Robert Georges

A. Ganneau, MD a Donald L. Renfrew, Y. El-Khoury, MD a James V. Nepola,

Glenoid

Labrum:

MD MD

M

Shoulder,

Shoulder, injuries,

studies,

414.1214

Radiology

1991;

dislocation,

414.436

a

Shoulder,

414.42

a

MR

resonance (MR) imaghas been proposed as a possible replacement for computed amthrotomogmaphy of the shoulder in the evaluation of the glenoid labmum (1-3). The purpose of our investigation was to determine how well abnommalities of the glenoid labmum can be evaluated with MR imaging.

SUBJECTS

AND

Nine patients

asymptomatic with shoulder

studied

with

MR

of

Radiology

(RAG., D.L.R., T.E.M., G.Y.E.K.), Orthopedic Surgery (J.V.N.), and Preventive Medicine (J.H.L.), College of Medicine, University of Iowa, Iowa City, IA 52242. From the 1990 27, sion ary C

scientific 1990; revision

assembly. requested

received January 29. Address reprint RSNA, 1991

22,

con-

institution

approved

the

study.

Imaging

was performed with a 1 .5-T superconducting magnet (Signa; GE Medical tems, Milwaukee), and we obtained ton-density

and

T2-weighted

axial

gap in a ma-

trix, and two signal averages were Three patients also underwent Tiweighted coronal oblique imaging.

The average men, 20-47

Syspro3-mm

sections with a 1-mm intersection all subjects. A 24-cm field of view, shoulder coil, a 192 X 256 acquisition

Received December 1991; requests

November 19; revi-

accepted Januto G.Y.E.K.

then brum

Imaging’

coached on MR

(five

was 29 years (range, of the volunteers com-

of these normal. The

in all

individuals

cases.

were

The

assumed

labra

to be

of the shown

la-

the junction of the fibrous labrum underlying cartilage. The anterior was considered blunt if it did not sharp

anterior

nor

margin

it was

case, out

margin,

was considered

the interpreting

ence,

location,

the

blunt

misshapen.

sheet,

have

whereas

significantly

a data

and the labrum

only For

and

filled

included

grade

the

of the

if

each

radiologists

which

a

poste-

pres-

labral

tear. The interpreters graded tears by means of Rowe and Zarin’s system (4): grade I = labrum separated from articular surface, grade II absent labrum, and grade III = absent labrum and deformity of the bony glenoid. Six months later, the same two interpreters

evaluated

the

aware of the overall al, they were blinded dividual

MR

images

for a second time using criteria. Even though

of

the

the same they were

results of the first tnto their previous in-

conclusions.

RESULTS The interpreters’ case-specific mesults, along with the standard of refemence, are shown in Table 1 The observer-specific MR imaging findings and the surgical findings are shown in Table 2. At the initial intempretation of the symptomatic patients, observer A achieved a sensitivity of 44.4% (exact 95% confidence interval [CI] = 13.7%, 78.8%) and a specificity of 66.7% (exact 95% CI 22.8%, 95.7%). Observer B had a sensitivity of 77.8% (exact 95% CI 40.0%, 97.2%) and a specificity of 66.7% (exact 95% CI = 22.8%, 95.7%). The specificities of the observers for the .

average

age

of the

consistent shoulder

with joint

patients

was

of arthroscopy Anthroscopy

28

by

subspecialist

with were

extensive available

by in all pawere per-

orthopedic experience. during

sunThe surgery.

and surgical findings standard of reference of glenoid abnormalities.

Two musculoskeletal interpreted

loskeletal

instability.

visualized

or surgery and surgery

formed

Anthroscopic sented the evaluation

shoulder

was

geons images

had

were

nal intensity within the labnum greater than that which is normally present at

plained of shoulder pain on had a history of shoulder problems. We imaged the arms

in interpretation images. They

examples of normal (Fig 1) and abnormal (Fig 2) labra. They then interpreted the MR images of the patients and volunteers without knowledge of the standard of reference. Decision criteria for evaluation of the labrum included a blunt margin of the labrum, absence of the labrum, or sig-

patients decision

used.

age of the volunteers

four women) years). None

means tients.

