MR Imaging of the Rotator Cuff.

The cause of rotator cuff tears is multifactorial with both intrinsic and extrinsic contributing factors. Understanding the normal MR anatomy of the rotator cuff and using an appropriate search pattern can help readers identify common pathologic conditions. Accurate designation using classification systems for tear thickness, size, and degree of retraction and muscle fatty infiltration and atrophy are important in guiding surgical management. Knowledge of common disease locations for the rotator cuff tendons can help focus reader searches and increase sensitivity.

Thrower's Shoulder: An Approach to MR Imaging Interpretation.

In this article, the authors aim to focus on the challenges of interpreting shoulder MR imaging in the throwing athlete with an approach formed by evidence-based literature and clinical experience, with a particular focus on superior labrum tears.

Diagnostic performance of shoulder magnetic resonance arthrography for labral tears having surgery as reference: comparison of high-resolution isotropic 3D sequence (THRIVE) with standard protocol.

PURPOSE: To compare the diagnostic performance of T1 high-resolution isotropic volume excitation (THRIVE) sequence with that of a standard protocol for direct shoulder magnetic resonance arthrography (MRA) for the diagnosis of superior labral anterior-to-posterior (SLAP) and Bankart lesions, using arthroscopy findings as a reference standard. MATERIALS AND METHODS: We retrospectively studied 84 patients who underwent direct shoulder 3T MRA using THRIVE and two-dimensional three-plane proton-density fat-suppressed (2D-PD-FS) sequences. One reviewer evaluated the contrast-to-noise ratio (CNR) as a quantitative image quality. Other two reviewers independently evaluated the subjective image noise, image sharpness, and radiologic diagnosis as qualitative image quality. Arthroscopic surgical findings were considered the reference standard. Wilcoxon rank sum, Chi-square/Fisher's exact, and DeLong's tests, as well as intraclass correlation coefficients (ICCs) were used to evaluate differences between THRIVE and 2D-PD-FS images. RESULTS: THRIVE images had significantly higher CNR (p < 0.001), and subjective ratings of image noise (p = 0.009) and sharpness (p = 0.039) than 2D-PD-FS images (p < 0.001). THRIVE images had similar (p ≥ 0.18) diagnostic performance (sensitivity, 93.0-97.2%; specificity, 95.8-100%; accuracy, 95.2-97.6%) for the diagnosis of SLAP and Bankart lesions with excellent agreement (ICC = 0.898-0.942) when compared to 2D-PD-FS images (sensitivity, 86.1-91.7%; specificity, 93.8-95.8%; accuracy, 90.5-92.9%; agreement, ICC = 0.782-0.858). The scan time was reduced by 69% for THRIVE sequence compared to 2D-PD-FS sequence (2 min 40 s vs. 8 min 40 s). CONCLUSION: The THRIVE sequence may be helpful in the diagnosis of SLAP and Bankart lesions, and may be routinely used during direct shoulder 3T MRA.

Imaging of shoulder instability.

This extended review tries to cover the imaging findings of the wide range of shoulder injuries secondary to shoulder joint instability. Usefulness of the different imaging methods is stressed, including radiography, computed tomography (CT) and magnetic resonance. The main topics to be covered include traumatic, atraumatic and minor instability syndromes. Radiography may show bone abnormalities associated to instability, including developmental and post-traumatic changes. CT is the best technique depicting and quantifying skeletal changes. MR-arthrography is the main tool in diagnosing the shoulder instability injuries.

Posterior Decentering of the Humeral Head on Shoulder MR Arthrography: Significant Association With Posterior Synovial Proliferation.

