The Changing Brain in Healthy Aging: a multi-MRI machine and multicenter surface-based morphometry study

Clinical practice on magnetic resonance imaging of the brain has been historically based on a comparative analysis using a well-trained eye to see whether different features corresponded to a healthy pattern or not. Several studies have described that healthy aging is associated with loss in tissue volume and expansion of cerebrospinal fluid cavities, making this healthy pattern a dynamical and complex model. For these reasons we propose that structural neurorradiology should be assisted by a quantitative and statistical model that can give meaning to a patient's brain morphometric measurements, giving additional information to the clinician about possible deviations from health. With this aim we obtained normative brain morphometric values by applying an automated voxel and surface-based processing pipeline using the well-known software package FreeSurfer. Employing the publicly available IXI Dataset created by Imperial College London we obtained 135 metrics of the aging process from 538 participant between 20 and 86 years old. In concordance with previous studies we found evidence of change in almost all analyzed features, for both brain's volumes and thicknesses, reproducing findings from several previous brain's morphometric studies. Finally, we explored how different stratified percentiles evolve with age, finding that aging is not a process that can be described by a mean descriptor but on the contrary should be analyzed by considering different percentile layers with its own specific aging dynamic.