Multidetector spiral CT arthrography of the shoulder. Clinical applications and limits, with MR arthrography and arthroscopic correlations

Although MR imaging and MR arthrography are the first choice modalities for shoulder imaging, CT arthrography (CTA) may be used successfully to address many clinical questions. The advent of submillimeter multiple detector CT technology and subsequent excellent three-plane resolution has considerably increased the quality of CTA examinations and has propelled this technique to the forefront in a growing number of indications. The combined use of iodinated contrast material for fluoroscopic confirmation of the articular position of the needle before injection of gadolinium chelates for MR arthrography offers the unique opportunity to compare CTA and MRA findings in carefully selected cases. This paper illustrates capabilities and limits of CTA for the study of rotator cuff tears, shoulder instability, cartilage lesions, anatomical variants and abnormalities of the glenoid labrum, with correlations to MR arthrography and surgical findings.     

Shoulder magnetic resonance imaging

MRI provides excellent soft tissue contrast and allows for multiplanar imaging in anatomic planes. Because of these advantages MRI has become the study of choice for imaging of shoulder pathology. Some structures, such as the rotator cuff, humeral head contour, and glenoid shape, are evaluated well with conventional MRI. When more sensitive evaluation of the labrum, capsule, articular cartilage, and glenohumeral ligaments is required or when a partial-thickness rotator cuff tear is suspected,magnetic resonance arthrography with intra-articular contrast can be performed. For MR arthrography contrast is injected directly into the glenohumeral joint. This article reviews the appearances of normal anatomic structures in MRI of the shoulder and disorders involving the rotator cuff and glenoid labrum.     

CT arthrography of capsular structures of the shoulder

The capsular mechanism of the shoulder joint consists of the joint capsule, which is strengthened by the glenohumeral ligaments and the rotator cuff, the glenoid labrum, and a variable number of synovial recesses. Although the fibrous capsule is a lax structure, the normal function of the capsular mechanism makes it an effective barrier against anterior dislocation, particularly in external rotation. There has been a tendency in the past to overestimate the role of the glenoid labrum in stability of the shoulder joint. In patients with instability, the significance of the capsular attachment or its anomalous insertions to the glenoid has not been adequately recognized. Labral tears may develop as secondary lesions due to repeated dislocations and subluxations rather than representing the primary lesion responsible for instability. Operative visualization of capsular defects or detachments is often difficult. Prior knowledge of these lesions can effectively help the choice of an appropriate surgical procedure and reduce operating time. The results of computed tomographic (CT) arthrography of the shoulder joint in 45 patients are reported and the normal and pathologic variations of the joint capsule and particularly the capsular insertions are described. Configuration of the joint recesses and the glenoid labrum are also evaluated. These CT findings were correlated and verified by surgery or arthroscopy in 26 cases.     

Direct MR arthrography of the shoulder: is exercise prior to imaging beneficial or detrimental?

PURPOSE: To define the beneficial and detrimental effects of adding exercise to direct magnetic resonance (MR) shoulder arthrography. MATERIALS AND METHODS: Direct, intraarticular, gadolinium arthrography of the shoulder was performed in 41 patients, who underwent 1.5-T MR imaging before and after 1 minute of arm swinging. Fourteen milliliters of dilute gadolinium solution was injected. Two readers blinded to exercise independently graded the randomly distributed images with a five-point scale for capsular contrast material resorption; extraarticular contrast material leakage; rotator cuff, glenoid labrum, and anterior capsule conspicuity; and partial-thickness or full-thickness rotator cuff tear and labral tear detectability. The sign test was performed to evaluate the significance of differences between preexercise and postexercise grading for each reader. A second review was performed, with direct side-by-side comparison of preexercise and postexercise images. RESULTS: There was evidence of increased capsular resorption after exercise but no alteration in the depiction of the rotator cuff tendons or glenoid labrum. There was no significant extraarticular contrast material leakage after exercise and no alteration in depiction of the anterior capsule. There was no difference in the detectability of rotator cuff or labral tears. CONCLUSION: Exercise with direct shoulder MR arthrography has no beneficial or detrimental effect on image quality or on the depiction of rotator cuff or labral tears.     

