[1] Addenbrookes Hosp, Dept Radiol, Cambridge CB2 0QQ, England
[2] Inst Canc Res, Surrey, England
[3] Royal Marsden Hosp, Surrey, England
[4] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Boston, MA USA
[5] Univ Toronto, Abdominal Div, Toronto, ON M5S 1A1, Canada
[6] Mem Sloan Kettering Canc Ctr, Dept Radiol, New York, NY 10021 USA