[1] Massachusetts Gen Hosp, Dept Med, Boston, MA 02114 USA
[2] Massachusetts Gen Hosp, Dept Radiol, Boston, MA USA
[3] Harvard Med Sch, Dept Med, Boston, MA 02115 USA
[4] Harvard Med Sch, Dept Radiol, Boston, MA USA
[5] NIDDK, Bethesda, MD USA
[6] NIH, Bethesda, MD USA
[7] Univ Cambridge, Dept Clin Biochem, Cambridge, England