OBJECTIVE: The purpose of this study is to analyze MRI findings associated with posterior decentering of the humeral head on shoulder MR arthrogram. MATERIALS AND METHODS: A total of 255 MR arthrograms were obtained during a 10-month period. MR arthrograms in patients with posterior decentering of the humeral head (n = 33) were reviewed and compared with those of randomly selected control group without posterior decentering (n = 66). MR arthrograms were retrospectively evaluated by two observers for posterior factors (posterior synovial proliferation, posterior capsular thickening, and posterior labral abnormality), rotator cuff factors related to fatty degeneration, glenoid version, and anterior factors (subcoracoid bursa effusion and rotator interval tear). The chi-square test, Fisher exact test, and linear-by-linear association were used for comparison of categoric data; the t test was used for comparison of the glenoid version; and multivariate stepwise logistic regression analysis was performed. RESULTS: At univariate analysis, posterior synovial proliferation (27.3% [9/33] in the posterior decentering group vs 6.1% [4/66] in the control group; p = 0.003); posterior capsule thickening (21.2% [7/33] vs 0.0% [0/66]; p < 0.001); fatty infiltration of the supraspinatus, infraspinatus, and teres minor (linear-by-linear association values, 7.944, 10.496, and 5.985, respectively; p = 0.005, 0.001, and 0.014, respectively); and rotator interval tear (51.5% [17/33] vs 30.3% [20/66]; p < 0.04) were more frequently found in the posterior decentering group, with a statistically significant difference. At multivariate analysis, only the posterior synovial proliferation was significantly associated with posterior decentering of the humeral head (odds ratio, 7.675; 95% CI, 2.159-27.288). CONCLUSION: Posterior decentering of the humeral head is most significantly associated with posterior synovial proliferation. In addition, rotator cuff interval abnormalities and rotator cuff atrophy are associated with posterior decentering of the humeral head to a lesser extent. Awareness of the association of the posterior decentering of the humeral head with the factors described here will facilitate the effective interpretation of routine MR arthrograms in daily practice.

Ultrasound-guided shoulder MR arthrography: comparison of rotator interval and posterior approach.

PURPOSE: The purpose of this study was to prospectively evaluate the two different ultrasound-guided injection techniques for magnetic resonance (MR) arthrography of the shoulder. METHODS AND MATERIALS: This study included 100 patients [50 rotator interval group (n=50) vs. 50 posterior approach group (n=50)]. All procedures were performed by the same radiologist. The two injection techniques were compared. The discomfort during and after arthrography was evaluated. Extraarticular contrast media extravasation was graded according to the MRI findings. The number of injection attempts, effect of contrast media extravasation rate on diagnostic quality and procedure times were recorded. RESULTS: There were no significant difference between the posterior and rotator interval puncture groups with regard to pain (P=.915), procedure times (P=.401) or attempt scores (P=.182). There were significantly more contrast media extravasations with rotator interval approach than posterior approach (P<.05). CONCLUSION: Both techniques were successful and well tolerated by patients. Posterior injection technique provided a more effective route with decreased extravasation rate and easier approach compared to the rotator interval approach.

Evaluation of the SLAP Lesion Using a Low-field (0.2T) Magnetic Resonance System

PURPOSE: To evaluate the diagnostic capabilities of the low-field (0.2T) magnetic resonance (MR) system in the detection of the superior labrum anterior to posterior (SLAP) lesion. MATERIALS AND METHODS: One hundred fifty patients underwent magnetic resonance imaging of the shoulder over a 7-month period. Forty-six patients underwent arthroscopic surgery, and the surgical results were correlated with the findings of the MR imaging. Arthroscopic procedures were performed within a mean of 8 days after MR imaging. MR imaging of the shoulder was conducted as follows: shoulder coil; T1-weighted spin echo, coronal-oblique images; T2-weighted gradient echo, coronal-oblique and axial images; and T2-weighted spin echo, coronal-oblique and sagittal-oblique images. Prospectively, one radiologist interpreted the MR images. RESULTS: The results of surgery were as follows: SLAP II in 26 shoulders, SLAP III in 1 shoulder, SLAP IV in 1 shoulder, normal labrum in 6 shoulders. For SLAP lesions with a higher grade than type 2, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the low-field MRI were 85.7%, 55.5%, 75%, 71%, and 74%, respectively. CONCLUSION: There was relatively good agreement for the comparison of the MR results obtained using a low-field MR system with the surgical findings for identifying SLAP lesions.

