1. A method for generating a map of a region of a patient's body that provides information about the nature of lesion(s) in the region, the region being composed of a two or three dimensional matrix of elemental subregions, said method comprising: performing at least one first scan of the region with an MRI apparatus set to a first b value, B 1 , to obtain a first matrix of pixel or voxel intensity values, int (B 1 ), each intensity value being derived from a respective subregion; performing at least one second scan of the region with the MRI apparatus set to a second b value, B 2 , to obtain a second matrix of pixel or voxel intensity values, int (B 2 ), each intensity value being derived from a respective volume subregion; deriving, for each subregion, a first computed value that is a logarithmic function of (int (B 1 )/int(B 2 )) or a monotonic function of ln (int(B 1 )/int(B 2 ); multiplying each computed value by a value proportional to int (B 1 ) for the same subregion to obtain a second computed value for each subregion; and producing a representation of all the second computed values.