A GENERAL COMPUTING METHOD FOR SPATIAL CARTILAGE THICKNESS FROM COPLANAR MRI

Techniques for assessing cartilage thickness from planar magnetic reso nance (MR) images have traditionally accounted for surface curvature o nly in the image plane. Many joints, such as the knee and hip, have si gnificant curvature normal (transverse) to the image plane which resul ts in overestimation of in-plane cartilage thickness measurements. We developed a generalized computing method for calculating spatial thick ness distribution of joint cartilage from co-planar MR images which ac counts for transverse surface curvature. We applied the technique usin g fat-suppressed SPGR (spoiled gradient recalled in the steady-state) MR images of two human acetabulae and compared the results with a prev iously validated spherical model of the acetabulum which also accounts for transverse curvature of the cartilage surface. The agreement betw een the generalized model and validated spherical model was very good for both acetabular specimens (correlation: r = 0.998, p < 0.001; diff erences: p > 0.63). We conclude that the generalized method is accepta ble for computing spatial cartilage thickness distribution of joints w ith complex geometries, such as the knee. (C) 1998 IPEM. published by Elsevier Science Ltd.