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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].