(Radiographics. 2002;22:1223-1246.)
© RSNA, 2002
Special Focus Session
MR Arthrography1
Lynne S. Steinbach, MD,
William E. Palmer, MD and
Mark E. Schweitzer, MD
1 From the Department of Radiology, University of California San Francisco, 505 Parnassus Ave, Suite M392, San Francisco, CA 94143-0628 (L.S.S.); the Department of Radiology, Massachusetts General Hospital, Boston, Mass (W.E.P.); and the Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, Pa (M.E.S.). Received April 16, 2002; revision requested May 10 and received June 6; accepted June 10. Address correspondence to L.S.S. (e-mail: lynne.steinbach@radiology.ucsf.edu).
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Abstract
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Direct magnetic resonance (MR) arthrography with injection of saline solution or diluted gadolinium can be useful for evaluating certain pathologic conditions in the joints. It is most helpful for outlining labral-ligamentous abnormalities in the shoulder and distinguishing partial-thickness from full-thickness tears in the rotator cuff, demonstrating labral tears in the hip, showing partial- and full-thickness tears of the collateral ligament of the elbow and delineating bands in the elbow, identifying residual or recurrent tears in the knee following meniscectomy, increasing the certainty of perforations of the ligaments and triangular fibrocartilage in the wrist, correctly identifying ligament tears in the ankle and increasing the sensitivity for ankle impingement syndromes, assessing the stability of osteochondral lesions in the articular surface of joints, and delineating loose bodies in joints. Indirect MR arthrography with intravenous administration of diluted gadolinium may be performed when direct arthrography is inconvenient or not logistically feasible. Although indirect MR arthrography has some disadvantages vis-à-vis direct MR arthrography, it does not require fluoroscopic guidance or joint injection and it is superior to conventional MR imaging in delineating structures when there is minimal joint fluid. In addition, vascularized or inflamed tissue will enhance with this method. Indirect MR arthrography can be used to rule in or diagnose abnormalities and to exclude abnormalities.
© RSNA, 2002
Index Terms: Ankle, arthrography, 46.12141, 46.122 • Arthrography, contrast media • Elbow, arthrography, 42.12141, 42.122 • Hip, arthrography, 44.12141, 44.122 • Joints, MR, 40.12141 • Knee, arthrography, 45.12141, 45.122 • Magnetic resonance (MR), arthrography, 40.12141, 40.122 • Shoulder, arthrography, 41.12141, 41.122 • Wrist, arthrography, 43.12141, 43.122
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Introduction
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Magnetic resonance (MR) arthrography is increasingly being used to evaluate certain joint disorders. In this article, we address the global considerations regarding this technique as well as more joint-specific issues. We discuss the use of direct MR arthrography in joints and provide an overview of the indirect form of MR arthrography.
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Direct MR Arthrography
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In magnetic resonance (MR) imaging of joints, diagnostic success requires delineation of complex anatomic structures and demonstration of subtle abnormalities. MR arthrography extends the capabilities of conventional MR imaging because contrast solution distends the joint capsule, outlines intraarticular structures, and leaks into abnormalities. MR arthrography exploits the natural advantages gained from joint effusion and is possible in any joint in which conventional arthrography is performed.
Either saline solution or diluted gadolinium may be injected as the MR arthrographic contrast material, but the majority of authors have chosen to investigate the role of the latter (1–8). Saline solution has diagnostic disadvantages compared with diluted gadolinium and does not overcome several major shortcomings encountered in conventional MR imaging. For example, in the shoulder, injected saline solution is isointense relative to bursal effusion in the subacromial-subdeltoid space. Thus, despite the leak of saline solution across the cuff tendon, it still may not be possible to differentiate partial- from full-thickness tear.
Radiologists should consider several issues before offering MR arthrography. The procedure converts MR imaging from a noninvasive examination into a mildly invasive one, exposing patients to ionizing radiation as well as the risk of intraarticular needle placement. The study requires the coordination of scheduling in two procedure rooms and becomes impractical if the fluoroscopy suite is too distant from the MR imager. Although gadolinium-based contrast agents have not been approved by the U.S. Food and Drug Administration for intraarticular injection, most radiologists no longer feel obliged to obtain approval from an institutional review board. Finally, the test is more expensive than either arthrography or conventional MR imaging.
Technique
The T1-weighted signal intensity of contrast material depends on the concentration of gadolinium and the magnetic field strength. To optimize the paramagnetic effect of gadolinium at 1.5 T, pharmaceutic preparations should be diluted to a concentration of 2 mmol/L (9). There are numerous ways to obtain this concentration, depending on whether iodinated contrast material is mixed with the gadolinium. If iodinated contrast material is used, 0.8 mL of gadopentetate dimeglumine or some other form of gadolinium can be added to 100 mL of normal saline solution. Ten mL of this solution can then be mixed with 5 mL of iodinated contrast material and 5 mL of lidocaine 1% (final gadolinium dilution ratio = 1:250). Following aspiration of any joint fluid, this mixture is injected until the joint capsule is properly distended (approximately 12 mL in the shoulder). Single-contrast technique is necessary to avoid magnetic susceptibility artifact from intraarticular gas. The use of iodinated contrast material allows fluoroscopic confirmation of intraarticular needle placement and acquisition of standard pre- and postexercise arthrographic spot images.
MR imaging should be initiated within 30 minutes following arthrography to minimize absorption of contrast solution and loss of capsular distention. The same dedicated coils and imaging planes are used in both MR arthrography and conventional MR imaging. T1-weighted spin-echo pulse sequences, with or without fat suppression, maximize the signal intensity of contrast solution. A T2-weighted sequence is helpful in the identification of extraarticular fluid collections, such as labral cysts, and the characterization of incidental bone marrow lesions or periarticular masses. With use of fat suppression, T2-weighted images can demonstrate subtle marrow edema.
Pitfalls
Diagnostic difficulties may arise because fat and gadolinium have similar signal intensities on T1-weighted images. In high-field systems, frequency-selective fat suppression makes use of the difference in the precessional frequencies of fat and water (chemical shift) by applying a presaturation pulse that is identical to the precessional frequency of fat. Mid- and low-field systems can achieve fat suppression with phase-shift techniques that create separate sets of images for water and fat. Because the signal from fat is decreased and the signal from contrast solution is preserved, fat-suppressed images delineate the boundary between contrast solution and fat and accurately demonstrate extraarticular contrast material.
Diagnostic difficulties can also result from extraarticular injection or leak of contrast material through the capsular puncture site. For example, in the shoulder, extraarticular contrast material can spread along fascial planes into the subacromial-subdeltoid space, creating a "bursogram" that can be mistaken for a full-thickness rotator cuff tear. Injecting less than 15 mL into the joint decreases the likelihood of extraarticular leak. To avoid contrast material injection into the subscapularis tendon or inferior glenohumeral ligament (IGL), a posterior approach may be preferable if anterior glenohumeral instability is suspected.
Inadvertent injection of gas into the joint may lead to a false-positive diagnosis of intraarticular loose bodies. However, gas bubbles will rise to nondependent regions of the joint, whereas loose bodies will gravitate to dependent locations.
Shoulder
Rotator Cuff.—
On MR arthrographic images, intraarticular contrast solution outlines the inferior cuff surface, fills partial cuff tears, and, in full-thickness tears, leaks from the glenohumeral joint into the subacromial-subdeltoid space (1–3). This leakage confirms the diagnosis of full-thick-ness cuff tear (Figs 1, 2). Thus, the presence or absence of extraarticular contrast solution allows differentiation of full-thickness from partial-thickness cuff tears. The sensitivity and specificity of MR arthrographic images in the diagnosis of full-thickness tear are comparable to those of conventional arthrography (ie, they approach 100%).
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Figure 1. Small full-thickness rotator cuff tear. On a coronal oblique T1-weighted MR arthrographic image (repetition time msec/echo time msec = 450/18), contrast material crosses a full-thickness cuff tear (large white arrow) and flows into the subacromial-subdeltoid space (small white arrows). The distal supraspinatus tendon (black arrow) is mildly retracted from its attachment site on the greater tuberosity.
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Figure 2. Moderate to large full-thickness rotator cuff tear. Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) shows contrast material as it crosses a moderate tear of the supraspinatus tendon (straight arrow) and passes distally into the subdeltoid space (small curved arrow). The tendon margin (large curved arrow) is retracted from the greater tuberosity.
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The usual impingement-related cuff tear is horizontal in configuration and begins at the anterior margin of the supraspinatus tendon. It propagates posteriorly into the infraspinatus tendon, which explains why larger tears always show the greatest degree of tendon retraction anteriorly. MR arthrographic images may facilitate the accurate measurement of horizontal cuff tears in terms of their anteroposterior dimension and their retraction from the greater tuberosity. Full-thickness vertical tears are relatively uncommon compared with horizontal tears and represent a longitudinal split in tendon fibers. Because there is no tendon retraction, they are difficult to diagnose on conventional MR images. On MR arthrographic images, vertical tears are visible because they fill with contrast material.
MR arthrographic images are particularly well suited to the diagnosis of partial-thickness tears,which usually begin at the articular (inferior) surface of the supraspinatus tendon (Fig 3). In this location, high-signal-intensity contrast solution can fill these defects and demonstrate planes of tendon delamination. Partial-thickness tears often propagate within the tendon without extending to the bursal surface. Bursal (superior) and interstitial partial-thickness tears do not fill with contrast material and may be overlooked on T1-weighted arthrographic images. MR arthrographic protocol should include T2-weighted imaging, which is used to identify these bursal tears in a manner similar to conventional MR imaging, as well as bursal fluid collections (Fig 3).
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Figure 3a. Large partial-thickness surface rotator cuff tears. (a) Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) demonstrates a contrast material collection in an inferior surface defect (arrow). No contrast material is present in the subdeltoid space, a finding that indicates a partial-thickness tear. (b) Adjacent T2-weighted MR arthrographic image shows focal fluid at the superior tendon surface (arrows). This defect was overlooked on T1-weighted images. Large partial-thickness cuff tears were surgically repaired.
