[1] Stanford Univ, Neuroradiol Sect, Sch Med, Dept Radiol, 300 Pasteur Dr,Grant S047, Stanford, CA 94305 USA
[2] Stanford Univ, Dept Med, Sch Med, Quantitat Sci Unit, Stanford, CA 94305 USA
[3] Stanford Univ, Div Cardiovasc Med, Stanford, CA 94305 USA
[4] Stanford Univ, Sch Med, Dept Radiol, Cardiovasc Imaging Sect, Palo Alto, CA 94304 USA
[5] Univ Calif San Francisco, Dept Radiol, San Francisco, CA USA
[6] Azienda Osped Univ Cagliari, Dipartimento Radiol, Cagliari, Italy
[7] Stanford Univ, Sch Med, Dept Med, Palo Alto, CA 94304 USA