[Automated image analysis of lateral roentgen images of the spine using anatomic models]

Analysis of a computer-assisted technique for measuring the lumbar spine on radiographs: correlation of two methods

RATIONALE AND OBJECTIVES

The authors performed this study to compare the effectiveness of two methods used to measure intervertebral space height and sagittal vertebral translation.

MATERIALS AND METHODS

Forty-five series of lateral lumbar spine radiographs were evaluated with two methods: distortion-corrected radiographic analysis (DCRA) and computer-assisted lumbar spine measurement (CALSM). Intervertebral space height and sagittal translation depicted on radiographs obtained before and after the patients underwent spinal fusion were measured with both methods. The values obtained with CALSM were then correlated with those obtained with DCRA.

RESULTS

The values of intervertebral space height and sagittal vertebral translation and of changes in both over time as assessed with CALSM did not show sufficient correlation with the values obtained with DCRA. Correlation coefficients ranged from -0.088 to 0.605 and were statistically highly significant (P < or = .01) for only six of the 48 items measured with both CALSM and DCRA. Moreover, without additional graphic constructs, CALSM provided sufficiently consistent identification of vertebral corner points in only 50% of cases.

CONCLUSION

With regard to the measurement of intervertebral space height and sagittal translation on lateral lumbar spine radiographs, DCRA appears to be more reliable than CALSM.