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Figure 3b. Large partial-thickness surface rotator cuff tears. (a) Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) demonstrates a contrast material collection in an inferior surface defect (arrow). No contrast material is present in the subdeltoid space, a finding that indicates a partial-thickness tear. (b) Adjacent T2-weighted MR arthrographic image shows focal fluid at the superior tendon surface (arrows). This defect was overlooked on T1-weighted images. Large partial-thickness cuff tears were surgically repaired.
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Diagnostic accuracy is increased when fat-suppressed images are acquired (3). Partial- and full-thickness cuff tears may not be distinguishable on standard T1-weighted images because fat and gadolinium have similar signal intensities. The greatest diagnostic difficulty occurs whenever cuff tendons show contrast solution that extends to the bursal surface but not definitely through it (Fig 4). On fat-suppressed T1-weighted images, the signal intensity of contrast solution is unchanged, whereas the signal intensity of normal fat is selectively decreased. Thus, persistent high signal intensity in the subacromial-subdeltoid space indicates a full-thickness cuff tear, whereas low signal intensity indicates a partial-thickness tear. Fat suppression also improves diagnostic accuracy in the detection of small partial-thickness tears at the inferior cuff surface.
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Figure 4a. Inferior partial-thickness surface rotator cuff tear. (a) On a coronal oblique T1-weighted MR arthrographic image (450/18), contrast material (white arrow) appears to cross the entire cuff tendon. Low-signal-intensity fluid is present in the subacromial space (black arrow). (b) On a corresponding fat-suppressed MR arthrographic image, the contrast material (white arrow) remains contained within the supraspinatus tendon, a finding that confirms the diagnosis of a partial-thickness cuff tear. The bursal effusion remains low in signal intensity (black arrow). A subtotal cuff tear was surgically repaired.
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Figure 4b. Inferior partial-thickness surface rotator cuff tear. (a) On a coronal oblique T1-weighted MR arthrographic image (450/18), contrast material (white arrow) appears to cross the entire cuff tendon. Low-signal-intensity fluid is present in the subacromial space (black arrow). (b) On a corresponding fat-suppressed MR arthrographic image, the contrast material (white arrow) remains contained within the supraspinatus tendon, a finding that confirms the diagnosis of a partial-thickness cuff tear. The bursal effusion remains low in signal intensity (black arrow). A subtotal cuff tear was surgically repaired.
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Glenoid Labrum and Labral Ligamentous Complex.—
On MR arthrographic images, the majority of anatomic variants are easily distinguished from labral abnormalities (Figs 5, 6). Articular cartilage that undercuts the labral fibrocartilage is rarely a source of diagnostic difficulty because the cartilage has lower signal intensity than the contrast solution. Whereas cartilage has uniform thickness, sublabral contrast material in a tear demonstrates variable width. Normal glenohumeral ligaments are distinguished from torn labra because the ligaments can be followed away from the glenoid rim until they merge with the distended capsule. In contrast, torn labral fragments can be followed back to the glenoid rim on sequential MR arthrographic images.
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Figure 5. Arthroscopically proved superior labral tear. Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) shows displacement of the superior labrum from the glenoid rim (arrowhead) with sublabral extension of contrast material (arrow). G = glenoid, H = humeral head.
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Figure 6. Arthroscopically proved posterosuperior labral tear. Axial fat-suppressed T1-weighted MR image (450/18) obtained through the upper glenoid (G) following arthrography shows extension of contrast material under the posterior labrum (white arrow). Normal sulci do not occur in this location. The anterior labrum (black arrow) is normal. H = humeral head.
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Some anatomic variants continue to create diagnostic problems on MR arthrographic images. Morphologic criteria may not be sufficient to distinguish a small, normal labrum from a blunted, deficient labrum. Normal sublabral sulci can mimic tears because they occur at the interface of the labrum with the articular cartilage and become filled with contrast solution (5,10). Occasionally, the labrum can be completely detached (sublabral hole or foramen). As normal sulci increase in size with age, the labrum becomes progressively separated from the glenoid rim, mimicking a displaced labral fragment. These variations in the appearances of sulci lead to both false-negative and false-positive diagnoses. The most common locations of sulci include the superior labrum at its junction with the bicipital tendon and the anterosuperior labrum between the origins of the middle and inferior glenohumeral ligaments (Fig 7).
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Figure 7. Normal anterosuperior sublabral sulcus. Axial T1-weighted MR image (450/18) obtained following arthrography shows a linear pattern of contrast material underlying the anterosuperior glenoid labrum (arrow). The labrum overlies the glenoid rim and is separate from the middle glenohumeral ligament (arrowhead). Normal anterosuperior sulci usually occur between the origins of the middle and inferior glenohumeral ligaments.
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One of the major advantages of MR arthrography is visualization of the labral-ligamentous complex, which consists of the glenoid labrum in combination with the superior, middle, and inferior glenohumeral ligaments. The glenohumeral ligaments reinforce the joint capsule and function as a unit with the glenoid labrum, which anchors the ligaments to the glenoid rim (5,6,11,12).
By demonstrating the inferior labral-ligamentous complex, MR arthrography makes a major contribution to the evaluation of patients with suspected glenohumeral instability. The anterior band of the IGL is critical in maintaining passive anterior stability of the shoulder and functions as a unit with the glenoid labrum, which anchors the ligament to the glenoid rim (11,12). The origin of the IGL creates a stress point on the labrum. Excessive tension can avulse the labrum from the glenoid rim, rendering the ligament incompetent.
Specific MR arthrographic criteria can be used in the differentiation between stable and unstable shoulders because these images can show the location and length of labral abnormalities relative to the origin of the IGL. If the torn labral segment involves the attachment site of the IGL, there is a high likelihood of anterior instability (Figs 8–10). This information may guide the orthopedic surgeon in preoperative planning and in the selection of appropriate surgical or conservative treatment. Rarely, patients develop trauma-related instability due to ligamentous stretching and laxity without an associated labral tear. MR arthrography is less valuable in these cases because the entire inferior labral-ligamentous complex appears intact. Currently, no accurate MR imaging criteria are recognized in the diagnosis of capsular laxity.
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Figure 8. Arthroscopically proved inferior labral-ligamentous avulsion and anterior instability. Axial T1-weighted MR arthrographic image (450/18) through the inferior glenoid fossa shows a normal middle glenohumeral ligament (arrowhead) and a torn anteroinferior labrum (arrow), which is displaced from the glenoid rim.
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Figure 9. Anteroinferior labral deficiency. On an axial T1-weighted MR arthrographic image (450/18) through the inferior glenoid fossa, the glenoid labrum has a rounded, irregular contour at the attachment site of the IGL (arrow). Although the adjacent capsule is normally positioned on the glenoid rim, anterior instability was proved at arthroscopy, and Bankart repair was performed.
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Figure 10a. Inferior labral-ligamentous tear and anterior instability. (a) On an axial T1-weighted MR arthrographic image (450/18) through the inferior glenoid fossa, contrast material fills an anterior labral tear (arrow). (b) Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) shows the IGL (white arrow) attached to the torn labrum (black arrow), which is displaced from the glenoid rim. Arthroscopic Bankart repair was performed.
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Figure 10b. Inferior labral-ligamentous tear and anterior instability. (a) On an axial T1-weighted MR arthrographic image (450/18) through the inferior glenoid fossa, contrast material fills an anterior labral tear (arrow). (b) Coronal oblique fat-suppressed T1-weighted MR arthrographic image (450/18) shows the IGL (white arrow) attached to the torn labrum (black arrow), which is displaced from the glenoid rim. Arthroscopic Bankart repair was performed.
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Although MR arthrographic images have demonstrated greater than 90% accuracy in the detection of anteroinferior glenoid labral tears, diagnostic confidence may be further increased when the shoulder is imaged in abduction and external rotation (ABER) (13,14). The ABER position is achieved by flexing the elbow and placing the patient’s hand posterior to the contralateral aspect of the head or neck (13). With use of a coronal localizer image, ABER images are then prescribed parallel to the long axis of the humerus. In the ABER position, the IGL is stretched, transmitting tension to the labrum. Thus, an anteroinferior glenoid labral tear that is nondisplaced when the shoulder in a neutral position has a greater likelihood of being displaced from the glenoid rim and becoming more conspicuous when the shoulder is in the ABER position.
Hip
Most hip disorders are self-limited and respond to conservative therapy. However, a subset of patients have chronic hip pain or mechanical symptoms (with or without antecedent trauma) and nondiagnostic radiographic examinations. The socioeconomic impact can be great because these patients miss work due to disabling symptoms, seek treatment from several orthopedic surgeons, and undergo repeated testing with conventional radiography, bone scintigraphy, computed tomography (CT), and conventional MR imaging. Eventually, arthroscopy or open surgery is performed as a combined diagnostic and therapeutic procedure.
At surgery, the acetabular labrum and hyaline cartilage are inspected for tears and focal defects, and the capsular recesses are examined for loose bodies. In this subpopulation of patients, acetabular labral tears are identified in over one-half of hips, loose bodies are removed in over one-third of hips, and chondral defects of the femoral head or acetabulum are detected in approximately one-quarter of hips (15,16). Thus, several intraarticular abnormalities are frequently detected in combination.
Preliminary investigations with hip MR arthrography have demonstrated a close correlation between imaging findings and surgical results (17). High diagnostic accuracy is achieved because contrast material outlines the labrum and cartilage and fills tears. Anatomic detail and signal-to-noise ratio are improved by imaging only one hip and by using a surface coil (eg, shoulder or cardiac coil) positioned over the femoral head. Sagittal and coronal T1-weighted images with or without fat suppression can show dysplastic changes, labral tears, and chondral defects. Sagittal oblique images, which are prescribed parallel to the femoral neck from coronal images, best depict the anterosuperior acetabular labrum, where sports-related labral tears and associated capsular defects usually occur (Fig 11). Axial T2-weighted images best depict intraarticular loose bodies.