Superior Labrum Anterior to Posterior Lesion Type II with Accompanied Findings: Assessment of Shoulder MR Arthrographic Findings

PURPOSE: To describe the pattern of various shoulder abnormalities with an associated superior labrum anterior to posterior (SLAP) lesion type II using magnetic resonance (MR) arthrography, and to assess the clinical significance of the associated abnormalities. MATERIALS AND METHODS: A retrospective review of the MR arthrographic findings of 92 cases of a shoulder with an arthroscopically confirmed SLAP lesion type II was performed. The MR arthrography images were reviewed and analyzed. MR arthrographic analysis noted the presence of a rotator cuff abnormality, acromioclavicular arthritis, adhesive capsulitis, glenohumeral arthritis, a labral abnormality besides the SLAP lesion, and a paralabral cyst. The patients with SLAP lesions were divided into two age groups: those over 40 years of age and those forty years old or younger. Statistical analysis was performed to evaluate the influence of age on the various shoulder abnormalities with associated SLAP lesion. RESULTS: Of the 92 SLAP lesions type II, there were 7 cases (8%) of isolated SLAP lesions without any associated any shoulder abnormality. Eighty-five (92%) SLAP lesions were associated with various shoulder abnormalities including rotator cuff tendinosis (30/92, 33%), partial-thickness tear (36/92, 39%), full-thickness tear (2/92, 2%), acromioclavicular arthritis (46/92, 50%), adhesive capsulitis (7/92, 8%), glenohumeral arthritis (15/92, 16%), labral abnormality (26/92, 28 %) and paralabral cyst (7/92, 8%). The SLAP lesions (60/92, 65%) in patients over forty years of age were accompanied by a significantly high number of rotator cuff abnormalities (p < 0.001), glenohumeral osteoarthritis (p = 0.001), and acromioclavicular osteoarthritis (p < 0.001). In contrast, the SLAP lesions (32/92, 35%) in patients forty years old or younger had a significantly high number of anterior or posterior labral lesions (p < 0.001). CONCLUSION: Isolated SLAP lesions type II without other associated shoulder abnormalities are uncommon, and the age of the patient influences the prevalence of other shoulder abnormalities associated with SLAP lesions. In addition, MR arthrography can help detect shoulder abnormalities accompanying the SLAP lesions.

Feasibility of Ultrasonography and MR Arthrography during Evaluation of Rotator Cuff Injury

PURPOSE: To evaluate the feasibility of MR arthrography and ultrasonography in evaluating shoulder pain. MATERIALS AND METHODS: The subject group consisted of all patients who visited our institute complaining of shoulder pain or instability from June 2002 to December 2004. There were a total of 92 patients with a mean age of 48. On the basis of arthroscopic results, the sensitivity, specificity, and accuracy of ultrasonography and MR arthrography were evaluated by comparing them with each other. RESULTS: In the diagnosis of supraspinatus tendon tears, ultrasonography had sensitivity and specificity of 100% and 64%, respectively, whereas MR arthrography had sensitivity and specificity of 80% and 94%, respectively. Ultrasonography also had high sensitivity and specificity in the diagnosis of subscapularis tendon tears (100% and 90%). MR arthrography was appropriate for identifying glenoid labral abnormalities (sensitivity, 95% and specificity, 61%). Similar results from ultrasonography and MR arthrography were obtained in the diagnosis of subscapular tendon tears or full-thickness tears of the rotator cuff tendons (kappa value, 0.644 and 0.911). CONCLUSION: While evaluating rotator cuff abnormalities, ultrasonography was appropriate for screening, whereas MR arthrography was useful to confirm the results of the ultrasonography.

