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Rotator Cuff Injury MRI

Bron: Medscape - Update 25/05/2011; Download 3/01/2012

Contributor Information and Disclosures

Author

Michael John Tuite, MD Director, Musculoskeletal Division, University of Wisconsin

Hospital and Medical School

Michael John Tuite, MD is a member of the following medical societies: American College of

Radiology, American Roentgen Ray Society, International Skeletal Society, Radiological

Society of North America, and Society of Skeletal Radiology

Coauthor(s)

Matthew F Sanford, MD Fellow in Musculoskeletal Radiology, Department of Radiology,

University of Wisconsin Medical School

Specialty Editor Board

David S Levey, MD, PhD Orthopedic/Neurospinal MRI TeleRadiologist, Poolside MRI, San

Antonio, TX

David S Levey, MD, PhD is a member of the following medical societies: American

Roentgen Ray Society, Radiological Society of North America, and Texas Medical

Association

Bernard D Coombs, MB, ChB, PhD Consulting Staff, Department of Specialist

Rehabilitation Services, Hutt Valley District Health Board, New Zealand

Lynne S Steinbach, MD Professor, Department of Radiology, University of California, San

Francisco, School of Medicine

Lynne S Steinbach, MD is a member of the following medical societies: American College of

Radiology, International Skeletal Society, and Radiological Society of North America

Robert M Krasny, MD Resolution Imaging Medical Corporation

Robert M Krasny, MD is a member of the following medical societies: American Roentgen

Ray Society and Radiological Society of North America

Chief Editor

Felix S Chew, MD, MBA, EdM Professor, Department of Radiology, Vice Chairman for

Radiology Informatics, Section Head of Musculoskeletal Radiology, University of

Washington School of Medicine

Felix S Chew, MD, MBA, EdM is a member of the following medical societies: American

Roentgen Ray Society, Association of University Radiologists, and Radiological Society of

North America

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Overview Shoulder pain is a common complaint by patients during physician visits, and it can be due to

a variety of causes. The major cause of shoulder pain in patients older than 40 years is rotator

cuff impingement and tears. With the development of new arthroscopic techniques for treating

rotator cuff disorders, magnetic resonance imaging (MRI) has played an increasingly

important role as a noninvasive test for determining which patients may benefit from surgery.

(See the images below.)[1, 2, 3, 4]

Partial-thickness tear seen better on angled oblique sagittal views.

Full-thickness tear.

A French study by Lambert et al found the positive predictive value of 3.0T MRI to be 100%

for the detection of rotator cuff tendon tears requiring surgery. In this prospective, follow-up

study of 48 patients from 2005 through 2007, when arthroscopy was performed based on the

MRI findings, there was no change in surgical management from that determined by MRI.[1]

Yoo et al found that preoperative MRI variables may help to predict incomplete arthroscopic

repair of large to massive rotator cuff tears. On preoperative MRIs of rotator cuff tears, the

authors found that fatty degeneration index (FDI) values greater than 3 on sagittal oblique

sections of the supraspinatus and values greater than 2 on sagittal oblique sections of the

infraspinatus, with greater than 31 mm in coronal oblique tear distance (COTD) and 32 mm in

sagittal oblique tear distance (SOTD), can help to predict incomplete arthroscopic repair of

the torn tendon.[5, 6]

Conventional MRI

Conventional MRI with T2-weighted images in the oblique coronal and oblique sagittal

planes is the preferred technique for imaging the rotator cuff. Most authors have found that

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fat-suppressed, fast spin-echo (FSE), T2-weighted images are the most accurate for detecting

rotator cuff tears (RCTs); a sensitivity of 84-100% and a specificity of at least 77-97% for

full-thickness tears can be expected with this pulse sequence.[7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

Although most RCTs can be seen on oblique coronal images, Patten et al reported that oblique

sagittal images provide approximately a 10% improvement in accuracy for detecting RCTs,

although this was not statistically significant.[21] The authors found that oblique sagittal images

are especially helpful for identifying tears involving the anterior edge of the supraspinatus.

Magnetic resonance arthrography

Some people prefer to perform either direct or indirect MR arthrography for imaging the

rotator cuff. The advantage of direct MR arthrography relative to MRI is that it distends the

joint, thus forcing the contrast agent into a small defect. T1-weighted images, which are faster

to acquire and have a superior signal-to-noise ratio, can also be used instead of T2-weighted

images. The disadvantages of direct MR arthrography are that it is mildly invasive and may

require imaging guidance to place a needle into the glenohumeral joint capsule. In addition,

bursal-surface partial-thickness tears are not directly opacified.

