Time course of LPC-induced edema as assessed by ADC measurements. (A) Quantification of ADC values (median, Q1-Q3) revealed a biphasic evolution (ANOVA) with a first phase characterized by a rapid increase in water content (§, p = 0.006, Wilcoxon test) peaking at 3 dpi, corresponding to the active phase of inflammation. The second phase was characterized by water resolution (*, p = 0.015, ANOVA), with ADC values that returned to baseline during the formation of a glial scar. ADC values of sham rats were stable over time and were not different from those measured in the contralateral side of LPC rats. The dotted line is the median value over the 5 time points for the sham group.(B) Representative illustration of the time course with T2WI (left panel) and merged T2/ADC maps (right panel) of the same animal taken at three different time points (3, 7 and 14 dpi) with corresponding histology at 14 dpi (Luxol Fast Blue coloration). A large area of edema with high ADC values was seen at 3 dpi along the right internal capsule (arrow) and spread through the extramedullary lamina and medial lemniscus tracts toward the midline (arrowheads). The majority of the edema was resolved by 7 and 14 dpi, with a slight cavitation at the site of injection (*) with cerebrospinal-fluid-like ADC values. Histological evaluation of the lesion at 14dpi confirmed the small cavitation (*) and showed large demyelination of the white matter tracts in which edema was initially observed. The myelin fibers of the internal capsule, stained in blue, were outlined (dotted lines) and a loss of myelin was seen in the internal capsule and also in the other white matter tracts (arrowheads).