1. From the Section of Cardiovascular Imaging, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, OH 44195 (T.K.M.W., B.P.G., L.L.R., R.A.G., B.X.); and Cardiovascular Imaging Laboratory, Imaging Institute, Cleveland Clinic, Cleveland, Ohio (T.K.M.W., S.D.G., P.S., L.L.R., R.A.G., B.X.).