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i 21

Rotator

Cuff

Tears:

Diagnosis

with

Sonography

C. Whitley Sidney

Vick1

The

purpose of this study was to determine the accuracy of sonography in the of rotator cuff tears. Eighty-one patients were referred by orthopedic specialists because of a clinical suspicion of rotator cuff tear. The standards of comparison were arthrography in 79 cases and surgery in two cases. The sonographic technique used was based on a review of the literature and experience gained by scanning normal

A. Bell2

detection

subjects.

The sonographic

criteria

for the diagnosis

of a complete

rotator

cuff tear were

a focal defect in the cuff or complete absence or nonvisualization of the cuff. All sonograms were interpreted prospectively without knowledge of arthrographic or surgical results. With arthrography as the standard of comparison for the diagnosis of rotator cuff tear, sonographic results included 15 true-positives, 52 true-negatives, eight false-negatives, and four false-positives. With surgery as the standard of comparison, the results were one true-positive and one true-negative sonogram. The sensitivity of sonography in detecting rotator cuff tear was 0.67, the specificity was 0.93, and the accuracy was 0.85. Our study found lower sensitivity and accuracy results for shoulder sonography than have been previously reported. 154:121-123,

AJR

Authors

January

of several

1990

recent

the use of sonography [1 2] have found the accuracy of shoulder sonography to be 0.87-0.94, the sensitivity 0.93, and the specificity 0.83-0.93. The procedure is appealing because, unlike shoulder arthrography, there is no discomfort to the patient, radiation exposure, or potential for adverse reactions. We describe our findings in using sonography to detect rotator

for the diagnosis

of tears

cuff

patients

tears

in 81

studies

of the

[i -4]

rotator

in whom

available

for use as the diagnostic

Patients

and Methods

have

cuff.

the

advocated

Prior

results

investigations

,

of arthrography

or

surgery

were

standard.

One hundred fifteen consecutive patients were referred for shoulder sonography. Of these, 79 who underwent arthrography and two who had surgery without arthrography were included in the study. All patients were referred by a group of six orthopedic surgeons because of a clinical suspicion of rotator cuff tear. Sonograms were obtained by using a 5-MHz linear phased-array transducer (Acuson 128, Received June 6, 1989; accepted after revision September 1

8, 1989.

Rome Radiology

Blvd., Rome, GA 30161 to C. W. Vick.

0361-803x/90/1541-0121 © American

Roentgen

View, used

,

humerus

adducted

to view

based

were

on a review

the fibers

in neutral

groove was located the rotator

Ray Society

CA). The procedures was

performed

of the

and interpreted

literature

and

by one radiologist.

experience

gained

normal subjects [1 , 2, 5-7]. Verbal consent was obtained in all cases. Both shoulders were scanned. The examination was done with the patient

Group, 1104 Martha Berry . Address reprint requests

2 The Harbin Clinic, 1825 Martha Berry Blvd. Rome, GA 30161 .

Mountain technique

supraspinatus

cuff.

The

examination

began

with

the

seated

transducer

of the rotator cuff in a transverse or cross-sectional plane. and used as a landmark for identification of the component

The transducer and

position.

infraspinatus

was tendons

then

moved from

their

laterally insertion

and posteriorly on

the

humerus

The

by scanning

with the oriented

The bicipital tendons of

to visualize to

the

the point

122

VICK

AND

where they became obscured by the acromion. The transducer was then brought back to the bicipital groove and then moved medially and superiorly to view the subscapularis tendon. The same areas were then scanned in the longitudinal plane. The sequence was repeated both with the shoulder elevated and with the arm pulled behind the patient’s back in a position of hyperextended internal

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rotation.