RSNA

Informed

years (range, 14-56 years). There were 11 male and five female subjects. All patients had a history of shoulder subluxation, and findings at a physical examination

179:519-522

Departments

imaging.

and 15 were

sent was obtained from all subjects foblowing explanation of the examination and the risks and benefits of the procedune. The Human Use Committee at our

The

the

METHODS volunteers instability

a

MR

ing

were

From

with

AGNETIC

nondominant terms:

E. Moore, FRACR H. Lemke, PhD

#{149} Jon

Evaluation

Fifteen patients with shoulder instability and nine asymptomatic volunteers were studied with magnetic resonance (MR) imaging. The shoulder joint was visualized by means of anthroscopy or surgery in all patients. Ten patients had abnonmalities of the glenoid labrum. Two musculoskeletal radiologists interpreted the MR images of the patients and volunteers without knowledge of the clinical history or surgical results. The surgical and anthroscopic results were used as the standard of reference in symptomatic patients. Observer A achieved a sensitivity of 44.4% and a specificity of 66.7%; observer B had a sensitivity of 77.8% and a specificity of 66.7%. In addition to the poor sensitivities and specificities, there was substantial intraand interobsenver variability. Assuming that the shoulders of the asymptomatic volunteers were normal, the specificities were 100.0% and 88.9% for observers A and B, respectively. In this small study, axial MR imaging was relatively insensitive and nonspecific in the evaluation of labral lesions. Further study will be necessary to determine the utility and limits of MR imaging in this regard. Index

#{149} Timothy

MR system

for

in

radiologists images at least

of the 2 years

MR

reprethe

who muscuwere

Abbreviation:

Cl

=

confidence

interval.

519

asymptomatic volunteers cannot be pooled with their specificities for the symptomatic patients. The specificities for the asymptomatic volunteers were 100% (exact 95% CI 66.4%, 100%) and 88.9% (exact 95% CI 51.8%, 99.7%) for observers A and B, respectively.

There was substantial interand intraobserver variability. At initial readings of the images of the symptomatic patients, the observers concummed on the true-positive findings in three of the nine subjects (33.3%) and on the true-negative findings in two of six subjects (33.3%). This result brings into question the interobserver variability. At the second evaluation, observer A concurred with himself in five of the nine patients (55.6%) with true-positive findings (three true-positive and two falsenegative findings) and in two of six patients (33.3%) with true-negative findings (two with false-positive findings). Observer B concurred with himself in seven of the nine patients (77.8%) with true-positive findings (six true-positive and one false-negative finding) and in four of six patients (66.6%) with true-negative findings (two true-negative and two false-positive findings). While the ability to correctly identify the presence of a tear was poor, grading of teams was even worse. Observer A correctly graded two of four tears (two of nine lesions) and observer B correctly graded four of seven (four of nine lesions). Figure 3 is an image of a grade I tear that neither observer correctly interpreted. Figure 4 is an image of a labrum that was incorrectly interpreted as a tear by observer B and correctly interpreted as normal by observer A.

Figure 1. MR image of normal shoulder of an asymptomatic volunteer. The anterior Iabrum (arrowhead) is pointed. There is signal intensity at the junction of the fibrous labrum and the anticulan cartilage of the glenoid, which is a normal finding. The postenor labrum (arrow) is rounded.

Figure 2. MR image of an abnormal shoulden. Surgical examination demonstrated an anterior labral tear. A segment of anterior labrum (large arrow) is separated from the remainder of the labrum by an area of intermediate signal intensity (small arrow).

Figure 3. MR image of a surgically proved grade I anterior labral tear. There is signal intensity within the anterior labrum (annow), but both observers decided that this signal intensity was within normal limits and read the study as negative.

