A method to investigate intervertebral disc morphology from MRI in early idiopathic scoliosis: a preliminary evaluation in a group of 14 patients

The aim of the study was to implement a methodology to quantify in vivo and from magnetic resonance imaging (MRI) the 3D geometrical properties of intervertebral discs (IVDs) in early idiopathic scoliosis with small curves. MRI data were posttreated using a custom-made image processing software to semiautomatically determine the location of disc centres, the location of the nucleus pulposus (NP) and the ratio between the NP volume and the disc volume. MRI was performed in a clinical protocol involving 14 patients having an early idiopathic scoliosis. First, the 3D reconstruction errors were quantified using a reproducibility test (intraoperator and interoperator) in one IVD (L5-S1). The maximal errors in location were 0.79 mm in the frontal plane, 1.84 mm in the sagittal plane and 0.76 mm in the vertical plane. The maximal error in relative volume was 42%. Second, the nucleus migration and relative volume were quantified in discs T5-T6 to L5-S1. No significant relative volume variation was detected. Concerning the disc migration, no significant differences were found in the sagittal and axial planes. In the frontal plane, significant differences were observed at the apex of the scoliotic curvature when the Cobb angle was ≥20°. This innovative study in early scoliosis showed reproducible preliminary results, and its application to improve diagnosis and follow-up will be established in an enlarged patient database.