Sonographic criteria for the diagnosis of a complete tear were a focal defect in the cuff or complete absence or nonvisualization of the rotator cuff. The sonograms were interpreted prospectively before arthrography or surgery as showing either the presence or the absence of a complete tear. A decision regarding tear vs no tear was made in each case, with no attempt to exclude or tabulate indeterminate cases. Sensitivity, specificity, and accuracy were determined. Subsequently, the sonograms were reviewed retrospectively to as-

sess possible causes of errors. Single-contrast arthrography was performed after the sonography on the same day. Knowledge of the results of the sonograms was usually available to the radiologist before arthrography was performed. The contrast agent used was either methylglucamine diatri-

zoate (Renografin,

Squibb, New Brunswick,

NJ) or iopamidol

(Isovue,

Squibb). Approximately 10-15 ml of contrast agent was injected into the joint under fluoroscopic guidance. Fluoroscopic spot films were made at the discretion of the radiologist, usually if contrast material was observed entering the subacromial bursa. After injection of contrast material, anteroposterior radiographs were made in internal and external rotation and an axillary view was made. If no gross abnormality was seen on these films, a second set of films was made after exercise. A full-thickness rotator cuff tear was diagnosed when

contrast

material entered the subacromial

bursa.

An arthrography, 23 patients had tears of the rotator cuff and 56 patients had no tear. At surgery, one patient had a rotator cuff tear and one patient had an intact cuff.

Results Using rotator

arthrography cuff

tears,

as the we found

1 5 true-positives, 52 and four false-positives. arthrography. true-positive;

the

standard

for the diagnosis

sonographic

true-negatives, Two patients

In one of these in the other, the

results

eight had

patients, sonogram

of

included

false-negatives, surgery without

the sonogram was was true-negative.

The sensitivity of sonography in detecting rotator cuff tear was 0.67, the specificity was 0.93, and the accuracy was 0.85. Retrospective analysis of all 1 6 of the true-positive cases showed that in 1 0 (63%), the sonographic finding was a focal defect in the rotator cuff, and in six (38%), the cuff was not visualized. Review of the eight false-negative cases showed that

four

thinning

had of the

no

sonographic

posterior

abnormality,

aspect

of the

one cuff

not

had

focal

Discussion The ences

sensitivity than

in study

dependent,

and

previously

accuracy

of sonography

reported.

This

the

that

design,

and technical

fact

limitations.

may

in our

be related

sonography

study to differ-

is operator

is

AJR:154,

January

1990

We believe the design of our study was comparable with those of studies reported previously [1 2]. Scanning technique and sonographic equipment used were the same or comparable. The sonographic criteria for rotator cuff tear were the same as those used by Mack et al. [2]. In both studies, visualization of a defect in the cuff was required to diagnose a tear. However, Middleton et al. [1] and Crass et al. [3] also include the finding of a central echogenic band or focus in the cuff as a sign of tear. Use of more liberal criteria such as these will increase sensitivity and lower specificity. In retrospect, three false-negative cases in our study had echogenic foci in the cuff, but 1 4 true-negative cases also had a similar-appearing echogenic area in the cuff. If we had included the criterion of a focal echogenic area in the cuff as a sign of tear, our sensitivity would have improved to 0.79, but specificity and accuracy would have dropped to 0.68 and 0.72, respectively. These figures are still well below those of earlier studies. Arthrography was used as the standard of comparison in ,

the majority

of our

cases

and

in previous

comparable

reports

[1 2]. It is recognized that errors may occur with arthrography, most notably failure to detect partial rotator cuff tears that do not communicate with the joint space. However, the majority of our sonographic errors involved failure to detect tears shown by arthrography. In this situation, contrast agent enters the subacromial bursa, and the likelihood that arthrography is in error is exceedingly low. Therefore we believe that using arthrography as the standard of comparison does not substantially affect our results or comparison with previous studies. Shoulder sonography is highly operator dependent. We cannot rule out the possibility that individual differences in technique or skill account for our less favorable results cornpared with those of previous reports. We believe that technical limitations of shoulder sonography contribute to its inability to identify some rotator cuff tears. Tears occurring in that portion of the cuff behind the acromion cannot be visualized [1 -4, 7, 8]. However, most tears occur near the insertion of the supraspinatus tendon, an area that is routinely seen with sonography. In this location, the size of a tear may affect sonographic visualization. Mack et al. [2] showed that some small (

Rotator cuff tears: diagnosis with sonography.

The purpose of this study was to determine the accuracy of sonography in the detection of rotator cuff tears. Eighty-one patients were referred by ort...
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