METHOD-BASED DIFFERENCES IN THE AUTOMATED-ANALYSIS OF THE 3-DIMENSIONAL MORPHOLOGY OF TRABECULAR BONE

The three-dimensional (3D) morphology of trabecular bone is frequently quantified using computer programs, However, there are no standardize d implementations of morphology programs and many variations are possi ble, Even though programs may use the same basic method, results can b e significantly different because of differences in implementation, Mo rphology data from different laboratories therefore may not be compara ble, The method of directed secants, with parallel plate assumptions, is commonly used to quantify 3D morphology. We examined the effect of several variations in the implementation of this method on measurement s of trabecular plate number (Tb.N), trabecular thickness, and trabecu lar spacing, Three-dimensional micromagnetic resonance images of 10 bo vine trabecular bone specimens were analyzed using several variations of the directed secant method, An analysis of covariance with repeated measures suggested that variations in the algorithm used to count tes t line intersections, variations in the criteria used to classify a te st coordinate as bone or marrow, and variations in the number of test grid rotations had significant effects on Tb.N (p < 0.0001), The large st difference in Tb.N (52%) was due to the method used to count test l ine intersections with the bone-marrow interface, Variations in the cl assification algorithm and variations in the number of test line grid rotations resulted in a 6% difference in Tb.N. The spacing of the test line grids did not affect Tb.N (p = 0.28), and all differences were i ndependent of volume fraction (p = 0.67), These data show that there c an be significant differences in trabecular bone morphology measuremen ts due only to the method used for the measurements, To facilitate com parisons between laboratories, we have made validated computer program s to measure trabecular bone morphology available over the internet.