Magnetic resonance-based vertebral morphometry of the thoracic spine: age, gender and level-specific influences

Objective. The aim of this study was to examine age, gender, and segmental trends in thoracic vertebral body shape, utilising thoracic spine magnetic resonance images involving an age range spanning the life span. Design. A quantitative, cross-sectional, retrospective study design involving a sample of convenience. Background. Thoracic vertebral shape data are commonly derived from radiographic resources. The non-ionising properties of magnetic resonance imaging and availability of digital data for image analysis suggest potential for MR-based morphometric studies. For the thoracic spine, there is limited vertebral shape data on males, while few studies have examined the pattern of age-related changes across the life span. Methods. Morphometry was performed on 220 mid sagittal T1-weighted MR images using image analysis software. Three indices of vertebral shape were utilised: the antero-posterior height ratio or anterior wedge index, mid-posterior height ratio or biconcavity index, and ratio of posterior vertebral height to mid antero-posterior diameter or compression index. Results. Different segmental patterns were noted for the vertebral shape indices. Significantly lower mean values were noted in males for the compression index. Age trends were significant, with a linear age-related decline demonstrated for the anterior wedge and biconcavity indices, and a quadratic trend noted for the compression index. Conclusions. Thoracic vertebral body shape may be uniquely described using specific shape indices, for examining various segmental, gender and age-associated changes.