Asynchronous, semi-reverberant elastography

Abstract

Optical coherence elastography measures elasticity—a property correlated with pathologies such as tumors due to fibrosis, atherosclerosis due to heterogeneous plaque composition, and ocular diseases such as keratoconus and glaucoma. Wave-based elastography, including reverberant elastography, leverages the properties of shear waves traveling through tissue primarily to infer shear modulus. These methods have already seen significant development over the past decade. However, existing implementations in OCT require robust synchronization of shear wave excitation with imaging, complicating widespread clinical adoption. We present a method for complete recovery of the harmonic shear wave field in an asynchronous, conventional frame-rate, raster-scanning OCT system by modeling raster-scanning as an amplitude modulation of the displacement field. This technique recovers the entire spatially and temporally coherent complex-valued shear wave field from just two B-scans, while reducing the time scale for sensitivity to motion from minutes to tens of milliseconds. To the best of our knowledge, this work represents the first successful demonstration of reverberant elastography on a human subject in vivo with a conventional frame-rate, raster-scanning OCT system, greatly expanding opportunity for widespread translation.