[1] Massachusetts Gen Hosp, Athinoula A Martinos Ctr Biomed Imaging, Dept Radiol, Charlestown, MA 02129 USA
[2] Harvard Med Sch, Boston, MA 02115 USA
[3] TH Mittelhessen Univ Appl Sci, Inst Med Phys & Radiat Protect, Dept Life Sci Engn, Giessen, Germany
[4] Phillipps Univ Marburg, Univ Hosp Marburg, Dept Diagnost & Intervent Radiol, Marburg, Germany
[5] Comp Engn Worcester Polytech Inst, Dept Elect, Worcester, MA 01609 USA
[6] Massachusetts Gen Hosp, Harvard Med Sch, Athinoula A Martinos Ctr Biomed Imaging, Dept Radiol, 149 13th St, Charlestown, MA 02129 USA