Low-field MR arthrography of the shoulder joint: technique,indications, and clinical results

In the age of cost containment and urgent reductions in health care expenditures, new options have to be explored to satisfy both diagnostic requirements and economic limitations. The introduction of low-field MR systems for assessment of joint disorders seemed to be an option for lower costs. The purpose of this article is to summarize available experiences with low-field MR arthrography of the glenohumeral joint with respect to image quality and diagnostic accuracy in detecting labral and rotator cuff lesions. Up to now, there has been only a limited number of studies available dealing with low-field MR arthrography of the glenohumeral joint. They reveal that, despite a minor image quality in comparison with high-field imaging, low-field MR arthrography of the shoulder allows for sufficient evaluation of intra- and extra-articular structures in the detection of major abnormalities such as glenohumeral instability or rotator cuff disease. Furthermore, open-configured MR scanners enable kinematic studies: Besides the analysis of normal motion, pathological findings in patients with instabilities and impingement syndrome can be delineated. They further offer the possibility for performing MR imaging-guided arthrography of the shoulder. This was first described using an open C-arm scanner with a vertically oriented magnetic field so that MR arthrography may be performed in one setting. Electronic Publication     

The anterior glenohumeral joint capsule: macroscopic and MRI anatomy of the <Emphasis Type="Italic">fasciculus obliquus</Emphasis> or so-called <Emphasis Type="Italic">ligamentum glenohumerale spirale</Emphasis>

The purpose of this study was to demonstrate the macroscopic and MRI anatomy of the fasciculus obliquus, otherwise known as the ligamentum glenohumerale spirale or spiral GHL of the anterior shoulder joint capsule. Conventional and MR arthrography (1.5-T device Somatom Symphony, Siemens with shoulder coil) images in standard planes were compared with gross anatomic dissection findings in six fresh shoulder specimens from three cadavers. The MR imaging protocol included T1, PD and DESS 3D WI sequences. The macroscopically recognisable band—the spiral GHL—was identified by anatomic dissection and MRI in all the specimens. It was best visualised by MR arthrography on axial and oblique sagittal planes (T1; PD WI) and appeared as a low signal intensity stripe within the superficial layer of the anterior joint capsule. The absence of the variable middle glenohumeral ligament did not influence the anatomic properties and the MR imaging of the spiral GHL. Diagnostic visualisation of the normal anatomic structures is a prerequisite to distinguish between normal and pathologic conditions. Anatomy of the spiral GHL can be used by radiologists for more detailed interpretation of the anterior shoulder joint capsule ligaments on MR images.     

Evaluation of articular cartilage thickness of the humeral head and the glenoid fossa by MR arthrography: anatomic correlation in cadavers

Objective. To evaluate the accuracy of MR arthrography in determining the thickness of articular cartilage of the humeral head and glenoid fossa. Design and patients. MR arthrography of the glenohumeral joint was performed in 17 cadaveric shoulders. Articular cartilage thickness was measured on the MR arthrographic images and corresponding anatomic sections. Results. The correlation coefficients for MR arthrographic measurement versus anatomic measurement of the cartilage thickness were 0.7324 and 0.8757 for humeral head and glenoid fossa, respectively. With regard to the humeral head, there was a tendency to overestimate regions of thin cartilage and underestimate regions of thick cartilage. This tendency was not found in the assessment of glenoid cartilage. The mean of the absolute value of MR-anatomic differences was similar on the glenoid side (0.27 mm) and the humeral side (0.29 mm). The accuracy of measurement was significantly better on the glenoid side (Fisher’s r-to-Z transformation: Z=5.21, P=0.000001). Conclusion. MR arthrography causes a moderate degree of error in the naked-eye measurement of the cartilage of the glenohumeral joint. The accuracy is higher on the glenoid side than on the humeral side.     

