[1] Stanford Univ, Med Ctr, Div Cardiovasc Med, Stanford, CA 94305 USA
[2] Stanford Univ, Dept Cardiothorac Surg, Stanford, CA 94305 USA
[3] Johns Hopkins Univ, Sch Med, Dept Radiol & Radiol Sci, Baltimore, MD USA
[4] Johns Hopkins Univ, Sch Med, Inst Cell Engn, Baltimore, MD USA
[5] Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA
[6] Stanford Univ, Dept Cardiac & Pulm Pathol, Stanford, CA 94305 USA