MR arthrography of the shoulder: comparison with conventional MR imaging

Twenty-three patients underwent both conventional MR imaging of the shoulder and MR shoulder arthrography for clinically suspected labral or rotator cuff abnormalities. Images obtained before and after contrast administration were studied independently, and without knowledge of clinical findings, by two radiologists for the presence of abnormalities of the glenoid labrum or rotator cuff. Results were correlated with surgical findings in all patients. Nine patients had surgically proved labral tears. MR arthrography detected all nine labral abnormalities, while six of the nine were missed on conventional MR imaging. Fourteen patients had surgically proved rotator cuff tears. MR arthrography detected 11 of the 14 tears and missed three partial tears on the bursal surface. Conventional MR imaging detected nine cuff tears and missed five tears; two of these were complete rotator cuff tears and three were partial tears of the undersurface of the rotator cuff. Our results suggest that MR arthrography enhances the accuracy of MR in the evaluation of the glenoid labrum and rotator cuff tendon.     

Fibro-cartilaginous lesions of the glenoid labrum in shoulder instability: a proposed classification using sagittal-oblique arthro-MRI

PURPOSE: To propose a graded classification of lesions of the fibrocartilaginous glenoid labrum in traumatic dislocations of the shoulder, based on arthro-MRI in sagittal-oblique views. MATERIALS AND METHODS: Seventy-one patients with histories of chronic post-traumatic shoulder instability were studied from May 2000 to May 2001. MR images were obtained using superconducting magnets operating at 1 and 1.5 Tesla, with a dedicated shoulder coil. The study was carried out in combination with arthrography, with axial sections oriented perpendicularly to the longitudinal axis of the glena, oblique coronal sections parallel to the course of the supraspinous muscle tendon and oblique sagittal sections with axis parallel to the longitudinal axis of the glena. RESULTS: In one case an anatomical variant was found (Buford complex). In 18 patients a simple fissuration of the fibrocartilaginous glenoid labrum was found, whereas 28 patients displayed more extensive lesions affecting the middle-inferior portions of the labrum. In 15 patients the lesion extended to the middle-superior third of the glena, involving the middle glenohumeral ligament. In 9 cases, in addition to a complete lesion of the labrum, with typical "bucket-handle" appearance, a lesion of the superior and middle glenohumeral ligaments was also observed. DISCUSSION AND CONCLUSIONS: In traumatic shoulder dislocations it is essential to provide the surgeon with precise information regarding the location, extension and degree of damage to the capsule, ligaments and especially the labrum of the glenohumeral joint. On the basis of the results obtained in the sagittal-oblique sections we propose an MR-arthrography classification dividing lesions of the fibrocartilaginous labrum into 4 grades.     

Increased risk of posterior glenoid labrum tears in football players

OBJECTIVE: This study was designed to test our hypothesis that football players with shoulder pain, shoulder instability, or both requiring MR arthrography for evaluation are at an increased likelihood relative to non-football players for having a tear of the posterior glenoid labrum. CONCLUSION: We conclude that posterior glenoid labrum tears are more prevalent in football players than in non-football players.     

Computed tomography (CT) arthrography of shoulder instabilities in athletes

Sixty professional and recreational athletes underwent CT arthrography of the shoulder for evaluation of suspected shoulder joint derangement. These athletes, 46 males and 14 females ranging in age from 15 to 60 years (mean, 32 years), all had persistent pain that interfered with their sports activity and was resistant to conservative treatment. Seventeen patients had shoulder instability based on clinical manifestations and CT arthrographic findings. An additional five patients, also based on clinical manifestations and CT arthrographic findings, were considered to have an unobtrusive degree of anterior joint laxity. Patients with anterior instability (20 cases) all had an anteroinferior tear or detachment of the glenoid labrum, as well as some violation of the insertion of the joint capsule onto the scapula. Those with posterior instability (two cases) had a combination of labral and capsular tears. Two other major patterns of labral tears, both unaffiliated with shoulder instability, were identified. These included total or partial detachment of superior segments of the labrum, and anterior labral tears at the midglenoid level. Moreover, various degrees of labral attenuation (or, less often, enlargement), osteophyte formation, and alterations in articular cartilage were observed. Surgical correlation was obtained in 25 patients, with 95% accuracy of CT arthrographic findings. CT arthrography is a minimally invasive and highly accurate technique for investigation of glenohumeral derangement. Specifically, the extent of pathologic changes associated with instability can be determined and differentiated from other intraarticular causes of incapacity, such as labral tears caused by throwing, or degenerative changes.     

