Determination of axial vertebral rotation in MR images: comparison of four manual and a computerized method.

Axial vertebral rotation (AVR) of 14 normal and 14 scoliotic vertebrae from magnetic resonance (MR) images was determined by three observers using four manual methods and a computerized method, which were based on the evaluation of vertebral symmetry in two dimensions (2D) and in three dimensions (3D). The method of Aaro and Dahlborn proved to be the manual method with the highest intra-observer (1.7 degrees SD) and inter-observer (1.2 degrees SD) reliabilities, and was also most in agreement with the computerized method (1.3 degrees SD, 1.0 degrees MAD). The computerized method yielded higher intra-observer (1.3 degrees SD) and inter-observer (1.4 degrees SD) reliabilities than the manual methods, indicating it to be an efficient alternative for repeatable and reliable AVR measurements.