Instructions and Background
Measurement of hippocampal volume has proven useful across a range of research studies to track progression in several brain disorders, most notably in Alzheimer’s disease (AD).
For example, an objective evaluation of a patient’s hippocampal volume status may provide important information that can assist diagnosis or risk stratification of AD. However, as
a reduction of hippocampal volume is also observed in healthy ageing, clinicians and researchers require access to age-related normative percentiles to reliably categorise a patient’s
hippocampal volume as being pathologically small.
Here we analysed effects of age, sex, and hemisphere on the hippocampus in over 19,700 generally healthy participants in the UK Biobank (find our publication here).
The UK Biobank cohort includes over 500,000 participants aged 40-80 years, of which a subset of 100,000 participants will receive brain imaging. Both the acquisition and analysis of MRI are standardised across the scanning sites according to publicly available protocols designed by the UK Biobank Imaging Working Group (www.ukbiobank.ac.uk/expert-working-groups). Based on these normative values for hippocampal and total grey matter volume over age, this automated percentile estimation tool calculates an individual’s hippocampal volume status, for reference in clinical and research settings.
Most precise percentile estimations will be obtained by using the same preprocessing pipeline on the original MR image as has been used in the preparation of the normative MR images from UK Biobank.
- Required values to calculate someone's brain volume percentile:
- Age in years (52-71 years for females, 53-72 years for males)
- Hemisphere (whether the volume estimate is taken from the left or right hemisphere)
- Head size correction (whether or not correction using head scaling from preprocessing pipeline should be applied). If head size correction should be applied, the value for head scaling derived from pipeline has to be entered
- Brain volume in mm3 (currently only hippocampal volume)