What is an MRI (Magnetic Resonance Imaging) arthrogram?

MR Arthrogram: Definition and Applications

An MR arthrogram is a specialized imaging technique that combines magnetic resonance imaging with the injection of contrast material directly into a joint to enhance visualization of internal joint structures. 1

What is an MR Arthrogram?

• MR arthrography involves the injection of contrast material (typically diluted gadolinium) directly into a joint space, followed by MRI scanning to provide detailed images of intra-articular structures 1
• The procedure consists of two parts: an interventional component (joint injection) and a diagnostic imaging component (MRI scan) 2
• The contrast material distends the joint capsule and outlines internal structures, making abnormalities more visible than with conventional MRI 3

Types of MR Arthrography

• Direct MR arthrography: Involves direct injection of contrast material (diluted gadolinium) into the joint space under fluoroscopic or ultrasound guidance 1, 3
• Indirect MR arthrography: Involves intravenous injection of contrast that eventually diffuses into the joint space; particularly useful for joints with less capacity for distension like the wrist 4

Clinical Applications

Wrist Joint Applications

• Superior for detecting triangular fibrocartilage complex (TFCC) tears with sensitivity ranging from 63% to 100% and specificity from 89% to 97% 1
• More accurate than conventional MRI for diagnosing scapholunate and lunotriquetral ligament tears 1
• Recommended for suspected intrinsic ligament injury, cartilage abnormality, or surgical planning 1
• Particularly valuable when conventional MRI results are equivocal or insufficient 5

Other Joint Applications

• Shoulder: Highly effective for evaluating labrocapsular-ligamentous abnormalities and distinguishing partial from full-thickness rotator cuff tears 3
• Hip: Provides detailed assessment of the acetabular labrum, which can be a source of pain in patients with otherwise normal joints 6
• Ankle: Useful for evaluating ligamentous injuries, impingement syndromes, cartilage lesions, and loose bodies 7

Technical Considerations

• Direct MR arthrography typically uses diluted gadolinium as the contrast agent 3
• For wrist MR arthrography, injection of any combination of the three compartments (distal radioulnar joint, radiocarpal, midcarpal) can be performed depending on the clinical question 1
• Wrist traction during imaging improves detection of cartilage, TFCC, and intrinsic ligament injuries 1
• A 3.0T MRI with dedicated coil provides better signal-to-noise ratio and better contrast compared to 1.5T systems 1

Advantages Over Conventional MRI

• Provides better diagnostic accuracy for determining scapholunate interosseous ligament tears 1
• Enhances visualization of internal joint derangements, especially abnormalities of ligaments, articular cartilage, and TFCC 1
• Helps distinguish between partial and complete tears of ligamentous structures 1
• Allows better delineation of articular structures by separating adjacent anatomic structures 4

When to Consider MR Arthrography

• When conventional MRI is insufficient for diagnosis or treatment planning 7
• For persistent pain despite conservative management 5
• When there is clinical suspicion of internal joint derangement not visible on standard imaging 1
• For preoperative planning, especially for ligamentous and early cartilage defects 1

Comparison to Other Techniques

• CT arthrography may be more sensitive for tears of the dorsal ligament fibers compared to conventional MRI 5
• Both MR arthrography and CT arthrography are recommended for diagnostic workup of ligamentous and early cartilage defects 1
• MR arthrography has largely supplanted conventional arthrography due to its superior ability to show partial-thickness tears and extra-articular abnormalities 1