Diagnostic ultrasound ( PDFDrive )

886 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
supraspinatus fossa. he central tendon should be visible within
the muscle.
To image the infraspinatus and teres minor muscles, the
transducer is moved distal to the scapular spine, remaining
perpendicular to the spine. A relative comparison and assessment
of muscle volume and echogenicity can easily be made by using
an extended ield-of-view scan technique.
ROTATOR CUFF DEGENERATION AND
TEARS
Background
Rotator cuf dysfunction, either due to tear or to tendon degeneration,
is the most common cause of referral for evaluation of the
shoulder. 53 Likewise, rotator cuf disease is the most frequent
cause for referral for shoulder ultrasound. he supraspinatus
tendon is the most commonly injured tendon in the rotator
cuf. 54 he incidence of rotator cuf tears rises as patients age.
Up to 22% of patients age 65 and older have rotator cuf tears. 55
It is interesting to note that 70% of imaged patients age 65 and
older have asymptomatic rotator cuf defects. 56 Rotator cuf tears
in patients younger than 40 are uncommon, but they do occur
in the setting of acute trauma or sports-related injuries. Rotator
cuf tears in patients older than 40 are usually secondary to
tendon degeneration.
Tendinosis
Tendinosis of the rotator cuf is a degenerative process that may
be associated with shoulder pain. Histologically, there is no
inlammatory component (hence the term “tendinitis” is not
appropriate for this condition), but rather mucoid degeneration
and frequently chondroid metaplasia are present. On ultrasound,
tendinosis appears heterogeneous or hypoechoic, with tendon
thickening, and loss of the normal ibrillar pattern 57 (Fig. 24.13).
Although discrete defects or tears are not encompassed by this
diagnosis, they may coexist.
Full-Thickness Rotator Cuff Tears
Ultrasound is a reliable method for diagnosis of rotator cuf
tears, with sensitivity and speciicity over 90% 21,26,28,29,58,59 for
full-thickness tears, and low interobserver variability. 60,61 Fullthickness
tears are visualized as a hypoechoic or anechoic gap
within the rotator cuf (Fig. 24.14), which may also have a concave
contour at its bursal border. 30,62 Alternatively, a greatly retracted
tear can result in nonvisualization of the rotator cuf tendon 62
(Fig. 24.15). his occurs because the tendon may retract deep
to the acromion, and is likely in cases in which the degree of
retraction exceeds 3 cm. 63 When a full-thickness tear is present,
the gap between the retracted tendon end and the greater tuberosity
or distal tendon stump may be illed with hypoechoic luid
or echogenic debris (Fig. 24.16) and granulation tissue. Alternatively,
the subacromial-subdeltoid bursa (frequently thickened)
and the deep surface of the deltoid muscle may occupy the defect
created by the tear. 29
Small foci of debris within the tear gap may give the appearance
of mobile or “loating” bright spots. 59 Fluid within the tear gap
my accentuate visualization of the underlying humeral head
articular cartilage owing to enhanced through transmission of
the ultrasound beam, referred to as the “cartilage interface sign” 64
(Fig. 24.17). Occasionally one may be uncertain as to whether
abnormal echotexture in the location of the rotator cuf represents
a partial tear or a full-thickness tear with intervening granulation
tissue and debris. Dynamic compression of the abnormal area
may clarify this confusion by causing complex luid and debris
to swirl within the rotator cuf tear.
It may be helpful to ascertain if a tear is more likely to be
acute or chronic because acute tears are felt to have a greater
chance of successful surgical outcome. In this regard, the indings
of glenohumeral and bursal efusions are more common in
acute tears. In addition, midsubstance tears, medial to the
bone-tendon junction, are more likely to be acute. On the other
hand, severely retracted tears are more likely to be chronic. 65 In
chronic full-thickness tears, the tendon gap may be illed with
FIG. 24.13 Tendinosis of the Supraspinatus. Long-axis image of the supraspinatus tendon (arrowheads) demonstrates hypoechogenicity and
diffuse loss of normal ibrillar echotexture.