1. A method of acquiring an image biomarker suitable for prognosis of a blood related disease, comprising the steps of: a) using an analyzing unit to acquire physical parameter sets, each including at least two physical parameters comprising a peak enhancement ratio, an initial maximum enhancement slope, a permeability parameter, and a vascularity parameter amplitude, respectively from at least two sets of time-signal intensity curve, each set of the time-signal intensity curve being respectively obtained from magnetic resonance image sets of different subjects that are diagnosed as having the blood-related disease, each of the magnetic resonance image sets being acquired by using one of first and second contrast agents, and by using one of first and second magnetic resonance imaging (MRI) scanners which is configured respectively by using one of first and second configuration parameter sets, wherein the first contrast agent(s) to be used is different from the second contrast agent(s) to be used, the first scanner to be used is different from the second scanner to be used, and the first configuration parameter set to be used is different from the second configuration parameter set to be used; b) using a parameter significance-evaluating unit to analyze the physical parameter sets thus acquired with reference to prognoses of the different subjects so as to evaluate significance of each of the physical parameters and obtain weight values corresponding to the physical parameters; and c) configuring a computing unit to establish a risk score function that is a sum of products of each of the physical parameters and the corresponding weight value, wherein a risk score obtained using the risk score function serves as the image biomarker suitable for prognosis of the blood-related disease, wherein the risk score function is: 
 risk score=(4.4×vascularity parameter amplitude)+(40.7×permeability parameter)+(1.7×peak enhancement ratio).