ADC measurements at low and high b values: insight into normal brain structure with clinical DWI

Abstract Purpose To demonstrate drop in brain ADC measurements from low to high b values; to evaluate the structural information provided based on those changes; and to discuss the anatomical reasons for ADC differences. Methods Four cerebral ROI (precuneus-PRC, hippocampus-HIP, and the genu-GCC and splenium-SCC of the corpus callosum-CC) were drawn for ADC measurements with low (1000) and high (3000) b -value DWI in 50 normal subjects. ANOVA and Bonferroni correction tested ADC differences between areas, between both hemispheres, between GCC and SCC, and between b -value related ADC drop within areas. Pearson test evaluated dependence of interhemispheric and intercallosum ADC measurements obtained with the same b -value, dependence between areas of intrazonal drop, and the interhemispheric and intercallosum dependence of intrazonal drop. Results ADCs differed between areas ( P b -value ( P b -value. ADC drop within PRC and HIP was similar but differed ( P P P P P =.007; HIP P Conclusion Low and high b -value measurements show different diffusion behaviours within different tissues, especially in a highly anisotropic structure as the corpus callosum. This fact can provide valuable information about brain structure and different diffusion compartments in clinical DWI.