ARTICULAR-CARTILAGE VOLUME IN THE KNEE - SEMIAUTOMATED DETERMINATION FROM 3-DIMENSIONAL REFORMATIONS OF MR-IMAGES

PURPOSE: To determine the accuracy of semiautomated quantification of articular cartilage volume from three-dimensional (3D) reformations of magnetic resonance (MR) images. MATERIALS AND METHODS: Sagittal, fat- suppressed, 3D, spoiled gradient-recalled-echo MR imaging of two bovin e and two human cadaver knees was performed. Articular cartilage volum e was calculated from 3D reformations of the MR images by using a semi -automated program written at the authors' institution. Calculated vol umes were compared with directly measured volumes of the surgically re moved articular cartilage. RESULTS: The percentage of error of the MR imaging-determined volumes was 6.53% +/- 4.75 (mean +/- standard devia tion). A strong correlation between the two sets of observations was s hown (r = .997). Linear regression showed the calculated volumes to be highly accurate (slope = 1.002, P >.25). Repeated reformations yielde d volumes that were reproducible (mean absolute error, 0.013 mt +/- 0. 019) and not significantly different from the measured volume (P >.10) . CONCLUSION: Semiautomated quantification of knee articular cartilage from MR images yields highly accurate cartilage volumes.