Evaluation of lumbar disc and spine morphology: long-term repeatability and comparison of methods.
Establishing the long-term repeatability of quantitative measures of lumbar intervertebral disc and spinal morphology is important for planning interventional studies. We aimed to examine this issue and to determine to what extent a smaller number of measurements per disc or vertebral level could be used to save operator time without compromising measurement precision. Twenty-one healthy male subjects were scanned at baseline and 1.5 years later. On sagittal MR-scans intervertebral disc cross-sectional area, anterior disc height, posterior disc height, intervertebral angle and intervertebral length were measured. The repeatability of the average value from all sagittal images or from 1, 3, 5 or 7 images centred at the spinous process was evaluated. Bland-Altman analysis showed all measurements to be repeatable between testing days. Intervertebral length was the most precise measurement (coefficients of variation [CVs] between 1.2% and 1.5%), followed by disc cross-sectional area (CVs between 2.9% and 3.6%). Variance component analysis showed that using 7 images, but not 1, 3 or 5 images, resulted in a similar level of measurement error as when measurements from all images were included.
Center for Muscle and Bone Research, Charité Universitätsmedizin Berlin, Hindenburgdamm 30, 12200 Berlin, Germany. belavy@gmail.com
D L
DL
Belavý
G
G
Armbrecht
D
D
Felsenberg
D000328:Adult; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology*; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D018401:Sample Size; D013997:Time Factors