Abstract 5811: Real time Non-Invasive Quantitative Imaging of arterial wall elasticity using Supersonic Shear Imaging
Background. Arterial stiffness is a growing epidemic associated with increased risk of cardiovascular events, dementia, and death. Supersonic Shear Imaging (SSI) is a novel technique based on remote palpation of biological tissues that can image with very high temporal resolution (10,000kHz) and quantify the local viscoelastic properties of tissues.
Objectives. The goal of this study was to validate in vitro and in vivo the feasibility and innocuity of this technique for precisely quantifying the elastic modulus of arterial walls.
Methods. A shear wave was generated on the artery wall using the acoustic radiation force induced by a conventional linear ultrasonic probe (8MHz). Shear wave propagation was imaged in real-time using an ultrafast scanner (10 000 frames/s) and the shear wave velocity and elastic modulus (EM) were than derived. Experiments were performed in 9 arterial phantoms composed of different elastic materials (polyvinylalcool, rubber, agar) and dimensions (wall thickness: 1; 1.5 and 2 mm with artery diameter of 6 mm) in which elastic modulus were measured using gold standard rheological technique (Anton Paar, Physica MCR 501). Finally, an in-vivo study on the left common carotid artery of 10 sheep was conducted to demonstrate the safety of the technique. Histological analysis was performed 24 hours after on the sonicated artery and the controlateral intact carotid artery.
Results. The mean shear wave velocity was 8 m/sec (from 5 to 25 m/sec) corresponding to a mean EM of 210 kPa (from 82 kPa to 2.1 MPa). We found an excellent correlation between the SSI derived EM and the rheological calculated EM across the wide spectrum of phantom artery stiffness (n=9 ; r2=0.93 ; p<0.01). After a protocol of 10 times per second of shear waves propagation during one minutes on sheep left carotid artery no histological differences (collagen disturbance or cell apoptosis) were observed between the sonicated carotid artery and the intact one.
Conclusions. These data suggest that Supersonic Shear imaging is a novel reliable and safe technique for evaluating in real time local arterial elastic modulus and stiffness. Clinical potential for cardiovascular risk factors evaluation and for rare collagen vascular diseases detection should be performed in the near future.