Quantification of hepatic iron by MRI is validated at 1.5 Tesla on a small number of subjects with some discrepancies between the two most used techniques (liver to muscle ratio or calculation of the decay rate of the T2 * signal). Since the initial publications at 1.5 Tesla, new technical innovations have emerged which can allow better quantification. Recently, the investigators have applied these innovations to Rennes and have validated (SURFER study) the possibility of making a quantification of iron and fat on two 3 Tesla devices with good results in a single apnea acquisition. But it is not uncommon to have, in a structure, different magnetic field devices, and it is important to ensure that the results are transposable. It is also crucial for multicentre or cohort studies to ensure consistency. It is therefore proposed to compare the results of two examinations at 1.5 and 3 Tesla obtained on the same day on a series of 80 patients.