Morphometrics of the Entire Human Spinal Cord and Spinal Canal Measured from in vivo High-Resolution Anatomical Magnetic Resonance Imaging.
Spine (Phila Pa 1976). 2013 Nov 18;
Authors: Fradet L, Arnoux PJ, Ranjeva JP, Petit Y, Callot V
Study Design. Measurements of cervical and thoraco-lumbar human spinal cord (SC) geometry based on in vivo MRI and investigation of morphological “invariants”.Objective. The current work aims at providing morphological features of the complete in vivo human normal spinal cord and at investigating possible “invariant” parameters that may serve as normative data for individualized study of SC injuries.Summary of Background Data. Few in vivo MR-based studies have described human SC morphology at the cervical level, and similar description of the entire SC only relies on post-mortem studies, which may be prone to atrophy biases. Moreover, large inter-individual variations currently limit the use of morphological metrics as reference for clinical applications or as modeling inputs.Methods. Absolute metrics of SC (transverse and antero-posterior diameters, anterior and posterior horns width, cross-sectional SC area and white matter percentage) were measured using semi-automatic segmentation of high resolution in vivo T2*-weighted transverse images acquired at 3T, at each SC level, on healthy young (N = 15) and older (N = 8) volunteers. Robustness of measurements, effects of subject, age, or sex, as well as comparison to previously published post mortem data were investigated using statistical analyses (Separate analysis of variance, Tukey-HSD, Bland-Altman). Normalized-to-C3 parameters were evaluated as invariants using a leave-one-out analysis. Spinal canal parameters were measured and occupation ratio (OR) border values were determined.Results. Metrics of SC morphology showed large intra- and inter-individual variations, up to 30% and 13% respectively in average. Sex had no influence except on posterior horns width (p<0.01). Age-related differences were observed for anteroposterior diameter and white matter percentage (p<0.05) and all postmortem metrics were significantly lower than in vivo values (p<0.001). In vivo normalized SC area and diameters appeared to be invariants (R>0.74, RMSE<10%) Finally, minimal and maximal OR were 0.2 and 0.6, respectively.Conclusion. This study presented morphological characteristics of the complete in vivo human spinal cord. Significant differences linked to age and postmortem state have been identified. Morphological “invariants” that could be used to accurately calculate the normally expected morphology, were also identified. These observations should benefit to biomechanical and spinal cord pathology studies.
PMID: 24253776 [PubMed – as supplied by publisher]