Anterior Labral Tear: Diagnostic Value of MR Arthrography of the Shoulder

PURPOSE: To assess the accuracy of magnetic resonance(MR) arthrography in the diagnosis of anterior labral tear of the shoulder. MATERIALS AND METHODS: Between Semptember 1996 and February 2000, MR arthrography of the shoulder was performed in 281 patients with a history of shoulder pain or instability. Among this total, only 157 shoulders in 154 patients who underwent arthroscopy or open surgery 0 to 230 (average, 20.9) days after MR arthrography were included in this study; the subjects comprised of 150 males and 4 females with an average age of 23.3 years. MR arthrographs of these 154 patients were analyzed for the presence of anterior labral tears, and the findings were correlated with the arthroscopic and surgical findings. Anterior labral tear was classified as A to D according to its location, as determined by arthroscopy and surgery. (A=4 to 6 o 'clock direction, anteroinferior; B=2 to 4 o 'clock direction, central; C=12 to 2 o 'clock direction, anterosuperior; D= SLAP lesions). The retrospective analysis of MR arthrographs showing false-positive and negative findings was also undertaken. RESULTS: In the diagnosis of anterior labral tear, MR arthrography showed a sensitivity of 94%, a specificity of 90% and an accuracy of 91%. Anterior labral tears were confirmed by arthroscopy or surgery in 62 of the 157 shoulders (39%). Among 62 lesions, two (3%) were observed in area A, 32(52%) in area A+B, nine (15%) in area A+B+C, one(2%) in area A+B+D, 13(21%) in area A+B+C+D, two (3%) in area B+C, one(2%) in area B+D, and two(3%) in area C. Among ten false-positive cases, seven were focal lesions (two, three and two lesions in area A, B and C, respectively), and in the remaining three cases, located in area A+B, MR arthrography revealed thickening and deformation. All four false negatives were focal lesions (two in area A and two in area C). CONCLUSION: Other than in focal lesions, in which accuracy was relatively low, MR arthrography showed high sensitivity, specificity and accuracy in the diagnosis of anterior labral tear of the shoulder.

Adhesive Capsulitis of the Shoulder: MR Arthrography

PURPOSE: Adhesive capsulitis is a clinical syndrome involving pain and decreased joint motion caused by thickening and contraction of the joint capsule. The purpose of this study is to describe the MR arthrographic findings of this syndrome. MATERIALS AND METHODS: Twenty-nine sets of MR arthrographic images were included in the study. Fourteen patients had adhesive capsulitis diagnosed by physical examination and arthrography, and their MR arthrographic findings were compared with those of 15 subjects in the control group. The images were retrospectively reviewed with specific attention to the thickness of the joint capsule, volume of the axillary pouch (length, width, height(depth)), thickness of the coracohumeral ligament, presence of extra-articular contrast extravasation, and contrast filling of the subcoracoid bursa. RESULTS: Mean capsular thickness measured at the inferior portion of the axillary pouch was 4.1 mm in patients with adhesive capsulitis and 1.5 mm in the control group. The mean width of the axillary pouch was 2.5 mm in patients and 9.5 mm in controls. In patients, the capsule was significantly thicker and the axillary pouch significantly narrower than in controls (p<0.05). Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch (sensitivity 93%, specificity 80%) and a pouch narrower than 3.5 mm (sensitivity 93%, specificity 100%) were useful criteria for the diagnosis of adhesive capsulitis. In patients with this condition, extra-articular contrast extravasation was noted in six patients (43%) and contrast filling of the subcoracoid bursa in three (21%). CONCLUSION: The MR arthrographic findings of adhesive capsulitis are capsular thickening, a low-volume axillary pouch, extra-articular contrast extravasation, and contrast filling of the subcoracoid bursa. Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch and a pouch width of less than 3.5 mm are useful diagnostic imaging characteristics.

