Validation of linear cerebral atrophy markers in multiple sclerosis

Linear measures of cerebral ventricular enlargement may act as surrogate measures of cerebral atrophy in multiple sclerosis (MS). Linear atrophy markers were measured from routine MRI scans during a population survey of 171 Tasmanian MS patients and 91 healthy controls. Thirty-five Victorian MS clinic patients were recruited as a validation cohort with 14 of these re-assessed 4 years later. In the population survey, we measured three linear brain atrophy markers: inter-caudate distance (ICD), third ventricle width (TVW) and frontal horn width (FHW). TVW (OR 2.0, p=0.001) and ICD (OR 16.1, p<0.001) differentiated between MS cases and controls. In the validation study, we correlated the intercaudate ratio (ICR=ICD/brain width) and third ventricular ratio (TVR=TVW/brain width) with brain parenchymal volume. Cross-sectionally, ICR (R=-0.453, p<0.01) and TVR (R=-0.653, p<0.01) were correlated with brain parenchymal volume. Longitudinally, brain parenchymal volume loss was inversely correlated with increased ICD (R=-0.77, p<0.01) and TVW (R=-0.71, p<0.01). This study shows that ICD measurements obtained from clinical MRI scans are valid brain atrophy measures for use in monitoring MS progression.