Non-invasive high-frequency vascular ultrasound elastography: in vitro and in vivo phantom investigations

Non-invasive vascular elastography (NIVE) was recently introduced to characterize the mechanical properties of superficial arteries. The feasibility of NIVE and its applicability in the context of high-frequency ultrasound imaging, is investigated. The experiments were performed in vitro on a vessel-mimicking phantom. Polyvinyl alcohol cryogel was used to create a double-layer vessel, with the stiffness of the inner layer softer. Radial stress was applied within the lumen of the phantom by applying incremental static pressure steps with a column of a flowing mixture of water-glycerol. The vessel was insonified at 32 MHz with an ultrasound biomicroscope to provide sequences of radio-frequency (RF) ultrasound data. The Lagrangian speckle model estimator (LSME) was used to assess the 2D-strain tensor, and the composite von Mises elastogram was computed. The use of the method for the purpose of studying small vessels in genetically-engineered rodents is supported by preliminary in vivo results.