In Vivo Validation of Echo Partical Image Velocimetry (Echo PIV) in Human Carotid Arteries Using Phase-Contrast MRI

Accurate non-invasive measurements of dynamic wall shear stresses (WSS) in the cardiovascular system should allow clinicians to evaluate the progression of atherosclerosis, estimate vulnerability of plaques, and assess hemodynamic changes in the proximity of implants such as vascular grafts and stents that may contribute to restenosis. Although computational methods have been used to obtain blood flow characteristics from patients, these methods are difficult to apply in routine fashion, are prone to errors due to incorrect application of boundary conditions and are time and resource intensive. Ultrasound Doppler methods [1] allow simple measurement of blood flow velocities but are not acceptable for shear measurements because they do not provide multiple-component velocity vectors, are prone to angulation error and have relatively poor spatial resolution. Phase contrast magnetic resonance imaging (PC-MRI) velocimetry [2] does provide good spatial resolution and multiple-component velocity vectors in vivo and is considered the gold-standard. However, PC-MRI is expensive, time consuming and possesses relatively poor temporal resolution.