Nondestructive measurement of anterior cerebral artery stiffness using optical coherence elastography

Cerebrovascular dysfunction is associated with aging and the progression of neurodegenerative diseases. Optical coherence elastography (OCE) is an emerging technique for measuring the stiffness of arteries nondestructively with high spatial resolution. In this study, we employed wave-based OCE to measure the shear modulus of human anterior cerebral arteries (ACA). Surface elastic waves were excited on ACA across a wide frequency range (2 to 100 kHz), at intra-vessel pressures ranging from 20 to 140 mmHg. Lamb wave theory was applied to analyze the propagation speeds of dispersive elastic waves guided along the arterial walls and determine shear modulus. The measured shear modulus increases linearly with pressure, reflecting the hyper-elastic properties of arterial walls. The data were compared with stiffness values derived from conventional biaxial extension-inflation mechanical testing. The shear modulus determined from high frequency OCE measurements are much higher when compared to those from the quasi-static mechanical tests. Nevertheless, both measurements demonstrated a consistent trend of cerebral artery stiffening with aging.