Figure 4. MR image of a surgically proved normal anterior labrum. Observer A interpreted the signal intensity within the antenor labrum (arrow) as indicating a tear, while observer B interpreted the labrum as being normal.

specificity

cannot

performance

DISCUSSION In 1923

Bankant besion”-that is, the single abnormality responsible for recurrent subluxation and dislocation of the shoulder-is a lesion of the glenoid labrum. Subsequent investigators have proposed the anterior capsule (7,8), the subscapulanis muscle (9), or the anterior glenohumeral ligaments (10) as the essential structure of glenohumenal (5,6)

and

proposed

joint

that

stability.

denies labrum

again

Kohn

the importance in shoulder

symptoms.

Current

ion

consensus

varies;

cate that sponsible 520

a

in 1938,

the

“essential

(11)

orthopedic appears

there is no one for glenohumeral

Radiology

specifically

of the gienoid stability and opinto

mdi-

structure nestability.

Labral tears continue to be considered a source of pain by many orthopedic surgeons (12-14). Even if an isolated labral team is considered insignificant, labral tears are, in fact, seldom isolated. The presence of a labral lesion often indicates an underlying anterior capsule disruption. Double-contrast arthrography (15,16), arthrotomography (17-22), computed anthrotomography (20,2333), MR imaging (1-3), and MR anthrognaphy (34) have all been used to evaluate the glenoid labrum. Kieft et al (2) reported a sensitivity and specificity

of

100%

in

the

MR

evaluation of the glenoid Seeger et ab (1) reported of

100%;

erence

they

had

for negative

no

imaging

standard

have

of

at

tenpreting the

the

patients

so

we

investigators (c)

MR

differences

obogy

Other our

of

our

ex-

in in-

alone,

had

patients

to

interpret);

images

research

our

Ia-

possible

(b) variation

chance

in

in

glenoid

radiologists observers

images;

between

that

three

have

“easier”

achieved

of the

(by

in other

with and

method-

investigation

and

others. cannot

dismiss

However,

penienced nef-

than

in

numbers

groups.

least

(a)

better

MR

labrum

MR evaluation

were

The of

the

results

planations:

ity.

of

other

poor

brum

calculated.

glenoid

short by

The

We

labrum. a sensitivity

the

fell

achieved

imaging

examinations,

of

hands

the

be

characteristics

and

were

tab

radiologists,

the

our in

MR

observers image

subspecialist and

first

possibil-

were

ex-

interpretation

muscuboskeletheir

performance

May

1991

Table 1 Subject-Specific

Evaluations

of Labral

Tears

Observer

Standard of Reference

Patient

in Symptomatic

Observer

2nd Evaluation

1st Evaluation

+,II

TP

TP5

TPt

TP5

+,1I

TP

FN

TP

TP

3 4

+,II +,II

FN FN

TP TP

TP* TP*

TP TP

5

+,I

TP*

TP

TP

TP5

6

+,I

T

TP*

FN

TI’5

7

+,I

FN

TP5

TP

TP

8 9

+,I +,I

FN FN

FN FN

TI’ FN

FN FN

-

TN

FP

TN

TN

-

TN

FP

TN

TN

TN TN FP FP

FP FP FP FP

FP FP TN TN

FP Fl’ FP FP

-

= positive at surgery or arthroscopy for labral tear, tear or presumed normal. I grade I labral tear (labrum grade II labral tear (absent labrum). TP true-positive findings, false-positive findings, TN true-negative findings. a The observer also made a correct determination of grade.

Table Initial

2 MR Imaging

Findin

gs for All

Negativet

Volunteers

Subjects Finding

Patients

at MR Imaging Observer Positive

Positive5 A

Negative

Observer

4

2

0

5

4

9

7 2

2 4

1 8

B

Positive Negative

Positive Negative

at surgery at surgery

for labral tear. for labral tear.