Comparison of Shoulder Positions at MR Arthrography: Change of Labroligamentous Complex Shape and Diagnosis of Labral Tears

PURPOSE: To compare the neutral, internal, and external rotation positions of the glenohumeral joint during magnetic resonance (MR) arthrography performed to assess changes in the shape of the labroligamentous complex (LLC) and in the labral tear. MATERIALS AND METHODS: MR arthrography of the shoulder was retrospectively evaluated in 36 patients aged 14-66 (mean, 40) years. Fourteen cases were confirmed by arthroscopic surgery (7 SLAP lesions, 2 Bankart lesions, 1 both SLAP and Bankart lesions). Axial fat-suppressed T1-weighted spin-echo images were acquired with each shoulder in the neutral position, and with internal and external rotations. In each position, we measured the angle of rotation between the perpendicular line on the glenoid fossa and the long axis of the humeral head, analyzing the relationship between the rotational angle and changes in the shape of the LLC at each internal and external rotation, relative to the neutral position. In addition, labral tears in 14 arthroscopically confirmed joints were evaluated in each position. RESULTS: Mean angles of rotation relative to the neutral position were 44.1 and 45.3 degrees in internal and external rotation, respectively. Changes in the anterior LLC occurred in 25 and 24 cases of internal and external rotation, respectively. There was a significantly meaningful relationship between rotational angle and change in the shape of the anterior LLC during external rotation, and when this change was noticed, the rotational angle was wider (p<0.05). The posterior LLC changed in shape in 13 and 16 cases of internal and external rotation, respectively, but changes according to the angle of rotation were not statistically significant. In arthroscopically confirmed joints, diagnosis of the eight SLAP lesions at external rotation tended to become more accurate, but no statistically significant differences were noted (p=0.07). Two Bankart lesions were interpreted as a tear in all three positions, and one other such lesion was interpreted as a tear in the neutral position and at external rotation, and a possible tear at internal rotation. CONCLUSION: In shoulder MR arthrography, changes in the shape of the anterior LLC were statistically prominent according to the angle of external rotation, and accuracy of diagnosis in SLAP lesions tended to be significantly higher at external rotation. If a SLAP lesion causes clinical concern, additional axial MR arthrography with the shoulder externally rotated is suggested.

Comparison between Conventional MR Arthrograhphy and Abduction and External Rotation MR Arthrography in Revealing Tears of the Antero-Inferior Glenoid Labrum

OBJECTIVE: To compare, in terms of their demonstration of tears of the anterior glenoid labrum, oblique axial MR arthrography obtained with the patient's shoulder in the abduction and external rotation (ABER) position, with conventional axial MR arthrography obtained with the patient's arm in the neutral position. MATERIALS AND METHODS: MR arthrography of the shoulder, including additional oblique axial sequences with the patient in the ABER position, was performed in 30 patients with a clinical history of recurrent anterior shoulder dislocation. The degree of anterior glenoid labral tear or defect was evaluated in both the conventional axial and the ABER position by two radiologists. Decisions were reached by consensus, and a three-point scale was used: grade 1=normal; grade 2=probable tear, diagnosed when subtle increased signal intensity in the labrum was apparent; grade 3=definite tear/defect, when a contrast material-filled gap between the labrum and the glenoid rim or deficient labrum was present. The scores for each imaging sequence were averaged and to compare conventional axial and ABER position scans, Student's t test was performed. RESULTS: In 21 (70%) of 30 patients, the same degree of anterior instability was revealed by both imaging sequences. Eight (27%) had a lower grade in the axial position than in the ABER position, while one (3%) had a higher grade in the axial position. Three whose axial scan was grade 1 showed only equivocal evidence of tearing, but their ABER-position scan, in which a contrast material-filled gap between the labrum and the glenoid rim was present, was grade 3. The average grade was 2.5 (SD=0.73) for axial scans and 2.8 (SD=0.46) for the ABER position. The difference between axial and ABER-position scans was statistically significant (p<0.05). CONCLUSION: MR arthrography with the patient's shoulder in the ABER position is more efficient than conventional axial scanning in revealing the degree of tear or defect of the anterior glenoid labrum. When equivocal features are seen at conventional axial MR arthrography, oblique axial imaging in the ABER position is helpful.

