ASSESSMENT OF ARTICULAR-CARTILAGE THICKNESS OF THE HUMERAL HEAD - MR-ANATOMIC CORRELATION IN CADAVERS

OBJECTIVE. The purpose of our study was to evaluate several commonly u sed MR sequences to determine how accurately each demonstrates the thi ckness of the articular cartilage of the humeral head. MATERIALS AND M ETHODS. Ten cadaveric shoulders (age at death, 58-92 years; mean, 79 y ears) were imaged with fat-suppressed transaxial T1-weighted spin-echo three-dimensional gradient-recalled sequences, both before and after injection of 12 ml of diluted gadopentetate dimeglumine. Articular car tilage was measured to the nearest 10th of a millimeter on the MR imag es and corresponding anatomic sections. RESULTS. Cartilage could not b e differentiated from surrounding structures in 14 of 112 locations (1 3%) on the spin-echo images obtained without contrast material, in 4 o f 112 locations (4%) on the spin-echo images obtained with contrast ma terial, in 4 of 112 locations (4%) on the gradient-echo images obtaine d without contrast material, and in 6 of 112 locations (5%) on the gra dient-echo images obtained with contrast material. Mean true cartilage thickness was 1.23 mm (SD, 0.52 mm). The mean NIR-anatomic difference s (absolute values) were 0.38 mm for the spin-echo images obtained wit hout contrast material, 0.42 mm for the spin-echo images obtained with contrast material, 0.49 mm for the gradient-echo images obtained with out contrast material, and 0.37 mm for the gradient-echo images obtain ed with contrast material. There was a tendency to overestimate thin c artilage and to underestimate thick cartilage. CONCLUSION. Several of the routinely used MR sequences, with and without intraarticular contr ast medium, may cause errors in the assessment of the articular cartil age of the humeral head, Some of these errors result from either insuf ficient contrast between cartilage and surrounding structures or inade quately concentrated contrast medium.