Anatomy,Variants, and Pathologies of the Superior Glenohumeral Ligament: Magnetic Resonance Imaging with Three-Dimensional Volumetric Interpolated Breath-Hold Examination Sequence and Conventional Magnetic Resonance Arthrography

The purpose of this review was to demonstrate magnetic resonance (MR) arthrography findings of anatomy, variants, and pathologic conditions of the superior glenohumeral ligament (SGHL). This review also demonstrates the applicability of a new MR arthrography sequence in the anterosuperior portion of the glenohumeral joint. The SGHL is a very important anatomical structure in the rotator interval that is responsible for stabilizing the long head of the biceps tendon. Therefore, a torn SGHL can result in pain and instability. Observation of the SGHL is difficult when using conventional MR imaging, because the ligament may be poorly visualized. Shoulder MR arthrography is the most accurately established imaging technique for identifying pathologies of the SGHL and associated structures. The use of three dimensional (3D) volumetric interpolated breath-hold examination (VIBE) sequences produces thinner image slices and enables a higher in-plane resolution than conventional MR arthrography sequences. Therefore, shoulder MR arthrography using 3D VIBE sequences may contribute to evaluating of the smaller intraarticular structures such as the SGHL.     

Superior labral anteroposterior lesions: MR arthrography with arm traction.

OBJECTIVE: The purpose of this study was to investigate the efficacy of arm traction combined with MR arthrography in the evaluation of superior labral anteroposterior (SLAP) lesions. MATERIALS AND METHODS: Cadaveric shoulders were studied with a 1.5-T MR imaging unit with the arm externally rotated. Fifteen milliliters of a gadolinium-containing contrast agent were injected into the glenohumeral joint. Twenty-four sets of images of cadaveric joints were evaluated independently by two observers. These sets consisted of MR arthrographic images obtained with traction (applied to the wrist using 1- to 3-kg weights) and without traction in five shoulders in which SLAP lesions had been excluded arthroscopically or by cadaveric sectioning; and MR arthrographic images obtained with and without traction in seven shoulders in which various types of SLAP lesions had been created arthroscopically and later confirmed by cadaveric sectioning. RESULTS: Analysis of the data indicated that MR arthrography in combination with arm traction and external rotation improved diagnostic accuracy with regard to identification and categorization of SLAP lesions when compared with studies made without traction. CONCLUSION: The combination of MR arthrography and arm traction with the shoulder in external rotation provides a more effective approach for detection of SLAP lesions than does similar MR arthrography performed without arm traction.     

Labral-ligamentous complex of the shoulder. Evaluation with double oblique axial MR arthrography

Purpose: 
To assess the ability of double oblique axial (DOA) MR arthrography in evaluating labral-ligamentous complex compared with conventional axial (CA) MR arthrography. Material and Methods: 
MR arthrography of 51 shoulders, subsequently examined with arthroscopy, were retrospectively reviewed. DOA imaging was performed in all 51 shoulders and both DOA and CA imaging in 37 using a 1.5 T unit with gradient recalled-echo T2*-weighted sequences. DOA imaging was performed using perpendicular planes to the long axis of the glenoid fossa obtained by an oblique sagittal scout image. We compared the ability of DOA with that of CA MR arthrography to assess labral injuries and to demonstrate the whole length of the anterior band of the inferior glenohumeral ligament (AIGHL), which were shown to be intact by arthroscopy. Results: 
For anterior labral injuries, sensitivity and specificity were 87% and 93% with CA, and 94% and 100% with DOA imaging, respectively. For posterior labral injuries, sensitivity and specificity were 47% and 100% with CA, and 79% and 96% with DOA imaging, respectively. There were no statistically significant differences between CA and DOA images, except for the ability to diagnose posterior labral injuries, where DOA imaging had a significant superior sensitivity (p = 0.0327). DOA images also demonstrated the whole length of the intact AIGHL in 10 of 11 shoulders, while CA imaging showed this in only 3 of 11. Conclusion: 
DOA imaging was equal or better than CA imaging for evaluating the labral-ligamentous complex.     

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician.     

MRI of shoulder instability

The most unstable joint in the body, the glenohumeral joint is subject to many insults including microinstability, subluxation and dislocation. During the last two decades, MRI has allowed for direct visualization of many of the lesions related to instability, aiding in diagnosis as well as therapeutic planning and follow-up. This article reviews the use of MRI for shoulder instability and describes the different types of lesions associated with this disorder. Topics include technical considerations, the use of MR arthrography, normal anatomy and variants, labral and glenohumeral ligament pathology, and osseous lesions related to instability.     

