Fig. 10.
Novel contrasts in apparent neurite and soma density of human brain. Qualitative comparison of MR soma signal fraction fis and MR cell fibers signal fraction fin maps with histological images (from different subjects) stained for brain cytoarchitectonic (Nissl staining for cell nuclei, left side) and myeloarchitectonic (myelin staining, right side), respectively. Brain histological images from the human brain atlas at https://msu.edu/∼brains/brains/human. The contrast in the MRI maps show remarkable similarity to the contrast from histological staining. Quantitative map of fis is expected to provide contrast related to soma density, while map of fin is expected to provide contrast related to neurite density. Since myelinated neurites (like axons) are the major constituent of white matter, fin is expected to provide contrast highly related to myelin in the white matter regions.