ARTIFICIALLY PRODUCED CARTILAGE LESIONS IN SMALL JOINTS - DETECTION WITH OPTIMIZED MRI-SEQUENCES

The purpose of this study was to evaluate different magnetic resonance imaging (MRI) pulse sequences in the detection of artificial cartilag e lesions in small joints using an animal model, A total of 32 artific ial cartilage lesions were created in the knee joints of 20 rabbits, T wenty lesions were produced 4 weeks and 12 lesions 1 h before the MRI examination, performed in an extremity coil at 1.0 T. All joints were examined with five imaging sequences: (1) a conventional T1-weighted s pin-echo (SE)-sequence (repetition time [TR] 600 ms, echo time [TE] 15 ms), (2) a T2-weighted turbo-SE-sequence (TR 2000 ms, TE 85 ms), (3) a two-dimensional (2D) gradient echo (GE)-sequence (TR 440 ms, TE 10 m s, flip angle 60 degrees) and (4,5) two three-dimensional (3D) GE-sequ ences (TR 40 ms, TE 7 ms, flip angle 40 degrees, with fat suppression (FS) and TR 30 ms, TE 9 ms, flip angle 40 degrees), Two examinations h ad to be excluded because of insufficient image quality and the remain ing examinations were analyzed by two experienced radiologists, The MR I images were correlated with the pathologic findings and anatomical s tructures were scored according to a 5-level scale, Direct comparison of the pathological and MRI findings showed that 19 of the 30 artifici ally induced cartilage lesions were detected with the FS 3D GE-sequenc e, 13 with the 2D GE-sequence, 11 with the 3D GE-sequence, 3 with the T1-weighted SE-sequence, and 2 with the T1-weighted SE-sequence, The h ighest percentage of artificial cartilage lesions was demonstrated usi ng a fat-suppressed 3D GE-sequence. However, the analysis of cartilage defects in small joints with optimized sequences as well as clinical routine hardware and software had limitations, Therefore a pilot study was performed analyzing newly developed high resolution FS 3D GE imag es obtained from 5 rabbit knees with 10 cartilage lesions at 1.5 T. Tw o sequences were used with 1.0 and 0.5 mm slice thickness, a matrix of 256 x 256 and 512 x 256 and a field of view of 12 x 6 and 8 x 6 cm. I n this small subset detection rates were substantially higher than in the 30 rabbit knees examined before. (C) 1997 Elsevier Science Inc.