Usefulness of two-dimensional measurements for the evaluation of brain volume and disability in multiple sclerosis

Background Two-dimensional (2D) measures have been proposed as potential proxies for whole-brain volume in multiple sclerosis (MS). Objective To verify whether 2D measurements by routine MRI are useful in predicting brain volume or disability in MS. Methods In this cross-sectional analysis, eighty-five consecutive Japanese MS patients-relapsing-remitting MS (81%) and progressive MS (19%)-underwent 1.5 Tesla T1-weighted 3D MRI examinations to measure whole-brain and grey matter volume. 2D measurements, namely, third ventricle width, lateral ventricle width (LVW), brain width, bicaudate ratio, and corpus callosum index (CCI), were obtained from each scan. Correlations between 2D measurements and 3D measurements, the Expanded Disability Status Scale (EDSS), or processing speed were analysed. Results The third and lateral ventricle widths were well-correlated with the whole-brain volume (p < 0.0001), grey matter volume (p < 0.0001), and EDSS scores (p = 0.0001, p = .0004, respectively).The least squares regression model revealed that 78% of the variation in whole-brain volume could be explained using five explanatory variables, namely, LVW, CCI, age, sex, and disease duration. By contrast, the partial correlation coefficient excluding the effect of age showed that the CCI was significantly correlated with the EDSS and processing speed (p < 0.0001). Conclusion Ventricle width correlated well with brain volumes, while the CCI correlated well with age-independent (i.e. disease-induced) disability.