did not improve with experience or time (indeed, their performance deteriorated at the second reading). may well be that others are more skilled at interpretation of MR images of the glenoid and are able to obtain better results. An important issue,

cate

however,

the

ogists

is whether

technique (or

even

for general all

It

to advo-

radiol-

muscuboskeletal

ra-

diobogists), and our results indicate that at least some subspecialists will have significant difficulties with interpretation of MR images of the labrum. It is of note that by obtaining MR images of the babrum before administration tmast material,

of intracapsular conFlannigan et al (34)

achieved a sensitivity much more comparable

33%, our mesults than those of Kieft et al (2) and Seeger et al (1). It is also of note that our interpreters could differentiate images from patients from those of asymptomatic volunteers quite well, an

observation

Volume

2nd

Evaluation

1

Note.-+ for labral

a

1st Evaluation

B

2

10 ii 12 13 14 15

t

Patients

A

179

that

a

Number

of only with

suggests

2

some

-

negative

at surgery

or arthroscopy

separated from articular surface), FN false-negative findings,

II FP

-

skill in the interpretation of images. Simply because a test may help distinguish healthy volunteers from patients, however, does not mean that the test will help distinguish patients with a particular disease from patients without a particular disease (35). Small sample sizes result in large CIs, and whereas the sensitivity on initial reading of observer A, for example, was 44.4%, the 95% CI was 13.7%, 78.8%. It may be that the labra of our patients were, by chance alone, more difficult to evaluate with use of MR imaging, and that MR imaging is a better test than is suggested by our results. It is also possible that other investigators have results similar to ours, but have not published their data because of the tendency to submit positive results. This would lead to a bias in the literature, with publication of those studies that, by chance alone, showed MR imaging of the glenoid to be efficacious. There are important differences in research methodology between our study and those of Kieft et ab (2) and Seeger et al (1). Kieft et al used a lowem field strength magnet (0.5 T vs 1.5 T) and thicker sections (5 mm vs 3 mm), but our studies were comparable with respect to imaging sequences, number of signal acquisitions, and matrix size. The images from the studies of Kieft et al and Seeger et al were interpreted by two radiologists in conference; our interpretems performed independently. Since (at least at the initial interpretation) one of our readers consistent-

ly undercabbed lesions while the othen consistently ovemcalied them, confemence interpretation may have improved our results. On only one case were both interpreters incorrect: both reported the images of one patient as negative (Fig 3), and at sumgery the patient was found to have a labmal tear. Assuming that the correct interpreter would have been able to convince the incorrect interpreter to change his mind (which may not have been the case), conference reading would have significantly improved sensitivity and specificity. In practice, most radiology intempretations are performed by a single radiobogist rather than by a team. Seeger et al (1) also report much better results of evaluation of the glenoid labrum with MR imaging. Their technique was very similar to ours with respect to section thickness and imaging plane; they used a lower field strength magnet (0.3 T vs 1.5 T) and a somewhat smaller field of view (17-19.2 cm vs 24 cm). However, the MR examination was used to determine whether the patients needed surgery; all 27 patients who underwent surgery in this retrospective study had positive MR imaging examinations. Limiting results to those with positive tests could significantly adversely affect the calculated sensitivity and specificity. Kieft et al (2) and Zlatkin et al (36) have observed that MR imaging cannot demonstrate the capsule insertion site in the absence of an effusion or arthmogram. Although we agree with Kieft et al that capsular stripping (or normal variation with the anterior

capsule

insertion

at

a point

other than on the labmum) will not require an arthrotomy in the absence of labmal abnormality, the converse is not true. Thus, if a patient has an abnormal labrum and a tight anterior capsule that inserts at the labrum, amthroscopic surgery is an option, whereas insertion of the capsule on the neck of the scapula (type II or III capsular insertion) precludes simple anthroscopic repair. Regarding technique, we used a 24-cm field of view for the following reasons: (a) Early in the study, use of a smaller field of view and thin sections damaged the gradient coils of our machine; (b) other investigators used a 24-cm field of view for study of the shoulder; and (c) a smaller field of view increases resolution but decreases signal-to-noise ratio (37). It is possible that a smaller field of view would result in increased image quality. Radiology

a

521

In conclusion, in our small series we found MR imaging to be insensitive and nonspecific in the evaluation of labral abnormalities. Since theme is presently a minimally invasive alternative that evaluates both the labmum and the capsule insertion site-CT arthmography-we do not believe that MR imaging should be the procedure of choice to evaluate the glenoid labrum. MR arthmography represents an alternative, but since it is as invasive and more costly than CT arthrography, while probably being no more sensitive or specific for glenoid labrum abnormalities, we advocate CT amthmogmaphy as the examination of choice for labral abnommalities. Further studies with more patients and, possibly, use of different imaging parameters (eg, a smaller field of view) will be helpful in determining the true utility of MR imaging in the evaluation of the glenoid labrum. U

dislocation Sung [Br] 9.

