Provided is technology to calculate oxygen extraction fraction distribution in a brain containing cerebral parenchyma using simple processing without applying a load such as caffeine administration to a patient when calculating the oxygen extraction fraction distribution using MRI. This MRI device for this purpose measures a complex image of a nuclear magnetic resonance signal and, from the measured complex image, calculates a physical property value distribution for calculating a physical property value image that reflects the oxygen extraction fraction. The calculated physical property value distribution is separated into at least two types of physical property value distributions (tissue separation images) for each tissue. After converting any of the tissue separation images into an oxygen extraction fraction, the oxygen extraction fraction distribution is estimated on the basis of the condition that the pixel value of an arbitrary pixel and the average value of pixels surrounding the pixel are substantially equal.
MAGNETIC RESONANCE IMAGING DEVICE AND METHOD FOR CALCULATING OXYGEN EXTRACTION FRACTIONS