Several authors have reported that direct MR arthrography is close to 100% sensitive and

specific for full-thickness and articular-surface partial-thickness RCTs.[22] A 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. (See the image

below.)

Rim-rent or partial-thickness articular-surface tendon avulsion (PASTA) tear.

When performing direct MR arthrography, it is important to use fat-suppression to decrease

the signal intensity of the peribursal fat plane around the subacromial-subdeltoid bursa;

without fat-suppression, the fat plane can mimic the contrast agent and lead to a false

interpretation of an RCT.

In a meta-analysis of studies on MRI, MR arthrography, and ultrasonography for rotator cuff

tears, de Jesus et al found MR arthrography to be more sensitive and specific than either MRI

or ultrasonography for diagnosing both full-thickness and partial-thickness tears. MRI and

ultrasonography showed no significant differences in sensitivity or specificity for full- or

partial-thickness tears.[2]

Indirect MR arthrography requires only an intravenous (IV) injection, but this modality has a

disadvantage in that it does not distend the joint. As in direct MR arthrography, short scanning

time T1-weighted images can be used instead of T2-weighted images. Several authors have

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shown that compared with conventional MRIs of the rotator cuff, RCTs are better

characterized on indirect MR arthrography and there is better correlation with surgical

findings. One study reported that 2 radiologists improved their accuracy for detecting RCTs

from 67% and 62% with conventional MRI to 92% and 96%, respectively, with indirect MR

arthrography.[23] Again, use of fat suppression is important, but exercising the joint does not

appear to improve accuracy.

Despite these studies, MR arthrography has not been as widely accepted for evaluating the

rotator cuff as it has been for imaging the glenoid labrum. Direct MR arthrography does

improve the depiction of posterior articular-surface partial-thickness tears that are observed in

overhead-throwing athletes, particularly if the shoulder is scanned in abduction and external

rotation. However, most authors have found that fat-suppressed, FSE, T2-weighted images

obtained with a quality shoulder coil are fairly accurate for most RCTs and that conventional

MRI is adequate for routine imaging of the rotator cuff.

Conventional arthrography was the traditional technique for detecting RCTs. However,

arthrography itself does not demonstrate bursal-sided, partial-thickness tears, and it may be

difficult at times to determine the size of a tear using this modality. With improvements in

computed tomography (CT) scanners, oblique coronal reformatted CT arthrogram images can

provide excellent images of the rotator cuff in patients who are unable to undergo an MRI.

Limitations of techniques

MRI is contraindicated in patients who have a cardiac pacemaker, ferromagnetic foreign

bodies (particularly in the orbit), and some cochlear implants. Some patients are extremely

claustrophobic in high-field-strength MRI scanners, although many of these patients can be

scanned in open MRI scanners after administration of a mild sedative.

MR arthrography is mildly invasive, and because the off-label use of gadolinium is not

currently approved by the US Food and Drug Administration (FDA) for intra-articular

injection, it may require written, informed patient consent. Imaging is also usually necessary

to correctly position the arthrogram needle within the joint capsule. Fluoroscopy is the most

common method of imaging guidance, but needle placement also can be performed under CT

scanning, by ultrasound, or within the MRI scanner. Conventional arthrography is also mildly

invasive and has the limitation of not being a tomographic technique.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate

dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK],

gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic

fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the

eMedicine topic Nephrogenic Systemic Fibrosis. The disease has occurred in patients with

moderate to end-stage renal disease after being given a gadolinium-based contrast agent to

enhance MRI or MRA scans.

NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark

patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow

spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms,

hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more

information, see Medscape.

Magic-angle effect

The histology of the rotator cuff contributes to one of the difficulties of rotator cuff MRI

interpretation, the magic-angle effect or angular anisotropy. This effect is an MRI artifact in

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which normally low-signal structures that are made of organized collagen fibers appear as a

higher signal intensity on images that are obtained with a short echo time (TE). The artifact

occurs when the long axes of the collagen fibers are oriented at 55° to the main magnetic

field.

In most high-field MRI scanners, the main magnetic field is oriented along the direction of the

bore (the central tunnel where the patient lies). The well-organized collagen fibers in the outer

portions of the rotator cuff are organized longitudinally; therefore, these normally low-signal

fibers have increased signal intensity on short-TE images as the fibers curve and become

oriented at the magic angle.

