The invention comprises systems, methods, and apparatus to correlate changes in MRI data with CA concentration, using an adaptive neural network In MRI techniques, CAs are used to estimate vascular properties such as blood flow, blood volume, and transfer constant of tissue microvessels However, the relationship between the contrast in the MRI image and the contrast agent concentration is not linear, instead depending on factors such as the nature of the sequence, the nature of the tissue, and the tissue concentration of contrast agent, and thus limiting the reliability of vascular properties using MRI.