Seeger LL, Gold RH, Bassett LW. Shoulden instability: evaluation with MR imag-

2.

Kieft

ing.

WR.

Radiology GJ,

1988;

Bloem

10.

11 .

Rozing

MR imaging

dislocation with CT

PM,

13.

14.

shoulder:

15.

AJR

anterior

Munk

HK. with

4.

5.

6.

7.

8.

PL,

Holt

Glenoid use

GR,

Helms

labrum:

CA,

16.

18.

of radial-sequence

ASB.

Recurrent

Moseley capsular

HF, Overgaand mechanism

imaging.

transient J Bone Joint

on habitual

cation of the shouiden joint. 1923; 2:1132-1133. Bankart ASB. The pathology ment of recurrent dislocation den. Br J Sung 1938; 26:23-29. Townley CO. The capsular recurrent dislocation of the Bone Joint Sung [Am] 1950; in

19.

work

MR

Radiology 1989; 173:751-753. Rowe CR, Zanins B. Recurrent subluxation of the shoulder. Sung [Am] 1981; 63:863-871. Bankant

Genant

preliminary

20.

dislo-

Br Med 21.

and treatof the shoulmechanism shoulder. 32:370-380.

B. The recurrent

anterior anterior

in

significance

of

SJ,

Panio

MW,

Pappas

Marshall

JL,

Goss

TP,

Goldman

a

Radiology

27.

shoulder

B.

The

arthrogram.

3:

PK,

Kanzania

El-Khouny

GY,

PK,

Goss

Shuman

WP,

M,

M,

Chandler

Kilcoyne

RF,

Matsen

RaC, et al. struc-

1986;

JJ.

Callaghan shoulder:

146:361-

CT anthrog-

variations

AJR

Firooznia

1987;

H,

in

injuries:

graphic

findings.

Radiology

the

149:963-966.

JJ, et al.

Bonamo

shoulder

Singson

RD.

ZS.

CT

anthno1987;

162:

M,

34.

35.

Sports

Med

Pennes

DR.

in neAJR

J, et al.

(CT) arthrognaphy in athletes.

1988;

Wilson

AJ,

Totty

external

1989;

WG,

WA,

Handy

anthrographic

follow-up,

WJ,

notation

153:1017-1019.

Murphy

joint:

long-term

Ribbans

and AJR

Shoulder

K, et al.

of the of examinations

internal

humerus.

of Am

K, Buckwalter

comparison

with

Corn-

16:352-361.

Jonsson

anthrotomography

with

CT surgical

Radiology

1989;

173:329-333.

Mitchell

R, Taylor

GJ.

Corn-

putenised arthnotornognaphy of primary anterior dislocation of the shoulder. BoneJoint Sung [Br] 1990; 72:181-185. Flannigan B, Kursunoglu-Brahme S. Snyden S. Kanzel R, Del Pizzo W, Resnick D. MR anthnognaphy of the shoulder: cornpanison with conventional MR imaging. AJR 1990; i55:829-832. Riegelman study and

medical Brown, 36.

J, Bonamo

tomography instabilities

DC.

33.

L, Rosen-

patterns instability.

Minkoff

puted shoulder

and

F, Bigliani

149:749-753.

Rafii

of the 32.

Feldman

CT anthrographic glenohumenal

1987; 30.

RK, testing

Hirsch RP. Studying a test: how to read

literature. 2nd 1989; 135-147.