Unfortunately, this effect occurs in the region of the critical zone where RCTs and

degenerative tendinopathy are prevalent. However, the magic angle’s high signal intensity

diminishes with increasing TE; thus, it is not usually a problem on the fat-suppressed, FSE,

T2-weighted MRIs most radiologists currently use to image the rotator cuff.

For excellent patient education resources, visit eMedicine's Breaks, Fractures, and

Dislocations Center. Also, see eMedicine's patient education articles, Shoulder Dislocation,

Shoulder Separation, and Magnetic Resonance Imaging (MRI).

Magnetic Resonance Imaging This section discusses the use of MRI in the assessment of full- and partial-thickness RCT

tears.

Full-thickness tears

For many orthopedic surgeons, the main role of shoulder MRI is to detect a full-thickness

rotator cuff tear (RCT). The most common appearance of a full-thickness tear is high signal

intensity on a T2-weighted image that extends from the articular surface of the rotator cuff to

the subacromial-subdeltoid bursa. (See the image below.)

Supraspinatus tendon. Reprinted with permission from Michael Tuite, MD.

Rafii et al reported that high signal was observed in approximately 90% of full-thickness tears

proven at surgery.[24] In chronic RCTs in which the shoulder joint has little or no effusion, the

humeral head may be high riding, such that not much high signal is seen at the tear site. (See

the image below.)

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Normal intratendinous signal.

Some patients may also develop fibrous thickening of the subacromial-subdeltoid bursa,

which can mimic an intact tendon in the absence of an effusion; therefore, it is important to

trace a low-signal structure as it passes over the humeral head. Rotator cuff fibers will end at

their insertion on the greater tuberosity, whereas fibrous thickening of the bursa will continue

deep to the deltoid muscle below the greater tuberosity.

In addition, acute RCTs can hemorrhage at the tear site, with the blood mimicking some intact

fibers. It is important to distinguish the smoothly curving, low-signal surfaces of the rotator

cuff from the disorganized low-signal surfaces of fibrin and other blood products.

Most small full-thickness tears arise in the anterior aspect of the supraspinatus tendon in the

critical zone. (See the images below.)

Partial-thickness tear seen better on angled oblique sagittal views.

Full-thickness tear.

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Localizing a small full-thickness tear to the rotator cuff crescent may be helpful for the

shoulder surgeon, who may then decide to only debride, but not repair, the cuff defect.

Although RCTs often begin in the critical zone, resorption of the tendon stump at the greater

tuberosity may occur if chronic full-thickness tears are left untreated. Full-thickness avulsion

tears of the tendon away from the greater tuberosity are less common. Massive tears often

extend posteriorly to involve the infraspinatus tendon or extend anteriorly to tear the anterior

interval and subscapularis tendon.

If a full-thickness tear is observed, it is important to document whether or not the entire

anterior-to-posterior width of the supraspinatus tendon is involved. In RCTs that involve the

entire tendon, the tendon edge can retract medial to the glenoid, where it becomes extremely

difficult to grasp and to reattach to the greater tuberosity.

Long-standing RCTs can also result in the development of muscle atrophy and fatty

degeneration that may prevent successful repair. It is important to expeditiously obtain

imaging studies in patients who have a possible acute full-thickness, complete-width,

supraspinatus tendon tear. If an acute complete supraspinatus tendon tear is identified, surgery

is often scheduled within the next several days so that the tendon can be repaired before the

development of retraction or atrophy.

Partial-thickness tears

Partial-thickness tears can be classified as articular, bursal, or intratendinous. Intratendinous

tears may be a cause of shoulder pain, but they are not observed at routine arthroscopy and are

rarely treated surgically. Articular-surface partial-thickness tears are more common than

bursal-surface tears (at an approximately 3:1 incidence rate).[25, 26] Many patients with a bursal-

surface tear also have an articular-surface tear.

The accuracy of MRI for partial-thickness tears is lower than that for full-thickness tears.