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Figure 11. Direct axial oblique MR arthrography of the hip. Such imaging optimizes detection of the most common sports-related acetabular labral tears (anterior and anterosuperior in location). On a midcoronal localizer image, the axial oblique sequence is prescribed perpendicular to the line drawn from the superior labrum to the transverse ligament. This line is usually oriented parallel to the long axis of the femoral neck.
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The acetabular labrum shares common histologic and morphologic features with the glenoid labrum (Fig 12). In both the hip and shoulder, the labrum creates a fibrocartilaginous rim that deepens the socket of the joint and increases its surface area for articulation. Whereas the labrum of the shoulder lines the rim of the entire glenoid fossa, the labrum of the hip terminates inferiorly and merges with the transverse acetabular ligament. This ligament connects the anterior and posterior horns of the acetabular labrum. The normal labral fibrocartilage merges with the hyaline cartilage to form a single histologic entity.
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Figure 12. Normal superior acetabular labrum. On a coronal fat-suppressed T1-weighted MR arthrographic image (450/15), the acetabular labrum (arrow) is triangular, smooth in contour, and continuous with the hyaline cartilage, which partially undercuts the labrum.
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Both the acetabular and glenoid labra show normal variations in size, shape, and signal intensity. They are usually triangular but can demonstrate rounding or flattening of the free margin. The labral contour is mostly smooth on MR arthrographic images but can show irregularities at the free margin and small sulci along its junction with articular cartilage. The signal intensity is low with all pulse sequences unless artificially increased on short-echo-time images due to the magic angle phenomenon.
Acetabular labral tears also share common MR arthrographic features with glenoid labral tears (Figs 13, 14). They usually begin at the junction of labral fibrocartilage and hyaline cartilage and can extend into the labral substance or propagate along the labral attachment to bone. Diagnostic specificity is increased if the labral fragment is displaced from the acetabular rim. Tear location depends on cause. Sports-related labral tears are anterosuperior on the acetabular rim. In hip dysplasia or other disorders that disrupt articular congruence (eg, slipped capital femoral epiphysis), labral tears tend to be superior (lateral) on the acetabular rim, where the labrum is susceptible to repeated impaction by the femoral head (18). MR arthrographic images may guide the hip arthroscopist by showing the lengths of labral abnormalities as well as their locations.
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Figure 13. Anterosuperior acetabular labral tear debrided at arthroscopy. Axial fat-suppressed T1-weighted MR arthrographic image (400/15) shows high-signal-intensity contrast material underlying the labrum (arrow), which is minimally displaced from the acetabular rim.
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Figure 14a. Anterosuperior acetabular labral tear resected at arthroscopy. (a) Axial fat-suppressed T1-weighted MR arthrographic image (400/15) shows displacement of a torn labral fragment (straight arrow) from the acetabular rim. High-signal-intensity contrast material extends under the periosteum (curved arrow), which has been stripped away from bone by the labrum. (b) On a sagittal T1-weighted MR arthrographic image (600/15), the contrast material (arrow) separates the torn labral fragment from the underlying articular cartilage.
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Figure 14b. Anterosuperior acetabular labral tear resected at arthroscopy. (a) Axial fat-suppressed T1-weighted MR arthrographic image (400/15) shows displacement of a torn labral fragment (straight arrow) from the acetabular rim. High-signal-intensity contrast material extends under the periosteum (curved arrow), which has been stripped away from bone by the labrum. (b) On a sagittal T1-weighted MR arthrographic image (600/15), the contrast material (arrow) separates the torn labral fragment from the underlying articular cartilage.
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Acetabular labral tear may lead to the formation of an extraarticular cyst when the tear passes through the capsule, allowing leakage of joint fluid. Acetabular labral cysts communicate with the hip joint and can fill with contrast solution following intraarticular injection, similar to the periarticular cysts that develop in patients with meniscal tears in the knee and labral tears in the shoulder. They typically measure 1–2 cm in diameter but can enlarge to 3–4 cm. T2-weighted images are valuable in the demonstration of cysts that do not fill with contrast material, increasing diagnostic specificity for nondisplaced labral tear.
Acetabular labral tear is a starting point for degenerative joint disease. As the torn labral fragment becomes separated from the acetabular rim, it loses its capacity for cushioning and protecting the adjacent articular cartilage. Loading forces across the joint are no longer distributed evenly over the entire cartilage surface. Repetitive impaction by the femoral head on the acetabulum eventually results in the development of chondral defects and progressive osteoarthritis. Therefore, the most important MR arthrographic diagnoses are labral tears, loose bodies (Fig 15), and chondral lesions that are amenable to arthroscopic débridement and repair.
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Figure 15. Intraarticular loose body. Axial fat-suppressed T2-weighted MR arthrographic image (2,800/60) shows a low-signal-intensity focus in the acetabular fossa (arrow) surrounded by contrast material and located adjacent to the ligamentum teres, which attaches to the humeral head. An intraarticular loose body was removed at open surgery.
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Elbow
Saline solution with or without iodinated contrast material or gadolinium can be introduced into the elbow joint. This is useful in patients with suspected collateral ligament tears (19,20). Schwartz et al (19) have recommended fluoroscopic injection of a mixture of 3 mL of iodinated contrast material in 7 mL of saline solution. One of the authors of this article (L.S.S.) uses iodinated contrast material to localize the joint and then injects a mixture of gadolinium and saline solution for a total of up to 10 mL of fluid in the joint. The joint can be entered laterally over the radial head under fluoroscopic guidance or posterolaterally between the olecranon, humerus, and radial head. The latter method has the advantage of not involving a major structure such as the lateral collateral ligament (LCL) complex in the path of the injection.
The 20° posterior coronal oblique plane is ideal for visualizing the ulnar collateral ligament (UCL) and radial collateral ligament (RCL) (Fig 16) (21). These ligaments are thickenings of the joint capsule that can degenerate and tear with or without injury to the overlying flexor or extensor tendons. The ligaments are well evaluated with MR arthrography. Conventional arthrography is not useful for detecting tears except in the early stages (within 24 hours) following acute rupture. Stress radiography can be used to diagnose tears of the UCL; however, additional abnormalities, which are frequently seen in association with these tears, cannot be completely assessed with this method.
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Figure 16. Oblique coronal MR arthrography of the elbow. Sagittal scout view shows how the oblique coronal plane can be obtained by angling the cursors 20° posterior oblique to the long axis of the humerus. (Reprinted, with permission, from reference 21.)
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Ulnar Collateral Ligament.—
The UCL originates from the medial epicondyle and attaches to the medial aspect of the ulna. The UCL complex consists of three parts. The major ligament is the anterior oblique bundle, which is taut with extension and inserts on the ulna along the medial aspect of the coronoid process (sublime tubercle) (Fig 17). The insertion on the sublime tubercle is tight, and there should be little or no contrast material or fluid between the ligament and the sublime tubercle. The other components of the UCL complex are (a) the posterior oblique segment, which is fan-shaped, smaller, and taut with flexion, and (b) the transverse segment, which bridges the ulnar attachments of the anterior and posterior bands. The posterior oblique and transverse segments are often difficult to define at MR imaging and may even be absent. The posterior oblique segment can be better evaluated on sagittal images of the flexed elbow.
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Figure 17. Normal elbow. Direct coronal oblique fat-suppressed T1-weighted MR arthrographic image demonstrates the anterior band of the UCL as a linear low-signal-intensity area (arrowhead) as well as the RCL (curved arrow). The anterior band of the UCL extends from the medial humeral epicondyle to the sublime tubercle of the ulna. The contrast material normally pools around the radial neck (open arrow).
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Rupture of the UCL usually occurs in the flexed elbow with valgus stress. This ligament is injured in sports that involve throwing. In contrast to medial epicondylitis, injury to the UCL in the throwing athlete can be devastating because athletic performance is hindered due to pain and altered biomechanics. One looks for increased signal intensity within and adjacent to the ligament at MR imaging. This can represent sprain, degeneration, hemorrhage, or edema due to microtears resulting from repetitive injury. A fullthickness tear manifests with interruption of the ligament (Fig 18), often accompanied by extravasation of fluid or contrast material into the surrounding soft tissues. Most tears occur in the midproximal fibers of the anterior bundle. The injured ligament can also demonstrate thickening and irregularity, ligamentous laxity, and poor definition (22). Partial-thickness tears are diagnosed when there is focal disruption that does not extend through the full thickness of the ligament. Partial-thickness tears of the ligaments are best visualized if there is fluid or other contrast material adjacent to the ligament. This can be accomplished with MR arthrography (19,23,24). A particular type of partial-thickness tear of the anterior bundle of the UCL manifests at the insertion on the sublime tubercle. This form of partial UCL tear is described as the "T sign," with contrast material extending medial to the tubercle (Fig 19). Lateral compartment bone contusions may be present in association with acute tears of the UCL. Overlying flexor tendon tears are also frequently seen.
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Figure 18. Full-thickness tear of the UCL. Direct coronal oblique fat-suppressed T1-weighted MR arthrographic image of the elbow demonstrates complete ligamentous disruption at the humeral attachment (arrow).
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Figure 19. T sign. Direct coronal oblique fat-suppressed T1-weighted MR arthrographic image of the elbow reveals a partial-thickness tear of the UCL at the attachment on the sublime tubercle (arrow). Note how the contrast material takes the shape of a T as it tracks up the sublime tubercle and into the joint.
