Magnetic resonance imaging of superficial cartilage lesions: role of contrast in lesion detection.

Excised patellar cartilage phantoms with artificial surface lesions were imaged in a 2 g/dl albumin solution to determine the effect of cartilage/fluid contrast on detection of early degenerative change. Surface lesions consisted of full-thickness holes, superficial grooves, and coarse abrasion. Phantoms were imaged with a T1-weighted fast low-angle shot (FLASH) and T2*-weighted dual-echo in the steady state (DESS) sequence. Although both sequences were able to identify full-thickness holes, they underestimated the presence of superficial grooves and extent of fibrillation. Despite greater bulk tissue contrast between cartilage and fluid for the FLASH sequence, detection of fibrillation was poorer compared with the DESS images. The results of this study suggest that surface properties of fibrillated cartilage contribute significantly to the insensitivity of magnetic resonance imaging in detecting superficial lesions. In contrast to previous papers suggesting that T1-weighted spoiled gradient-echo imaging provides the greatest accuracy for lesion detection, our results indicate that, in the presence of joint fluid, T2*-weighted imaging increases detection of superficial lesions. J. Magn. Reson. Imaging 1999;10:178-182.