MR imaging of recurrent anterior dislocation of the shoulder: comparison with CT arthrography

Posttrauma damage due to anterior glenohumeral joint dislocation may result in recurrent dislocation. Currently CT arthrography is the method of choice to evaluate the extent of osseous and soft-tissue changes before reconstructive surgery. This study was undertaken to determine if MR was able to depict postdislocation abnormalities and if MR is a possible replacement for CT arthrography. Thirteen patients with recurrent anterior shoulder dislocation were evaluated with conventional radiography and MR; CT arthrography was performed in 10. Twelve patients underwent surgery, and the findings of MR and CT arthrography were verified. MR and CT arthrography showed the integrity of the glenoid labrum equally well. All humeral head defects, detected in nine patients with plain film radiography and CT, were easily identified with MR. Information about anterior joint capsule abnormalities is difficult to obtain with MR. However, separation of the capsule from the bony glenoid can be detected if a joint effusion is present to adequately distend the joint. Preliminary results of this study indicate that MR is useful in the assessment of postdislocation abnormalities and may possibly replace CT arthrography in the evaluation of patients with recurrent shoulder dislocation.     

Hypoplasia of the glenoid neck of the scapula: imaging findings and report of 16 patients

OBJECTIVE: Our purpose was to describe the primary and associated imaging findings in patients with glenoid hypoplasia required for an accurate diagnostic appraisal of this uncommon abnormality. METHODS: The medical records and imaging studies of 16 patients with glenoid hypoplasia were retrospectively reviewed. Plain films were available in all patients, arthrography in 2, computed tomography (CT) in 5, CT arthrotomography in 3, magnetic resonance (MR) imaging in 9, and MR arthrography in 3 patients. The imaging studies were reviewed with special attention to the primary and secondary findings associated with glenoid hypoplasia. RESULTS: On radiographs, the 21 abnormal shoulders documented in the 16 patients with glenoid hypoplasia had an irregular (n=15) or shallow and smooth (n=6) articular surface of the glenoid. Computed tomography findings showed subluxation of the humeral head in 5 cases. On MR images, the hypoplastic bony glenoid and scapular neck were replaced by abnormal tissue of inhomogeneous signal intensity, showing the signal intensity characteristics of fibrocartilage (n=6) or fat (n=5). Widening of the inferior glenohumeral joint space was seen in all cases. Magnetic resonance imaging or MR arthrography revealed variable abnormalities of the labrum, including enlargement (10 shoulders), detachment of labrum from the bony glenoid (6 shoulders), intrasubstance tear (4 shoulders), and perilabral cyst (2 shoulders). The posterior labrum was absent (n=1) or torn (n=1) in one patient with bilateral deformity. Other findings included partial tear of the subscapularis tendon (n=1) and rotator cuff atrophy (n=1) and tear (n=2). CONCLUSION: Glenoid hypoplasia is a developmental skeletal anomaly comprising a spectrum of associated osseous and cartilaginous changes of the articular cartilage and glenoid labrum. Cross-sectional imaging studies, with or without arthrography, may help further characterize associated derangements of the shoulder, some of which are indicative of shoulder instability.     

Indirect MR arthrography of the unexercised glenohumeral joint in patients with rotator cuff tears.

RATIONALE AND OBJECTIVES: To evaluate the diagnostic utility of indirect MR arthrography of the unexercised glenohumeral joint in patients with rotator cuff tears confirmed by arthroscopy or arthrotomy as the gold standard. METHODS: Twenty-six patients underwent conventional MR imaging and indirect MR arthrography of the stationary glenohumeral joint using a wrap-around surface coil. Unenhanced T1-weighted spin echo/T2-weighted fast spin echo sequences and T1-weighted gradient echo sequences, adding spectral fat suppression after intravenous administration of contrast medium, were performed in the oblique coronal and oblique sagittal planes. Images were analyzed by three experienced radiologists in consensus. Levels of diagnostic confidence were evaluated using a four-point scale of diagnostic certainty. RESULTS: Performing indirect MR arthrography of the unexercised shoulder leads to a diagnostically efficient enhancement of joint fluid (120% at 4 minutes and 145% at 8 minutes after intravenous injection of gadodiamide). In terms of soft tissue delineation, characterization of rotator cuff tears was significantly improved by using enhanced fat-suppressed T1-weighted gradient echo sequences compared with conventional MR imaging. CONCLUSIONS: Indirect MR arthrography without glenohumeral joint exercise in the diagnosis of rotator cuff tears is feasible and represents a more convenient and less time-consuming alternative to indirect MR arthrography after joint exercise.     

