1. A method for estimating and presenting a representation of one or more haemodynamic perfusion parameters of an elementary volume, referred to as a voxel, of an organ, said method being implemented by a processing unit of a perfusion imaging analysis system, and comprising: obtaining perfusion signals S(t) derived from images of the organ; estimating the haemodynamic parameter or parameters using a joint estimation of the parameters Θ of a global perfusion model comprising: a first relationship between the perfusion signal S(t) and a concentration C(t) of a contrast agent circulating in said voxel over a time t, a second relationship between the concentration C(t) of a contrast agent, the blood flow BF, a parametric or semiparametric model C a (t,Θ a ) of an arterial input function and a parametric or semiparametric model R(t,Θ R ) of a complementary cumulative distribution function of the transit time in the voxel, Θ a and Θ R being respectively the parameters of the models C a (t,Θ a ) and R(t,Θ R ), and a third relationship Ψ(Θa)=0 between the parameters Θa of the model of the arterial input function Ca(tΘ a ); and displaying a graphical representation of the estimated value or values for the parameter or parameters on a human-machine interface for evaluation by a user.