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Radial Collateral Ligament.—
The RCL complex is weaker and thinner than the UCL complex. This ligament provides varus stability and is rarely stressed in the athlete. The anconeus muscle also contributes to joint stability. The RCL complex is variable and has three components: the RCL proper, which extends from the lateral epicondyle of the humerus to the annular ligament surrounding the radial head; the accessory collateral ligament; and the lateral UCL. The lateral UCL lies posterior to the RCL, arising from the lateral epicondyle and extending along the posterior aspect of the radius to insert on the supinator crest of the ulna (Fig 20). The lateral UCL is present in 90% of people and provides the primary restraint to varus stress. Disruption of the LCL results in the pivot shift phenomenon and posterolateral rotatory instability of the elbow (25). The RCL proper and the lateral UCL are best evaluated on coronal and axial MR images. Most tears of the lateral UCL occur at the humeral attachment. Unsuspected ruptures of the RCL may also be accompanied by tears of the common extensor tendon (Fig 21).
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Figure 20. Normal lateral UCL. Coronal oblique fat-suppressed T1-weighted MR arthrographic image of the elbow shows the course of the lateral UCL from the lateral humeral epicondyle to the supinator crest of the ulna (arrows).
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Figure 21. Torn RCL extensor tendons. Coronal fat-suppressed T2-weighted MR arthrographic image of the elbow shows disruption of the humeral attachments of the RCL and common extensor tendon (arrows).
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Synovial Folds.—
MR arthrography can also demonstrate synovial folds (plicae) within the elbow joint (Fig 22) (26). A synovial fold that extends from the posterior fat pad in the elbow is a common finding. In some patients, thickened folds may cause locking. There is overlap between the thickness of symptomatic and asymptomatic folds, making clinical correlation imperative.
Knee
MR arthrography of the knee is used to evaluate residual or recurrent meniscal tears following meniscal surgery. It also has the potential to demonstrate loose bodies, synovial plicae, and osteochondral lesion stability.
Direct MR arthrography of the knee is performed by injecting up to 40 mL of diluted gadolinium into the knee joint following aspiration of any effusion. The injection can be performed without fluoroscopic guidance with use of either a medial or lateral patellofemoral approach. Images are obtained with either fat-suppressed T1-weighted or spoiled gradient-echo sequences, along with T2-weighted or short-inversion-time inversion recovery sequences.
The detection of residual or recurrent meniscal tears following meniscectomy or meniscal repair is difficult with conventional MR imaging, and many are turning to MR arthrography for this purpose. Applegate et al (27) compared findings at direct MR arthrography with those at conventional MR imaging in patients who had undergone meniscectomy with follow-up arthroscopy. Overall accuracy was 66% for conventional MR imaging compared with 88% for MR arthrography. In particular, MR arthrography was more accurate when more than 25% of the meniscus was resected. Most other authors have had similar results (28). The diagnosis of a recurrent tear is made when intraarticular gadolinium tracks into the meniscus (Fig 23). It has been suggested that, when a primary suture repair of the meniscus has been performed, one can distinguish a partially healed tear (in which gadolinium contacts only one meniscal surface) from a tear (characterized by extension of gadolinium between superior and inferior meniscal surfaces) (29). Recently, a prospective study of 104 postoperative menisci by White et al (30) showed a small incremental increase in accuracy for the detection of meniscal tear following meniscal surgery with direct MR arthrography compared with conventional MR imaging and indirect MR arthrography. However, no significant difference in diagnostic accuracy (P > .54) was apparent between the three techniques.
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Figure 23. Meniscal tear following meniscal surgery. Coronal fat-suppressed T1-weighted MR arthrographic image of the knee shows high-signal-intensity diluted gadolinium within the meniscus (arrow), a finding that is consistent with a radial tear.
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Wrist
MR arthrography is useful for evaluation of the ligaments and triangular fibrocartilage (TFC) of the wrist (31–33). It combines the advantages of arthrographic depiction of anatomic perforation with the direct visualization of marrow, cartilage, and soft tissues allowed by MR imaging and can be performed with single-, double-, or triple-compartment injection. The extrinsic ligaments will not be discussed in this article.
We favor the single-compartment radiocarpal injection technique. Approximately 4 mL of a mixture of diluted gadolinium and iodinated contrast material is injected into the wrist. This can be performed with fluoroscopy or with anatomic guidance at the MR imager (34). The wrist is exercised and videotaped when fluoroscopy is used. Coronal gradient-echo images with volume acquisition of 1-mm section thickness or less aid in precise localization of the perforations in these smaller structures. We also obtain fat-suppressed T1-weighted and fast spin-echo images in the coronal and axial planes. The normal radiocarpal arthrogram shows contrast material confined to the compartment between the proximal carpal row, radius, and ulna (Fig 24).
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Figure 24. Normal wrist. Coronal oblique spoiled gradient-echo radiocarpal MR arthrographic image demonstrates high-signal-intensity contrast material confined to the space between the radius, ulna, and proximal carpal row. The scapholunate bone, lunotriquetral ligament (LTL), and TFC are not disrupted by contrast material.
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Intrinsic Proximal Carpal Row Ligaments.—
The two most important intercarpal ligaments are the scapholunate ligament (SLL) and the lunotriquetral ligament (LTL). The SLL and LTL are crescentic or delta-shaped ligaments with at least three separate anatomic zones. The dorsal and volar segments are composed of dense fibrous tissue with strong attachments to the adjacent carpal bones and extrinsic ligaments. The central segment of these ligaments is a thin membrane with relatively weak attachments to the adjacent carpal bones. The middle third of the SLL and LTL inserts directly on the hyaline cartilage of the scaphoid, lunate, and triquetral bones, whereas the dorsal and volar components often insert directly on the carpal bones. The shape and signal intensity characteristics of the interosseous ligaments are variable. Although these ligaments usually have low signal intensity, there can be an occasional area of intermediate signal intensity that traverses the interosseous ligaments. This intermediate-signal-intensity area can be distinguished from a ligament tear because the signal intensity is not as high as that of fluid. Such a pattern of increased signal intensity on T1-weighted images and decreased signal intensity on T2-weighted images has been seen with ligament degeneration. Nonvisualization of the interosseous ligaments is a rare manifestation of SLL or LTL tear. Fluid signal intensity or diluted gadolinium that traverses the interosseous ligaments remain useful signs of ligament perforation or tear (Fig 25). The location of the tear in both anteroposterior and mediolateral directions is important. A perforation is not always symptomatic and should be correlated with clinical findings. Surface irregularity is a sign of fraying and partial tear. Perforations of the central segment of the interosseous ligaments are part of the aging process and may not produce any symptoms or instability.
Triangular Fibrocartilage Perforations.—
The TFC is an important structure that cushions the ulnocarpal articulation and stabilizes the distal radioulnar joint. Tears of the TFC result in nonspecific pain, crepitus, and weakness and can be difficult to distinguish from other causes of ulnar wrist pain.
The TFC is a low-signal-intensity bow tie–like structure that extends radially from the intermediate-signal-intensity hyaline cartilage located at the dorsal ulnar aspect of the lunate fossa to the fovea at the base of the radial aspect of the ulnar styloid process and to the ulnar styloid process itself. The ulnar attachment is often obscured by surrounding loose vascular connective tissue, which has intermediate signal intensity. The prestyloid recess is an extension of the radiocarpal joint, which also lies near the ulnar attachment of the TFC. Fluid in this recess produces increased signal intensity. The low-signal-intensity dorsal and volar distal radioulnar ligaments are most easily seen on sagittal and axial images. It is best to image the TFC with the forearm in neutral rotation (35).
Degeneration of the TFC is frequently seen and often asymptomatic. Progressive degeneration of the proximal surface leads to erosion, thinning, and perforation of the TFC. Degenerative perforations are more common in the thinner central portion of the TFC, whereas traumatic tears tend to occur in the radial portion. When there is degeneration of the TFC, MR imaging demonstrates intermediate signal intensity on short-echo-time images that does not increase on T2- or T2*-weighted images. Perforations of the TFC can be asymptomatic or posttraumatic and may contain high-signal-intensity fluid on T2-weighted and fat-suppressed T1-weighted MR arthrographic images (Fig 26). Some tears are partial and may extend only to the superior or inferior surface. With a traumatic TFC tear, fluid or contrast material is usually present in the distal radioulnar joint. The presence of fluid alone in this location with no gadolinium should suggest synovitis or mechanical irritation of the distal radioulnar joint.
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Figure 26. Triangular fibrocartilage perforation. Coronal fat-suppressed gradient-echo MR arthrographic image shows a small perforation filled with high-signal-intensity diluted gadolinium (arrow).
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Detection of TFC tear with conventional MR imaging alone has been investigated by several groups over the past two decades. In a study of 41 patients, Zlatkin et al (36) reported a sensitivity of 100% and a specificity of 93% compared with arthrography and a sensitivity of 89%, a specificity of 92%, and an accuracy of 90% compared with arthroscopy and arthrotomy. Golimbu et al (37) found a sensitivity of 93% and an accuracy of 95% in 20 patients with surgical correlation. Schweitzer et al (38) compared MR imaging with arthrography as a standard of reference in 15 patients with chronic wrist pain and found MR imaging to have a sensitivity, specificity, and accuracy of 72%, 94%, and 89%, respectively. In a prospective study of 77 patients, 59 of whom had tears at arthroscopy, Potter et al (39) demonstrated that high-resolution MR imaging has a sensitivity of 100%, a specificity of 90%, and an accuracy of 97%. Oneson et al (40) evaluated 56 patients who underwent arthroscopic evaluation of the TFC. In 27 patients, the TFC was intact at surgery; 27 patients had complete perforations; and two patients had partial defects. There was a 91% sensitivity for detecting central degenerative perforations, and the rate of detection of radial slitlike tears for two different observers was 100% and 86%, respectively. Sensitivity for detecting ulnar-sided avulsions was 25% and 50%, respectively, for these two observers. This suggests that ulnar-sided tears are more difficult to depict with routine MR imaging. Haims et al (41) most recently confirmed the limitations of nonarthrographic MR imaging in the diagnosis of peripheral ulnar-sided tears of the TFC. They found the sensitivity for evaluation of tears of the peripheral TFC complex to be 17%, with a specificity of 79% and an accuracy of 64%. It seems that MR arthrography may play an important role in improving sensitivity for TFC lesions, although this remains to be proved.
