Magnetic resonance imaging-based assessment of cartilage loss in severe osteoarthritis - Accuracy, precision, and diagnostic value

Objective. To examine the in vivo accuracy and precision of magnetic resona nce imaging (MRI)-based assessment of cartilage loss in patients with sever e osteoarthritis (OA) of the knee. Methods. High-resolution MRI images of the tibial cartilage were obtained i n 8 patients prior to total knee arthroplasty, using a water-excitation gra dient-echo MRI sequence (acquisition time 6 minutes 19 seconds, spatial res olution 1.2 X 0.31 X 0.31 mm(3)). The MRI measurements were repeated after joint repositioning. The precision of the cartilage volume and thickness co mputations was determined after 3-dimensional reconstruction. During surger y, the tibial plateaus were resected, and the MRI data were compared with w ater displacement of surgically retrieved cartilage. Results. The standard deviation (coefficient of variation) of repeated tibi al cartilage volume measurements was 56 mm(3) (5.5%) medially and 59 mm(3) (3.8%) laterally. The deviation from surgically removed tissue was -13%, on average, with a high linear correlation between both methods (r = 0.98). I n patients with varus OA, the tissue loss was estimated to be 1,290 mm(3) i n the medial tibia and 1,150 mm(3) in the lateral tibia, compared with the data in healthy volunteers. Conclusion. Noninvasive quantitative MRI-based analysis of cartilage morpho metry in severe OA is accurate, precise, and displays high potential diagno stic value.