Quantitative forward-viewing 3D intravascular ultrasound imaging of hemodynamics.

Percutaneous coronary intervention (PCI) is a common minimally-invasive procedure performed in cardiac catheterization labs to treat coronary stenosis by stent deployment. Use of intravascular imaging (e.g. intravascular ultrasound, IVUS) to guide PCI improves clinical outcomes relative to angiography alone. In addition to intravascular imaging, coronary physiological measurements (e.g. wire-based measurements) have demonstrated improved clinical outcomes when used to guide PCI. Forward-viewing, 3D IVUS imaging is proposed to image both anatomy and hemodynamics (blood flow velocity and imaging-derived wall shear stress, WSS). This physiological imaging could guide complex procedures and reduce rates of restenosis by monitoring WSS surrounding the stent during and after stent placement. To enable this imaging, two technologies have been developed: 1) a 3 mm-diameter forward-viewing, catheter-based 2D array, and 2) ultrasound imaging-derived WSS in coronary geometries. Development of this 136 element array and initial imaging results with a 1 m long cable are presented. Methods for WSS estimation based on high frequency, forward-viewing ultrasound are presented, and imaging results in coronary artery phantoms are compared with computational fluid dynamics for the first time. Root mean square error (RMSE) for ultrasound imaging-derived velocities was 4.47%-11.00% compared to CFD.