Subchondral Cysts of the Humeral Head: MR Imaging Findings

PURPOSE: To evaluate the findings of subchondral cyst of the humeral head, as seen on shoulder MRarthrography MATERIALS AND METHODS: Sixty-three patients( M:F=62:1 ; mean age 23 years) who underwent shoulder MRarthrography between September 1996 and May 1998 were retrospectively reviewed. No patient had a history of eithershoulder dislocation or certain diseases known to be commonl accompanied by subchondral cysts. All MR images wereobtained using a 1.5 Tesla unit after intraarticular injection of 20ml of diluted contrast material. T1 andT2-weighted axial, oblique coronal, and oblique sagittal images were analysed for the presence, location, number,shape, size, and connection to the joint cavity of subchondral cysts. RESULTS: We identified 58 subchondral cystsin 43(71.7%) of 63 cases. All were located in the posterolateral portion of the humeral head, and on the physealline. Twenty-eight patients(65.1%) had one cyst, and 15(34.9%) had two. Thirty-four cysts(58.6%) were round orovoid in shape and, 2-8mm in diameter(average, 3.9mm) ; 24(41.4%) were lobulated and 3-10mm in diameter(average5.3mm). Fifty-three cysts(91.4%) were connected to the joint cavity. CONCLUSIONS: In symptomatic patients, the incidence of subchondral cyst of the humeral head was 71.7%. All were located in the posterolateral portion, andon the physeal line. Most subchondral cysts were connected with the joint cavity.

Ganglionic Cysts Related to the Scapula: MR Findings

PURPOSE: To evaluate the magnetic resonance (MR) imaging characteristics of ganglionic cysts related to thescapula. MATERIAL AND METHOD: We retrospectively reviewed 15 ganglionic cysts diagnosed by MR imaging in 14pa-tients who subsequently underwent surgical excision (n=8) or needle aspiration (n=1). Five other patients whoselesion-related symptoms were not too severe to manage underwent conservative treatment. We ana-lyzed MR findingswith regard to the size, shape and presence of internal septa, the location and signal intensity of the lesion,and associated findings such as change of rotator cuff muscle, labral tear and bone erosion. We also evaluated thepresence of tear of rotator cuff tendon, tendinosis, and subacromial enthesophyte. RESULTS: The diameter ofganglionic cysts was 0.5 -5.5 (mean, 2.8)cm, and they were round (n=2), ovoid (n=6), or elongated (n=7). Whereinternal septa were present (n=13), cysts were lobulated. Lesions were located in both scapular and spinoglenoidnotches (n=9), only in the scapular notch (n=2), only in the spinoglenoid notch (n=2) or within the bone (n=2). Ineleven cases they were very close to the superoposterior aspect of the glenoid labrum (n=11). On T1-weightedimages, all lesions were seen to be iso- or hypointense to mus-cle, while on T2-weighted images, they werehyperintense, resembling joint fluid (n=14), except in one patient with hemorrhage. Associated findings were edemaof the infraspinatus muscle (n=4), pressure erosion of the scapular neck (n=1), and labral tear (n=1). A tornsupraspinatus tendon (n=2), supraspinatus tendinosis(n=3), and subacromial enthesophyte (n=2) were also present.CONCLUSION: MR imaging was helpful in diagnosing ganglionic cysts and detecting associated lesions.