Although some authors have reported a sensitivity greater than 0.90 for partial-thickness tears,

others have reported sensitivities as low as 0.17-0.56.[10, 13, 24, 27, 28]

Reinus et al were unable to correctly identify the side of the affected rotator cuff (articular vs

bursal) in 50% of their patients with a partial-thickness tear.[8] One reason for the low accuracy

is that a high-signal defect on T2-weighted images is a less common finding in partial-

thickness tears than in full-thickness tears; in a study by Rafii et al, this high-signal defect was

seen in only 7 of 16 cases of partial-thickness tears.[24]

Partial-thickness tears often appear on MRI as only an intermediate signal, isointense to

muscle, which disrupts the normal low-signal surface of the rotator cuff.

Absence of fluid in an RCT on MRI may be from the presence of a poor-quality scar or

granulation tissue within the defect, and this can be difficult to distinguish from tendon

degeneration or a healed RCT. Partial-thickness tears may also have smooth margins that

taper gradually so that the rotator cuff appears to be only somewhat thinned. (See the image

below.)

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Chronic full-thickness tear.

Although most partial-thickness tears occur in the critical zone of the supraspinatus tendon,

some RCTs occur in less common locations. In younger patients, a small articular-surface

avulsion-type partial-thickness tear can occur adjacent to the greater tuberosity; this is termed

a rim-rent tear. (See the image below.)

Rim-rent or partial-thickness articular-surface tendon avulsion (PASTA) tear.

Tears isolated to the infraspinatus tendon occur in 1-7% of patients with RCTs, but these tears

are more common in athletes who perform overhead activities.[29] MR arthrography in which

the patient is positioned with the arm in abduction and external rotation is the best technique

for identifying these infraspinatus articular-surface partial-thickness tears, which often are

associated with adjacent glenoid labral fraying.

Although the most important MRI criterion of a partial-thickness tear is the presence of an

increased signal that disrupts the normally low-signal surface of the rotator cuff, some authors

have described some secondary signs that may be helpful in improving the accuracy of MRI.

Sanders et al demonstrated that an intramuscular cyst, typically in the supraspinatus muscle, is

always associated with articular-surface involvement by a tear.[30] The authors suggested that

when such cysts are present, associated rotator cuff pathology should be investigated.

Inferiorly directed acromioclavicular joint osteophytes, a hooked anterior acromion, and an os

acromiale have all been associated with a higher incidence of RCTs; therefore, these findings

should prompt a careful evaluation of the rotator cuff. Subacromial-subdeltoid fluid is

common in full-thickness tears, but a small amount can be observed in patients without a

bursal-surface tear; thus, the presence of this fluid is not an accurate secondary sign of a

bursal-surface partial-thickness tear.

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Degree of confidence

Studies investigating the use of fat-suppressed, FSE imaging have reported a sensitivity of 84-

100% and a specificity of 77-97% for full-thickness tears[10, 11, 12, 13] ; however, the accuracy for

partial-thickness tears is lower. MR arthrography may be helpful for better demonstrating

articular-surface partial-thickness tears. Angling the oblique coronal or oblique sagittal

images to the rotator cuff surface at the suspected tear site can improve the accuracy of

conventional MRI.

False positives/negatives

There are 3 other abnormalities of the rotator cuff that can mimic an RCT: degeneration,

tendinopathy, and cuff strain. Rotator cuff degeneration is common in older individuals and

appears as an ill-defined area of increased signal on T2-weighted MRIs within the substance

of the cuff. All rotator cuffs undergo age-related degeneration in which the normally compact

and well-organized collagen fibers are replaced by intermediate-signal myxoid and

eosinophilic material.

As aging progresses and the rotator cuff is put under repeated stress, small fissures can

develop within the cuff substance and appear as thin areas of fluid on MRI. If the MRI

contrast and brightness are set too high (ie, windowed too tightly), these fissures can

occasionally bloom and appear as a tear that extends to the surface of the cuff. (See the image

below.)

Articular- and bursal-surface partial-thickness tears.

Tendinopathy, occasionally incorrectly termed tendinitis, is a related intratendinous process

that is histologically similar to rotator cuff degeneration. Although the term tendinopathy is

occasionally used interchangeably with age-related cuff degeneration, some clinicians reserve

the term for younger symptomatic patients.

As with patellar "tendinitis," tendinopathy is not truly an inflammatory process, because there

is no edema, vascular invasion, or acute inflammatory cells. Instead, what occurs

pathologically is severe mucoid and eosinophilic degeneration with intratendinous clefts,

often causing focal tendon swelling and, occasionally, surface fibrillation. If windowed

incorrectly during imaging, tendinopathy can also appear to extend to involve the surface of

the rotator cuff. (See the images below.)

