Effects of software on myocardial T1 measurements: a 3 T multicentre single vendor phantom study by Atkinson, D, Popescu, I, Thomas, KE, Yun, C-H, Werys, K, Burrage, MK, Greenwood, JP, Raman, B, Gonzales, RA, Kim, YJ, Sanchez Panchuelo, RM, Davies, NP, Chow, K, Neubauer, S, Piechnik, SK, Ferreira, VM