MR Arthrography of the Knee

The role of magnetic resonance imaging (MRI) in the evaluation of musculoskeletal injuries has been well documented during the last decade. There remain several important clinical situations in which noncontrast MRI has been disappointing. In the knee, magnetic resonance arthrography (MRA) can supplement noncontrast MRI in the evaluation of specific conditions, such as postoperative meniscus and osteochondritis dissecans. MRA significantly increases accuracy in the diagnosis of meniscal retear, as is seen in cases in which there has been a meniscal resection of more than 25% or after meniscal suturing. Also, in the evaluation of osteochondritis dissecans, the addition of intra-articular contrast has proved beneficial. Aside from assessing the integrity of the articular cartilage surface and documenting loose bodies, the contrast allows the clinician to distinguish fibrovascular granulation tissue from fluid partially or completely surrounding the osteochondritic fragment. These topics are discussed in this article.