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Tendinopathy.

Intramuscular cyst and partial-thickness tear.

Rotator cuff strain after acute trauma has been described as another potential cause of

increased intratendinous signal on MRI. This typically occurs in younger patients (< 35 y)

who have an associated bone bruise and focal increased signal intensity in the posterior aspect

of the supraspinatus tendon, as distinguished from cuff degeneration, which involves a larger

area that is centered in the anterior critical zone. Patients with presumed rotator cuff strain as

demonstrated on MRI are less likely to require surgery than older patients who develop

shoulder pain after acute trauma.

In summary, fat-suppressed, FSE, T2-weighted images obtained with a quality shoulder coil

are accurate for diagnosing RCTs. False-negative full-thickness tears typically occur when the

patient does not have an effusion and when the subdeltoid bursal capsule is thickened. False-

negative partial-thickness tears are fairly common, especially for tears that are not very deep.

Failure to diagnose partial-thickness tears can be minimized by radiologists carefully

inspecting the low-signal surfaces of the rotator cuff and noting whether the low-signal

surface layers are disrupted, as well as by use of both intra-articular and IV gadolinium to

enhance the conspicuity of these lesions

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References

1. Lambert A, Loffroy R, Guiu B, Mejean N, Lerais J, Cercueil J, et al. [Rotator cuff

tears: value of 3.0T MRI.]. J Radiol. May 2009;90(5 Pt 1):583-8. [Medline].

2. de Jesus JO, Parker L, Frangos AJ, Nazarian LN. Accuracy of MRI, MR arthrography,

and ultrasound in the diagnosis of rotator cuff tears: a meta-analysis. AJR Am J

Roentgenol. Jun 2009;192(6):1701-7. [Medline].

3. Burks RT, Crim J, Brown N, Fink B, Greis PE. A prospective randomized clinical trial

comparing arthroscopic single- and double-row rotator cuff repair: magnetic resonance

imaging and early clinical evaluation. Am J Sports Med. Apr 2009;37(4):674-82.

[Medline].

4. Murray PJ, Shaffer BS. Clinical update: MR imaging of the shoulder. Sports Med

Arthrosc. Mar 2009;17(1):40-8. [Medline].

5. Yoo JC, Ahn JH, Yang JH, Koh KH, Choi SH, Yoon YC. Correlation of arthroscopic

repairability of large to massive rotator cuff tears with preoperative magnetic

resonance imaging scans. Arthroscopy. Jun 2009;25(6):573-82. [Medline].

6. Yoo JC, Ahn JH, Lee YS, Koh KH. Magnetic resonance arthrographic findings of

presumed stage-2 adhesive capsulitis: focus on combined rotator cuff pathology.

Orthopedics. Jan 2009;32(1):22. [Medline].

7. [Best Evidence] Burks RT, Crim J, Brown N, Fink B, Greis PE. A prospective

randomized clinical trial comparing arthroscopic single- and double-row rotator cuff

repair: magnetic resonance imaging and early clinical evaluation. Am J Sports Med.

Apr 2009;37(4):674-82. [Medline].

8. Reinus WR, Shady KL, Mirowitz SA, Totty WG. MR diagnosis of rotator cuff tears of

the shoulder: value of using T2-weighted fat-saturated images. AJR Am J Roentgenol.

Jun 1995;164(6):1451-5. [Medline].

9. Quinn SF, Sheley RC, Demlow TA, Szumowski J. Rotator cuff tendon tears:

evaluation with fat-suppressed MR imaging with arthroscopic correlation in 100

patients. Radiology. May 1995;195(2):497-500. [Medline].

10. Singson RD, Hoang T, Dan S, Friedman M. MR evaluation of rotator cuff pathology

using T2-weighted fast spin-echo technique with and without fat suppression. AJR Am

J Roentgenol. May 1996;166(5):1061-5. [Medline].

11. Sonin AH, Peduto AJ, Fitzgerald SW, Callahan CM, Bresler ME. MR imaging of the

rotator cuff mechanism: comparison of spin-echo and turbo spin-echo sequences. AJR

Am J Roentgenol. Aug 1996;167(2):333-8. [Medline].

12. Carrino JA, McCauley TR, Katz LD, Smith RC, Lange RC. Rotator cuff: evaluation

with fast spin-echo versus conventional spin-echo MR imaging. Radiology. Feb

1997;202(2):533-9. [Medline].