MR arthrography of the posterior labrocapsular complex: relationship with glenohumeral joint alignment and clinical posterior instability

OBJECTIVE: The purpose of our study was to investigate the relationship between tears of the posterior labrocapsular complex and glenohumeral alignment on MR arthrography and the presence and extent of posterior labrocapsular tears in patients with posterior instability. MATERIALS AND METHODS: Posterior labrocapsular tears identified on 24 MR arthrograms and surgically confirmed were evaluated for length of tear and labrocapsular avulsion. These examinations and a comparison cohort of 70 normal MR arthrograms with normal findings were also evaluated for humeral head position relative to the glenoid fossa. Medical records were reviewed for clinical diagnosis of posterior instability and history of shoulder trauma. RESULTS: The position of the humeral head relative to the glenoid was significantly more posterior in patients with posterior labral tear than in patients with a normal posterior labrum (4.9 mm versus 0.7 mm; p < 0.0001). The mean length (+/- SD) of posterior labral tear was 15.9 +/- 1.7 mm, and a direct correlation was found between tear length and posterior humeral translation (r = -0.65; p = 0.002). Posterior labral tears were significantly longer (18.6 vs 13.1 mm; p = 0.04), and posterior humeral translation was greater (6.4 vs 3.4 mm; p = 0.006) in patients with labrocapsular avulsion than in those without avulsion. Twelve (50%) of the patients with posterior labrocapsular tear had posterior instability, and 10 (83%) had a history of macrotrauma. On MR arthrography, the mean posterior humeral translation was greater (6.2 mm +/- 0.08; p = 0.019), posterior labral tears were longer (19.4 mm +/- 1.7; p = 0.0008), and labrocapsular avulsion was more common (83%; p = 0.0001) in patients with posterior instability than in patients who had a posterior labral tear but a clinically stable shoulder. CONCLUSION: Clinical posterior instability is associated with excessive posterior humeral translation, long posterior labral tears, and posterior labrocapsular avulsion.     

Schultergelenkinstabilität

Shoulder instability is a common clinical feature leading to recurrent pain and limited range of motion within the glenohumeral joint. Instability can be due a single traumatic event, general joint laxity or repeated episodes of microtrauma. Differentiation between traumatic and atraumatic forms of shoulder instability requires careful history and a systemic clinical examination. Shoulder laxity has to be differentiated from true instability followed by the clinical assessment of direction and degree of glenohumeral translation.Conventional radiography and CT are used for the diagnosis of bony lesions. MR imaging and MR arthrography help in the detection of soft tissue affection, especially of the glenoid labrum and the capsuloligamentous complex.The most common lesion involving the labrum is the anterior labral tear, associated with capsuloperiostal stripping (Bankart lesion). A number of variants of the Bankart lesion have been described, such as ALPSA, SLAP or HAGL lesions.The purpose of this review is to highlight different forms of shoulder instability and its associated radiological findings with a focus on MR imaging.     

CT空气—碘水双对比造影对肩关节不稳定诊断的意义

目的：探讨ＣＴ空气－碘水双对比造影对诊断肩关节不稳定的临床意义。材料与方法：８例患者做肩前穿刺，分别注入７６％泛影葡胺４ｍｌ和过滤空气１０ｍｌ，在全身ＣＴ机上行肩关节扫描。结果：所有患者气－碘双对比造影ＣＴ表现均与术中所见一致。主要特征为：（１）盂唇前部变钝、撕脱、游离；（２）关节囊前部撕脱或者关节囊破裂；（３）关节囊松弛、囊腔扩大。结论：ＣＴ气－碘双对比造影可以明确诊断肩关节不稳定，并为肩关节不稳定的解剖修复提供重要的影像学信息。     

Indirect MR arthrography: techniques and applications

Indirect MR arthrography is a relatively new MR technique improving articular and periarticular contrast. It is achieved by injection of paramagnetic MR contrast media intravenously instead of intra-articular injection as in direct MR arthrography. After the injection exercising the joint results in considerable signal intensity increase within the joint cavity. Fat saturated MR sequences then yield arthrographic images. The method is less invasive than direct MR arthrography and first results showed comparable sensitivities and specificities for rotator cuff and glenoid labrum pathology. In this article the technique, established and potential future indications, drawbacks and limitations of the method are reviewed. Received: 26 March 1997; Revision received 31 July 1997; Accepted 1 August 1997     

