[1] Heriot Watt Univ, Sch Engn & Phys Sci, Edinburgh, Scotland
[2] Micronit BV, Enschede, Netherlands
[3] Univ Edinburgh, Usher Inst, Ctr Med Informat, Edinburgh, Scotland
[4] Queen Elizabeth Univ Hosp, Renal Transplant Unit, 1345 Govan Rd, Glasgow G51 4TF, Scotland