A Study to Assess by Means of MR Arthrography the Causal Relationship between Anterior Capsular Attachment Typeand Anterior Instability of the Glenohumeral Joint

PURPOSE: To evaluate by means of MR arthrography the causal relationship between anterior capsularattach-ment type and anterior instability of the glenohumeral joint. MATERIALS AND METHODS: Sixty-five patients (M:F=64:1; mean age, 23 years), who had undergone shoulder MR arthrography were retrospectively reviewed. There wasno history of traumatic dislocation, and medical records relating to anterior instability were available. Physicalexamination revealed anterior instability in 25 patients(Group A), while in 40 (Group B), this was eithersuspicious or absent. With the aid of general anesthe-sia, 32 patients who had undergone surgery were physicallyexamined. Anterior instability was evident in 16 patients(Group C), and suspicious or absent in the remaining 16(Group D). All images were obtained after in-traarticular injection of Gd-DTPA. Fat-suppressed T1 axial imagingwas used to evaluate anterior capsular at-tachment type at mid and distal three-fourths levels of the glenoidfossa. The causal relationship between ante-rior capsular attachment types and anterior instability was analyzedusing the x2 test RESULTS: In group A, type I was most common at distal three-fourths level, and types I and IIwere equal and more common than type III at mid level. In group B, type I anterior capsular attachment type wasmost com-mon at both mid and distal three-fourths level. In these groups, no statistical significance was notedbetween anterior capsular attachment type and anterior instability (p value 0.611: 0.567). In group C, types I andII were equal and more common than type III at both mid and distal three-fourths level, while in group D, type IIwas most common at mid level, and type I was most common at distal three-fourths level. In these groups, nostatistical significance was noted between anterior capsular attachment type and anterior instability (p val-ue,0.772). CONCLUSION: There was no statistically significant difference between anterior capsular attachment typeand anterior instability of the shoulder joint.

Shoulder Impingement Syndrome: Evaluation of the Causes with MRI

PURPOSE: Various mechanical causes which induce shoulder impingement syndrome have been identified with the help of MRI. The aim of this study is to evaluate the incidence of such causes. MATERIALS AND METHODS: A total of 54 patients with clinically confirmed shoulder impingement syndrome and a normal control group(n=20) without symptoms were included. We evaluated the incidence of hook shaped acromion, low lying acromion, downward slope of the acromion, subacromial spur, acromioclavicular joint hypertrophy, coracoacromial ligament hypertrophy, high cuff muscle bulk, and os acromiale. RESULTS: Among the 54 patients, the following conditions were present: acromioclavicular joint hypertrophy(n=36), coracoacromial ligament hypertrophy(n=20), subacromial spur(n=18), downward sloping of the acromion(n=16), hook shaped acromion(n=11), relatively high cuff muscle bulk(n=6), low lying acromion relative to the clavicle(n=3), and os acromiale(n=1). In the normal control group there were nine cases of acromioclavicular joint hypertrophy, nine of coracoacromial ligament hypertrophy, nine of downward sloping acromion, and three of low lying acromion, but hook shaped acromion, high cuff muscle bulk, and os acromiale were not found. Among 54 patients, the syndrome was due to five simultancous causes in one patient, four causes in two, three causes in 12, two causes in 22, and one cause in 17. CONCLUSION: Hook shaped acromion and subacromial spur are the statistically significant causes of shoulder impingement syndrome. In 69 % of patients, the condition was due to more than one cause.

Subacromial Bursitis with Rice Bodies: A Case Report

Multiple rice bodies in joints or bursae are rarely encountered in patients with rheumatoid arthritis. Wereport the radiologic findings of massive subacromial bursitis with innumerable rice bodies on the right shoulderof a 38-year-old man with rheumatoid arthritis. Subacromial bursography showed markedly distended bursa withmultiple nodular filling defects. Preconstrast CT scanning revealed well-demarcated hypodense lesion withoutcalcification in subacromio-subdeltoid bursa. Multiple rice bodies showed slightly high signal intensity on T1WIand T2WI, and no enhancement after gadolinium injection.

