E2594. Measuring Brain Stiffness of Normal Adult According to Age and Sex Using Virtual MR Elastography
  1. Jung Hyun Park; Seoul Metropolitan Government-Seoul National University Boramae Medical Center
  2. Miran Han; Ajou University Hospital
  3. Jin Wook Choi; Ajou University Hospital
  4. Sun-Won Park; Seoul Metropolitan Government-Seoul National University Boramae Medical Center
To investigate the change of brain stiffness according to aging and gender using the virtual magnetic resonance elastography (vMRE) which is noninvasive and novel technique based on diffusion weighted imaging (DWI).

Materials and Methods:
We retrospectively reviewed heathy 96 adults (31 - 80 years, 51 men, 45 women) who underwent MR imaging for routine medical examination. Shifted apparent diffusion coefficient was calculated from DWI (b = 200 and 1500 sec/mm2) and converted to DWI-based virtual shear modulus. Brain stiffness was measured in thirteen brain lesions; cerebrum, cerebral gray/white matter, basal ganglia, thalamus, frontal lobe, parietal lobe, temporal lobe, occipital lobe, cerebellum, middle cerebellar peduncle, hippocampus, amygdala. The brain volume of each region was also measured. Linear regression and multiple comparison tests were performed for evaluating influence of aging and regional difference.

The brain stiffness showed regional differences, and higher shear modulus value were calculated in deep structures (thalamus, basal ganglia) compared to lobar regions (p < 0.001). In the lobar area, the occipital lobe was hardest and temporal lobe was softest (p < 0.001). Following adjustment for volume, linear regression revealed significant negative correlation between age and stiffness of brain (-0.13%/year, R2=0.40, p < 0.001 in grossly) except area of parietal lobe, amygdala, and middle cerebellar peduncle. The highest decline in elasticity (-0.30% /year, R2=0.61, p < 0.001) was observed in cerebral gray matter. Stiffness of hippocampus decreased significantly after 50s decade. Sex dimorphism was observed only in parietal (p = 0.04) and occipital lobe (p = 0.04). Female brain is stiffer than male brain.

Virtual MR elastography, which is a novel technique based on DWI, can measure the elastic property of brain. As the brain ages, there is softening but the changes vary across the different regions.