Indirect magnetic resonance arthrography: applications in sports imaging.

Indirect magnetic resonance (MR) arthrography is an imaging tool with several advantages over both direct MR arthrography and unenhanced musculoskeletal magnetic resonance imaging. It is based upon the idea that paramagnetic contrast agents injected intravenously into the plasma compartment ultimately will perfuse the articular space. Advantages of indirect MR arthrography include enhancement of both intra-articular and extra-articular pathology without the need for an invasive, fluoroscopically guided arthrogram, as well as high sensitivity for reinjury in postoperative patients. Some potential disadvantages of this technique are enhancement of normal vascular tissues and difficulty in making a diagnosis dependent upon joint space distension in the absence of an effusion. Important technical issues when performing indirect arthrography include choosing an appropriate delay between contrast injection and imaging, as well as the potential use of patient exercise to improve image quality. In sports medicine, indirect MR arthrography is most useful in and about small joints such as the wrist and ankle; in articulations with potential internal derangements, as well as bony or osteochondral injuries; and in injured joints that have been altered surgically.