Zlatkin M, V. Resnick imaging

of

Bjorkengren D, Santonis the

glenohurneral

Pap-

JB, Al-

D, et al.

shoulder.

AJR

Athlete

correlation.

bright JP. Shoulder instability: impact of glenohumeral anthrotomognaphy on treatment. Radiology 1986; 160:669-673. 23.

Rafii

Resnick

H, Golimbu of the capsular

labrum.

shoulder:

arthrotomognaphy of AJR 1984; 141:993-

Kathol

LM, of the

current

Yousef

TP,

Ia-

RadioGnaphics

AL,

shoulder.

Computed

MM, Montgomery WJ, Tuck SL. Arthrotomography of the glenoid labnum. Radiology 1979; 131:333-337. McGlynn FJ, Ei-Khoury GY, Albnight JP. Anthrotomography of the glenoid labrum in shoulder instability. J Bone Joint Sung [Am] 1982; 64:506-518. Braunstein EM. O’Connor G. Doublecontrast arthrotomography of the shoulden. J Bone Joint Sung [Am] 1982; 64:192195. Deutsch AL, Resnick D, Mink JH, et al. Computed and conventional anthrotomography of the glenohumeral joint: nonmal anatomy and clinical experience. Radiology 1984; 153:603-609. Kleinman

29.

double-

Abu

con-

glenoid

559-564.

Radiology

JP,

Double the

of the 4:963-976.

1984;

of the

367. McNiesh

made

Albnight

Deutsch

Rafii M, Firooznia CT anthrognaphy

gienoid

127:655-663.

GY,

girdle.

CS,

berg

Mink JH, Richardson A, Grant TT. Evaluation of the glenoid labrum by doublecontrast shoulder anthrography. AJR 1979; 133:883-887. El-Khoury

Resnik

naphy

31. Ghelman

shoulder

and

tunes

PK.

Rogers JV. Mack LA. Double-contrast computed tomography of the glenoid brum. AJR 1983; 141:581-584.

522

26.

Girgis

15:579-585. AB,

WP. of

Arthnotomography dioGraphics

Symptomatic shoulder instability due to lesions of the glenoid labrum. Am J Sports Med 1983; 11:279-288. Garth WP, Aliman FL, Armstrong WS. Occult anterior subluxations of the shoulden in noncontact sports. Am J Sports Med

pas AM. Axillary the glenoid labrum. 999. 22.

Kleinman

Shuman

anthrography

1984; 4:411-421. 25.

28.

AM,

DR, CT

bnum

the

Andrews JR. Carson WG, McCleod WD. Glenoid labrum tears related to the long head of the biceps. Am J Sports Med 1985; 13:337-341.

1978;

1083-1087. 3.

The

Haynor trast

FG. Stabilizing mechanisms preventing anterior dislocation of the glenohumeral joint. J Bone Joint Sung [Am] i98i; 63: 1208-1217. Kohn D. The clinical relevance of glenoid labnum lesions. Anthroscopy 1987;

contrast

17.

comparison 1988; i50:

Turkel

1987;

Obenmann

of recurrent

of the anthrography.

PP.

24.

Joint

223-230.

12.

168:695-697.

JL,

Symeonides

J Bone

subscapulanis muscle in the pathogenesis of recurrent anterior dislocation of the shoulder. J Bone Joint Sung [Br] 1972; 3: 476-483.

References 1.

of the shoulder. 1962; 4:913-927.

ed.

Little,

AG, Gylys-Monin DJ. Cross-sectional

capsular joint.

Boston:

a the

mechanism AJR

1988;

of the 150:151-

158. 37.

Wood VM,

ed.

aging.

ML. Imaging technique. In: Clinical magnetic resonance

Philadelphia:

Lippincott,

Runge im-

1990;

477-500.

FA,

la-

May

1991

Glenoid labrum: evaluation with MR imaging.

Fifteen patients with shoulder instability and nine asymptomatic volunteers were studied with magnetic resonance (MR) imaging. The shoulder joint was ...
826KB Sizes 0 Downloads 0 Views