In a method to measure characteristic structure sizes of the human brain, which structure sizes can be used as biomarkers for a diagnosis of Alzheimer's, using a magnetic resonance device, manual and/or automatic localization of the hippocampus takes place in a preliminary magnetic resonance acquisition, followed by selection of at least one measurement axis that proceeds through the hippocampus. For each selected measurement axis, magnetic resonance data are acquired for a longitudinal, in particular rod-shaped, acquisition region proceeding along the measurement axis. Determination of the spatially resolved structure sizes is implemented from the magnetic resonance data.