Ankle
MR arthrography can be used in selected cases of ankle MR imaging to assess ligamentous damage, impingement, and loose bodies. The following technique is recommended: Under fluoroscopic guidance, a 23-gauge needle is introduced with use of sterile technique into the ankle joint medial to the extensor hallucis longus muscle with a slight cranial tilt. Intraarticular needle placement is confirmed with an injection of up to 5 mL of iodinated contrast material. Subsequently, 5–7 mL of a mixture of 0.1 mL of diluted gadolinium, 20 mL of saline solution, and .3 mL of epinephrine (ratio, 1:1000) is injected. Thin-section (
1-mm) three-dimensional volume spoiled gradient-echo or fat-suppressed T1-weighted images are obtained in all three planes (axial, sagittal, coronal), followed by either fat-suppressed fast spin-echo proton-density–weighted, T2-weighted, or short-inversion-time inversion recovery images in at least two planes. The examination can be made shorter by tailoring the planes and sequences to the particular problem. A normal MR arthrogram of the ankle may be associated with contrast material that enters the flexor hallucis longus and flexor digitorum longus tendon sheaths as well as the subtalar joint in up to 25% of cases (42).
Ankle Ligaments.—
Sprains of the LCL complex typically follow an inversion injury and are one of the most common musculoskeletal injuries, comprising up to 10% of all injuries treated in emergency departments in the United States and 15%–25% of all sports injuries (43). Although most ankle inversion injuries are self-limited, 10%–20% of patients may develop chronic lateral instability (44). Surgical repair is considered for grade III sprains, high-level athletes, and patients with chronic pain and instability (44). In all of these cases, MR arthrography might prove beneficial.
MR arthrography better demonstrates the ligaments than does conventional MR imaging, as shown in several studies, including one that looked at normal ligaments in cadavers (45). In one study, conventional MR imaging had a sensitivity of 50% for diagnosing tears of either the anterior talofibular ligament (ATL) or calcaneofibular ligament (CFL), whereas MR arthrography had a sensitivity of 100% for ATL tears and of 90% for CFL tears. In subacute and chronic cases, fluid is often absent, and MR arthrography is helpful for assessing ligamentous damage (43,46).
When injury occurs to the lateral ankle joint, the weaker ATL is torn first and most frequently. Half of all ATL tears occur at the talar insertion, and most of the others are located in the midsubstance. The CFL may be injured with more severe inversion and is almost always associated with an ATL injury. The CFL is disrupted in up to 20% of all LCL tears (42). Patients with complete disruption of the CFL are at risk for developing chronic instability. Posterior talofibular ligament injury is uncommon and is seen in combination with injury to both the ATL and CFL.
In first-degree ligament sprains, a focal area of high signal intensity is seen within the ligament on T2-weighted MR images. Contrast material does not enter the ligament. Second-degree sprains demonstrate partial discontinuity of the ligament, irregularity, beading, or fraying. Third-degree sprains manifest as discontinuity or absence of the ligament with passage of contrast material or fluid through the ligamentous disruption into the surrounding soft tissues (Fig 25). Chronically injured ligaments may also appear wavy or thickened at MR imaging.
An ATL tear manifests as nonvisualization or extravasation of contrast material anteriorly through a defect in the ligament. A CFL tear is evident when there is contrast material lateral to the ligament or in the peroneal tendon sheaths (Fig 27). Extravasation of contrast material into the soft tissue behind the posterior talofibular ligament (PTL) indicates a tear of this structure. In a cadaver study, MR arthrography was not shown to be more sensitive or specific than conventional MR imaging for evaluation of the medial collateral ligament complex (45).
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Figure 27. Torn LCL. Coronal fat-suppressed T1-weighted MR arthrographic image demonstrates contrast material that surrounds the peroneal tendon (arrow), a finding that is consistent with a CFL tear.
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The anterior tibiofibular ligament complex extends from the longitudinal tubercle located on the anterior border of the lateral malleolus to the anterolateral tubercle of the tibia. The posterior tibiofibular ligament complex extends from the posterolateral tibial tubercle to the posterior and distal aspect of the lateral malleolus. A deep transverse ligamentous component is located inferiorly. The third component of the posterior tibiofibular ligament complex is the posterior intermalleolar ligament (47). It extends between the posterior aspect of the medial and lateral malleoli and is often not visualized on MR imaging examinations. The interosseous ligament is located at the most caudal end of the interosseous membrane. It is approximately 1 cm high and has a globular configuration. The intermalleolar ligament is known to cause posterior impingement in ballet dancers (47). MR arthrography improves visualization of the tibiofibular and intermalleolar ligaments (45). Posterior ligaments are best seen with the ankle in dorsiflexion, and subsequent plantar flexion demonstrates impingement. Potential pitfalls of MR arthrography of the ankle ligaments include accumulation of contrast material in the anterior and posterior recesses of the ankle joint, which manifests as smooth, encapsulated fluid outside of these ligaments. The bulbous appearance of the PTL and posterior tibiofibular ligament on sagittal images can simulate loose bodies. Serial evaluation of sagittal images and knowledge of the characteristic location of these ligaments help avoid this pitfall.
Ankle Impingement Syndromes.—
Ankle impingement is a clinical diagnosis. At times, MR arthrography is useful for demonstrating anterolateral, anteromedial, and posterior impingement syndromes in the ankle because it is the most accurate means of assessing the capsular recesses of the ankle (48,49).
The anterolateral recess of the tibiotalar joint is a site of repeated microtrauma and hemorrhage from forced plantar flexion and supination of the ankle. Hypertrophy of the inferior portion of the ATL and osseous spurs can also contribute to this form of impingement. This can result in synovial scarring, inflammation, and hypertrophy, which produce symptoms that are relieved with physical therapy and débridement. The characteristic appearance of this form of impingement is nodular capsular thickening or a low-signal-intensity mass in the lateral gutter bounded posteromedially by the tibia, laterally by the fibula, and anteriorly and posteriorly by the tibiotalar joint capsule and ligaments (Fig 28). Absence of fluid between the anterolateral soft tissues and the anterior surface of the fibula is invariably associated with scarring and synovitis. However, findings should be correlated with clinical signs of impingement because a substantial number of asymptomatic ankles have similar appearances (48).
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Figure 28. Anterolateral impingement of the ankle. Axial fat-suppressed T1-weighted MR arthrographic image shows intermediate-signal-intensity soft tissue in the lateral aspect of the ankle joint (arrow). (Courtesy of David Salonen, MD, Department of Radiology, University of Toronto, Canada.)
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Anteromedial ankle impingement syndrome is generally thought to result from supination (inversion) injury. An anteromedial synovial mass or synovial thickening is well seen when there is fluid in the joint. There may also be associated tibial or talar osteophytes.
Posterior impingement has been described following forced plantar flexion with compression of the osseous and soft tissues between the calcaneus and tibia, including the intermalleolar ligament (47).
Osteochondral Injuries
The medial femoral condyle, talar dome, and capitellum are frequent sites of osteochondral injury. Treatment is based on the degree of stability of the osteochondral fragment. If the fragment is attached to bone, the joint is managed conservatively. If there is partial or complete detachment, the fragment is either removed or reattached (pinned) to the parent bone. MR arthrography is helpful in evaluating the articular cartilage, and partial or complete loosening of the fragment manifests as contrast material entering the fragment–parent bone interface (Fig 29). In one study, MR arthrography had a sensitivity of 85% in the detection of osteochondral lesions, compared with a 69% sensitivity for conventional MR imaging (50). MR arthrography had an accuracy of 93% in the evaluation of instability, compared with a 39% accuracy for conventional MR imaging.
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Figure 29. Unstable osteochondral lesion of the talar dome. Sagittal fat-suppressed T1-weighted MR arthrographic image demonstrates high-signal-intensity diluted gadolinium surrounding the osteochondral fragment (arrow).
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Intraarticular Osteochondral Bodies
CT arthrography is very useful for identifying loose bodies. However, it is less capable of detecting other abnormalities in the joint, such as a cartilaginous donor site or associated ligamentous damage, so that one may prefer to go directly to MR arthrography for delineation of loose cartilage and bone in the joint (Fig 15) (46). Gadolinium-enhanced MR arthrography has demonstrated a high accuracy in the detection of osseous and cartilaginous bodies combined (92%) and was significantly better than MR imaging (57%–70% accuracy) in this setting (51). Air bubbles can mimic loose bodies at MR arthrography, but most air bubbles can be distinguished by their nondependent position and typical appearance.
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Indirect MR Arthrography
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Indirect MR arthrography is predicated on the concept that contrast material injected intravenously over time will diffuse into the joint space, so that quasiarthrographic T1-weighted images can be obtained (52). It is helpful to use a fluid compartment model to understand the physiologic foundations of indirect MR arthrography (53). MR imaging contrast agents have variable degrees of weak protein binding. Consequently, most contrast agents can be thought of as existing in the plasma compartment. Another compartment is the interstitial space, which exists in the soft tissues within and between organs. There is normally little movement from the plasma compartment into the interstitial space because in most of the body there is a tight basement membrane in the walls of the blood vessels. Last and most important, for indirect MR arthrography there is another compartment: the joint space. The joint space normally contains small but variable amounts of synovial fluid (54). Because the blood vessels in the synovial membrane lack a basement membrane, the synovial fluid is equivalent to lightly filtrated plasma. Consequently, a fairly rapid steady state develops in which substances develop equal concentrations in plasma as in the joint fluid (53).
MR imaging contrast agents do not produce signal themselves but affect the relaxivity of the surrounding structures; consequently, a very low concentration can affect numerous surrounding molecules. After a period of time, the contrast material that has diffused into the joint space will have a signal intensity similar to that of contrast material injected directly into the joint space (55).
