MRI of the Meniscus

The menisci of the knee are accurately evaluated by MRI. Knowledge of normal anatomy, imaging parameters, imaging appearance of the normal and torn meniscus, and common anatomic variants and pitfalls are essential in obtaining the correct imaging diagnosis. There are multiple imaging signs of meniscal tear, including linear signal intensity extending to an articular surface on at least 2 images, altered meniscal shape, displaced meniscal flap, ghost meniscus, meniscal extrusion, and parameniscal cyst. After surgery, granulation tissue may mimic tear. Diagnosis is improved by comparison to preoperative images, operative note, and intra-articular contrast administration.