3-DIMENSIONAL THICKNESS AND VOLUME MEASUR EMENTS OF KNEE-JOINT CARTILAGE WITH MRI - VALIDATION IN ANATOMICAL SPECIMENS VIA CT ARTHROGRAPHY

Purpose: In the present study we intended to validate knee joint carti lage volume and thickness measurements with MRI. Methods: Ten fresh ca daver knees (age 29 to 64 yrs.) were sagitally imaged, using a fat-sup pressed FLASH-3D sequence with a resolution of 2 x 0,31. x 0,37 mm(3). Then, a contrast agent was injected and the specimens submitted to CT arthrography. From both modalities the patellar, femoral, and tibial cartilages were segmented semiautomatically and reconstructed three-di mensionally. The cartilage thickness was determined independently of t he sectional plane, based on a ''minimal distance algorithm''. Results : The volumes and the regional distribution patterns yielded a very hi gh degree of similarity on direct comparison of both imaging modalitie s. The average volume error between MRI and CT was 3.8% (+/-3.0%), the correlation 0.998, the slope of the regression line 1.04 and the y-in tercept -80 mm(3). The analysis yielded no significant differences bet ween the two methods (Wilcoxon signed rank test, 5% level) in the pate lla, femur, medial, and lateral tibia. Conclusion: The results suggest that, based on a fat-suppressed FLASH sequence with high resolution a nd three-dimensional concepts of digital image analysis, the cartilage volume and thickness can be analysed non-invasively and with high acc uracy by MRI.