A method for quantifying iron deposits in tissues using diffusion-weighted Magnetic Resonance Imaging with a high accuracy, comprising the steps of: - acquiring a first series of MRI images of a Field Of View of a biological tissue by using a MonoPolar pulse-diffusion Gradient sequence as a MonoPolar pulse-diffusion Gradient Spin-Echo sequence (PGSE), and by varying a programmed gradient attenuation factor b over a first plurality of values, the programmed gradient attenuation factor depending only on the set of the diffusion gradient pulses of the first sequence; - acquiring a second series of MRI images of the same Field of View FOV of the biological tissue by using as a BiPolar pulse-diffusion Gradient sequence a cross-term-free pulse-diffusion gradient spin echo sequence having a similar diffusion time as the MPG sequence, said cross-term-free pulse diffusion gradient spin echo sequence having diffusion-sensitizing gradients and RF pulses arranged so that cross terms between an imaging gradient, a local gradient, a sensitizing gradient are equal to zero at the echo time period, and by varying a programmed gradient attenuation factor b over a second plurality of values, the programmed gradient attenuation factor depending only on the set of the diffusion gradient pulses of the BPG sequence; - providing an attenuation model of the diffusion MRI attenuated signal S/S 0 representative of the observed tissue expressed as a model function f(x) depending on a variable x equal to the product of an apparent model diffusion coefficient ADC and the programmed gradient attenuation factor b used; - on a one-per-one voxel basis or on a predetermined Region Of Interest including a set of voxels, - estimating a first apparent diffusion coefficient ADC MPG by fitting the MRI images acquired by using the MPG sequence and the first plurality of programmed gradient attenuation factors b with the model function f(b.ADC); - estimating a second apparent diffusion coefficient ADC BPG by fitting the MRI images acquired by using the BPG sequence and the second plurality of programmed gradient attenuation factors b with the model function f(b.ADC); characterized in that the method further comprises the step of: - calculating an iron induced local gradient factor ξ Fe from the estimated values of the first apparent diffusion coefficient ADC MPG and the second apparent diffusion coefficient ADC BPG through the relationship: ξ Fe = 1 − ADC MPG ADC BPG; - acquiring a first series of MRI images of a Field Of View of a biological tissue by using a MonoPolar pulse-diffusion Gradient sequence as a MonoPolar pulse-diffusion Gradient Spin-Echo sequence (PGSE), and by varying a programmed gradient attenuation factor b over a first plurality of values, the programmed gradient attenuation factor depending only on the set of the diffusion gradient pulses of the first sequence; - acquiring a second series of MRI images of the same Field of View FOV of the biological tissue by using as a BiPolar pulse-diffusion Gradient sequence a cross-term-free pulse-diffusion gradient spin echo sequence having a similar diffusion time as the MPG sequence, said cross-term-free pulse diffusion gradient spin echo sequence having diffusion-sensitizing gradients and RF pulses arranged so that cross terms between an imaging gradient, a local gradient, a sensitizing gradient are equal to zero at the echo time period, and by varying a programmed gradient attenuation factor b over a second plurality of values, the programmed gradient attenuation factor depending only on the set of the diffusion gradient pulses of the BPG sequence; - providing an attenuation model of the diffusion MRI attenuated signal S/S 0 representative of the observed tissue expressed as a model function f(x) depending on a variable x equal to the product of an apparent model diffusion coefficient ADC and the programmed gradient attenuation factor b used; - on a one-per-one voxel basis or on a predetermined Region Of Interest including a set of voxels, - estimating a first apparent diffusion coefficient ADC MPG by fitting the MRI images acquired by using the MPG sequence and the first plurality of programmed gradient attenuation factors b with the model function f(b.ADC); - estimating a second apparent diffusion coefficient ADC BPG by fitting the MRI images acquired by using the BPG sequence and the second plurality of programmed gradient attenuation factors b with the model function f(b.ADC); - calculating an iron induced local gradient factor ξ Fe from the estimated values of the first apparent diffusion coefficient ADC MPG and the second apparent diffusion coefficient ADC BPG through the relationship: ξ Fe = 1 − ADC MPG ADC BPG;