There are two physical processes that cause contrast material to move into the joint space: bulk flow and diffusion (53). Bulk flow is related to the pressure gradient from the vascular system into the joint space. Because the joint spaces are low-resistance structures, with the contrast material in the arterial system or even the venous system, there is almost always a pressure gradient from the plasma. Pathophysiologic processes that act to increase intraarticular pressure will decrease the amount and rate of bulk flow. The most important of these processes are either tense effusions or effusions with high viscosity. The former occur with hemorrhagic effusions following trauma or in septic arthritis; the latter occur with arthritic diseases or chronic infections. These conditions will decrease the indirect arthrographic effect and prolong the time interval until a steady state occurs between the vascular compartment and the joint compartment. To some degree, exercise will also increase intraarticular pressure, and although it has other positive effects on indirect arthrographic images, it has the negative effect of decreasing bulk flow (56). However, if exercise is passive, the intraarticular pressure does not increase and there is little negative effect on bulk flow (53). Passive exercise is done by the contralateral extremity moving the ipsilateral extremity without muscle contraction of the extremity to be imaged. Exercise, specifically active exercise, increases vascular pressure, thereby improving bulk flow into the joint (57). Therefore, both passive and active exercise can accentuate the indirect arthrographic effect by means of slightly different processes. Interestingly, anxiety, by increasing arterial pressure, theoretically should increase bulk flow and, consequently, the indirect arthrographic effect.
Diffusion is based on the difference in concentration between plasma and joint fluid (58). One way of increasing the diffusion gradient is to increase the dose of contrast material administered intravenously, and, thus, the plasma concentration. Double- and triple-dose intravenous injections have a positive effect on indirect arthrography but not nearly as much as one might think (59). Exercise decreases the perisynovial concentration of the joint fluid by moving joint fluid away from the membrane, thereby increasing the concentration gradient. This is another important positive effect of exercise on indirect MR arthrography.
Contrast agents that have high relaxivity, particularly when placed in a proteinaceous environment, have the most prominent indirect effect. This differs from the relaxivity required for intravenous use, which is measured in a saline environment. In addition, the weaker the protein binding of the agent, the greater the diffusion and the greater the indirect effect. Lastly, the ionicity of these agents leads to positive secondary effects. Specifically, highly charged agents will bind to proteoglycans in cartilage, providing additional information on early cartilage loss (60). Therefore, the ideal contrast agent with indirect MR arthrography is weakly protein-based, highly charged, and has high relaxivity in a proteinaceous environment.
Indirect MR arthrography generally works best in joints that have the bulk of the joint fluid in proximity to the synovial membrane. Such joints are small or have large amounts of synovial invagination. Consequently, indirect MR arthrography works best in the wrist, ankle, fingers, and toes because these joints are small, or in the shoulder, which has a fair amount of synovial invagination (Figs 30, 31) (61–68). Indirect arthrography is not as successful in joints that have a large distance for the contrast material to diffuse across, most prominently the knee (Fig 32) (57,69).
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Figure 30. Full-thickness rotator cuff tear. Coronal oblique T1-weighted MR image of the shoulder (500/12) obtained following indirect MR arthrography demonstrates focal enhancement of the critical zone from a full-thickness rotator cuff tear (arrow).
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Figure 32. Retorn meniscus in a patient who had undergone partial meniscectomy. Indirect MR arthrographic image of the knee (600/8) shows no opacification of the joint fluid around the meniscus because of inadequate delay related to joint effusion, resulting in obscuration of the retorn meniscus (arrow).
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In the interpretation of indirect MR arthrographic images, it is important to understand the differences between indirect and direct MR arthrography. The most important difference is that contrast enhancement is not affected by compartmental anatomy at indirect MR arthrography; every joint space will enhance (53). Consequently, contrast material in the subacromial-subdeltoid bursa enhances and may be seen regardless of whether a rotator cuff tear is present (Fig 33). However, one may use the enhancement relative to a standard of reference as a window into the vascularity of that structure. Hyperemia related to disease will cause an articulation to enhance more quickly and intensely and is usually an indication of an internal derangement or some other type of pathologic process affecting the joint (Fig 34) (62). Joints that opacify slowly may have fibrotic synovium or viscous effusions (Fig 32). This information based on differential enhancement is an advantage of indirect MR arthrography.
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Figure 33. Rotator cuff tear. Indirect axial MR arthrographic image of the shoulder (480/12) demonstrates focal enhancement of a rotator cuff tear (solid arrow) in the anterior leading edge of the cuff. A small amount of bursal enhancement is also seen (open arrow), a finding that is in fact seen in most individuals.
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Figure 34. Cartilage defect. Indirect coronal T1-weighted MR arthrographic image demonstrates a normal rotator cuff. Glenoid enhancement is seen secondary to a nonvisualized cartilage defect (arrow). Indirect MR arthrography is exquisitely sensitive to cartilage defects related to the alteration that occurs in the subchondral marrow.
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Another difference between indirect and direct MR arthrography is that every abnormality or vascularized structure will enhance with the indirect method. This includes not only joint effusions, but also abnormal marrow, tendons, or cartilage (Fig 35) (59). Consequently, a rotator cuff tear will directly enhance from the hyperemic blood flow (Fig 33) and indirectly enhance through contrast material imbibition into the defect from the joint fluid. However, this is a diagnostic disadvantage in the shoulder because tendinosis enhancement limits the conspicuity of rotator cuff tears (Fig 36) (65).
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Figure 35. De Quervain stenosing tenosynovitis. Indirect axial MR arthrographic image of the wrist (600/10) demonstrates enhancement in the first extensor compartment (arrow), a finding that is consistent with de Quervain stenosing tenosynovitis. The greatest advantage of indirect MR arthrography is visualization of both intraarticular and extraarticular disease processes.
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Figure 36. Rotator cuff tendinosis. Indirect coronal oblique T1-weighted MR arthrographic image demonstrates rotator cuff tendinosis with focal enhancement (arrow). At surgery, no rotator cuff tear was present. Because all hypervascular processes enhance to some degree, it becomes difficult to distinguish tendon degeneration from rotator cuff tear at indirect MR arthrography.
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Most extraarticular pathologic processes will also enhance to some degree. These include plantar fasciitis, sinus tarsi syndrome, carpal tunnel syndrome, and nerve entrapment disorders, among many others (20). Finally, cartilaginous defects will almost always be quite visible at indirect MR arthrography due to enhancement of the subchondral bone related to trabecular disruption and hyperemia and visualization of enhanced fluid filling the defect (Fig 34). Bone bruises, geodes, and inflammatory erosions from arthritis also enhance prominently. However, some articular and extraarticular pathologic processes do not enhance. The most important of these are meniscal tears, which may not be visible without significantly delayed images because imbibition is required for diagnosis (30).
The most important advantages of indirect MR arthrography are logistic. No fluoroscopic guidance is required, there is no articular injection, and imaging can be performed during off-hours or offsite. In addition, the normal concerns about scheduling MR imaging shortly after injection do not apply to indirect MR arthrography.
These all represent significant advantages of indirect MR arthrography over direct MR arthrography. However, there are some disadvantages with indirect MR arthrography. One is related to the direct vascular effect of intravenous contrast material used for indirect arthrography. This becomes a clinical problem in structures in which contrast enhancement is seen, not as a sign of disease, but of normal vascularity. These vascularized structures include the periphery of the menisci and of the TFC (Fig 37) (41). Both of these structures can be difficult to evaluate on unenhanced images, but evaluation becomes even more difficult on enhanced images. In addition, structures that depend on distention for visualization—in particular, the labrum—are poorly seen (67). With direct MR arthrography, distention is predictable; with indirect MR arthrography, visualization depends on the presence and size of the effusions (Fig 38) (53). As discussed earlier, most of the spectrum of disorders will enhance at indirect MR arthrography, not just the "tears." This may make the more severe stages of disease less conspicuous against the background enhancement. This occurs in the shoulder (rotator cuff) as previously discussed as well as in the labrum.
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Figure 37. Normal wrist. Indirect coronal MR arthrographic image (600/26) demonstrates focal enhancement of the periphery of the TFC (arrow). Because this area is normally vascularized, it is extremely difficult to distinguish a tear from normal findings at indirect MR arthrography.
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Technically, indirect MR arthrography involves protocol considerations similar to those of direct arthrography, with T1-weighted images, often with fat suppression, obtained in multiple planes. These T1-weighted images can be obtained with conventional spin-echo, fast spin-echo, or gradient-echo sequences (either three-dimensional or multisection) (Fig 39). As with direct MR arthrography, T2-weighted imaging is suggested in a plane that allows optimal visualization of extraarticular disease. There are, however, two important differences between indirect and direct MR arthrography in terms of imaging protocol. One is that fat suppression is almost mandatory in indirect MR arthrography. Because the concentration of the contrast agents in the joint fluid is so low, they may be quite difficult to visualize without fat suppression. The second protocol-related consideration is the concept of biphasic indirect MR arthrography.
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Figure 39. Indirect axial T1-weighted MR arthrographic image of the wrist (500/15) demonstrates no opacification of the synovial sheath or joint spaces. Because no joint effusions or synovitis is present, there is no space for the diluted gadolinium to diffuse into and, hence, no indirect effect.
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Biphasic indirect arthrography takes advantage of the fact that the gadolinium-based agents are vascular agents. Consequently, vascular information can be gleaned and direct enhancement of the pathologic processes discussed earlier can be seen. Therefore, we often obtain an initial T1-weighted image immediately following contrast material administration (Fig 40a). These early images are the vascular images. T2-weighted imaging is used to visualize extraarticular disease. This is followed by "delayed" fat-suppressed T1-weighted imaging performed in three planes. These final sets of images are the indirect MR arthrographic images (Fig 40b). Thus, two sets of T1-weighted images (early and late) are obtained; hence the term biphasic. This technique can only be used without patient exercise.
