Three-dimensional imaging of the spine using the EOS system: is it reliable? A comparative study using computed tomography imaging.

The aim of this study was to evaluate the precision of three-dimensional geometry compared with computed tomography (CT) images. This retrospective study included patients who had undergone both imaging of the spine using the EOS imaging system and CT scanning of the spine. The apical vertebral orientation was also measured using the EOS imaging system and by CT. Other measures such as the Cobb angle and apical vertebral rotation and translation were used as the control variables to evaluate the potential discrepancy between the standing position in EOS imaging and the supine position in CT scanning. The apical vertebral orientations were 8.7° for the first measurement and 8.4° for the second measurement made by the first author, and 10.3° for the measurement made by the second author. The average of these measurements was 9.3° compared with 6.6° (P=0.65) obtained on CT scanning. The precision of EOS-based measurements of vertebral rotation has never been tested in clinical practice. Although it has limitations, this study suggests that the results obtained using EOS are comparable to those obtained on CT.