Correlation of diffusion tensor imaging with histology in the developing human frontal cerebrum.

Transient early cerebral laminar organization resulting from normal developmental events has been revealed in human beings through histology and imaging studies. DTI studies have postulated that the fractional anisotropy (FA)-based differentiation of different laminar structures reflects both differing cellular density over the glial fibers and fiber alignment in respective regions. The aim of this study was to correlate FA values in these transient zones with histology. Brain DTI was performed on 50 freshly aborted human fetuses with gestational ages (GA) ranging from 12 to 42 weeks. Regions of interest were placed on the cortical plate, subplate, intermediate and germinal matrix (GMx) zones of the frontal lobe to quantify FA values. Glial fibrillary acidic protein (GFAP), neurofilament (NF) and neuron-specific enolase (NSE) immunohistochemical analyses were performed for the cortical plate, intermediate zone and GMx. In the cortical plate, a significant positive correlation was observed between FA values and percentage area of GFAP expression in fetuses <or=28 weeks of GA (r = 0.56, p = 0.01). FA values showed a significant positive correlation with the percentage area of NF expression in the intermediate zone (r = 0.54, p = 0.05). A significant positive correlation was also observed between FA and the number of NSE-positive cells per mm(2) in the GMx (r = 0.76, p < 0.01) and subplate (r = 0.59, p = 0.03) zones. The results of our study suggest that the FA can be used as noninvasive marker of neurodevelopmental events in the frontal lobe of human fetal brain.