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.     

Supraspinatus tendon tears: comparison of US and MR arthrography with surgical correlation

The aim of this study was to compare the diagnostic reliability of US with MR arthrography in diagnosing supraspinatus tendon tears. Surgical findings were used as the gold standard in detecting tears. A total of 44 patients were assessed with transverse and longitudinal US scans with respect to the long axis of the rotator cuff tendons and then examined with MR arthrography. This technique involved free-hand injection of contrast medium into the shoulder joint. At surgery 20 incomplete and 24 complete tears were observed. Ultrasound offered good results for the large tears, but its sensitivity decreased proportionally with the size of the tears. Magnetic resonance arthrography correctly diagnosed 43 tears, whereas only one false-negative diagnosis of tendinosis was made for a partial tear on the bursal side. Since it improves the diagnosis of small tears, MR arthrography must be performed on all patients for whom surgical repair is necessary in order to restore normal functions.     

Glenohumeral instability: evaluation using MR arthrography of the shoulder

In the setting of glenohumeral instability or when internal derangement of the shoulder joint is suspected, MR arthrography has been demonstrated to be an accurate diagnostic imaging technique. Knowledge of the complex anatomy of the shoulder and its variations is essential in order to maximize diagnostic accuracy. Received: 24 February 1999 Revision requested: 19 April 1999 Revision received: 12 May 1999 Accepted: 13 May 1999     

Utility of MR arthrography in the diagnosis of adhesive capsulitis

Objective. Arthrographically, adhesive capsulitis is characterized by decreased joint volume; histologically, the capsule and synovium are thickened. We therefore compared using MR arthrography the joint volumes and capsule/synovial thickness of patients with and without adhesive capsulitis in order to assess the utility of MR arthrography in diagnosing adhesive capsulitis. Design and patients. The 1.5 T MR arthrography images of 28 subjects with (n=9) and without (n=19) adhesive capsulitis were compared. Adhe- sive capsulitis was diagnosed when there was an injected glenohumeral joint volume of less than 10 ml. Two masked observers working in consensus assessed the images for the relative amount of fluid in the biceps tendon sheath and axillary recess, corrugation at the margin of the capsule, capsule/synovial thickness, abnormalities of the rotator interval capsule, and for the presence of a cuff tear. Results. There was a trend towards differences in capsular and synovial thickness (P>0.07) between the subjects with and without adhesive capsulitis; however, the controls had thicker synovium/capsules. Surprisingly, the amount of fluid in the axillary recess and biceps tendon sheath was not significantly different between the groups (P>0.25). There were more tears of the rotator cuff in controls than in patients with adhesive capsulitis (6, 3 vs 1, 1: complete, partial). Also, both corrugation (7 vs 0) and interval abnormalities (7 vs 0) were more common in the controls. Conclusion. There appear to be no useful MR arthrographic signs of adhesive capsulitis. Capsular/synovial thickness, static fluid volume, and the presence of corrugation are inconclusive as MR arthrographic signs for distinguishing shoulders with adhesive capsulitis from those without. Received: 1 June 2000 Revision requested: 11 September 2000 Revision received: 13 November 2000 Accepted: 27 November 2000     

Multimodality imaging of the postoperative shoulder

Multimodality imaging of the postoperative shoulder includes radiography, magnetic resonance (MR) imaging, MR arthrography, computed tomography (CT), CT arthrography, and ultrasound. Target-oriented evaluation of the postoperative shoulder necessitates familiarity with surgical techniques, their typical complications and sources of failure, knowledge of normal and abnormal postoperative findings, awareness of the advantages and weaknesses with the different radiologic techniques, and clinical information on current symptoms and function. This article reviews the most commonly used surgical procedures for treatment of anterior glenohumeral instability, lesions of the labral-bicipital complex, subacromial impingement, and rotator cuff lesions and highlights the significance of imaging findings with a view to detection of recurrent lesions and postoperative complications in a multimodality approach.     