13. Sahin-Akyar G, Miller TT, Staron RB, McCarthy DM, Feldman F. Gradient-echo

versus fat-suppressed fast spin-echo MR imaging of rotator cuff tears. AJR Am J

Roentgenol. Jul 1998;171(1):223-7. [Medline].

12

14. Ardic F, Kahraman Y, Kacar M, et al. Shoulder impingement syndrome: relationships

between clinical, functional, and radiologic findings. Am J Phys Med Rehabil. Jan

2006;85(1):53-60. [Medline].

15. Dinter DJ, Martetschläger F, Büsing KA, Schönberg SO, Scharf HP, Lehmann LJ.

[Shoulder injuries in overhead athletes: utility of MR arthrography]. Sportverletz

Sportschaden. Sep 2008;22(3):146-52. [Medline].

16. Koivikko MP, Mustonen AO. Shoulder magnetic resonance arthrography: a

prospective randomized study of anterior and posterior ultrasonography-guided

contrast injections. Acta Radiol. Oct 2008;49(8):912-7. [Medline].

17. Borick JM, Kurzweil PR. Magnetic resonance imaging appearance of the shoulder

after subacromial injection with corticosteroids can mimic a rotator cuff tear.

Arthroscopy. Jul 2008;24(7):846-9. [Medline].

18. Reuter RM, Hiller WD, Ainge GR, Brown DW, Dierenfield L, Shellock FG, et al.

Ironman triathletes: MRI assessment of the shoulder. Skeletal Radiol. Aug

2008;37(8):737-41. [Medline].

19. Chang D, Mohana-Borges A, Borso M, Chung CB. SLAP lesions: anatomy, clinical

presentation, MR imaging diagnosis and characterization. Eur J Radiol. Oct

2008;68(1):72-87. [Medline].

20. Duc SR, Mengiardi B, Pfirrmann CW, et al. Diagnostic performance of MR

arthrography after rotator cuff repair. AJR Am J Roentgenol. Jan 2006;186(1):237-41.

[Medline].

21. Patten RM, Spear RP, Richardson ML. Diagnostic performance of magnetic resonance

imaging for the diagnosis of rotator cuff tears using supplemental images in the

oblique sagittal plane. Invest Radiol. Jan 1994;29(1):87-93. [Medline].

22. Palmer WE, Brown JH, Rosenthal DI. Rotator cuff: evaluation with fat-suppressed

MR arthrography. Radiology. Sep 1993;188(3):683-7. [Medline].

23. Yagci B, Manisali M, Yilmaz E, et al. Indirect MR arthrography of the shoulder in

detection of rotator cuff ruptures. Eur Radiol. 2001;11(2):258-62. [Medline].

24. Rafii M, Firooznia H, Sherman O, et al. Rotator cuff lesions: signal patterns at MR

imaging. Radiology. Dec 1990;177(3):817-23. [Medline].

25. Ozaki J, Fujimoto S, Nakagawa Y, Masuhara K, Tamai S. Tears of the rotator cuff of

the shoulder associated with pathological changes in the acromion. A study in

cadavera. J Bone Joint Surg Am. Sep 1988;70(8):1224-30. [Medline].

26. Budoff JE, Nirschl RP, Guidi EJ. Débridement of partial-thickness tears of the rotator

cuff without acromioplasty. Long-term follow-up and review of the literature. J Bone

Joint Surg Am. May 1998;80(5):733-48. [Medline]. [Full Text].

27. Robertson PL, Schweitzer ME, Mitchell DG, et al. Rotator cuff disorders:

interobserver and intraobserver variation in diagnosis with MR imaging. Radiology.

Mar 1995;194(3):831-5. [Medline].

13

28. Wnorowski DC, Levinsohn EM, Chamberlain BC, McAndrew DL. Magnetic

resonance imaging assessment of the rotator cuff: is it really accurate?. Arthroscopy.

Dec 1997;13(6):710-9. [Medline].

29. Tuite MJ, Turnbull JR, Orwin JF. Anterior versus posterior, and rim-rent rotator cuff

tears: prevalence and MR sensitivity. Skeletal Radiol. May 1998;27(5):237-43.

[Medline].

30. Sanders TG, Tirman PF, Feller JF, Genant HK. Association of intramuscular cysts of

the rotator cuff with tears of the rotator cuff: magnetic resonance imaging findings and

clinical significance. Arthroscopy. Apr 2000;16(3):230-5. [Medline].