MR arthrography of the shoulder and hip after fluoroscopic landmarking

Purpose. To describe a technique for intra-articular injection in the MR suite after conventional fluoroscopic landmarking in order to streamline MR arthrography. Design and patients. This technique was performed on 33 consecutive patients referred for MR arthrography of the shoulder to evaluate the glenoid labrum and on 15 consecutive patients referred for MR arthrography of the hip to evaluate the acetabular labrum. The patients were landmarked in the fluoroscopy suite, followed by a conventional MR examination. The intra-articular injection was then performed on the MR table and the MR arthrographic sequences obtained. Results. One of the 48 injections was extra-articular, requiring a second injection. The other injections were performed without incident, and the average total procedure time for all injections was 10 min. Conclusions. This technique is a reliable method of streamlining intra-articular injections when performing conventional MR imaging prior to the MR arthrographic portion of the examination. It shortens the total MR examination time by eliminating a visit to the fluoroscopy suite in the middle of the MR study, and its use of a straight anterior approach for both the shoulder and hip joints should be familiar to most people who perform conventional arthrography. Received: 27 August 1999 Accepted: 26 October 1999     

64-slice MDCT arthrography in shoulder instability: our experience

PURPOSE: This study was performed to assess the diagnostic accuracy of air-contrast 64-slice multidetector computed tomography (MDCT) arthrography in the evaluation of glenohumeral joint instability by comparison with conventional arthroscopy. MATERIALS AND METHODS: Fifty patients with a history of shoulder instability underwent MDCT arthrography with thin collimation scans. The raw data were transferred to a workstation and processed using multiplanar reformation (MPR) and volume rendering (VR) algorithms. All patients subsequently underwent conventional arthroscopy. The results of the two techniques were compared and their sensitivity and specificity calculated. RESULTS: We diagnosed eight anterosuperior labrum lesions (group 1), 32 anteroinferior labrum lesions (group 2) and two posterior labrum lesions (group 3). Overall sensitivity and specificity (groups 1, 2, 3) were 88% and 100%, respectively. In group 1, sensitivity was only 66% (four false negatives), whereas in groups 2 and 3, it was 94% (two false negatives) and 100%, respectively. The labrum lesions were also found to be associated, with 100% sensitivity and specificity, with 20 lax capsules, 17 Hill-Sachs lesions, five Bankart lesions, two Perthes lesions and three complete rotator-cuff tears. CONCLUSIONS: Air-contrast MDCT arthrography is fast, reproducible, well tolerated and very accurate in the evaluation of lesions causing shoulder instability.     

Double-contrast computed tomography of the glenoid labrum

Imaging of glenoid labrum pathology is useful to help plan surgical repair of the dislocating shoulder. Eleven patients with suspect labrum damage were imaged with computed tomography (CT) immediately after routine double-contrast shoulder arthrography. Lesions identified included attenuation, tears, and displacement of the labrum as well as stripping and stretching of the anterior shoulder joint capsule. Surgical confirmation of pathology was available in all but one case. CT of the glenoid labrum is easy to perform, low in radiation dose, and accurate.     

MR arthrography of the hip: normal intra-articular structures and common disorders

This pictorial review illustrates the anatomical features of normal intra-articular components of the hip and their common disorders on MR arthrography. On T1-weighted MR arthrograms, the normal contrast-filled joint cavity shows a homogeneous high signal intensity. Normal acetabular labrum appears as a well-delineated triangle showing a low signal intensity, surrounded by contrast material in the perilabral recess. Intra-articular paramagnetic contrast outlines labral tears, loose bodies, communicating labral cysts and cartilage lesions (traumatic tears, focal defects, degenerative fissures and thinning), and improves their detection. Overall, MR arthrography enables accurate detection and staging of hip intra-articular structure abnormalities. Received: 6 June 1998; Revision received: 2 January 1999; Accepted: 2 April 1999     

Arthroscopic assessment of the unstable shoulder

The purpose of this study was to evaluate prospectively the findings during shoulder arthroscopy in patients with recurrent anterior instability of the gleno-humeral joint. One hundred and seventy-eight patietns who fulfilled the criteria of having had at least one documented shoulder dislocation were included in the study. The pathological findings most frequently noted at arthroscopy were: anterior glenoid labral tears (85%), ventral capsule insufficiency (80%), Hill-Sachs compression fractures (67%), glenohumeral ligament insufficiency (55%), rotator cuff tears (20%), posterior glenoid labral tears (8%), and SLAP lesions (5%). Abnormalities were noted more frequently than expected, and there were significant differences between preoperative and postoperative diagnoses. Our study has taught us that a mulitplicity of morphological changes are associated with instability of the glenohumeral joint, and that there is no single cause. The labrum and rim of the anterior inferior glenoid, for instance, showed typical abnormalities corresponding to different entities of anterior instability. In practice, this is very important, as the abnormalities visualized by imaging methods determine the surgical treatment.