Evaluation of articular cartilage: radiographic and cross-sectional imaging techniques.

Many diagnostic modalities may be used to evaluate articular cartilage. Plain radiography remains the preferred initial study for cartilage evaluation, although even specialized views such as weight-bearing, tunnel, and flexion lateral projections are insensitive in the detection of early cartilage loss. Compared with newer modalities, conventional arthrography has limited capacity for the assessment of cartilage. Computed tomography performed after intraarticular injection of contrast material (ie, CT arthrography) has improved accuracy but is essentially limited to the axial plane. Magnetic resonance (MR) imaging, with its superb soft-tissue contrast and multiplanar capabilities, has shown promise in depicting articular cartilage. Cartilage is best depicted when an "arthrogram effect" is present, achieved with T2-weighted spin-echo imaging, with some gradient-echo pulse sequences, and when intraarticular contrast material is used. If performed with such techniques, MR imaging is the method of choice for evaluating specific cartilage loss, osteochondritis dissecans, and other osteochondral abnormalities.