MAGNETIC RESONANCE MORPHOMETRY OF THE ADULT NORMAL LUMBAR INTERVERTEBRAL SPACE

Abstract

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Aim. This study aims to a) quantify and evaluate normal relationships between neighboring spinal units by using MR imaging indices, b) propose an easy to apply and reproduce method of estimating the correct amount of distraction when surgically restoring a collapsed intervertebral disc, based on individualized measurements. Material and Methods. This is a retrospective cross-sectional MR imaging study of 119 adult subjects, aged 18 to 54, asymptomatic for low back pain. Each of the examinees should demonstrate two or more consecutive intervertebral discs classified as Pfirrmann grade I or II in order to be included. We measured and studied the relationships of disc height index, Dabbs index, Farfan index, disc convexity index and mean and posterior disc height per spinal level by using multiple regression analysis. All measurements were tested for intra- and interobserver agreement by two raters. Results and Discussion. DHI, Dabbs, Farfan, and mean disc height had a statistically significant correlation with the spinal level and age. Our results were highly reproducible. Furthermore, we expressed each intervertebral space as a percentage of its adjacent space, introducing the coefficient α factor for every intervertebral space. Conclusions.The results suggest that a normal values’ database to refer to during preoperative planning of correction of a degenerated intervertebral disc, is feasible. Our study offers new anatomical and radiological insight in terms of spinal measurements and their potential correlation with current surgical techniques. A new approach for calculating disc space as an expression of its adjacent disc has been introduced, with various potential applications.