated [11].

fibers at its insertion in the lateral epicondyle.

**3.3 Common extensor tendon**

**3. Elbow**

**3.1 MRI protocol**

suspected [10].

When shoulder effusion is present, fluid may be seen sonographically surrounding the biceps tendon at the level of the bicipital groove given the normal communication between the tendon sheath and joint. Joint effusion appears anechoic, however if fluid is complex it may be hypoechoic, isoechoic or hyperechoic relative to muscle, resembling synovial hypertrophy [8]. Tenosynovitis is favored over joint fluid extending into the sheath if there is focal distention of the tendon sheath with hyperemia and it is symptomatic with transducer pressure. Tendinosis of the long head of the biceps brachii should be considered when the tendon is abnormally hypoechoic and increased in thickness with lack of fiber disruption. Anechoic clefts or surface irregularity of the tendon favor a partialthickness tear [9]. The primary finding in a full-thickness tear is lack of visualization of the biceps tendon or empty bicipital groove. As mentioned before, one must also consider tendon subluxation or dislocation when encountered with an empty bicipital groove. In this case, the tendon can be seen medially displaced, usually

Patients should be supine in a comfortable position with the arm to be imaged in supine position as well. Images should include from the distal humeral metaphysis up to the radial tuberosity and this area should be imaged in axial, coronal and sagittal planes. Sequences should include non-fat saturated T1, PD, and fat-saturated T2WI; gradient echo (GRE) may also be included depending on the pathology

Ultrasound of the elbow usually focuses on the area of clinical interest, nonetheless, the anterior, lateral, medial and posterior compartments should all be evaluated. A high frequency linear transducer of 12–17 mHZ is preferred. To evaluate the anterior compartment of the elbow, which includes the distal biceps tendon, it should be extended with a supine forearm. Evaluation should include transverse and longitudinal planes from 5 cm proximal and distal to the joint. The lateral elbow compartment, which includes the common extensor tendon, is evaluated with the arm placed in internal rotation and elbow joint in flexion. The medial compartment includes the common flexor tendons, which is evaluated sonographically by extending the forearm in forceful external rotation. Lastly, the posterior elbow, which contains the distal triceps tendon, is evaluated by placing the elbow in 90° flexion

The common extensor tendon attaches to the humeral lateral epicondyle uniting the individual tendons of the extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and the extensor carpi ulnaris. Normally the common extensor tendon is a band of low signal intensity on both T1WI and T2WI, seen superficial to the radial collateral ligament complex and the tendon should show complete

A common cause for elbow pain is lateral epicondylitis, also known as tennis elbow. In these cases, the tendon may appear thickened with increased intermediate

### *Imaging of Tendons DOI: http://dx.doi.org/10.5772/intechopen.84521*

When shoulder effusion is present, fluid may be seen sonographically surrounding the biceps tendon at the level of the bicipital groove given the normal communication between the tendon sheath and joint. Joint effusion appears anechoic, however if fluid is complex it may be hypoechoic, isoechoic or hyperechoic relative to muscle, resembling synovial hypertrophy [8]. Tenosynovitis is favored over joint fluid extending into the sheath if there is focal distention of the tendon sheath with hyperemia and it is symptomatic with transducer pressure. Tendinosis of the long head of the biceps brachii should be considered when the tendon is abnormally hypoechoic and increased in thickness with lack of fiber disruption. Anechoic clefts or surface irregularity of the tendon favor a partialthickness tear [9]. The primary finding in a full-thickness tear is lack of visualization of the biceps tendon or empty bicipital groove. As mentioned before, one must also consider tendon subluxation or dislocation when encountered with an empty bicipital groove. In this case, the tendon can be seen medially displaced, usually superficial to the lesser tuberosity.
