[MR-arthrography: general principles and applications]

The recent approval by the French Ministry of Health of the use of intra-articular Gadolinium could promote the increasing use of MR-arthrography in France. Although useful in specific pathologies, it should not be overly prescribed and should be considered only if it provides a more accurate diagnosis than other less invasive techniques. The technical aspects and medico-legal implications of MR-arthrography as well as its various indications are reviewed in this article. There are three possible techniques: indirect MR-arthrography with IV Gadolinium injection, direct MR-arthrography with intra-articular Gadolinium injection and lastly, direct MR-arthrography with intra-articular injection of iodinated contrast media (or saline solution). Indirect MR-arthrography cannot be recommended because of insufficient contrast enhancement and the absence of joint filling. Conversely, direct MR-arthrography allows joint expansion which smooths out capsule and ligaments, better delineates articular surfaces and yields a homogeneous high intensity signal of the entire joint. Direct MR-arthrography with iodinated contrast media combines standard arthrography with conventional MRI. Direct MR-arthrography with intra-articular injection of dilute Gadolinium is associated with T1WI, usually of higher quality than T2WI, even though the latter remains part of the protocol. Although, the last two techniques yield higher image quality and are often performed for various articular pathologies, they should not be randomly carried out in the evaluation of joint pathology. However, they should be recommended as the first step in the diagnosis of painful shoulders or hips in young adults and athletes.