A method of acquiring an image biomarker suitable for prognosis of a blood-related disease, such as acute myeloid leukemia, includes the steps of: (a) acquiring physical parameter sets, each including at least two parameters, respectively from time-signal intensity curves, these curves being respectively obtained from magnetic resonance image sets of different subjects; each of the image sets being acquired through MRI scanning using one of first and second configuration parameter sets; (b) analyzing the physical parameter sets thus acquired and (c) establishing 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.