FAT-SUPPRESSED 3-DIMENSIONAL SPOILED GRADIENT-ECHO MR-IMAGING OF HYALINE CARTILAGE DEFECTS IN THE KNEE - COMPARISON WITH STANDARD MR-IMAGING AND ARTHROSCOPY

OBJECTIVE. The sensitivity of fat-suppressed three-dimensional spoiled gradient-echo (SPGR) images was compared with that of standard MR ima ges for detecting hyaline cartilage defects of the knee, using arthros copy as the standard of reference. SUBJECTS AND METHODS. We assessed 1 14 consecutive patients for hyaline cartilage defects of the knee with both standard MR imaging sequences and a sagittal fat suppressed thre e-dimensional SPGR sequence. Of these patients, 48 with meniscal or li gament injury, or persistent symptoms, underwent subsequent arthroscop y. The standard MR images and SPGR images of these 48 patients were th en retrospectively analyzed for articular defects in a blinded fashion by two independent observers, Sensitivity, specificity, and intraobse rver and interobserver agreement were determined for the different ima ging techniques. RESULTS. One fourth of the patients who went on to ar throscopy were shown to have isolated hyaline cartilage lesions that w ere clinically confused with meniscal tears and that were missed on th e standard MR images. When looking at all surfaces combined for each r eader, the SPGR imaging sequence had a significantly higher sensitivit y than the standard MR imaging sequences for detecting hyaline cartila ge defects (75-85% versus 29-38%, p <.001 for each comparison). When l ooking at individual surfaces for each reader, significant differences in sensitivity were shown for each surface except the trochlear and l ateral tibial surfaces. We found no difference in specificity (97% ver sus 97%, p >.99). We also found that combined evaluation of standard M R and SPGR images gave no added diagnostic advantage (sensitivity, 86% ; specificity, 97%; p >.42). Except for the lateral tibial surface, th e study achieved excellent reproducibility among readings and between readers. CONCLUSION. Fat-suppressed three-dimensional SPGR imaging is more sensitive than standard MR imaging for the detection of hyaline c artilage defects of the knee.