[1] SUNY Stony Brook, Univ Hosp, Dept Radiol, Stony Brook, NY 11794 USA
[2] Schering AG, Dept Imaging Technol & Preclin Contrast Media Res, D-1000 Berlin, Germany
[3] Brookhaven Natl Lab, Dept Med, Upton, NY 11973 USA
[4] Univ Hawaii, Dept Phys, Honolulu, HI 96822 USA