MR imaging in sports-related glenohumeral instability

Sports-related shoulder pain and injuries represent a common problem. In this context, glenohumeral instability is currently believed to play a central role either as a recognized or as an unrecognized condition. Shoulder instabilities can roughly be divided into traumatic, atraumatic, and microtraumatic glenohumeral instabilities. In athletes, atraumatic and microtraumatic instabilities can lead to secondary impingement syndromes and chronic damage to intraarticular structures. Magnetic resonance (MR) arthrography is superior to conventional MR imaging in the diagnosis of labro-ligamentous injuries, intrinsic impingement, and SLAP (superior labral anteroposterior) lesions, and thus represents the most informative imaging modality in the overall assessment of glenohumeral instability. This article reviews the imaging criteria for the detection and classification of instability-related injuries in athletes with special emphasis on the influence of MR findings on therapeutic decisions.     

Arthrography of the shoulder: A modified ultrasound guided technique of joint injection at the rotator interval

Objective

To describe an ultrasound guided technique of shoulder joint injection at the rotator interval space, using an endocavitary transducer and performed by a radiologist with no previous experience with arthrography.

Materials and method

Accuracy of the intra-articular puncture and incidence of complications were evaluated in 180 consecutive patients submitted to joint puncture for shoulder MR arthrography.

Results

Puncture was accomplished successfully in all cases, of which 92% with one attempt, and 8% with two, both well tolerated by patients. No relevant complications were reported after the procedure.

Conclusion

This study has shown that puncture of the glenohumeral joint guided by ultrasound at the rotator interval space using an endocavitary transducer is easy and quick, even when performed by radiologists with no experience in arthrographic procedures.     

Synovial fold of the posterior shoulder joint capsule

Purpose  The purpose of the study is to describe, based on shoulder MRI and MR arthrography with arthroscopic correlation, a posterior joint capsule fold. Materials and methods  A retrospective review of 410 shoulder MRIs and direct MR arthrograms with arthroscopic correlation in positive cases (when available) was obtained with IRB approval and HIPPA compliance. The study was performed by three musculoskeletal radiologists. The criteria utilized to establish the diagnosis of posterior synovial fold included: (1) axial T1-weighted (T1W) on MR arthrography or axial T2* GRE-weighted on MRI demonstrating rounded thickening of the posterior shoulder joint capsule with a thickness at least 2 mm in diameter. (2) The posterior synovial fold extends in an oblique craniocaudal direction from the posterior–inferior joint capsule adjacent to the posterior–inferior glenoid labrum (7 o'clock) and continues superiorly away from the glenoid labrum to the posterior–superior joint capsule (11 o'clock). Results  Although uncommon, the posterior synovial fold was present in 2% (8/410) of studies reviewed and found predominantly in women (75%, 6/8). Four patients had arthroscopic confirmation of the posterior synovial fold. A higher percentage of posterior synovial folds were observed on shoulder MR arthrography (2.7%, 4/150) than on shoulder MRI (1.5%, 4/260). Conclusion  Although rare, the posterior synovial fold can be recognized and should not be confused with a posterior labral tear. Further investigation is needed to assess its histologic properties and its clinical significance.     

MR arthrographic findings in tenosynovitis of the long bicipital tendon of the shoulder

 Purpose. To assess the MR arthrographic findings of bicipital tenosynovitis in correlation with arthroscopy. Design and patients. The shoulder MR arthrographies of 500 consecutive patients were retrospectively analyzed for signs of bicipital tenosynovitis and associated pathologies. Forty patients (8%) had MR evidence of bicipital tenosynovitis, but only 17 (3%) with arthroscopic confirmation were included in the study. The MR findings in these patients were compared with those of 10 patients with rotator cuff lesions but arthroscopically normal long biceps tendons. MR arthrography was performed with 10–15 ml of a 250 mmol/l gadoterate meglumine (Gd-DOTA) solution injected under fluoroscopic guidance, and transaxial, oblique coronal and sagittal MR sequences were obtained. Results. All 17 patients showed one or more abnormal findings: signal increase in the tendon with or without fusiform distension was seen in 12, surface irregularities in six, adhesions in 11 and noncommunicating effusions of the tendon sheath in six. Associated abnormalities of the rotator cuff were present in 16 while the seventeenth patient had glenohumeral synovitis without rotator cuff pathology. MR arthrograms correlated with arthroscopic findings in the joint but comparison was not possible in the intertubercular groove portion of the biceps tendon. None of the 10 patients with an arthroscopically normal biceps tendon showed any of the MR findings of bicipital tenosynovitis. Conclusion. Bicipital tenosynovitis is detectable by MR arthrography. In most cases it is an associated finding of rotator cuff abnormalities and likely to have a similar etiology. When lesions of the anterior rotator cuff are recognized, the biceps tendon should be scrutinized for inflammatory changes.     

