Radiographic measurements of the normal distal radius: reliability of computer-aided CT versus physicians’ radiograph interpretation

We examined the reliability of a computer-aided cone-beam CT analysis of radiographic parameters of 50 normal distal radii and compared it with interobserver agreement of measurements made by three groups of physicians on two-dimensional plain radiographs. The intra-rater reliability of the computer-aided analysis was evaluated on 33 wrists imaged twice by cone-beam CT. The longitudinal axis, anterior tilt, radial inclination and ulnar variance were measured. The reliability of computer-aided analysis was excellent (intraclass correlation coefficient (ICC) 0.94-0.96) while the interobserver agreement of two-dimensional radiograph interpretation was good (ulnar variance, ICC 0.80-0.84) to poor (anterior tilt and radial inclination, ICC 0.20-0.42). We conclude that computer-aided cone-beam CT analysis was a reliable tool for radiographic parameter determination, whereas physicians demonstrated substantial variability especially in interpreting the angular parameters.