Deep learning methods to quantitatively assess disease-specific brain atrophy from CT and MRI images are rapidly gaining popularity, and a new era of clinical neuroimaging will soon arrive.
We investigated the effects of aging and gender differences in volumes and volume ratios of regional brain and cerebrospinal fluid (CSF) spaces in healthy volunteers using the Brain Subregion Analysis application working on a SYNAPSE 3D workstation, which is the most popular workstation in Japan. Using this artificial intelligence-based automatic region segmentation application, the 3D T1-weighted brain MRI is automatically segmented into 21 brain subregions and 5 CSF subregions, and the volume and volume ratio of each region is accurately measured within 1 min. In a healthy brain, the cortical gray matter decreases linearly with aging from the 20s, whereas the cerebral white matter increases until the 40s and begins to decrease from the 50s. The subcortical gray matter, such as the hippocampus, maintains its volume throughout its lifespan. With this age-related decrease in brain volume, the intracranial CSF increases. The CSF volume in a healthy person in their 20s is about 265 mL (<20% of intracranial volume), increasing by about 3 mL (around 0.2%) each year to over 450 mL (>30%) at age ≥80 years. The subarachnoid space covering the brain surface increases linearly from the 20s, while the ventricle inside the brain maintains around 20 mL (<2%) until the 60s and increases after the 60s. This post-60s ventricular enlargement may be the key to causing chronic hydrocephalus in the elderly.
- The brain and CSF spaces were automatically segmented using an artificial intelligence-based application.
- The total subarachnoid spaces increased linearly with aging, whereas the total ventricle volume was around 20 mL (< 2%) until the 60s and increased in ages above 60 years.
- The cortical gray matter gradually decreases with aging, whereas the subcortical gray matter maintains its volume, and the cerebral white matter increases slightly until the 40s and begins to decrease from the 50s.
Authors: Shigeki Yamada, Tomohiro Otani, Satoshi Ii, Hiroto Kawano, Kazuhiko Nozaki, Shigeo Wada, Marie Oshima & Yoshiyuki Watanabe