Fast MR arthrography using VIBE sequences to evaluate the rotator cuff

Purpose  The purpose of this paper was to evaluate if short volumetric interpolated breath-hold examination (VIBE) sequences can be used as a substitute for T1-weighted with fat saturation (T1-FS) sequences when performing magnetic resonance (MR) arthrography to diagnose rotator cuff tears. Materials and methods  Eighty-two patients underwent direct MR arthrography of the shoulder joint using VIBE (acquisition time of 13 s) and T1-FS (acquisition time of 5 min) sequences in the axial and paracoronal plane on a 1.0-T MR unit. Two radiologists scored rotator cuff tendons on VIBE and T1-FS images separately as normal, small/large partial thickness and full thickness tears with or without geyser sign. T1-FS sequences were considered the gold standard. Surgical correlation was available in a small sample. Results  Sensitivity, specificity, and positive and negative predictive values of VIBE were greater than 92% for large articular-sided partial thickness and full thickness tears. For detecting fraying and articular-sided small partial thickness tears, these parameters were 55%, 94%, 94%, and 57%, respectively. The simple kappa value was 0.76, and the weighted kappa value was 0.86 for agreement between T1-FS and VIBE scores. All large partial and full thickness tears at surgery were correctly diagnosed using VIBE or T1-FS MR images. Conclusion  Fast MR arthrography of the shoulder joint using VIBE sequences showed good concordance with the classically used T1-FS sequences for the appearance of the rotator cuff, in particular for large articular-sided partial thickness tears and for full thickness tears. Due to its very short acquisition time, VIBE may be especially useful when performing MR arthrography in claustrophobic patients or patients with a painful shoulder.     

MR arthrography of the labral capsular ligamentous complex in the shoulder: imaging variations and pitfalls

OBJECTIVE: Using MR arthrography, we examined normal anatomy, anatomic variations, and pitfalls of imaging the labral capsular ligamentous complex in the asymptomatic shoulder. SUBJECTS AND METHODS: We obtained 108 MR arthrograms of the glenohumeral joint in 95 asymptomatic volunteers with axial (108 shoulders) and oblique coronal (56 shoulders) images. We examined labral shape, patterns of capsular insertion, presence or absence of glenohumeral ligaments, and pitfalls of imaging. Our patients were men (auxiliary policemen) between 19 and 24 years old (mean age, 21 years). RESULTS: The shapes of labra were triangular (anterior part, 64%; posterior part, 47%), round (17%; 33%), flat (2%; 17%), cleaved (11%; 1%), notched (3%; 0%), or absent (2%; 2%). Using the system of Mosely and Overgaard, the anterior capsular insertion was type 1 in 63% of shoulders, type 2 in 20%, and type 3 in 17%; the posterior capsular insertion was type 1 in 60% of shoulders, type 2 in 31%, and type 3 in 9%. The superior and inferior glenohumeral ligaments were present in 99% of shoulders, but the middle glenohumeral ligament was present in only 79%. We also detected many pitfalls of MR imaging in identifying findings such as the undercutting of the labrum by cartilage (32% of shoulders), prominent axillary folds (46%), sublabral holes (7%) or recesses (33%), Buford complexes (2%), and sulci between the biceps tendon and superior labrum (30%). CONCLUSION: Knowledge of normal anatomy and anatomic variations of the labral complex is important for the examination of the shoulder with MR arthrography.