The time evolution of the histogram (number of pixels versus signal intensity) is used to calculate delta R2 parameters from dynamic contrast-enhanced magnetic resonance (MR) imaging of the brain. This method partially corrects for partial volume effects and is an improvement over the approach using the signal intensity as a function of time when confounding factors such as changing cortical cerebrospinal fluid volumes are involved. The maximum value for delta R2 is found to correlate with relative cerebral blood flow as assessed by xenon inhalation and can be used to discriminate between vascular dementia and healthy volunteers. With this method, the normal range for delta R2 values is found to be the same for both young (19-40 years old) and elderly (65-85 years old) healthy volunteers.