A diffusion‐weighted template for gestational age‐related apparent diffusion coefficient values in the developing fetal brain

Objective To determine the pattern of apparent diffusion coefficient (ADC) values in the normal fetal brain obtained with diffusion‐weighted images (DWI) on magnetic resonance imaging (MRI) as a template for normal brain development throughout gestation. Methods This was a prospective study of 46 fetuses without suspicion of brain pathology undergoing a total of 66 ultrasound examinations between 17 and 37 weeks of gestation. At T2‐weighted MRI, four left and four right brain regions were delineated on transverse slices of the native DWI using a b‐value of 0 s/mm2 (b0 images). We examined native b‐value images and calculated ADCavg, ADClow and ADChigh in the basal ganglia, cerebellar hemisphere, frontal parenchyma and occipital parenchyma. Linear regression analysis was used to assess the relationship between gestational age and b0 values as well as the calculated ADC values. Results Delineations were successful in all fetuses for all regions except for the cerebellar hemispheres in four fetuses. There was a negative correlation between gestational age and b0 values in all examined anatomical regions (P