[1] PHILIPS MED SYST, SHELTON, CT USA
[2] UNIV PALERMO, I-90134 PALERMO, ITALY
[3] UNIV CALIF SAN FRANCISCO, DEPT MED, SAN FRANCISCO, CA 94143 USA
[4] UNIV CALIF SAN FRANCISCO, DEPT RADIOL, SAN FRANCISCO, CA 94143 USA
[5] UNIV CALIF SAN FRANCISCO, DEPT PHARMACEUT CHEM, SAN FRANCISCO, CA 94143 USA