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Figure 40a. Wrist abnormalities. (a) Early indirect T1-weighted biphasic MR arthrographic image demonstrates synovitis in the distal radioulnar joint (white arrow). The synovitis enhances disproportionately to the rest of the joint. There are also cartilage defects with enhancing underlying marrow edema in the proximal capitate, lunate, and triquetral bones (black arrows). The first defect is related to a dysfunctional SLL. The latter two defects are associated with a TFC tear. (b) Later image demonstrates more uniform joint enhancement and the TFC tear. The distal radioulnar joint is seen to contain an intraarticular body.
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Figure 40b. Wrist abnormalities. (a) Early indirect T1-weighted biphasic MR arthrographic image demonstrates synovitis in the distal radioulnar joint (white arrow). The synovitis enhances disproportionately to the rest of the joint. There are also cartilage defects with enhancing underlying marrow edema in the proximal capitate, lunate, and triquetral bones (black arrows). The first defect is related to a dysfunctional SLL. The latter two defects are associated with a TFC tear. (b) Later image demonstrates more uniform joint enhancement and the TFC tear. The distal radioulnar joint is seen to contain an intraarticular body.
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Overall, exercise tends to improve the indirect effect. The patient undergoes injection in the waiting area or a staging area, and the contrast material subsequently diffuses. It is our opinion that in this situation, images obtained prior to contrast material administration are not worth the logistic difficulties. Exercise can be passive or active, each with its own advantages as discussed earlier. However, it is not necessary for the patient to exercise for more than 10 minutes (70).
Imaging should be delayed when the traditional indirect MR arthrographic technique (as opposed to the biphasic technique) is used (53). General guidelines for the delay time are 5–10 minutes in the wrist, elbow, or ankle; 15 minutes in the shoulder and hip; and at least 30 minutes in the knee. If there is hyperemia or synovitis of the structure of interest, these times can be decreased by one-half. However, if there is clinically suspected joint effusion, particularly tense effusion, the time should be at least doubled.
Indirect arthrography is also useful in postoperative situations, similar to those situations in which one would use direct MR arthrography. The one time that indirect MR arthrography is not recommended is for labral tears, particularly in the shoulder but also in the hip, although to a lesser degree. For this indication, distention of the joint is necessary for the contrast material to dissect between small tears or detachments of the labrum.
In our opinion, the overall advantage of indirect MR arthrography lies in gathering combined intraarticular and physiologic information, especially in the wrist, foot, ankle, and elbow (Fig 41). Indirect MR arthrography can be used effectively in the knee. However, the biphasic technique cannot be used because it takes longer for the contrast material to diffuse into the knee due to the large, or potentially large, joint volume. Because there is no control of articular distention as with direct MR arthrography, it is hard to anticipate how much time should transpire before obtaining delayed images.
The most important indication for indirect MR arthrography is the need for detailed evaluation of intra- and extraarticular disease in any joint. Indirect MR arthrography can be used to rule in or diagnose abnormalities as well as to exclude abnormalities. If a structure with questionable clinical features does not enhance, it is almost invariably normal, and therefore disease in this region can be excluded with confidence.
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Footnotes
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Abbreviations: ABER = abduction and external rotation,
ATL = anterior talofibular ligament,
CFL = calcaneofibular ligament,
IGL = inferior glenohumeral ligament,
LCL = lateral collateral ligament,
LTL = lunotriquetral ligament,
PTL = posterior talofibular ligament,
RCL = radial collateral ligament,
SLL = scapholunate ligament,
TFC = triangular fibrocartilage,
UCL = ulnar collateral ligament
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References
|
|---|
- Flannigan B, Kursunoglu-Brahme S, Snyder S, Karzel R, Del Pizzo W, Resnick D. MR arthrography of the shoulder: comparison with conventional MR imaging. AJR Am J Roentgenol 1990; 155:829-832.[Abstract/Free Full Text]
- Hodler J, Kursunoglu-Brahme S, Snyder SJ, et al. Rotator cuff disease: assessment with MR arthrography versus standard MR imaging in 36 patients with arthroscopic correlation. Radiology 1992; 192:431-436.
- Palmer WE, Brown JH, Rosenthal DJ. Fat-suppressed MR arthrography of the shoulder: evaluation of the rotator cuff. Radiology 1993; 188:683-687.[Abstract/Free Full Text]
- Chandnani VP, Yeager TD, DeBerardino T, et al. Glenoid labral tears: prospective evaluation with MR imaging, MR arthrography and CT arthrography. AJR Am J Roentgenol 1993; 161:1229-1235.[Abstract/Free Full Text]
- Palmer WE, Brown JH, Rosenthal DJ. Labral-ligamentous complex of the shoulder: evaluation with MR arthrography. Radiology 1994; 190:645-651.[Abstract/Free Full Text]
- Chandnani VP, Gagliardi JA, Murnane TG, et al. Glenohumeral ligaments and shoulder capsular mechanism: evaluation with MR arthrography. Radiology 1995; 196:27-32.[Abstract/Free Full Text]
- Palmer WE, Caslowitz PL. Anterior shoulder instability: diagnostic criteria determined from prospective analysis of 121 MR arthrograms. Radiology 1995; 197:819-825.[Abstract/Free Full Text]
- Willemsen UF, Wiedemann E, Brunner U, et al. Prospective evaluation of MR arthrography performed with high-volume saline enhancement in patients with recurrent anterior dislocations of the shoulder. AJR Am J Roentgenol 1998; 170:79-84.[Abstract/Free Full Text]
- Hajek PC, Sartoris DJ, Neumann CH, Resnick D. Potential contrast agents for MR arthrography: in vitro evaluation and practical observations. AJR Am J Roentgenol 1987; 149:97-104.[Abstract/Free Full Text]
- Kreitner KF, Botchen K, Rude J, Bittinger F, Krummenauer F, Thelen M. Superior labrum and labral-bicipital complex: MR imaging with pathologic-anatomic and histologic correlation. AJR Am J Roentgenol 1998; 170:599-605.[Abstract/Free Full Text]
- Bowen MK, Warren RF. Ligamentous control of shoulder stability based on selective cutting and static translation experiments. Clin Sports Med 1991; 10:757-782.[Medline]
- O’Connell PW, Nuber GW, Mileski RA, Lautenschlager E. The contribution of the glenohumeral ligaments to anterior stability of the shoulder joint. Am J Sports Med 1990; 18:579-584.[Abstract/Free Full Text]
- Cvitanic O, Tirman PFJ, Feller JF, Bost FW, Minter J, Carroll KW. Using abduction and external rotation of the shoulder to increase the sensitivity of MR arthrography in revealing tears of the anterior glenoid labrum. AJR Am J Roentgenol 1997; 169:837-844.[Abstract/Free Full Text]
- Kwak SM, Brown RR, Trudell D, Resnick D. Glenohumeral joint: comparison of shoulder positions at MR arthrography. Radiology 1998; 208:375-380.[Abstract/Free Full Text]
- Hodler J, Yu JS, Goodwin D, Haghighi P, Trudell D, Resnick D. MR arthrography of the hip: improved imaging of the acetabular labrum with histologic correlation in cadavers. AJR Am J Roentgenol 1995; 165:887-891.[Abstract/Free Full Text]
- Petersilge CA, Haque MA, Petersilge WJ, Lewin JS, Lieberman JM, Buly R. Acetabular labral tears: evaluation with MR arthrography. Radiology 1996; 200:231-235.[Abstract/Free Full Text]
- McCarthy JC, Busconi B. The role of hip arthroscopy in the diagnosis and treatment of hip disease. Can J Surg 1995; 38(suppl 1):S13-S17.
- McCarthy JC, Mason JB, Wardell SR. Hip arthroscopy for acetabular dysplasia: a pipe dream? Orthopedics 1998; 21:977-979.[Medline]
- Schwartz ML, Al-Zahrani S, Morwessel RM, Andrews JR. Ulnar collateral ligament injury in the throwing athlete: evaluation with saline-enhanced MR arthrography. Radiology 1995; 197:297-299.[Abstract/Free Full Text]
- Carrino JA, Morrison WB, Zou KH, Steffen RT, Snearly WN, Murray PM. Noncontrast MR imaging and MR arthrography of the ulnar collateral ligament of the elbow: prospective evaluation of two-dimensional pulse sequences for detection of complete tears. Skeletal Radiol 2001; 30:625-632.[CrossRef][Medline]
- Cotten A, Jacobson J, Brossmann J, et al. Collateral ligaments of the elbow: conventional MR imaging and MR arthrography with coronal oblique plane and elbow flexion. Radiology 1997; 204:806-812.[Abstract/Free Full Text]
- Mirowitz SA, London SL. Ulnar collateral ligament injury in baseball pitchers: MR imaging evaluation. Radiology 1992; 185:573-576.[Abstract/Free Full Text]
- Steinbach LS, Schwartz ML. Elbow arthrography. Radiol Clin N Am 1998; 36:635-649.[CrossRef][Medline]
- Hill NB, Bucchieri JS, Shon F, Miller TT, Rosenwasser MP. Magnetic resonance imaging of injury to the medial collateral ligament of the elbow: a cadaver model. J Shoulder Elbow Surg 2000; 9:418-422.[CrossRef][Medline]
- O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am 1991; 73:440-446.[Abstract/Free Full Text]
- Awaya H, Schweitzer ME, Feng SA, et al. Elbow synovial fold syndrome: MR imaging findings. AJR Am J Roentgenol 2001; 177:1377-1381.[Abstract/Free Full Text]
- Applegate GR, Flannigan BD, Tolin BS, Fox JM, Del Pizzo W. MR diagnosis of recurrent tears in the knee: value of intraarticular contrast material. AJR Am J Roentgenol 1993; 161:821-825.[Abstract/Free Full Text]
- Sciulli RL, Boutin RD, Brown RR, et al. Evaluation of the postoperative meniscus of the knee: a study comparing conventional arthrography, conventional MR imaging, MR arthrography with iodinated contrast material, and MR arthrography with gadolinium-based contrast material. Skeletal Radiol 1999; 28:508-514.[CrossRef][Medline]
- Haims AH, Katz LD, Ruwe PA. MR arthrography of the knee. Semin Musculoskelet Radiol 1998; 2:385-395.[Medline]
- White LM, Schweitzer ME, Weishaupt D, Kramer J, Davis A, Marks PH. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. Radiology 2002; 222:421-429.[Abstract/Free Full Text]
- Brown RR, Fliszar E, Cotten A, Trudell D, Resnick D. Extrinsic and intrinsic ligaments of the wrist: normal and pathologic anatomy at MR arthrography with three-compartment enhancement. RadioGraphics 1998; 18:667-674.[Abstract]
- Zanetti M, Bram J, Hodler J. Triangular fibrocartilage and intercarpal ligaments of the wrist: does MR arthrography improve standard MRI? J Magn Reson Imaging 1997; 7:590-594.[Medline]
- Sheck TJ, Kubitzek C, Kierner R, et al. The scapholunate interosseous ligament in MR arthrography of the wrist: correlation with non-enhanced MRI and wrist arthroscopy. Skeletal Radiol 1997; 26:263-271.[CrossRef][Medline]
- Beaulieu CF, Ladd AL. MR arthrography of the wrist: scanning-room injection of the radiocarpal joint based on clinical landmarks. AJR Am J Roentgenol 1998; 170:606-608.[Free Full Text]
- Pfirrmann CWA, Theumann NH, Chung CB, Botte MJ, Trudell D, Resnick D. What happens to the triangular fibrocartilage complex during pronation and supination of the forearm? analysis of its morphology and diagnostic assessment with MR arthrography. Skeletal Radiol 2001; 30:677-685.