The Utility of MR Imaging of the Shoulder Joint: Comparison of the MR Imaging between Conventional MR Imagingand Arthrographic MR Imaging

PURPOSE: To evaluate the diagnostic value of MRI of the shoulder. MATERIALS AND METHODS: Between January andJune 1997, shoulder MRI and arthroscopy were performed in a total of 48 patients with shoulder pain (n=30) orshoulder instability (n=18). Forty-five were males and three were females; their ages ranged from 16 to 67 (mean32.5) years. The period between shoulder MRI and arthroscopy was between one and 390 (mean, 42.2) days. Twenty-sixpatents underwent MR arthrography (AMR), and 22 conventional MRI(CMR). Each image was analyzed for rotator cuffinjury, glenoid labral injury, SLAP lesion, and biceps tendon injury. RESULTS: On arthroscopy, one disease wasfound in 34 patients, two were found in six, three diseases were found in seven, and one patient had fourdiseases. Arthroscopic diagnosis was as follows: rotator cuff injury, 29 ; SLAP lesion, 12 ; glenoid labralinjury, 10 ; biceps tendon injury, 4 ; subacromial bursitis, 2 ; chronic synovitis, 1 ; adhesive capsulitis, 1 ;superior glenohumeral ligament injury, 1 ; normal, 1. For rotator cuff injury, the sensitivity of MRI was 65.5%and specificity was 93.0% (AMR : 66.7%, 95.8%, CMR : 65.2%, 86.4%). For SLAP lesion, sensitivity was 58.3% andspecificity was 97.2% (AMR : 66.7%, 100%, CMR : 50%, 93.8%) ; for glenoid labral injury, sensitivity was 80.0% andspecificity was 89.5% (AMR : 85.7%, 84.2%, CMR : 66.7%, 94.7%), and for biceps tendon injury, the false negativerate was 100%. CONCLUSION: In cases involving glenoid labral injury, the diagnostic accuracy of shoulder MRI wasrelatively high ; in rotator cuff injury and SLAP lesion, however, diagnosis was limited, and in biceps tendoninjury was difficult. We suggest, however, that MR arthrography has certain diagnostic advantages overconventional MRI.

MR Arthrography of the Labral-Capsular-Ligamentous Complex: Normal Anatomy, Anatomic Variations, and Pitfalls - Preliminary Study

PURPOSE: To evaluate anatomic variations and pitfalls of the labral-capsular-ligamentous complex in the shoulder joint for the proper interpretation of magnetic reasonance arthrographic images. MATERIALS AND METHODS:To determine the presence of sublabral sulci, undercutting of the base of the glenoid labrum by the articular cartilage, and the proximity of the middle glenohumeral ligament to the anterior glenoid labrum, 56 MR arthrograms of 41 asymptomatic volunteers were prospectively evalvated for labral shape and capsular insertion. We also evaluated the axillary fold, which was often confused with a loose body. RESULTS: The anterior and posterior parts of the labra, varied but their shape showed several dominant features; triangular(72%, 36%, respectively), rounded(13%, 35%), cleaved(8%, 1%), notched(2%, 0%), flat(5%, 24%), and absent(0%, 4%). Anterior capsular insertion was type 1 in 82% of cases, type 2 in 13% and type 3 in 5%, whereas posterior insertion was type 1 in 62%, type 2 in 36% and type 3 in 2%. We could also detect many pitfalls, such as undercutting of the base of theglenoid labrum by the articular cartilage(29%), sublabral sulci(25%), a prominent axillary fold(38%), and the middle glenohumeral ligament in proximity to the anterior labrum(5%). CONCLUSION: Our study revealed wide variability in the MR arthrographic appearance of the labral-capsular-ligamentous complex in asymptomatic shoulders. A good understanding of normal variation and pitfalls of the normal shoulder may be helpful pathologic condition in case of glenouhumeral instability.