- Zlatkin MB, Chao PC, Osterman AL, Schnall MD, Dalinka MK, Kressel HY. Chronic wrist pain: evaluation with high-resolution MR imaging. Radiology 1989; 173:723-729.[Abstract/Free Full Text]
- Golimbu CN, Firooznia H, Melone CP, Rafii M, Weinreb J, Leber C. Tears of the triangular fibrocartilage of the wrist: MR imaging. Radiology 1989; 173:731-733.[Abstract/Free Full Text]
- Schweitzer ME, Brahme SK, Hodler J, et al. Chronic wrist pain: spin echo and short tau inversion recovery MR imaging and conventional and MR arthrography. Radiology 1992; 182:205-211.[Abstract/Free Full Text]
- Potter HG, Asnis-Ernberg L, Weiland AJ, Hotchkiss RN, Peterson MG, McCormack RR, Jr. The utility of high-resolution magnetic resonance imaging in the evaluation of the triangular fibrocartilage complex of the wrist. J Bone Joint Surg Am 1997; 79:1675-1684.[Abstract/Free Full Text]
- Oneson SR, Timins ME, Scales LM, Erickson SJ, Chamoy L. MR imaging diagnosis of triangular fibrocartilage pathology with arthroscopic correlation. AJR Am J Roentgenol 1997; 168:1513-1518.[Abstract/Free Full Text]
- Haims AH, Schweitzer ME, Morrison WB, et al. Limitations of MR imaging in the diagnosis of peripheral tears of the triangular fibrocartilage of the wrist. AJR Am J Roentgenol 2002; 178:419-422.[Abstract/Free Full Text]
- Boruta PM, Bishop JO, Braly WG, Tullos HS. Acute lateral ankle ligament injuries: a literature review. Foot Ankle Int 1990; 11:107-113.
- Helgason JW, Chandnani C. Magnetic resonance imaging arthrography of the ankle. Top Magn Reson Imaging 1998; 9:286-294.[Medline]
- Peters JW, Trevino SG, Renstrom PA. Chronic lateral ankle instability. Foot Ankle 1991; 12:182-191.[Medline]
- Lee SH, Jacobson J, Trudell D, Resnick D. Ligaments of the ankle: normal anatomy with MR arthrography. J Comput Assist Tomogr 1998; 22:807-813.[CrossRef][Medline]
- Chandnani VP, Harper MT, Ficke JR, et al. Chronic ankle instability: evaluation with MR arthrography, MR imaging, and stress radiography. Radiology 1994; 192:189-194.[Abstract/Free Full Text]
- Rosenberg ZS, Cheung YY, Beltran J, et al. Posterior intermalleolar ligament of the ankle: normal anatomy and MR imaging features. AJR Am J Roentgenol 1995; 165:387-390.[Abstract/Free Full Text]
- Robinson P, White LM, Salonen DC, Daniels TR, Ogilvie-Harris D. Anterolateral ankle impingement: MR arthrographic assessment of the anterolateral recess. Radiology 2001; 221:186-190.[Abstract/Free Full Text]
- Robinson P, White LM, Salonen D, Ogilvie-Harris D. Anteromedial impingement of the ankle: using MR arthrography to assess the anteromedial recess. AJR Am J Roentgenol 2002; 178:601-604.[Abstract/Free Full Text]
- Kramer J, Stiglbauer R, Engel A, Prayer l, Imhof H. MR contrast arthrography (MRA) in osteochondrosis dissecans. J Comput Assist Tomogr 1992; 16:254-260.[Medline]
- Brossmann J, Preidler KW, Daenen B, et al. Imaging of osseous and cartilaginous intraarticular bodies in the knee: comparison of MR imaging and MR arthrography with CT and CT arthrography in cadavers. Radiology 1996; 200:509-517.[Abstract/Free Full Text]
- Carrino JA, Smith DK, Schweitzer ME. MR arthrography of the elbow and wrist. Semin Musculoskelet Radiol 1998; 2:397-414.[Medline]
- Schweitzer ME, Natale P, Winalski CS, Culp R. Indirect wrist MR arthrography: the effects of passive motion versus active exercise. Skeletal Radiol 2000; 29:10-14.[CrossRef][Medline]
- Nazarian LN, Rawool NM, Martin CE, Schweitzer ME. Synovial fluid in the hindfoot and ankle: detection of amount and distribution with US. Radiology 1995; 197:275-278.[Abstract/Free Full Text]
- Winalski CS, Aliabadi P, Wright RJ, Shortkroff S, Sledge CB, Weissman BN. Enhancement of joint fluid with intravenously administered gadopentetate dimeglumine: technique, rationale, and implications. Radiology 1993; 187:179-185.[Abstract/Free Full Text]
- Suh K, Kim YS, Lee SK, Rheum HK, Yim YJ, Kang DS. Glenohumeral MR arthrography with intravenously administered Gd-DTPA: evaluation of clinical utility and effect of exercise time and amount of contrast medium (abstr). Radiology 1996; 201(P):157.
- Vahlensieck M, Peterfy CG, Wischer T, et al. Indirect MR arthrography: optimization and clinical applications. Radiology 1996; 200:249-254.[Abstract/Free Full Text]
- Drape JL, Thelan P, Gay-Depassier P, Silbermann O, Benacerraf O. Intraarticular diffusion of Gd-DTPA after intravenous injection in the knee: MR imaging evaluation. Radiology 1991; 181:227-234.
- Burstein D, Velyvis J, Scott KT, et al. Protocol issues for delayed Gd(DTPA)(2-)-enhanced MRI (dGEMRIC) for clinical evaluation of articular cartilage. Magn Reson Med 2001; 45:36-41.[CrossRef][Medline]
- Wintzell G, Haglund-Akerlind Y, Larsson H, Zyto K, Larsson S. Joint fluid enhancement at MRI of the glenohumeral joint with intravenous injection of gadodiamide in standard and triple dose: a prospective comparative study of stable and unstable shoulders. Skeletal Radiol 1998; 27:87-91.[CrossRef][Medline]
- Peh WC, Cassar-Pullicino VN. Magnetic resonance arthrography: current status. Clin Radiol 1999; 54:575-587.[CrossRef][Medline]
- Yanagawa A, Takano K, Nishioka K, Shimada J, Mizushima Y, Ashida H. Clinical staging and gadolinium-DTPA enhanced imaging of the wrist in rheumatoid arthritis. J Rheumatol 1993; 20:781-784.[Medline]
- Wallny T, Sommer T, Steuer K, et al. Klinische und kernspintomographische diagnostik von labrum-glenoidale-verletzungen. Unfallchirurg 1998; 101:613-618.[CrossRef][Medline]
- Wintzell G, Larsson H, Larsson S. Indirect MR arthrography of anterior shoulder instability in the ABER and the apprehension test positions: a prospective comparative study of two different shoulder positions during MRI using intravenous gadodiamide contrast for enhancement of the joint fluid. Skeletal Radiol 1998; 27:488-494.[CrossRef][Medline]
- Yagci B, Manisals M, Yilmaz E, Ekin A, Ozaksoy D, Kovanlikaya I. Indirect MR arthrography of the shoulder in detection of rotator cuff ruptures. Eur Radiol 2001; 11:258-262.[CrossRef][Medline]
- Herold T, Lenhart M, Held P, et al. Indirekte MR-arthrographie des handgelenks bei TFCC-lasionen. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2001; 173:1006-1011.[Medline]
- Wagner SC, Schweitzer ME, Morrison WB, Fenlin JM, Bartolozzi AR. Shoulder instability: accuracy of MR imaging performed after surgery in depicting recurrent injury—initial findings. Radiology 2002; 222:196-203.[Abstract/Free Full Text]
- Nishii T, Nakanishi K, Sugano N, Naito H, Tamura S, Ochi T. Acetabular labral tears: contrast-enhanced MR imaging under continuous leg traction. Skeletal Radiol 1996; 25:349-356.[CrossRef][Medline]
- Yamato M. Intravenous MR arthrography of the knee. Nippon Igaku Hoshasen Gakkai Zasshi 1996; 55:466-469[Japanese].
- Allman K, Schafer O, Hauer M, et al. Indirect MR arthrography of the unexercised glenohumeral joint in patients with rotator cuff tears. Invest Radiol 1999; 34:435-440.[CrossRef][Medline]
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Top
Abstract
Introduction
